CN116029141A - Stress-strain calculation method and device for irregular concave morphology of pipeline - Google Patents

Abstract

The specification relates to pipeline stress analysis, in particular to a stress-strain calculation method and device for irregular concave morphology of a pipeline. The method comprises the steps of obtaining parameters of the pipeline size and the concave morphology; determining the actual shape of the three-dimensional concave by utilizing laser scanning; extracting three-dimensional data points of the concave region according to the three-dimensional concave actual shape of the concave region; according to the three-dimensional data points of the concave area, adopting a cubic B spline interpolation function, and restoring the shape of the pressure head based on parameters of the pipeline size and the concave morphology; and establishing a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, and obtaining a stress strain state of the concave region through post-treatment. Through this description embodiment, the problem of the security of unable quick evaluation pipeline sunk under the actual operating mode has been solved, has realized carrying out the evaluation of high-efficient accuracy in pipeline sunk region.

Description

Stress-strain calculation method and device for irregular concave morphology of pipeline

Technical Field

The specification relates to the field of safety evaluation, in particular to a stress-strain calculation method and device for irregular concave morphology of a pipeline.

Background

Because pipeline transportation is relatively safe and does not affect the environment, the pipeline transportation is the most common transportation mode for petroleum and natural gas. However, in the laying and long-term service process of the pipeline, the pipeline wall is permanently and plastically deformed due to the impact of an external object or the impact of a load on the pipeline, and the like, so that the cross section of the pipeline is deformed, namely the pipeline is sunken. The dent has a considerable influence on the service life of the pipeline, and is a main cause of fatigue fracture of the pipeline, and the dent deformation damage is accumulated to a certain extent to cause the pipeline to be broken and damaged, so that accidents such as pipeline leakage or breakage and the like are caused, and huge safety hazard and economic loss are caused. In practical engineering, the depth of the pit is generally adopted as the basis for judging the severity of the pit, but the conventional laser detection technology cannot directly evaluate the pit deformation of the pipeline, the stress strain state of the pit area of the pipeline is ignored by the pit depth-based evaluation method, and when the pipelines with the same pit depth and different parameters are evaluated, the accuracy of the evaluation result can have errors due to the parameter change.

What is needed is a stress-strain calculation method and device for irregular concave morphology of a pipeline to improve reliability of a structural integrity assessment technology of the pipeline with the concave, so that the problem that safety of the pipeline with the concave can not be rapidly assessed based on the concave actual morphology under actual working conditions is solved.

Disclosure of Invention

In order to solve the problem that in the prior art, the stress strain state of a concave pipeline cannot be rapidly and accurately evaluated, so that whether the stress state of a concave area of the pipeline accords with the material strength check or not can not be judged under the actual working condition, and therefore the safety of the pipeline cannot be accurately judged, the embodiment of the specification provides a stress strain calculation method and a stress strain calculation device for irregular concave shapes of the pipeline, the displacement condition of the pipeline influenced by a pressure head can be combined, the calculation can be performed by using a finite element method, the stress strain behavior of the concave pipeline is analyzed, and therefore an accurate basis is provided for evaluating the structural integrity of the pipeline containing the concave, and the safety evaluation of the concave pipeline under the actual working condition is improved.

In order to solve the technical problems, the specific technical scheme in the specification is as follows:

in one aspect, embodiments of the present disclosure provide a method for calculating stress-strain of irregular concave features of a pipe, comprising,

obtaining the shape parameters of the pipeline size and the concave area;

scanning a concave area of the pipeline to determine the actual shape of the three-dimensional concave;

according to the three-dimensional concave actual morphology, three-dimensional data points of the concave area are obtained;

according to the three-dimensional data points of the concave area, adopting a cubic B spline interpolation function, and reducing the shape of the pressure head based on the pipeline size and the shape parameters of the concave area;

and establishing a concave pipeline finite element model according to the pipeline size and the pressure head shape, and obtaining the stress strain state of the concave area.

Further, obtaining the parameters of the pipe dimension and the morphology of the concave area further comprises,

the shape parameters of the pipeline size and the concave area comprise pipeline diameter, wall thickness, steel grade, concave area and concave depth.

Further, the concave area of the scanning pipeline further comprises,

the scan range boundary is greater than the recessed region boundary.

