CN116141681A - Structure-mechanical composite parameter monitoring method and device for 3D printing process - Google Patents

Structure-mechanical composite parameter monitoring method and device for 3D printing process Download PDF

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CN116141681A
CN116141681A CN202310029191.3A CN202310029191A CN116141681A CN 116141681 A CN116141681 A CN 116141681A CN 202310029191 A CN202310029191 A CN 202310029191A CN 116141681 A CN116141681 A CN 116141681A
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王玲
徐铭恩
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Regenovo Biotechnology Co ltd
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Abstract

The invention provides a structure-mechanics composite parameter monitoring method and equipment for a 3D printing process, which are applied to a three-dimensional imaging detector, wherein the three-dimensional imaging detector is connected with a 3D printing platform, and the three-dimensional imaging detector is used for acquiring process parameters of the 3D printing platform in the printing process; inputting the process parameters into a pre-established calculation model, and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model; the mechanical property parameters include a first mechanical parameter and a second mechanical parameter. According to the invention, two mechanical characteristic parameters of the printing material structure body can be calculated and obtained in the 3D printing process, the mechanical characteristics of the whole process of the printing material structure body are calculated and obtained, the 3D printing material can be measured and modulated even in a complex structural environment, decoding and regulation of the printing structure and viscoelasticity synergistically influencing the tissue morphogenesis mechanism are realized, and a technical support is provided for monitoring the mechanical environment of the printing structure in the 3D printing field.

Description

Structure-mechanical composite parameter monitoring method and device for 3D printing process
Technical Field
The invention relates to the technical field of 3D printing structures, in particular to a structure-mechanical composite parameter monitoring method and device in a 3D printing process.
Background
The biological 3D printing can construct a tissue organ bionic structure based on a digital model, and provides technical support for reconstructing tissue organs by regulating and controlling geometric information (Nat Mater.2021). The generation and establishment of tissue organs are space-time procedural processes (Nature reviews, 2021) cooperatively regulated by geometric, mechanical and biochemical signals, and the mechanical environment is a key factor regulating stem cell fate and morphogenesis.
Among these, viscoelastic is a common feature of living tissue and extracellular matrix (ECM), which manifests as a time-dependent response to loading or phase change, affecting cell proliferation, growth, proliferation and fate. During printing, the viscoelasticity of the high water content biomaterial/bioink is affected by factors such as the temperature of the spray head, the temperature of the platform, and the like, and time-dependent deformation, including creep (creep) and stress relaxation (stress relaxation), occurs in the structure under the action of gravity (gravity), pressure (tension), tension (tension), and the like. However, existing mechanical detection methods include: the rheological instrument can detect the viscoelasticity of a fixed macroscopic morphology material, and the atomic force microscope can detect the viscoelasticity of single molecules and single cells, however, a good method for detecting the viscoelasticity of the material under the structure of 10 micrometers-1000 micrometers is lacked, and the scale is the key of tissue morphogenesis. Due to the lack of measuring and modulating tools for complex mechanical environment in the 3D printing structure, decoding and regulating of the mechanism of tissue morphology generation is hindered by the synergistic influence of the printing structure and viscoelasticity, and the biological 3D printing has a technical bottleneck that the mechanical environment of the printing structure cannot be monitored.
Disclosure of Invention
In view of the above, the present invention aims to provide a method and a device for monitoring a structure-mechanical composite parameter in a 3D printing process, which can monitor a mechanical characteristic parameter of a 3D printing material structure at a high speed or in real time.
In a first aspect, an embodiment of the present invention provides a method for monitoring a structure-mechanical composite parameter in a 3D printing process, where the method is applied to a three-dimensional imaging detector, and the three-dimensional imaging detector is connected to a 3D printing platform, and the method includes: acquiring process parameters of the 3D printing platform in the printing process by using a three-dimensional imaging detector; the process parameters correspond to the printing structure; inputting the process parameters into a pre-established calculation model, and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model; wherein the mechanical property parameter comprises a first mechanical parameter and a second mechanical parameter; the process parameter corresponds to the first mechanical parameter or the second mechanical parameter; the first mechanical parameter is used for representing the corresponding deformation characteristic of the material structure of the printed structure, and the second mechanical parameter is used for representing the mechanical characteristic of the material structure of the printed structure related to vibration caused by external excitation.
With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, wherein, when the process parameter corresponds to the first mechanical parameter, the step of acquiring, by using the three-dimensional imaging detector, the process parameter of the 3D printing platform in the printing process includes: acquiring a three-dimensional high-resolution image of a printing structure in the printing process by using a three-dimensional imaging detector; quantifying the parameter changes of the printing structure at different time points based on the three-dimensional high-resolution image, establishing micro deformation based on time dependence, and obtaining a process parameter corresponding to the first mechanical parameter; the process parameters include squareness characteristics of the printed structure, which are determined from the three-dimensional high-resolution image data.
With reference to the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, wherein the step of quantifying the parameter changes of the printed structure at different time points based on the three-dimensional high-resolution image, establishing micro-deformations based on time dependence, and obtaining the process parameters corresponding to the first mechanical parameters includes: acquiring three-dimensional high-resolution image data of a printing layer of each section of printing structure in the printing process; based on the three-dimensional high-resolution image data, square characteristics of the channel section of each section of printing structure are obtained; the squareness feature is stored as a process parameter of the first force parameter.
With reference to the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where the step of inputting the process parameter into a pre-established calculation model and calculating, by the calculation model, a mechanical characteristic parameter corresponding to the process parameter includes: determining an output result of the calculation model according to the squareness characteristics of each section of printing structure in the process parameters and the time information corresponding to the three-dimensional high-resolution image data; comparing the output result with a preset comparison parameter, and determining a first mechanical parameter of the printing structure based on the comparison result.
With reference to the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, wherein the pre-established calculation model includes:
Figure BDA0004046006720000031
P r for indicating the squareness feature of the channel cross-section,
Figure BDA0004046006720000032
for indicating the ratio of the diameters of the upper and lower cross-section channels of the channels in each section of the printing structure during printing>
Figure BDA0004046006720000033
For the ratio of the measured channel height of the printing structure to the preset layer height, h 0 Is a preset layer height; determining an output result of the calculation model according to the squareness feature of each section of printing structure in the process parameters and the time information corresponding to the three-dimensional high-resolution image data, wherein the step comprises the following steps: based on the squareness characteristics of each section of printing structure and the moment information corresponding to the three-dimensional high-resolution image data, determining the square average value of the current moment and the continuous multiplication parameter of the diameter ratio of the upper section channel to the lower section channel of each section of the internal channel of each section of the structure; determining a layer height base corresponding to each section of printing structure based on preset layer height parameters and layer height data of the printing structure; and determining an output result of the calculation model according to the square degree mean value, the continuous multiplication parameter and the layer height base number.
