CN117476145A - Finite element simulation-based composite material part curing deformation compensation design method - Google Patents
Finite element simulation-based composite material part curing deformation compensation design method Download PDFInfo
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Abstract
The invention discloses a finite element simulation-based composite material workpiece solidification deformation compensation design method, which comprises the steps of establishing a geometric model of a composite material workpiece and a forming tool thereof, carrying out finite element simulation calculation by assigning values to material characteristics of the composite material workpiece and the forming tool thereof, carrying out compensation design on molded surface nodes of the composite material workpiece according to a finite element calculation result by a node displacement method, and directly calculating the geometric molded surface of a compensated mold, thereby realizing accurate compensation design on the molded surface of the composite material. The method adopts a reverse iterative optimization method, optimizes the molding surface through the reverse compensation of node displacement, is very convenient and feasible for rebound compensation of complex molding surfaces, can realize the node displacement compensation of molding surfaces with different structures in different processes, obtains accurate optimal design, reduces errors caused by setting rebound values depending on experience, and has good practical value.
Description
Technical Field
The invention relates to a finite element simulation-based composite material part curing deformation compensation design method.
Background
The composite material has the advantages of higher specific strength, corrosion resistance, fatigue resistance, strong designability and the like, and is widely applied to the field of aerospace.
The autoclave curing molding process is a main molding process of a composite material member, and is influenced by reasons such as inconsistent thermal expansion coefficients of a composite material and a mold, chemical shrinkage deformation of resin, interaction between the mold and a part and the like, internal stress can be generated on the composite material member in the curing process, after the composite material part is demolded, the stress is released, so that rebound deformation is generated, and the deformation has extremely adverse effects on the profile quality of the part and the matching relationship between the parts.
At present, cure deformation is reduced or counteracted mainly by two methods: optimizing a curing and forming process method of the autoclave, for example, optimizing heating and cooling rates, adjusting layering angles and the like to reduce deformation; another approach is to correct the mold profile by setting the rebound angle. However, both methods are based on a large number of experiments, and the curing deformation is reduced by repeatedly correcting the technological parameters and the mould size, so that a large amount of manpower and material resources are consumed.
With the development of finite element technology and computer computing capability, autoclave molding simulation prediction is performed on composite members based on a finite element method, and the tool profile is compensated according to a prediction result, so that repeated iteration experiments can be replaced, and the effect of reducing solidification deformation can be achieved. Researches show that the most effective method for curing deformation is to compensate the molding surface of a forming tool, for example, chinese patent document CN113221398B discloses a prediction method for the curing deformation rebound angle of an L-shaped composite material workpiece, wherein a model surface is constructed in graphic processing software, and a characteristic structure variable of the model is assigned, wherein the characteristic structure variable comprises a curvature radius of an R region, an opening angle of the R region, a laminate thickness and lengths of flat plate regions at two sides, and then the model surface is imported into finite element processing software, and grid division, boundary constraint and material layering are carried out; then performing simulation calculation of the curing process in finite element processing software according to a preset curing deformation subroutine; then, measuring and calculating the rebound angle by adopting the same standard for the result of finite element calculation; and finally, the measuring result of the rebound angle corresponds to the geometric structure deformation, and the solidification deformation rebound angle prediction model under any geometric structure parameter is realized.
However, the molded surface of the composite material member in actual engineering is very complex, the molded surface is corrected through the rebound angle, errors easily brought by the design of setting the rebound value depending on experience are easy, the correction process is very complex, and the research and development period is long; and after the part is solidified, force application detection is usually needed to further verify whether the profile precision meets the design requirement or not, and the quality of the composite material part cannot be ensured.
Therefore, how to further improve the manufacturing precision of the composite material part, shorten the research and development period, and reduce or eliminate the use of force application detection, so as to achieve the purpose of ensuring the quality of the composite material part to meet the design requirement, is still a problem to be solved.