Further, according to the three-dimensional concave actual shape, the three-dimensional data points of the concave area are obtained,

the scanning is carried out to extract the actual shape of the three-dimensional concave;

performing transverse and longitudinal arc surface segmentation on the three-dimensional concave actual morphology to obtain three-dimensional concave actual morphology coordinates of a plurality of arc surfaces as three-dimensional data points of the concave area, wherein the axial distance between the arc surfaces is not less than 20mm,

the number of sections along the axial direction of the pipeline is not less than 11 concave sections.

Further, a cubic B-spline interpolation function is adopted, based on the pipeline size and the morphological parameters of the concave area, the shape of the pressure head is restored, further comprising,

generating a concave circumferential curve by utilizing a cubic B spline interpolation function according to the three-dimensional data points of the concave region;

and (5) smoothing all concave circumferential curves by using a skin means, and restoring the shape of the pressure head.

Further, the cubic B-spline interpolation function further comprises,

wherein x represents the coordinate parameter of the contour point of the concave-shaped curved surface, B _i Is a control vertex of the curved surface; n (N) _i,3 (t) is a base function of a B-spline, the expression of which is:

wherein N is _i,k (t) is a k-th order B-spline basis function, t= [ t ] ₀ ，t ₁ ，t ₂ ，…，t _i ]Is a node vector.

Further, establishing a concave conduit finite element model based on the conduit dimensions and the ram shape further includes,

the cell type, contact conditions, boundary conditions and load are set.

Further, in establishing a concave pipeline finite element model according to the pipeline size and the pressure head shape, further comprising,

setting a saddle to limit the displacement of the pipeline along the direction of the pressure head, wherein the saddle boundary condition is full constraint of all nodes; the contact surfaces of the pressure head and the pipeline and the contact surfaces of the pipeline and the saddle are required to be contacted, the pipeline is respectively set as a target surface, and the surfaces of the pressure head and the saddle are contact surfaces.

Further, establishing a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, further comprises

Internal pressure is applied to the inner surface node of the selected pipeline, and the pressure head is limited to be free from displacement;

the displacement load applied by the ram is selected to be the depression depth +a, where a is the load correction factor.

On the other hand, the embodiment of the specification also provides a stress-strain calculating device of the irregular concave shape of the pipeline, which comprises,

the parameter collecting unit is used for obtaining the pipeline size and the morphology parameters of the concave area;

the scanning unit is used for scanning the concave area of the pipeline and determining the actual shape of the three-dimensional concave;

the three-dimensional data point unit is used for obtaining three-dimensional data points of the concave area according to the three-dimensional concave actual morphology;

the B spline interpolation unit is used for adopting a cubic B spline interpolation function according to the three-dimensional data points of the concave area and restoring the shape of the pressure head based on the pipeline size and the morphological parameters of the concave area;

and the finite element model unit is used for establishing a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, and obtaining the stress strain state of the concave area.

In another aspect, embodiments of the present disclosure further provide a computer device, including a memory, a processor, and a computer program stored on the memory, where the processor implements the method described above when executing the computer program.

Finally, the embodiments of the present specification also provide a computer storage medium having stored thereon a computer program which, when executed by a processor of a computer device, performs the above-described method.

By means of the embodiment of the specification, the safety of the concave pipeline is evaluated under the actual working condition, in order to improve the accuracy of evaluation, the actual appearance of the concave surface of the concave position of the pipeline is scanned through a scanning method, the three-dimensional appearance of the concave area is obtained, then three-dimensional data points of the concave area are extracted according to the three-dimensional appearance of the concave area, the shape of the pressure head is restored based on the irregular concave appearance by adopting a cubic B spline interpolation method, the detailed parameters of the concave appearance of the pipeline are obtained, a finite element model of the concave pipeline under the shape of the pressure head is constructed by utilizing the detailed parameters, the obtained parameters are processed according to the finite element model, the stress strain state of the concave area is obtained, and the efficiency and reliability of the evaluation technology of the concave area of the pipeline are improved. The problem of unable quick evaluation pipeline under the actual condition security of sunkening in the prior art is solved.