With reference to the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where a dynamic excitation source is integrated on the three-dimensional imaging detector, and the dynamic excitation source performs a dynamic excitation operation on the printing structure in the 3D printing process through timing control; a step of acquiring a process parameter of the 3D printing platform during printing using the three-dimensional imaging detector when the process parameter corresponds to the second mechanical parameter, comprising: responding to dynamic excitation operation applied by the 3D printing platform when each section of printing structure is printed; measuring detection signals corresponding to each position of each section of printing structure based on dynamic excitation operation by a three-dimensional imaging detector; wherein each segment of the printing structure comprises a multi-layer printing structure; the detection signal comprises vibration distribution corresponding to elastic waves generated by the printing structure based on dynamic excitation operation; preprocessing the detection signals to obtain structure-mechanical signals corresponding to each position of the printing structure; wherein the structure-mechanical signal comprises a phase value parameter and an amplitude parameter; the phase value parameter and the amplitude parameter for each location are stored as process parameters of the printed structure corresponding to the second mechanical parameter.
With reference to the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, where the detection signals are acquired by using an M-B scanning mode, where the detection signals correspond to sub-detection signals with multiple moments; inputting the process parameters into a pre-established calculation model, and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model, wherein the method comprises the following steps of: determining vibration information corresponding to the printing structure of the current position according to sub-detection signals and phase value parameters of a plurality of moments corresponding to each position; wherein the vibration information includes a vibration speed and a vibration displacement of the printing structure; determining an elastic frequency of the printing structure based on the vibration information; determining the elastic wave speed at each elastic frequency based on the elastic frequency, and drawing a wave speed dispersion curve; calculating a second mechanical parameter corresponding to the printing structure according to the wave velocity dispersion curve; wherein the second mechanical parameter is used to calculate the axial elastic modulus and the lateral elastic modulus.
With reference to the first aspect, an embodiment of the present invention provides a seventh possible implementation manner of the first aspect, where the step of determining vibration information corresponding to the printing structure at the current position according to sub-detection signals and phase value parameters at a plurality of moments corresponding to each position includes: determining the phase change condition corresponding to each moment based on the phase value parameters corresponding to two adjacent moments of the current position; calculating the vibration speed of the printing structure at each moment according to the phase change condition; and determining vibration displacement corresponding to each moment according to the vibration speed, and constructing a space-time displacement diagram based on the vibration displacement of each moment to obtain vibration information.
With reference to the first aspect, an embodiment of the present invention provides an eighth possible implementation manner of the first aspect, wherein the elastic frequency of the printing structure is determined based on the vibration information; a step of determining an elastic wave velocity at each elastic frequency based on the elastic frequencies, comprising: performing two-dimensional discrete Fourier transform on the space-time displacement map to obtain a frequency domain-wave number domain map; extracting the maximum value of the frequency value from the frequency domain-wave number domain graph, and carrying out normalization processing on the maximum value to obtain an energy distribution curve; determining a target frequency value corresponding to the highest energy point in the energy distribution curve; based on the frequency domain-wave number domain diagram, determining the ratio of the corresponding frequency of the target frequency value to the wave number domain as the elastic wave speed; elastic wave velocities include shear wave propagation velocities and rayleigh wave propagation velocities.
In a second aspect, an embodiment of the present invention further provides a structure-mechanical composite parameter monitoring device for a 3D printing process, where the device is configured in the above method; the device comprises an excitation module, a three-dimensional imaging detection module and a signal processing module; the excitation module is used for generating an excitation signal when acquiring a process parameter corresponding to the second mechanical parameter so as to enable the printing structure to generate elastic waves; the three-dimensional imaging detection module is connected with the excitation module and is used for emitting imaging detection light according to the triggering operation of the excitation signal and acquiring an imaging signal corresponding to the imaging detection light; the signal processing module is connected with the three-dimensional imaging detection module and is used for processing the imaging signals acquired by the three-dimensional imaging detection module, extracting the process parameters corresponding to the first mechanical parameters or the process parameters corresponding to the second mechanical parameters from the imaging signals, and determining the mechanical characteristic parameters corresponding to the process parameters of the printing structure.
The embodiment of the invention has the following beneficial effects: the structure-mechanical composite parameter monitoring method and the device for the 3D printing process can calculate and acquire two mechanical characteristic parameters of the printing material structure in the 3D printing process by utilizing the three-dimensional imaging detector so as to calculate and acquire the mechanical characteristics of the whole process of the 3D printing material structure, and even if the 3D printing material can measure and modulate the mechanical characteristics in a complex structural environment, in addition, the invention also provides a measuring and modulating tool for the complex mechanical environment in the 3D printing structure, which can realize decoding and regulating of the structure and the viscoelasticity of the printing structure to cooperatively influence the tissue morphology generation mechanism, and provides technical support for monitoring the mechanical environment of the printing structure in the field of 3D printing.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for monitoring a structure-mechanical composite parameter of a 3D printing process according to an embodiment of the present invention;
FIG. 2 is a flow chart of another method for monitoring a structure-mechanical composite parameter of a 3D printing process according to an embodiment of the present invention;
FIG. 3 is an abstract modeling schematic diagram of a printing structure under different mechanical environments according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of abstract modeling of a print structure under another different mechanical environment according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of abstract modeling of a print structure under another different mechanical environment according to an embodiment of the present invention;
FIG. 6 is a cross-sectional view of the P-OCT test gelatin/alginic acid printed with different layers according to an embodiment of the present invention;
FIG. 7 is a view showing an XY cross section of the P-OCT test gelatin/alginic acid printed with different layers at a distance of 0.1mm from the bottom surface according to an embodiment of the present invention;
FIG. 8 is a flow chart of another method for monitoring a structure-mechanical composite parameter of a 3D printing process according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a device for monitoring a structure-mechanical composite parameter in a 3D printing process according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of integrating a p-OCE probe with a printing device according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of operation of a device for monitoring a structure-mechanical composite parameter in a 3D printing process according to an embodiment of the present invention;
fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The biological 3D printing can construct a tissue organ bionic structure based on a digital model, and provides technical support for reconstructing tissue organs by regulating and controlling geometric information (Nat Mater.2021). The generation and establishment of tissue organs are space-time procedural processes (Nature reviews, 2021) cooperatively regulated by geometric, mechanical and biochemical signals, and the mechanical environment is a key factor regulating stem cell fate and morphogenesis.