Disclosure of Invention
Aiming at the technical problems and in order to achieve the purposes, the invention provides a finite element simulation-based composite material part curing deformation compensation design method. The specific technical scheme is as follows:
a composite material workpiece solidification deformation compensation design method based on finite element simulation is characterized in that a geometric model of a composite material workpiece and a forming tool thereof is built, finite element simulation calculation is carried out by assigning values to material characteristics of the composite material workpiece and the forming tool thereof, compensation design is carried out on molded surface nodes of the composite material workpiece through a node displacement method according to finite element calculation results, and the compensated mold geometric molded surface is directly calculated, so that accurate compensation design of the composite material molded surface is realized.
The method for designing the solidification deformation compensation of the composite material workpiece based on finite element simulation comprises the following steps:
step one, building a three-dimensional model
Establishing a three-dimensional model of a composite material workpiece in three-dimensional software, extracting a molding surface of the composite material workpiece, and designing a molding tool of the composite material workpiece according to the molding surface to form a three-dimensional model of the molding tool;
step two, establishing a finite element model
Leading a three-dimensional model of a composite material part established by three-dimensional software and a three-dimensional model of a forming tool thereof into finite element software, defining the interaction relation of contact surfaces, and assembling the finite element model for curing analysis;
step three, solidification simulation
Assigning a value to the finite element model structure according to the material characteristics of the composite material part and the forming tool thereof, setting a curing temperature field and boundary conditions, and performing curing simulation on the composite material part according to a curing process;
step four, profile compensation calculation
According to the finite element software, a composite material workpiece curing simulation calculation result is obtained, and a composite material workpiece demolding rebound profile node is obtained; leading out the node of the rebound molding surface, comparing the rebound surface with a theoretical molding surface, and reversely compensating the node to form a compensation molding surface of the molding tool;
step five, verifying the compensation result
And (3) manufacturing a molding tool of the composite material part according to the molded surface compensation calculation result, paving the material, curing and molding the composite material part by adopting an autoclave, and verifying the compensation calculation result and optimizing the compensation coefficient by detecting the molded surface of the prepared composite material part.
The method for designing the solidification deformation compensation of the composite material workpiece based on finite element simulation comprises the step of establishing a three-dimensional model by using CATIA as software.
The method for designing the solidification deformation compensation of the composite material workpiece based on the finite element simulation comprises the following steps of preprocessing before the three-dimensional model is imported into finite element software, namely, meshing the built three-dimensional model of the composite material workpiece and a forming tool thereof by adopting software, and importing finite element analysis software.
According to the method for designing the solidification deformation compensation of the composite material part based on the finite element simulation, the software for carrying out grid division on the three-dimensional model of the composite material part and the forming tool of the composite material part is preferably Hypermesh; the finite element analysis software is preferably PAM-compositions.
In the method for designing the solidification deformation compensation of the composite material workpiece based on finite element simulation, when the composite material workpiece is a C-section frame workpiece, the preparation material assignment of the composite material workpiece is T800/epoxy resin prepreg, and the material assignment of the molding tool is Q235 steel; the set curing temperature field and boundary conditions are as follows: the pressure maintaining pressure of the autoclave is 0.6MPa, the pressure maintaining time is 150min, the heat preservation temperature is 180 ℃, and the temperature rising and reducing speed is 2 ℃/min.