Drawings

In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present description, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an implementation system of a stress-strain calculation method for irregular concave morphology of a pipe according to an embodiment of the present disclosure;

FIG. 2 is a flowchart of a stress-strain calculation method for irregular concave morphology of a pipe according to an embodiment of the present disclosure;

FIG. 3 shows a step of reducing the shape of the indenter by a 3D laser scan in an embodiment of the present disclosure;

FIG. 4 illustrates a coordinate system including concave topographical surface data points in an embodiment of the present disclosure;

FIG. 5 shows a finite element model of a recessed conduit in an embodiment of the present disclosure;

FIG. 6 is a graph of pipe stress strain clouds with concave topography in the text embodiment;

FIG. 7 is a schematic structural diagram of a stress-strain calculating device with irregular concave morphology of a pipe according to an embodiment of the present disclosure;

fig. 8 is a schematic structural diagram of a computer device according to an embodiment of the present disclosure.

[ reference numerals description ]:

101. a terminal;

102. a server;

501. a pipe ram;

502. a pipe;

503. a saddle;

701. a parameter collecting unit;

702. a scanning unit;

703. a three-dimensional data point unit;

704. a B spline interpolation unit;

705. a finite element model unit;

802. a computer device;

804. a processing device;

806. storing the resource;

808. a driving mechanism;

810. an input/output module;

812. an input device;

814. an output device;

816. a presentation device;

818. a graphical user interface;

820. a network interface;

822. a communication link;

824. a communication bus.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only 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.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or device.

It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer executable instructions, and that although a logical order is illustrated in the flowcharts, in some cases the steps illustrated or described may be performed in an order other than that illustrated herein.

Fig. 1 is a schematic diagram of a system for implementing a stress-strain calculation method for irregular concave morphology of a pipeline according to an embodiment of the present invention, which may include a terminal 101 and a server 102, where a communication connection is established between the terminal 101 and the server 102, so as to enable data interaction. The terminal 101 may input the pipeline size and the concave morphology parameters to the server 102, where the pipeline size and the concave morphology parameters include the diameter, the wall thickness, the steel grade, the concave length, and the concave depth of the pipeline, and the server 102 processes, calculates, and models the pipeline size and the concave morphology parameters to obtain a finite element model of the concave pipeline, analyzes the finite element model and the stress-strain state thereof as the stress-strain state of the concave pipeline, and sends the stress-strain state of the concave pipeline to the terminal 101 for display or preservation.

In this embodiment of the present disclosure, the server 102 may be an independent physical server, or may be a server cluster or a distributed system formed by a plurality of physical servers, or may be a cloud server that provides cloud services, a cloud database, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, and basic cloud computing services such as big data and an artificial intelligence platform.

In an alternative embodiment, terminal 101 may include, but is not limited to, a smart phone, a desktop computer, a tablet computer, a notebook computer. Alternatively, the operating system running on the electronic device may include, but is not limited to, an android system, an IOS system, linux, windows, and the like.

It should be noted that, fig. 1 is only one application environment provided by the present disclosure, and in practical application, other application environments may also be included, which is not limited in the embodiment of the present invention.

In order to solve the problems in the prior art, the embodiment of the invention provides a stress-strain calculation method for irregular concave shapes of pipelines, which realizes the evaluation of the safety of the concave pipelines under the actual working condition, scans the concave areas through a 3D laser scanning method to determine the actual shapes of the concave surfaces of the concave areas of the pipelines, obtains the three-dimensional shapes of the concave areas, extracts three-dimensional data points of the concave areas according to the three-dimensional shapes of the concave areas, adopts a cubic B spline interpolation method, restores the shape of a pipeline pressure head based on the irregular concave shapes, realizes the acquisition of detailed parameters of the concave shapes of the pipelines, utilizes the detailed parameters to construct a finite element model of the concave pipelines under the pressure head shape, processes the acquired parameters according to the finite element model to obtain the stress-strain state of the concave areas, improves the efficiency and the reliability of the evaluation technology of the pipeline concave areas, and only needs to obtain different stress-strain states through adjusting the parameters of the finite element model when evaluating pipelines with different parameters, thereby being used for solving the problem that the safety of the pipelines cannot be evaluated rapidly under the actual working conditions in the prior art.