Among these, viscoelastic is a common feature of living tissue and extracellular matrix (ECM), which manifests as a time-dependent response to loading or phase change, affecting cell proliferation, growth, proliferation and fate. During printing, the viscoelasticity of the high water content biomaterial/bioink is affected by factors such as the temperature of the spray head, the platform temperature, the printing pressure, and the like, and time-dependent deformation, including creep (creep) and stress relaxation (stress relaxation), occurs in the structure under the action of gravity (gravity), pressure (compression), tension (tension), and the like. However, existing mechanical detection methods include: the rheological instrument can detect the viscoelasticity of a fixed macroscopic morphology material, and the atomic force microscope can detect the viscoelasticity of single molecules and single cells, however, a good method for detecting the viscoelasticity of the material under the structure of 10 micrometers-1000 micrometers is lacked, and the scale is the key of tissue morphogenesis. Due to the lack of measurement and modulation tools for complex mechanical environments in 3D printed structures, decoding and regulation of the mechanisms of tissue morphogenesis are hindered by the synergistic effects of printed structures, viscoelasticity. Biological 3D printing has a technical bottleneck that the mechanical environment of the printing structure cannot be monitored.
Based on the above, the structure-mechanical composite parameter monitoring method and the device for the 3D printing process provided by the embodiment of the invention can be used for monitoring the mechanical characteristic parameters of the material structure body of the 3D printing structure at high speed or in real time.
For the convenience of understanding the embodiment, the structure-mechanical composite parameter monitoring method for the 3D printing process disclosed by the embodiment of the invention is described in detail, and the method is applied to a three-dimensional imaging detector, and the three-dimensional imaging detector is connected with a 3D printing platform;
fig. 1 shows a flowchart of a method for monitoring a structure-mechanical composite parameter of a 3D printing process according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:
step S102, acquiring process parameters of the 3D printing platform in the printing process by using a three-dimensional imaging detector.
Step S104, inputting the process parameters into a pre-established calculation model, and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model.
The process parameters correspond to the printing structure and are structural parameters of the 3D printing platform in the process of printing the printing structure; the mechanical characteristic parameter includes a first mechanical parameter and a second mechanical parameter, the process parameter corresponding to the first mechanical parameter or the second mechanical parameter; specifically, the mechanical characteristic parameters of the printed structure include the first mechanical parameter and the second mechanical parameter, where the first mechanical parameter is used to characterize mechanical deformation characteristics related to deformation caused by actions of self gravity, surface tension and the like of the material structure of the printed structure, and the second mechanical parameter is used to characterize mechanical characteristics related to vibration caused by external excitation of the material structure of the printed structure.
In the embodiment of the invention, the first mechanical parameter or the second mechanical parameter of the printing structure can be determined by utilizing the three-dimensional imaging detector according to the requirement, and at the moment, different process parameters can be acquired by the three-dimensional imaging detector.
Specifically, in order to realize real-time monitoring of physical characteristic parameters of a printed structure in a biological 3D printing process, the three-dimensional imaging detector in the embodiment of the invention adopts an optical coherence tomography (Optical CoherenceTomography, OCT for short), such as sweep frequency OCT, spectral domain OCT, time domain OCT, full-field OCT, which are integrated with a printing platform, and is called Printing platform-OCT, p-OCT for short, or ultrasonic imaging, photoacoustic microscopy acquisition techniques, which are integrated with the printing platform, a three-dimensional high-resolution image of the printed structure in the printing process is acquired by using the three-dimensional imaging detector, corresponding process parameters are determined according to the acquired three-dimensional high-resolution image, and the process parameters are input into a pre-established calculation model to calculate first mechanical parameters of the structure of the printed structure.
In addition, the embodiment of the invention integrates a dynamic excitation source on a three-dimensional imaging detector to form an optical coherence elastography (Optical Coherence Elastography, OCE for short), then is fused with a biological 3D printing technology, p-OCE for short, and combines the microscopic fault structure-mechanical composite imaging characteristics of OCE and a 3D printing discrete manufacturing principle to realize the composite imaging, characterization and feedback control of the printing structure-mechanics, parameters in the 3D printing process are obtained through the optical coherence elastography, and then the mechanical property of the printing structure is evaluated according to a pre-established calculation model, such as a viscoelastic creep model, so as to obtain a second mechanical characteristic parameter.
According to the structure-mechanical composite parameter monitoring method for the 3D printing process, provided by the embodiment of the invention, two mechanical characteristic parameters of a printing material structure body can be calculated and obtained in the printing process of the 3D printing structure body by utilizing the three-dimensional imaging detector, wherein corresponding printing process parameters can be obtained according to requirements, and then the first mechanical characteristic parameter or the second mechanical characteristic parameter of the 3D printing material structure body can be determined according to the obtained printing process parameters so as to calculate and obtain the mechanical characteristics of the whole process of the 3D printing material structure body, even if the 3D printing material can be measured and modulated in a complex structure-mechanical environment, decoding and regulation of a structure morphology mechanism which is cooperatively affected by the printing structure body and the viscoelasticity are realized, and technical support is provided for monitoring the mechanical environment of the printing structure in the 3D printing field.
Further, on the basis of the above method embodiment, the embodiment of the present invention further provides another method for monitoring a structure-mechanical composite parameter of a 3D printing process, where the method includes introducing a specific monitoring process when a process parameter corresponds to a first mechanical parameter, and fig. 2 shows a flowchart of another method for monitoring a structure-mechanical composite parameter of a 3D printing process according to the embodiment of the present invention, as shown in fig. 2, where the method includes the following steps:
Step S202, a three-dimensional imaging detector is utilized to acquire a three-dimensional high-resolution image of a printing structure in the printing process.
Step S204, quantifying the parameter changes of the printing structure at different time points based on the three-dimensional high-resolution image, and establishing micro deformation based on time dependence to obtain the process parameters corresponding to the first mechanical parameters.
In specific implementation, the embodiment of the invention can utilize the three-dimensional imaging detector to detect the printing structure in the printing process and detect the time-dependent micro in the printing processAnd (3) small deformation, representing the mechanical state of the printing material structure, inputting the corresponding process parameters of the mechanical state into a pre-established deformation model, and calculating the first mechanical parameters. In the embodiment of the invention, the shape change of the vertical channel in the printing material structure body is taken as a modeling object, and in the printing process, the viscoelastic material is subjected to time-dependent deformation and stress release under the actions of gravity, surface tension and the like, so that the cross section area of the vertical channel is reduced, the roundness is increased and the height is reduced. Based on the above geometric deformation characteristics, a first mechanical parameter P is defined VE 。
In a specific implementation, the three-dimensional high-resolution image may be OCT data obtained by an optical coherence tomography technique, and the embodiment of the present invention uses the three-dimensional high-resolution image as OCT data for illustration, where OCT data of a print layer of each section of a print structure in a printing process may be obtained, and square features of a channel section of each section of the print structure are obtained based on the OCT data, and the square features are stored as process parameters of the first mechanical parameter.