The method for designing the solidification deformation compensation of the composite material workpiece based on finite element simulation comprises the following steps of:
setting:
P n representing an initial position of a composite member node n; wherein, n=1, 2,3 · N is the same as the sum of the values of N, N is the total number of nodes of the original molded surface of the composite material component;
A nk indicating that the node n is solidified and deformed after k times of compensationIs a position of (2); wherein, k=0, 1,2 · the flow rate of the product is as follows, representing the number of compensations experienced by the composite member node n when it reaches the ideal profile; when k=0, the node n of the composite material component is not subjected to node profile compensation, and the position of the node n is calculated for the first finite element; when k=m, the composite member node n undergoes m times of compensation;
C nk representing the position of the node n after the kth compensation;
P n A nk representing the displacement vector of the node n relative to the reference point after k times of compensation;
P n C nk representing the position vector of the node n after k times of compensation;
C nk A n(k+1) representing the compensation displacement vector of the node n in k+1 times;
then: the initial state of the node n of the composite material component is P n After curing at the initial position, the deformed position is A n0 The deformation vector is P n A n0 ；
The reverse compensation algorithm defining any node of the composite member is as follows:
the reverse compensation direction is along the normal direction of the curved surface where the node is located at the node and is opposite to the deformation direction; the compensation step length is as follows:
||C n(k-1) C nk ||＝||P n B nk ||＝||λP n A nk || (1)；
the compensation step length of the initial deformation is as follows:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (2)；
wherein B is nk The position of the compensation for the Kth time relative to the previous compensation result is represented by lambda, which is a compensation coefficient and takes a value of 1;
if the deformation simulation value after compensation is still greater than the precision requirement of the composite member, the composite member is required to be assembled according to the node group C n0 Performing secondary reverse compensation on the new composite material component molded surface;
simulation of knots at second deformationAfter the beam, the deformation vector of the node n is C n0 A n1 At this time, the deformation position is opposite to the reference point P n The deformation of (C) is P n A n1 The corresponding compensation step size that can be found according to equation (1) is:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (3)；
thus, the reverse compensation quantity of the node n relative to the reference point can be obtained as follows;
P n C n1 ＝P n C n0 +C n0 C n1 ＝P n C n0 +λP n A n1 (4)；
and so on, after k times of compensation, the deformation vector of the node n is C nk A n(k+1) The deformation amount of the deformation position relative to the reference datum point is P n A n(k+1) The deformation compensation vector of the node n is P n B n(k+1) ；
Note that the set of nodes within the composite member is p= (P) 1 ,P 2 ,P 3 ···P n ···P N ) The deformation quantity set X= { X of each node relative to the theoretical profile after each step of compensation can be obtained by performing the compensation calculation on all the nodes 1 ,x 2 ,x 3 ···x N }；
The condition for the end of the deformation compensation is that after the kth compensation, all nodes in the node deformation set X satisfy the following inequality:
x nk ＝||P n A n(k+1) || max ＜ε(x nk ∈X k ) (5)。
according to the method for designing the solidifying deformation compensation of the composite material workpiece based on finite element simulation, the molded surface of the prepared composite material workpiece is detected by adopting three-coordinate detection equipment.
The invention has the following beneficial effects:
compared with the prior art, the invention performs finite element calculation by establishing the three-dimensional geometric model and assigning values to the material characteristics, compensates the profile by a node displacement method, finally performs optimal design on the parts, and is very convenient and feasible for rebound compensation of the complex profile.
The compensation mode adopts a reverse iteration optimization method, optimizes the molding surface through the reverse compensation of the node displacement, and provides a basis for the optimization design of the molding tool.
In addition, the invention can realize the displacement compensation of profile nodes with different processes and structures, can obtain accurate optimal design in simulation and experiments, reduces errors caused by setting rebound value design by relying on experience in the past, can directly obtain the compensated molding surface of the molding die, provides a method for controlling solidification deformation, and has good practical value.
Drawings
FIG. 1 is a flow chart of a method for designing the curing deformation compensation of a composite material part in finite element simulation;
FIG. 2 is a cross-sectional view of a structure of a composite material part of the frame type with a C section according to the present invention;
FIG. 3 is a schematic diagram showing the deformation of the model of the C-section frame composite material part in the finite element analysis result;
FIG. 4 is a schematic diagram of the principle of the compensation of the profile nodes of the C-section frame type composite material workpiece;
FIG. 5 is a schematic view showing the result of compensating the nodes of the molded surface of the C-section frame composite material product of the present invention
FIG. 6 is a schematic view of the compensated profile deformation of a composite material part of the C-section frame type according to the present invention.