Specifically, as shown in fig. 2, the method may include:

step 201: obtaining parameters of the pipeline size and the concave morphology;

step 202: scanning a concave area of the pipeline to determine the actual shape of the three-dimensional concave;

step 203: extracting three-dimensional data points of the concave region according to the three-dimensional concave actual shape of the concave region;

step 204: according to the three-dimensional data points of the concave area, adopting a cubic B spline interpolation function, and restoring the shape of the pressure head based on parameters of the pipeline size and the concave morphology;

step 205: and establishing a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, and obtaining a stress strain state of the concave area through post-treatment.

According to the method provided by the embodiment of the invention, firstly, a pipeline with a dent on the surface is measured to obtain the pipeline size and the shape parameters of the dent, then, a 3D laser scanning method is utilized to scan the dent of the pipeline to obtain the three-dimensional dent actual shape, three-dimensional data points of the dent are extracted according to the three-dimensional shape of the dent, the dent of the pipeline is converted into coordinate points in a three-dimensional coordinate system, then, a three-time B spline interpolation method is adopted according to the obtained three-dimensional data points to obtain a B spline curve, the actual shape of a pressure head is restored based on the irregular dent shape, finally, a finite element model of the dent pipeline under the actual shape of the pressure head is established, and the stress strain state of the dent is obtained by processing the finite element model.

In embodiments of the present invention, the types of pipelines may include petroleum transportation pipelines, natural gas transportation pipelines, and embodiments of the present specification are not limited. The pipeline dent is the most easily produced mechanical damage form in the long-term service process of the oil gas pipeline, and is often expressed as radial plastic deformation of a local area of the pipeline wall, and the dent is mainly formed by the impact of foreign objects, such as rocks, excavating machinery, heavy objects and the like, which are all possible reasons for causing the dent of the pipeline, so that the embodiment of the specification is not limited. The depressions produced by the presence of a plurality of different depression-producing reasons may exhibit different depression shapes, depression areas and depression depths. Therefore, the parameters of the concave morphology need to be measured on a basis, then the 3D laser scanning is utilized to scan, and the scanned area is ensured to contain the complete concave area, wherein the 3D laser scanning system mainly comprises a 3D laser scanner, a computer, a power supply system, a bracket and system matched software, and the three-dimensional coordinates of a large number of dense points on the surface of the pipeline are recorded by utilizing the principle of laser ranging. Specifically, a reference cylinder slightly larger than the diameter of a pipeline can be input according to the known diameter and wall thickness of the pipeline, the 3D laser scanner is kept perpendicular to the surface of the pipeline, the reference cylinder is aligned with the pipeline, 360-degree scanning is carried out, transverse and longitudinal cambered surface segmentation is required to be carried out on the concave morphology in the scanning process, the distance between cambered surfaces is not smaller than 20mm, the region with an imaging cavity is required to be scanned again until the region is completely displayed in imaging software, the origin and the coordinate axis are set, and the setting and scanning results are stored, so that the three-dimensional concave actual morphology is obtained.

In the embodiment of the specification, the pipeline size comprises a pipeline diameter, a pipeline wall thickness and a steel grade, the pipeline diameter can be 660mm-1016mm in a range of pipeline diameter, the pipeline wall thickness can be 7.1mm-14.6mm, the steel grade can be X60 and X80, and the data such as the elastic modulus, the yield strength, the material hardening index, the load correction coefficient and the like of the pipeline can be obtained according to the steel grade of the pipeline; furthermore, the on-site 3D laser scanning data extraction needs to comprise a complete concave area, the scanning area needs to be larger than 150mm of a concave boundary, the concave area needs to be cut into transverse and longitudinal cambered surfaces by taking three-dimensional coordinates of the concave area, the distance between the cambered surfaces needs to be not smaller than 20mm, the number of sections along the axial direction of a pipeline is not smaller than 11 concave sections, the complete and accurate scanning of the concave area of the pipeline is realized, and the three-dimensional coordinate points obtained by scanning the surface are ensured to accord with the actual shape of the concave. A specific coordinate system of surface data points with concave morphology is shown in fig. 3, and the step of reducing the shape of the indenter by 3D laser scanning may include:

step 301: extracting the actual three-dimensional concave shape by 3D laser scanning;

step 302: performing transverse and longitudinal arc surface segmentation on the three-dimensional concave actual morphology to obtain three-dimensional concave actual morphology coordinates of a plurality of arc surfaces as three-dimensional data points of the concave region;

step 303: generating a concave circumferential curve by utilizing a cubic B spline interpolation function according to the three-dimensional data points of the concave region;

step 304: and (5) smoothing all concave circumferential curves by using a skin means, and restoring the shape of the pressure head.