Specifically, in the embodiment of the invention, the data of the 3D printing platform are acquired through OCT in the printing process corresponding to the printing structure, so that the data such as creep deformation, collapse, displacement and fusion of the viscoelastic material under the action of gravity, pressure and tension along with the superposition of the printing layers of the printing structure can be observed, and the height of the vertical channel is reduced, the cross section area is reduced, the shape is rounded and the like. When the OCT is acquired in real time in the printing process of the printing material structure, OCT data corresponding to squareness characteristics of each section of printing structure can be acquired, namely the process parameters of the printing structure.
Step S206, determining an output result of the calculation model according to the squareness characteristics of each section of printing structure in the process parameters and the time information corresponding to the three-dimensional high-resolution image data.
After the process parameters are obtained, the process parameters can be input into a pre-established calculation model, wherein the calculation model is a time-dependent deformation model, and the time information of three-dimensional high-resolution image data corresponding to the squareness characteristics of each section of printing structure in the process parameters is also input into the time-dependent deformation model, so that an output result of the deformation model is obtained.
Specifically, the pre-established time-dependent deformation model includes:
Figure BDA0004046006720000111
wherein P is r The squareness of the channel section can be expressed as:
Figure BDA0004046006720000112
l is the perimeter of the section of each printing channel, A is the area of the section of each printing channel, +.>
Figure BDA0004046006720000113
Is a segment-by-segment square average value. d is the diameter of the cross-section of the channel,
Figure BDA0004046006720000114
is the product of the diameter ratio of the upper section channel and the lower section channel of each section of the structure in the printing process. t is t c For a single print time, Δt is the time interval between printing and image acquisition (Δt is set according to the material deformation speed). d, d i (i×t c ) For the lower cross-sectional diameter, d 'of a three-dimensional channel obtained by a three-dimensional imaging detector immediately after printing the ith segment' i (i×t c +Δt) is the upper cross-sectional diameter of the three-dimensional channel obtained by the three-dimensional imaging detector at the interval Δt after printing the ith segment, +.>
Figure BDA0004046006720000115
H is the ratio of the measured channel height of the printing structure to the preset layer height 0 Is a preset layer height.
The printing layer number of each section of printing structure is set according to the penetration depth of the three-dimensional imaging detector, the lowest printing layer number is set to be 2 layers, and the 2 layers can form a square channel; the number of print layers per print structure needs to be set to an even number.
Based on the definition of each variable in the model, the embodiment of the invention firstly determines the square average value of the square characteristic of each section of printing structure and the square average value of the current moment according to the square characteristic of each section of printing structure and the moment information corresponding to the three-dimensional high-resolution image data; and determining the layer height base number corresponding to each section of printing structure based on the preset layer height parameter and the layer height data of the printing structure. And then determining an output result of the deformation model according to the square degree mean value, the continuous multiplication parameter and the layer height base number.
Step S208, comparing the output result with a preset comparison parameter, and determining a first mechanical parameter of the printing structure based on the comparison result.
Specifically, the feature P is calculated by the above formula based on the 2D image at the printing end time point r P corresponding to the time r The value may reflect the printability of the material, while the output result P of the deformation model VE The values may reflect initial viscoelasticity and structural stress relaxation characteristics of the printed material. Specifically, fig. 3, fig. 4, and fig. 5 respectively show abstract modeling diagrams of a printing structure under different mechanical environments. When P VE At values greater than or equal to 1.1, the creep of the material is small, the stress relaxation is slow, the printing material at this time can lead to the twisting of the extruded filament structure, and the printing channel is a square cylinder with irregular surfaces, as shown in fig. 5. When 0.9<P VE Value of<1.1, the creep of the material is moderate, the surface of the extruded wire is smooth, the layer thickness is stable, and the printing channel structure of the printing material is similar to a square cylinder, as shown in fig. 4. When P VE When the value is less than or equal to 0.9, the creep of the material is large, and the collapse and roundness of the printing channel of the printing material are increased at the moment, and the material is close to an inverted conical cylinder, as shown in figure 3. At this time, first mechanical parameters such as printability characteristic parameters of the printed material structure and initial viscoelasticity of the material and relaxation characteristic parameters of internal stress of the structure can be obtained.
In practical applications, different gel states, such as overgel, normal gel, undergel, and different stress relaxation and creep states of the viscoelastic material locally, show different characteristics in structural deformation. Fig. 6 shows XZ cross-sectional views of p-OCT detected gelatin/alginic acid printed with different layers, fig. 6 shows a structure diagram of the different printed layers observed by p-OCT in XZ cross-section and XY cross-section in different gel states, and fig. 6 shows the following steps from top to bottom: overgel, undergel, normal gel. FIG. 7 shows an XY cross-section of the p-OCT test gelatin/alginic acid printed in different layers 0.1mm from the bottom surface, with the following steps in the order of from top to bottom in FIG. 7: overgel, undergel, normal gel.
According to the structure-mechanical composite parameter monitoring method for the 3D printing process, a method for defining and regulating the viscoelastic state of a printing material structure body through detecting time-dependent deformation is established based on the viscoelastic mechanism of the printing structure deformation, an OCT technology is integrated with a printing platform, a structure image is acquired in the printing process of the printing structure to feed back and regulate the mechanical state of the printing material structure body, a novel method is provided for regulating and controlling tissue morphology generation, and a technical foundation is laid for recursively printing a novel biological component.
Further, on the basis of the above embodiment, the embodiment of the present invention further provides another method for monitoring a structure-mechanical composite parameter of a 3D printing process, where the method includes introducing a specific monitoring process when a process parameter corresponds to a second mechanical parameter, where a dynamic excitation source is integrated on a three-dimensional imaging detector, where the dynamic excitation source is controlled by a timing sequence to perform a dynamic excitation operation on a printing structure in the 3D printing process; fig. 8 is a flowchart of another method for monitoring a structure-mechanical composite parameter of a 3D printing process according to an embodiment of the present invention, as shown in fig. 8, the method includes the following steps:
step S302, responding to a dynamic excitation operation applied by the 3D printing platform when printing each section of the printing structure.
Step S304, measuring, by the three-dimensional imaging detector, each position of each section of the printing structure based on the detection signal corresponding to the dynamic excitation operation.