Detailed Description
The technical solution of the present invention will be clearly and completely described in conjunction with the following embodiments, and it is apparent that the described embodiments are merely preferred embodiments of the present invention, not all embodiments, nor are other forms of limitation of the present invention, and any person skilled in the art may make modifications or adaptations using the disclosed technical content. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Example 1
The embodiment is a composite material workpiece curing deformation compensation design method based on finite element simulation, as shown in fig. 1, by establishing a geometric model of a composite material workpiece and a forming tool thereof, assigning values to material characteristics of the composite material workpiece and the forming tool thereof, performing finite element simulation calculation, compensating the profile nodes of the composite material workpiece according to a finite element calculation result by a node displacement method, and directly calculating the compensated geometric profile of a die, thereby realizing the precise compensation design of the composite material profile. The method specifically comprises the following steps:
step one, building a three-dimensional model
Establishing a three-dimensional model of a composite material workpiece in three-dimensional software, extracting a molding surface of the composite material workpiece, and designing a molding tool of the composite material workpiece according to the molding surface to form a three-dimensional model of the molding tool; the software used to build the three-dimensional model is CATIA, preferably CATIA V5R18.
Step two, establishing a finite element model
Leading the three-dimensional model of the composite material part established by the three-dimensional software and the three-dimensional model of the forming tool into finite element software; before finite element software is introduced, the established three-dimensional model of the composite material part and the forming tool thereof is subjected to grid division by adopting software, then the initial geometric grid is introduced into finite element analysis software, and the interaction relation of the contact surface is defined to be assembled into a finite element model for curing analysis. The software for carrying out grid division on the three-dimensional model of the composite material part and the forming tool of the composite material part is preferably Hypermesh; the finite element analysis software is preferably PAM-components, and in other embodiments, other simulation software may be used, as long as the same function can be achieved, and parameters may be set to perform the curing molding simulation.
Step three, solidification simulation
Assigning a value to the finite element model structure according to the material characteristics of the composite material part and the forming tool thereof, setting a curing temperature field and boundary conditions, and performing curing simulation on the composite material part according to a curing process; when setting parameters for curing simulation, the parameters can be correspondingly adjusted according to specific curing process requirements so as to meet simulation requirements.
Step four, profile compensation calculation
According to the finite element software, a composite material workpiece curing simulation calculation result is obtained, and a composite material workpiece demolding rebound profile node is obtained; and leading out the node of the molding surface after rebound, comparing the rebound surface with the theoretical molding surface, and forming the compensation molding surface of the molding tool by reversely compensating the node. The node reverse compensation is performed to form a compensation molding surface, and the specific algorithm is as follows:
setting:
P n representing an initial position of a composite member node n; wherein, n=1, 2,3 · N is the same as the sum of the values of N, N is the total number of nodes of the original molded surface of the composite material component;
A nk representing the position of solidification deformation of the node n after k times of compensation; wherein, k=0, 1,2 · the flow rate of the product is as follows, representing the number of compensations experienced by the composite member node n when it reaches the ideal profile; when k=0, the node n of the composite material component is not subjected to node profile compensation, and the position of the node n is calculated for the first finite element; when k=m, the composite member node n undergoes m times of compensation;
C nk representing the position of the node n after the kth compensation;
P n A nk representing the displacement vector of the node n relative to the reference point after k times of compensation;
P n C nk representing the position vector of the node n after k times of compensation;
C nk A n(k+1) representing the compensation displacement vector of the node n in k+1 times;
then: the initial state of the node n of the composite material component is P n After curing at the initial position, the deformed position is A n0 The deformation vector is P n A n0 ；
The reverse compensation algorithm defining any node of the composite member is as follows:
the reverse compensation direction is along the normal direction of the curved surface where the node is located at the node and is opposite to the deformation direction; the compensation step length is as follows:
||C n(k-1) C nk ||＝||P n B nk ||＝||λP n A nk || (1)；
the compensation step length of the initial deformation is as follows:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (2)；