According to the method provided by the embodiment of the invention, a scanning three-dimensional model of the three-dimensional depression actual morphology of the pipeline depression as shown in fig. 4 can be obtained, three-dimensional data points of the depression actual morphology in a coordinate system are extracted, a three-time B spline interpolation method is utilized, data under the same axis is taken as a group to generate an interpolation curve, and then the curves under different axes are covered to obtain a depression curved surface. The B spline interpolation function of the cubic B spline interpolation method is as follows:

wherein x represents the coordinate parameter of the contour point of the concave curved surface, B _i Is the control vertex of the curve; n (N) _i,3 (t) is a base function of a B-spline, the expression of which is:

/>

wherein N is _i,k (t) is a k-th order B-spline basis function, t= [ t ] ₀ ，t ₁ ，t ₂ ，…，t _i ]Is a node vector. Determining n+1 control points by giving n+1 data points and a base function of the B spline, so that the generated B spline curve can generate a section curve through all the data points, and the number of the data points cannot be less than 7; and obtaining a concave circumferential curve after performing a cubic B spline interpolation method, smoothing all concave section curves by using a skin means to form a concave curved surface, and extending the concave curved surface to form a pressure head containing a concave actual shape.

In the embodiments of the present disclosure, parameters of pipe dimensions, material parameters, and pit morphology are required to build a finite element model; establishing a geometric model according to the pipeline size, wherein the representation form of the geometric model in a computer comprises a solid model, a curved surface model and a wire frame model, and when the geometric model is established, the shape and the size of the pipeline are required to be necessarily simplified, changed and processed according to the specific characteristics of the pipeline so as to adapt to the characteristics of finite element analysis; determining the type of the adopted unit, wherein the unit selection needs to be comprehensively considered according to the type, shape characteristics, stress and strain curves of the pipeline structure; and the cell type further includes a set of internal characteristic data required for calculation to define the material parameters, modulus of elasticity, yield strength, cross-sectional shape and size of the pipe; the grid division is the core work of establishing a finite element model, and the node and unit data are defined by a grid assembly generated by the grid division; on the basis of the geometric model, automatically dividing grids by a computer through certain control; after the grid model is subjected to necessary inspection and corresponding processing, boundary conditions of the grid are set, wherein the boundary conditions reflect complex loads born by the pipeline and are expression forms of actual stress states on the finite element model; two links are generally needed for establishing the boundary condition, namely, the actual stress state is quantized, namely, the stress state is expressed as a definable mathematical form on a geometric model, for example, the distribution rule of surface pressure and the internal pressure distribution of a pipeline are determined, test data are needed, and then the quantized stress state is defined as the boundary condition on the model. The boundary condition reflects the interaction between the analysis object and the outside, is the expression form of the actual working condition on the finite element model, such as axial movement or lateral constraint, compression load, bending load and internal pressure, and is provided with a saddle to limit the displacement of the pipeline along the direction of the pressure head, and the saddle boundary condition is all the node full constraint. The contact surfaces of the pressure head and the pipeline and the contact surfaces of the pipeline and the saddle are required to be contacted, the pipeline is respectively set as a target surface, and the surfaces of the pressure head and the saddle are contact surfaces. After reasonable grid forms are divided and correct boundary conditions are defined, a complete finite element model is built, and then a corresponding analysis program can be called to calculate the model, and then calculation results are displayed, processed and studied. The finite element model is adopted to analyze the stress strain state of the pipeline, so that the actual shape of the sunken pipeline is realized, the condition that the pipeline is influenced by the pressure head to displace is restored, the stress strain of the pipeline after being pressed is calculated by using the finite element method, and an accurate basis can be provided for evaluating the structural integrity of the pipeline containing the sunken pipeline.