In specific implementation, the embodiment of the invention utilizes the dynamic excitation source integrated on the three-dimensional imaging detector to apply dynamic excitation to the printing structure in the printing process of the 3D printing platform to induce the printing structure to generate elastic waves, and then the three-dimensional imaging detector is used for measuring the propagation speed and vibration displacement of the elastic waves to obtain the detection signals, wherein the detection signals comprise vibration distribution corresponding to the elastic waves generated by the printing material structure body based on dynamic excitation operation. And then calculating a second mechanical parameter of the printing material structure according to a pre-established viscoelastic creep model, and carrying out visual reconstruction on the propagation of elastic waves in the printing material structure according to the measured vibration distribution condition in the printing material structure under dynamic excitation so as to realize the composite imaging of the printing material structure-mechanics.
Specifically, each section of printing structure in the printing process comprises a multi-layer printing structure, a dynamic excitation source integrated on the three-dimensional imaging detector is controlled through time sequence, the printing structure is subjected to dynamic excitation operation in the printing process, the dynamic excitation is generated and detected to be applied to each section of printing structure, the number of printing layers N of each section of printing structure is set according to the penetration depth of the three-dimensional imaging detector, and N is equal to the whole of the penetration depth divided by the thickness of each layer. Based on the dynamic excitation operation, elastic waves are induced to generate in the printing structure, detection signals of each position of each section of printing structure are obtained through the three-dimensional imaging detector, and therefore second mechanical parameters are calculated according to process parameters indicated by the detection signals.
The printing structure is excited to generate micro vibration by piezoelectric excitation, ultrasonic excitation or jet excitation and the like, elastic waves are induced to generate in a printing structure sample, the p-OCE is utilized to detect and track the elastic waves of the printing structure sample, and then the mechanical properties of a printing tissue are quantitatively evaluated based on viscoelastic creep modeling of a printing material. When a sample of the printed structure is dynamically excited at a specific location using an external excitation source, the material of the printed structure produces a slightly elastic vibration at the excitation point. Elastic vibrations propagate from the excitation site in the form of elastic waves into the surrounding medium inside the sample or near the surface. Due to the difference in the propagation positions of the elastic waves, different types of elastic waves may be generated in the material. Elastic waves that propagate inside thicker samples are called bulk waves, including compression waves and shear waves, while elastic waves that propagate near the surface of the material are called surface Rayleigh waves.
In the process of obtaining the detection signal of the 3D printing structure body at each position by using the p-OCE, the detection signal is obtained through an M-B scanning mode, so that the maximization of the imaging frame rate can be realized, and the sub detection signals at a plurality of corresponding moments are obtained. The p-OCE signal changes at different times at the same location are analyzed by performing a set of samples containing hundreds of A scans at each lateral location of the sample being tested. When imaging is carried out, the p-OCE imaging unit and the piezoelectric excitation unit are provided with synchronous trigger clocks, the sampling trigger clock signals of the p-OCE imaging unit simultaneously trigger the signal generator to output sine wave signals, and the sine wave signals are amplified by the power amplifier and then drive the piezoelectric transducer to vibrate so as to excite the tested sample to generate elastic vibration. A set of a-scan samples and one piezoelectric transducer vibration excitation will be performed at each lateral position of the sample under test. And then, the galvanometer moves the p-OCE scanning beam to the next lateral position, and the same scanning protocol is repeatedly executed until the scanning area is sampled.
Step S306, preprocessing the detection signals to obtain structure-mechanical signals corresponding to each position of the printing structure.
The embodiment of the invention also carries out DC removal, wave number linear interpolation and Fourier transformation processing on the detection signals to obtain structure-mechanical signals of the printing structure body at each position, wherein the structure-mechanical signals comprise phase signals and amplitude signals, the amplitude signals can extract geometric information of the printing structure after processing, and the phase signals can obtain propagation speed, vibration displacement and other information of elastic waves after processing.
Among them, in order to realize propagation imaging of a weak amplitude elastic wave by using p-OCE to detect minute vibrations in a material with high sensitivity, a high-sensitivity phase measurement method of p-OCE is required. The complex OCT signal corresponding to the p-OCE includes a phase value parameter and an amplitude parameter, that is, the phase signal and the amplitude signal. After the detection signals corresponding to the acquired elastic wave data are subjected to fast Fourier transform, OCT complex signals comprising phases and amplitudes at various spatial positions are obtained
Figure BDA0004046006720000141
Where (x, y, z) represents the spatial position of the sample and t represents time.
Step S308 stores the phase value parameter and the amplitude parameter of each position as process parameters of the printing structure corresponding to the second mechanical parameter.
Step S310, determining vibration information corresponding to the printing structure of the current position according to sub-detection signals and phase value parameters of a plurality of moments corresponding to each position in the process parameters.
When the method is specifically implemented, the phase change condition corresponding to each moment is determined based on the phase value parameters corresponding to two adjacent moments of the current position; calculating the vibration speed of the printing structure at each moment according to the phase change condition; and determining vibration displacement corresponding to each moment according to the vibration speed, and constructing a space-time displacement diagram based on the vibration displacement of each moment to obtain vibration information. Wherein the vibration information includes a vibration speed and a vibration displacement of the printing structure.
In particular. The embodiment of the invention can obtain the phase change condition of the internal vibration of the material of the printing structure by using a phase analysis Doppler method, and calculate the internal vibration information of the material, as shown in the following formula:
Figure BDA0004046006720000151
wherein V is x,y,z,t Is the vibration velocity of the material particles at the (x, y, z) position at time t, lambda is the center wavelength of the swept source, n is the refractive index of the medium, tau is the time interval,
Figure BDA0004046006720000152
is the phase change of the OCT signal between two moments in time at the same location. The (x, y, z) position inside the material is at t 1 To t 2 The displacement of the moment in time can be expressed by the following formula:
Figure BDA0004046006720000153
step S312, based on the vibration information, determines the elastic frequency of the printing structure.
Step S314, based on the elastic frequencies, determining the elastic wave velocity at each elastic frequency, and drawing a wave velocity dispersion curve.
In specific implementation, performing two-dimensional discrete Fourier transform on the space-time displacement diagram to obtain a frequency domain-wave number domain diagram; extracting the maximum value of the frequency value from the frequency domain-wave number domain graph, and carrying out normalization processing on the maximum value to obtain an energy distribution curve; determining a target frequency value corresponding to the highest energy point in the energy distribution curve; based on the frequency domain-wave number domain diagram, determining the ratio of the corresponding frequency of the target frequency value to the wave number domain as the elastic wave velocity, and drawing a wave velocity dispersion curve according to the elastic wave velocity at each frequency. The elastic wave velocity includes a shear wave propagation velocity and a Rayleigh wave propagation velocity.