wherein B is nk The position of the compensation for the Kth time relative to the previous compensation result; lambda is a compensation coefficient, and the value is 1;
if the deformation simulation value after compensation is still greater than the precision requirement of the composite member, the composite member is required to be assembled according to the node group C n0 Performing secondary reverse compensation on the new composite material component molded surface;
after the second deformation simulation is finished, the deformation vector of the node n is C n0 A n1 At this time, the deformation position is opposite to the reference point P n The deformation of (C) is P n A n1 The corresponding compensation step size that can be found according to equation (1) is:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (3)；
thus, the reverse compensation quantity of the node n relative to the reference point can be obtained as follows;
P n C n1 ＝P n C n0 +C n0 C n1 ＝P n C n0 +λP n A n1 (4)；
and so on, after k times of compensation, the deformation vector of the node n is C nk A n(k+1) The deformation amount of the deformation position relative to the reference datum point is P n A n(k+1) The deformation compensation vector of the node n is P n B n(k+1) ；
Note that the set of nodes within the composite member is p= (P) 1 ,P 2 ,P 3 ···P n ···P N ) The deformation quantity set X= { X of each node relative to the theoretical profile after each step of compensation can be obtained by performing the compensation calculation on all the nodes 1 ,x 2 ,x 3 ···x N }；
The condition for the end of the deformation compensation is that after the kth compensation, all nodes in the node deformation set X satisfy the following inequality:
x nk ＝||P n A n(k+1) ‖ max ＜ε(x nk ∈X k ) (5)。
step five, verifying the compensation result
Manufacturing a forming tool of the composite material part according to the profile compensation calculation result, paving a material, curing and forming the composite material part by adopting an autoclave, detecting and verifying the compensation calculation result on the prepared composite material part profile by adopting three-coordinate detection equipment, and if the profile tolerance requirement is met in a free state of the part, obtaining an accurate calculation result; if the verification result is inaccurate, the out-of-tolerance direction and trend are analyzed, the compensation coefficient is adjusted according to the out-of-tolerance value, and the design is compensated again.
The foregoing is based on a finite optimized compensation coefficient. The method for designing the solidifying deformation compensation of the composite material part comprises the steps that when the composite material part is a C-section frame type part, the preparation material assignment of the composite material part is T800/epoxy resin prepreg, and the material assignment of a forming tool is Q235 steel; the set curing temperature field and boundary conditions are as follows: the pressure maintaining pressure of the autoclave is 0.6MPa, the pressure maintaining time is 150min, the heat preservation temperature is 180 ℃, and the temperature rising and reducing speed is 2 ℃/min.
Example 2
The method for designing the curing deformation compensation of the composite material part based on finite element simulation, which is described in the embodiment 1, is adopted to perform the curing deformation compensation design on the composite material part of the C section frame type of the large-scale aircraft. The cross section of the component is shown in fig. 2, the structure is in an irregular circular arc shape, the profile structure is special, the profile is corrected through the rebound angle, errors are easy to generate, the rebound angle to be corrected is more, the process is very complicated, the research and development period is long, and the subsequent assembly efficiency and quality are affected after the molding.
In the embodiment, the method for designing the solidification deformation compensation of the composite material part based on finite element simulation, which is described in embodiment 1, is adopted, three-dimensional models of the C-section frame type composite material part are established by CATIA three-dimensional software, forming surfaces of the three-dimensional models are extracted, and forming tools of the three-dimensional models are designed; and then leading in finite element analysis software to carry out calculation analysis and compensation. The method comprises the following steps:
step one, building a three-dimensional model
And (3) establishing a three-dimensional model of the C-section frame composite material workpiece in CATIA dimensional software, extracting a molding surface of the C-section frame composite material workpiece, and designing a molding tool of the C-section frame composite material workpiece.
Step two, establishing a finite element model
Dividing a three-dimensional model of the C-section frame type composite material workpiece and a forming tool three-dimensional model of the C-section frame type composite material workpiece into grids by adopting Hypermesh which is a finite element preprocessing software, and importing an initial geometric grid into PAM-COMPOSITS finite element software; in preparation for cure analysis.
Step three, solidification simulation
Assigning the prepreg of the C-section frame composite material part as T800/epoxy resin prepreg, and assigning the material of a forming tool of the prepreg as Q235 steel; setting a curing temperature field and boundary conditions as follows: the autoclave has a dwell pressure of 0.6MPa, dwell time of 150min, holding temperature of 180 ℃, heating and cooling rates of 2 ℃/min, and curing simulation to obtain the profile deformation, as shown in figure 3.