According to one embodiment of the present disclosure, a finite element model of a pipeline is built by using an actual pressure head including a depression, as shown in fig. 5, which is a finite element model of a depression pipe section including an actual pressure head 501, and based on the actual shape of a reduced depression pipeline, the situation that the pipeline is displaced under the influence of the pressure head is considered, and the stress strain of the pipeline after being pressed is obtained by calculating by a finite element method, so that an accurate basis is provided for evaluating the structural integrity of the pipeline including the depression. Firstly, selecting a unit type of a pipe section, dividing grids, setting boundary conditions and applying loads, and establishing a finite element model, wherein the process further comprises the steps of selecting a Solid unit for the pipeline and a pressure head unit type, selecting a unit of a full-size finite element model of a concave pipeline with an axial grid of 10mm and an annular grid of 5mm and a radial grid of 5mm, and the unit selection comprises a 3D Solid unit Solid 45 with 8 nodes, a target unit target 170 and a Contact unit Contact 174. Further, the saddle 503 is arranged to limit the displacement of the pipeline along the direction of the pressure head, wherein the saddle 503 is positioned at the bottom of the pipeline 502, so that the pipeline is buried in the ground under the actual working condition, the transverse displacement cannot occur, and the saddle is provided with the boundary condition to fully restrict all nodes; then, contact conditions are set, including setting contact between the pressure head 501 and the contact surface of the pipeline and between the pipeline and the saddle, respectively setting the pipeline as a target surface, and setting the pressure head and the saddle surface as contact surfaces, so as to ensure that the pipeline is not deformed and restrict translation and rotation of the pipeline.

In the embodiment of the present description, after a complete finite element model is constructed, the model is calculated by calling a corresponding analysis program, a combined load is applied, the load needs to be set in two steps,

selecting the inner surface of the pipeline for pressurization, setting an internal pressure load and setting a pressure head to have no displacement;

setting a displacement load of the pressing head, and applying the displacement load of the pressing head to be the concave depth +a, wherein a is a load correction coefficient. The value is taken according to the steel grade of the pipeline, when the steel grade is X60, the value of a is 5-10, and when the steel grade is X80, the value of a is 10-15. According to the above value range and the material parameters obtained in step 201, the pipeline stress strain cloud image of the actual concave morphology is finally obtained, and the maximum equivalent stress and the maximum equivalent strain of the pipeline concave surface are further obtained according to the stress strain cloud image of the finite element model, the stress strain cloud image can realize the distribution trend of the stress and the strain, the actual situation is generally simulated according to the stress or the strain size and the distribution situation borne by the color distinguishing model, the stress strain critical value of the pipeline concave position, namely the maximum equivalent stress and the maximum equivalent strain, can be obtained, and when the stress or the strain borne by the pipeline concave position exceeds the critical value, the pipeline is likely to break or generate a groove, and the safe operation of the pipeline is threatened.

Illustratively, according to one embodiment of the present description, the collection pipe parameters are as follows: the diameter of the pipeline is 1016mm, the wall thickness of the pipeline is 14.6mm, the steel grade is X80, the length of the recess is 290mm, and the depth of the recess is 45.76mm; based on a 3D laser scanning method, extracting three-dimensional data points of a concave contour with a step length of 10mm to obtain three-dimensional data points of a concave region; and then generating an interpolation curve by using the cubic B-spline interpolation method and taking the data under the same axis as a group. Then, the curve under different axes is covered to obtain a concave curved surface, the curved surface is further extended for 10mm to form an actual pressure head shape of the pipeline, a saddle is arranged at the opposite bottom of the pressure head to limit the displacement of the pipeline and restrict the translational and rotational displacement of the saddle, the pipeline and the pressure head unit type are Solid units, the axial and circumferential direction grids are 10mm, the radial direction grids are 5mm, and the unit selection of the concave pipeline full-size finite element model comprises a 3D Solid unit Solid 45 with 8 nodes, a target unit target 170 and a Contact unit Contact 174. In addition, contact conditions are set at the contact position of the pressure head and the pipeline and at the contact position of the saddle and the pipeline, and the load is applied to the model in two steps. Selecting a pipeline inner surface node in the first step, applying internal pressure of 5MPa, and limiting the pressure head to have no displacement; in the second step, a displacement load of 55.76 is applied to the pressure head, a load correction coefficient is 10, and finally, a pipeline stress strain cloud chart with an actual concave shape is obtained, as shown in fig. 6, the stress strain cloud chart can realize the distribution trend of stress and strain, and according to the size and distribution condition of stress or strain borne by the color distinguishing model, the stress strain of the area is closer to a critical value, namely the maximum equivalent stress and the maximum equivalent strain, the shallower the color is. The maximum equivalent stress of the surface of the concave tube body is 663.603MPa, and the maximum equivalent strain is 5.29%.