Specifically, after vibration information in the material is measured, the propagation of elastic waves in the material can be visually reconstructed by analyzing the vibration distribution conditions in the material at different moments. In order to analyze the propagation characteristics of the elastic wave, the Doppler phase diagram is Fourier transformed, and the propagation characteristics such as the spectral distribution, the energy distribution, the wave velocity dispersion curve, and the like of the Doppler phase diagram are analyzed. In order to obtain the dispersion characteristic of the elastic wave, the obtained space-time displacement diagram is required to be subjected to two-dimensional discrete Fourier transform, so that the space-time displacement diagram is converted into a frequency-wave number domain from a time-space domain, and a corresponding frequency-wave number domain diagram is obtained. In the frequency domain-wave number domain diagram, the magnitude of each coordinate point represents the energy level. And then, selecting the maximum value corresponding to each frequency along the frequency axis, and carrying out normalization processing to obtain a normalized energy distribution curve, thereby representing the distribution condition of the elastic wave energy. The frequency corresponding to the highest point of energy in the curve is the center frequency of the elastic wave. Based on the frequency-wave number domain diagram, the elastic wave speed at each frequency can be obtained by calculating the ratio of the horizontal coordinate to the vertical coordinate at the maximum amplitude point, and finally the wave speed dispersion curve is obtained.
Step S316, calculating a second mechanical parameter corresponding to the printing structure according to the wave velocity dispersion curve.
When an external excitation source is used to dynamically excite a sample at a specific position, the material generates tiny elastic vibration at an excitation point. Elastic vibrations propagate from the excitation site in the form of elastic waves into the surrounding medium inside the sample or near the surface. Due to the difference in the propagation positions of the elastic waves, different types of elastic waves can be generated in the material. Elastic waves that propagate inside thicker samples are called bulk waves, including compression waves and shear waves, while elastic waves that propagate near the surface of the material are called surface Rayleigh waves.
In a specific implementation, the second mechanical parameter is used to calculate the axial elastic modulus and the lateral elastic modulus. The second mechanical parameters comprise an axial shear wave propagation speed and a lateral shear wave propagation speed of a structural body of the printing structure and a lateral Rayleigh wave propagation speed according to a wave velocity dispersion curve; and calculating Young modulus and shear modulus according to the axial shear wave propagation speed, the lateral shear wave propagation speed and the lateral Rayleigh wave propagation speed, and obtaining the axial elastic modulus and the lateral elastic modulus of the printing material structure according to the Young modulus and the shear modulus.
Specifically, young's modulus E, e=2ρ× (1+v) ×v is calculated from shear wave propagation velocity S 2 ，V S When Vs is the lateral shear wave propagation speed, the lateral elastic modulus in the printing material structure is obtained according to the formula; when Vs is the axial shear wave propagation velocity, the axial elastic modulus in the printed material structure is obtained according to the above formula. Where v is the poisson's ratio of the material and ρ is the density of the material. In the case of less strain, the material may be considered as an incompressible material, with a poisson's ratio v of 0.5.
And determining the lateral Young's modulus E near the surface of the sample according to the Rayleigh wave propagation speed. Rayleigh waves, which are a common surface wave, appear in a depth range of about one wavelength along the surface of a material, and the Young's modulus versus the surface Rayleigh wave propagation velocity can be given by the following equation:
Figure BDA0004046006720000171
V R obtaining the vicinity of the surface of the printing material structure body according to the above formula for Rayleigh wave propagation speedIs a Young's modulus in the lateral direction. Where ρ is the density of the material, V is the Poisson's ratio of the material, V R Is the rayleigh wave propagation velocity. Rayleigh wave propagation velocity measurements of the material surface can be used to quantify the lateral Young's modulus of the surface attachment of the printed material structure. When the bio-ink is slowly solidified and formed and is easy to deform, distortion of a structure of the bio-3D printing can be caused.
According to the mechanical characteristic parameter determining method of the 3D printing structure, an OCE technology and a printing platform are integrated, 2-15 layers of printing structures can be penetrated through by OCE according to different material scattering characteristics, the whole-structure image reconstruction of p-OCE quantitatively represents the material deformation and performance of a printing material structure body by judging the structure, deformation and viscoelasticity differences acquired by the same layer at different times, and the printing parameters are controlled in a feedback mode. The structure-mechanical composite parameter monitoring method based on the 3D printing process can rapidly acquire second mechanical characteristic parameters such as axial elastic modulus, lateral elastic modulus and the like of the 3D printing structure.
Further, on the basis of the device embodiment, the embodiment of the invention also provides a structure-mechanical composite parameter monitoring device for a 3D printing process, wherein the device is configured in the method; the device comprises an excitation module, a three-dimensional imaging detection module and a signal processing module; the excitation module is used for generating an excitation signal when acquiring a process parameter corresponding to the second mechanical parameter so as to enable the printing structure to generate elastic waves; the three-dimensional imaging detection module is connected with the excitation module and is used for emitting imaging detection light according to the triggering operation of the excitation signal and acquiring an imaging signal corresponding to the imaging detection light; the signal processing module is connected with the three-dimensional imaging detection module and is used for processing the imaging signals acquired by the three-dimensional imaging detection module, extracting the process parameters corresponding to the first mechanical parameters or the process parameters corresponding to the second mechanical parameters from the imaging signals, and determining the mechanical characteristic parameters corresponding to the process parameters of the printing structure. The process parameters respectively comprise a structure-mechanics composite image of the corresponding printing process.
In the specific implementation, the p-OCE excites the printing product in an excitation mode such as piezoelectric excitation, ultrasonic excitation or jet excitation to generate micro vibration, and the mechanical vibration induces shear waves and surface waves which propagate in different directions in the printing product. Phase sensitive OCE can be implemented using swept OCT techniques. The swept laser source and the signal processing module correspond to the swept OCT technique described above.
Specifically, in order to be able to induce both surface waves and shear waves in biological materials, a piece of cover glass may be stuck to the bottom of the piezoelectric transducer as an excitation source. The top of the piezoelectric transducer is bonded to a rigid, fixed glass plate and the bottom coverslip is in intimate contact with the surface of the sample. After the sine wave generated by the signal generator passes through the amplifier, the piezoelectric transducer is driven to generate micro displacement, and elastic vibration is induced on the surface of the sample. The excitation module is realized by sticking a cover glass on the bottom of the piezoelectric transducer as an excitation source and generating sine waves through a signal generator.