Based on the same inventive concept, fig. 7 is a schematic structural diagram of a stress-strain calculating device with irregular concave shape of a pipe according to an embodiment of the present disclosure, which specifically includes,

a parameter collecting unit 701, configured to obtain a pipeline size and a morphology parameter of a concave region;

the scanning unit 702 is used for scanning the concave area of the pipeline by using 3D laser to determine the actual shape of the three-dimensional concave;

a three-dimensional data point unit 703, configured to obtain a three-dimensional data point of the concave region according to the three-dimensional concave actual morphology;

a B-spline interpolation unit 704, configured to restore a ram shape based on the pipeline size and the morphological parameters of the recessed area by adopting a cubic B-spline interpolation function according to the three-dimensional data points of the recessed area;

and the finite element model unit 705 is configured to establish a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, so as to obtain the stress-strain state of the concave region.

The beneficial effects obtained by the device are consistent with those obtained by the method, and the embodiments of the present disclosure are not repeated.

Fig. 8 is a schematic structural diagram of a computer device according to an embodiment of the present invention, where the apparatus in the present invention may be the computer device in the present embodiment, and perform the method of the present invention. The computer device 802 may include one or more processing devices 804, such as one or more Central Processing Units (CPUs), each of which may implement one or more hardware threads. The computer device 802 may also include any storage resources 806 for storing any kind of information, such as code, settings, data, etc. For example, and without limitation, storage resources 806 may include any one or more of the following combinations: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any storage resource may store information using any technology. Further, any storage resource may provide volatile or non-volatile retention of information. Further, any storage resources may represent fixed or removable components of computer device 802. In one case, the computer device 802 may perform any of the operations of the associated instructions when the processing device 804 executes the associated instructions stored in any storage resource or combination of storage resources. The computer device 802 also includes one or more drive mechanisms 808, such as a hard disk drive mechanism, an optical disk drive mechanism, and the like, for interacting with any storage resources.

The computer device 802 may also include an input/output module 810 (I/O) for receiving various inputs (via an input device 812) and for providing various outputs (via an output device 814). One particular output mechanism may include a presentation device 816 and an associated Graphical User Interface (GUI) 818. In other embodiments, input/output module 810 (I/O), input device 812, and output device 814 may not be included, but merely as a computer device in a network. The computer device 802 may also include one or more network interfaces 820 for exchanging data with other devices via one or more communication links 822. One or more communications buses 824 couple the above-described components together.

The communication link 822 may be implemented in any manner, such as, for example, through a local area network, a wide area network (e.g., the internet), a point-to-point connection, etc., or any combination thereof. Communication link 822 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

Corresponding to the method in fig. 2 to 5, an embodiment of the invention also provides a computer readable storage medium having a computer program stored thereon, which computer program, when being executed by a processor, performs the above steps.

Embodiments of the present invention also provide a computer readable instruction, wherein the program therein causes a processor to perform the method as shown in fig. 2 to 5 when the processor executes the instruction.

Embodiments of the invention also provide a computer program product which, when run by a processor of a computer device, performs a method according to the method shown in fig. 2 to 5.

It should be understood that, in various embodiments of the present invention, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

It should also be understood that, in the embodiment of the present invention, the term "and/or" is merely an association relationship describing the association object, indicating that three relationships may exist. For example, a and/or B may represent: a exists alone, A and B exist together, and B exists alone. In the present specification, the characters "," generally indicate that the front and rear related objects are in an "or" relationship.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and the various illustrative elements and steps are described above in terms of functions generally in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or elements, or may be an electrical, mechanical, or other form of connection.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present invention.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention is essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied 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, or 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.

The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.

Claims (10)

1. The stress-strain calculation method for the irregular concave morphology of the pipeline is characterized by comprising the following steps of:

obtaining the shape parameters of the pipeline size and the concave area;

scanning a concave area of the pipeline to determine the actual shape of the three-dimensional concave;

according to the three-dimensional concave actual morphology, three-dimensional data points of the concave area are obtained;

according to the three-dimensional data points of the concave area, adopting a cubic B spline interpolation function, and reducing the shape of the pressure head based on the pipeline size and the shape parameters of the concave area;

and establishing a concave pipeline finite element model according to the pipeline size and the pressure head shape, and obtaining the stress strain state of the concave area.

2. The method of claim 1, wherein the parameters of the pipe dimensions and the morphology of the recessed area include pipe diameter, wall thickness, steel grade, recessed area and recessed depth.

3. The method of claim 1, wherein scanning the recessed region of the pipe comprises scanning a range boundary greater than the recessed region boundary.

4. A stress-strain calculation method for irregular pit morphology of a pipe according to claim 1 or 3, wherein obtaining three-dimensional data points of the pit region based on the three-dimensional pit actual morphology comprises,

extracting the three-dimensional concave actual morphology by scanning;

performing transverse and longitudinal arc surface segmentation on the three-dimensional concave actual morphology to obtain three-dimensional concave actual morphology coordinates of a plurality of arc surfaces as three-dimensional data points of the concave area, wherein the axial distance between the arc surfaces is not less than 20mm,

the number of sections along the axial direction of the pipeline is not less than 11 concave sections.

5. The method for calculating stress-strain of irregular concave morphology of pipeline according to claim 1, wherein the reducing the shape of the indenter based on the pipeline size and the morphology parameters of the concave region by adopting a cubic B-spline interpolation function comprises,

generating a concave circumferential curve by utilizing a cubic B spline interpolation function according to the three-dimensional data points of the concave region;

and (5) smoothing all concave circumferential curves by using a skin means, and restoring the shape of the pressure head.

6. The method for calculating stress-strain of irregular concave morphology of a pipe according to claim 1, wherein the cubic B-spline interpolation function is:

wherein x represents the coordinate parameter of the contour point of the concave-shaped curved surface, B _i Is a control vertex of the curved surface; n (N) _i,3 (t) is a base function of a B-spline, the expression of which is:

wherein N is _i,k (t) is a k-th order B-spline basis function, t= [ t ] ₀ ，t ₁ ，t ₂ ，…，t _i ]Is a node vector.

7. The method of claim 1, wherein the step of creating a finite element model of the recessed pipe based on the shape of the indenter comprises,

the cell type, contact conditions, boundary conditions and load are set.

8. The method of claim 7, further comprising creating a finite element model of the recessed conduit based on the conduit dimensions and the ram shape,

setting a saddle to limit the displacement of the pipeline along the direction of the pressure head, wherein the saddle boundary condition is full constraint of all nodes; the contact surfaces of the pressure head and the pipeline and the contact surfaces of the pipeline and the saddle are required to be contacted, the pipeline is respectively set as a target surface, and the surfaces of the pressure head and the saddle are contact surfaces.

9. The method of claim 7, further comprising creating a finite element model of the recessed conduit based on the conduit dimensions and the ram shape,

the first section loading mode is that internal pressure is applied to the inner surface node of the selected pipeline, and the pressure head is limited to have no displacement;

and in the second stage loading mode, selecting the displacement load applied by the pressure head as the concave depth +a, wherein a is a load correction coefficient.

10. A stress-strain calculating device for irregular concave morphology of a pipeline is characterized by comprising,

the parameter collecting unit is used for obtaining the pipeline size and the morphology parameters of the concave area;

the scanning unit is used for scanning the concave area of the pipeline and determining the actual shape of the three-dimensional concave;

the three-dimensional data point unit is used for obtaining three-dimensional data points of the concave area according to the three-dimensional concave actual morphology;

the B spline interpolation unit is used for adopting a cubic B spline interpolation function according to the three-dimensional data points of the concave area and restoring the shape of the pressure head based on the pipeline size and the morphological parameters of the concave area;

and the finite element model unit is used for establishing a finite element model of the concave pipeline according to the pipeline size and the pressure head shape, and obtaining the stress strain state of the concave area.

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