Fig. 9 shows a schematic structural diagram of a structure-mechanical composite parameter monitoring device for a 3D printing process according to an embodiment of the present invention, where the schematic structural diagram is a schematic structural diagram of a swept frequency p-OCE structure-elastic bimodal imaging system; FIG. 10 shows a schematic diagram of a p-OCE probe integrated with a printing device; fig. 11 shows a schematic diagram of the operation of a structure-mechanical composite parameter monitoring device for a 3D printing process, where the schematic diagram is a schematic diagram of the p-OCE structure-elastic bimodal imaging principle. The top of the piezoelectric transducer is bonded to a rigidly fixed glass plate, wherein the piezoelectric transducer comprises annular PZT with a cover glass at the bottom in close contact with the surface of the sample. After passing through the PZT amplifier, the sine wave generated by the signal generator drives the piezoelectric transducer to generate micro displacement, and induces elastic vibration on the surface of the sample to generate elastic wave.
The three-dimensional imaging detection module is realized based on a sweep frequency laser source, wherein the sweep frequency laser source is used for dividing emitted laser into two beams after passing through a 99/1 beam splitting coupler, one beam of light enters a reference arm, and the other beam of light enters a sample arm. The reference arm comprises an optical fiber circulator, a collimator and a focusing lens, and the beam split entering the reference arm sequentially passes through the optical fiber circulator, the collimator and the focusing lens and is finally reflected by a plane mirror at the tail end of the reference arm, and the reflected beam returns to the optical fiber along the original path. The sample arm comprises an optical fiber circulator, a scanning galvanometer and a scanning lens, and the beam split entering the sample arm finally enters the sample at the tail end of the sample arm after passing through the optical fiber circulator, the scanning galvanometer and the scanning lens and is scattered by a medium in the sample. The back-scattered light of the sample is collected and returned to the optical path. The signal processing module is used for interfering return light of the two light paths in a coupler with a 50/50 beam splitting ratio, detecting interference signals by the balance detector, and transmitting the interference signals to the computer for subsequent processing through analog-to-digital conversion so as to obtain second mechanical parameters of the 3D printing structure body.
Further, the structure-mechanical composite parameter monitoring device for the 3D printing process provided by the embodiment of the invention has the same technical characteristics as the structure-mechanical composite parameter monitoring method for the 3D printing process provided by the embodiment, so that the same technical problems can be solved, and the same technical effects can be achieved.
The embodiment of the invention also provides an electronic device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the computer program to realize the steps of the method shown in the figures 1 to 8.
The embodiments of the present invention also provide a computer readable storage medium having a computer program stored thereon, which when executed by a processor performs the steps of the method shown in fig. 1 to 8 described above.
The embodiment of the present invention further provides a schematic structural diagram of an electronic device, as shown in fig. 12, where the electronic device includes a processor 61 and a memory 60, where the memory 60 stores computer executable instructions that can be executed by the processor 61, and the processor 61 executes the computer executable instructions to implement the methods shown in fig. 1 to 8.
In the embodiment shown in fig. 12, the electronic device further comprises a bus 62 and a communication interface 63, wherein the processor 61, the communication interface 63 and the memory 60 are connected by the bus 62.
The memory 60 may include a high-speed random access memory (RAM, random Access Memory), and may further include a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory. The communication connection between the system network element and at least one other network element is achieved via at least one communication interface 63 (which may be wired or wireless), and may use the internet, a wide area network, a local network, a metropolitan area network, etc. The Bus 62 may be an ISA (Industry Standard Architecture ) Bus, a PCI (Peripheral Component Interconnect, peripheral component interconnect standard) Bus, an EISA (Extended Industry Standard Architecture ) Bus, or the like, or an AMBA (Advanced Microcontroller Bus Architecture, standard for on-chip buses) Bus, where AMBA defines three buses, including an APB (Advanced Peripheral Bus) Bus, an AHB (Advanced High-performance Bus) Bus, and a AXI (Advanced eXtensible Interface) Bus. The bus 62 may be classified as an address bus, a data bus, a control bus, or the like. For ease of illustration, only one bi-directional arrow is shown in FIG. 12, but not only one bus or type of bus.
The processor 61 may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuits of hardware in the processor 61 or by instructions in the form of software. The processor 61 may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; but also digital signal processors (Digital Signal Processor, DSP for short), application specific integrated circuits (Application Specific Integrated Circuit, ASIC for short), field-programmable gate arrays (Field-Programmable Gate Array, FPGA for short) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present application may be embodied directly in hardware, in a decoded processor, or in a combination of hardware and software modules in a decoded processor. The software modules may be located in a random access memory, flash memory, read only memory, programmable read only memory, or electrically erasable programmable memory, registers, etc. as well known in the art. The storage medium is located in a memory and the processor 61 reads the information in the memory and in combination with its hardware performs the method described above with reference to fig. 1 to 8.
The computer program product of the method and the device for determining the structure-mechanical composite parameter of the 3D printing process provided by the embodiments of the present invention includes a computer readable storage medium storing program codes, and the instructions included in the program codes may be used to execute the method described in the foregoing method embodiment, and specific implementation may refer to the method embodiment and will not be described herein.
It will be clear to those skilled in the art that, for convenience and brevity of description, reference may be made to the corresponding process in the foregoing method embodiment for the specific working process of the above-described system, which is not described herein again. In addition, in the description of embodiments of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood by those skilled in the art in specific cases.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above examples are only specific embodiments of the present invention for illustrating the technical solution of the present invention, but not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the foregoing examples, it will be understood by those skilled in the art that the present invention is not limited thereto: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. A method for monitoring a structure-mechanics composite parameter of a 3D printing process, the method being applied to a three-dimensional imaging detector, the three-dimensional imaging detector being connected to a 3D printing platform, the method comprising:
acquiring process parameters of the 3D printing platform in the printing process by using the three-dimensional imaging detector; the process parameter corresponds to a print structure;
Inputting the process parameters into a pre-established calculation model, and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model;
wherein the mechanical property parameters include a first mechanical parameter and a second mechanical parameter; the process parameter corresponds to a first mechanical parameter or a second mechanical parameter; the first mechanical parameter is used for representing deformation characteristics corresponding to the material structure body of the printing structure, and the second mechanical parameter is used for representing mechanical characteristics of the material structure body of the printing structure related to vibration caused by external excitation.
2. The method of claim 1, wherein the step of acquiring the process parameters of the 3D printing platform during printing with the three-dimensional imaging detector when the process parameters correspond to the first force parameters comprises:
acquiring a three-dimensional high-resolution image of the printing structure in the printing process by using the three-dimensional imaging detector;
based on the three-dimensional high-resolution image, quantifying the parameter changes of the printing structure at different time points, establishing micro deformation based on time dependence, and obtaining process parameters corresponding to the first mechanical parameters; wherein the process parameter comprises a squareness feature of the printed structure, the squareness feature being determined from three-dimensional high resolution image data.
3. The method according to claim 2, wherein the step of quantifying the parameter variations of the printed structure at different points in time based on the three-dimensional high-resolution image, creating a time-dependent based micro-deformation, resulting in a process parameter corresponding to the first mechanical parameter, comprises:
acquiring three-dimensional high-resolution image data of a printing layer of each section of printing structure in the printing process;
acquiring square degree characteristics of a channel section of each section of the printing structure based on the three-dimensional high-resolution image data;
the squareness feature is stored as a process parameter of the first mechanical parameter.
4. A method according to claim 3, wherein the step of inputting the process parameters into a pre-established calculation model, and calculating the mechanical property parameters corresponding to the process parameters by the calculation model comprises:
determining an output result of the calculation model according to the squareness characteristics of each section of the printing structure in the process parameters and the time information corresponding to the three-dimensional high-resolution image data;
comparing the output result with a preset comparison parameter, and determining a first mechanical parameter of the printing structure based on the comparison result.
5. The method of claim 4, wherein the pre-established computational model comprises:
Figure FDA0004046006710000021
the P is r For indicating the squareness feature of the channel cross-section,
Figure FDA0004046006710000022
for indicating the ratio of the diameters of the upper and lower cross-section channels of each section of said printing structure during printing>
Figure FDA0004046006710000023
H is the ratio of the measured channel height of the printing structure to the preset layer height 0 Is a preset layer height;
the step of determining an output result of the calculation model according to the squareness feature of each section of the printing structure in the process parameters and the time information corresponding to the three-dimensional high-resolution image data includes:
determining a square average value of the current moment and a continuous multiplication parameter of the diameter ratio of the upper section channel to the lower section channel of the channel in each section of the structure based on the square characteristic of each section of the printing structure and the moment information corresponding to the three-dimensional high-resolution image data;
determining a layer height base corresponding to each section of the printing structure based on a preset layer height parameter and layer height data of the printing structure;
and determining an output result of the calculation model according to the square degree mean value, the continuous multiplication parameter and the layer height base number.
6. The method of claim 1, wherein the three-dimensional imaging detector has integrated thereon a dynamic excitation source that is controlled by a timing sequence to dynamically excite the printing structure during 3D printing;
the step of acquiring the process parameters of the 3D printing platform during the printing process by using the three-dimensional imaging detector when the process parameters correspond to the second mechanical parameters comprises:
responding to dynamic excitation operation applied by the 3D printing platform when each section of the printing structure is printed;
measuring, by the three-dimensional imaging detector, a detection signal corresponding to each position of each segment of the printed structure based on the dynamic excitation operation;
wherein each segment of the printing structure comprises a multi-layer printing structure; the detection signal comprises vibration distribution corresponding to elastic waves generated by the printing structure based on the dynamic excitation operation;
preprocessing the detection signals to obtain structure-mechanical signals corresponding to each position of the printing structure; wherein the structure-mechanical signal comprises a phase value parameter and an amplitude parameter;
the phase value parameter and the amplitude parameter for each location are stored as process parameters of the printing structure corresponding to the second mechanical parameter.
7. The method of claim 6, wherein the detection signals are acquired in an M-B scan mode, the detection signals corresponding to sub-detection signals at a plurality of times;
the step of inputting the process parameters into a pre-established calculation model and calculating mechanical characteristic parameters corresponding to the process parameters through the calculation model comprises the following steps:
determining vibration information corresponding to the printing structure at the current position according to sub-detection signals at a plurality of moments corresponding to each position in the process parameters and the phase value parameters;
wherein the vibration information includes a vibration speed and a vibration displacement of the printing structure;
determining an elastic frequency of the printing structure based on the vibration information;
based on the elastic frequencies, determining the elastic wave speed at each elastic frequency, and drawing a wave speed dispersion curve;
calculating a second mechanical parameter corresponding to the printing structure according to the wave velocity dispersion curve;
wherein the second mechanical parameter is used to calculate the axial elastic modulus and the lateral elastic modulus.
8. The method of claim 7, wherein the step of determining vibration information corresponding to the printed structure for the current location based on the sub-detection signals for a plurality of times corresponding to each location in the process parameters and the phase value parameters, comprises:
Determining the phase change condition corresponding to each moment based on the phase value parameters corresponding to two adjacent moments of the current position;
calculating the vibration speed of the printing structure at each moment according to the phase change condition;
and determining vibration displacement corresponding to each moment according to the vibration speed, and constructing a space-time displacement diagram based on the vibration displacement of each moment to obtain the vibration information.
9. The method of claim 8, wherein the elastic frequency of the printed structure is determined based on the vibration information; a step of determining an elastic wave velocity at each elastic frequency based on the elastic frequencies, comprising:
performing two-dimensional discrete Fourier transform on the space-time displacement map to obtain a frequency domain-wave number domain map;
extracting the maximum value of the frequency value from the frequency domain-wave number domain diagram, and carrying out normalization processing on the maximum value to obtain an energy distribution curve;
determining a target frequency value corresponding to an energy highest point in the energy distribution curve;
determining a ratio of a corresponding frequency and wavenumber domain of the target frequency value as the elastic wave velocity based on the frequency-wavenumber domain map; the elastic wave velocities include shear wave propagation velocities and rayleigh wave propagation velocities.
10. A structure-mechanical composite parameter monitoring device for a 3D printing process, characterized in that the device is configured in a method according to any one of claims 1 to 9; the device comprises an excitation module, a three-dimensional imaging detection module and a signal processing module;
the excitation module is used for generating an excitation signal when acquiring a process parameter corresponding to the second mechanical parameter so as to enable the printing structure to generate elastic waves;
the three-dimensional imaging detection module is connected with the excitation module and is used for emitting imaging detection light according to the triggering operation of the excitation signal and acquiring an imaging signal corresponding to the imaging detection light;
the signal processing module is connected with the three-dimensional imaging detection module and is used for processing the imaging signals acquired by the three-dimensional imaging detection module, extracting process parameters corresponding to first mechanical parameters or process parameters corresponding to second mechanical parameters from the imaging signals, and determining mechanical characteristic parameters corresponding to the process parameters of the printing structure.
CN202310029191.3A 2023-01-09 2023-01-09 Structure-mechanical composite parameter monitoring method and device for 3D printing process Pending CN116141681A (en)

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