Step four, profile compensation calculation
And calculating a demolding rebound profile node of the C-section frame type composite material workpiece through finite element software, guiding out the rebound molding surface node, comparing the rebound surface with a theoretical profile, and forming a compensation profile of the molding tool through reversely compensating the node. The node reverse compensation is performed to compensate the molding surface, as shown in fig. 4, and the specific algorithm is as follows:
setting:
P n representing the initial position of a node n of the C-section frame type composite material workpiece; wherein, n=1, 2,3 · N is the same as the sum of the values of N, N is the total number of nodes of the original molded surface of the C-section frame type composite material product, and in the embodiment, N is165195；
A nk Representing the position of the solidification deformation of the node n after k times of compensation; wherein, k=0, 1,2 · the flow rate of the product is as follows, representing the compensation times of the node n of the C section frame type composite material part when the node n reaches an ideal molded surface; when k=0, the node n of the composite material component is not subjected to node profile compensation, and the position of the node n is calculated for the first finite element; when k=m, the composite member node n undergoes m times of compensation;
C nk representing the position of the node n after the kth compensation;
P n A nk representing the displacement vector of the node n relative to the reference point after k times of compensation;
P n C nk representing the position vector of the node n after k times of compensation;
C nk A n(k+1) representing the compensation displacement vector of the node n in k+1 times;
it can be seen from fig. 4 that: the initial state of the node n of the C-section frame type composite material part is P n After curing at the initial position, the deformed position is A n0 The deformation vector is P n A n0 ；
The reverse compensation algorithm for defining any node of the C-section frame type composite material part is as follows:
the reverse compensation direction is along the normal direction of the curved surface where the node is located at the node and is opposite to the deformation direction; the compensation step length is as follows:
||C n(k-1) C nk ||＝||P n B nk ||＝||λP n A nk || (1)；
the compensation step length of the initial deformation is as follows:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (2)；
wherein B is nk The position of the compensation for the Kth time relative to the previous compensation result is represented by lambda, which is a compensation coefficient and takes a value of 1;
if the deformation simulation value after compensation is still larger than the C section frame complexThe precision requirement of the composite material part is that according to the node group C n0 Performing secondary reverse compensation on the molded surface of the novel C-section frame composite material molded part;
after the second deformation simulation is finished, the deformation vector of the node n is C n0 A n1 At this time, the deformation position is opposite to the reference point P n The deformation of (C) is P n A n1 The corresponding compensation step size that can be found according to equation (1) is:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (3)；
thus, the reverse compensation quantity of the node n relative to the reference point can be obtained as follows;
P n C n1 ＝P n C n0 +C n0 C n1 ＝P n C n0 +λP n A n1 (4)；
and so on, after k times of compensation, the deformation vector of the node n is C nk A n(k+1) The deformation amount of the deformation position relative to the reference datum point is P n A n(k+1) The deformation compensation vector of the node n is P n B n(k+1) ；
Note that the set of nodes within the composite member is p= (P) 1 ,P 2 ,P 3 ···P n ···P N ) The deformation quantity set X= { X of each node relative to the theoretical profile after each step of compensation can be obtained by performing the compensation calculation on all the nodes 1 ,x 2 ,x 3 ···x N }；
The condition for the end of the deformation compensation is that after the kth compensation, all nodes in the node deformation set X satisfy the following inequality:
x nk ＝||P n A n(k+1) ‖ max ＜ε(x nk ∈X k ) (5)。
the compensation results are shown in fig. 5 and 6.
Step five, verifying the compensation result
And manufacturing a forming tool of the C-section frame type composite material workpiece according to the molded surface compensation calculation result, paving the material, curing and forming the C-section frame type composite material workpiece by adopting an autoclave, detecting the molded surface of the prepared C-section frame type composite material workpiece by adopting a three-coordinate detection device, meeting the molded surface tolerance requirement in the free state of the part, and verifying that the result is accurate.
According to the invention, the three-dimensional geometric model is established, finite element calculation is performed through material characteristic assignment, the profile is compensated through a node displacement method, and finally, the parts are optimally designed, so that rebound compensation of the complex profile is very convenient and feasible. The compensation mode adopts a reverse iterative optimization method, and the forming surface is optimized through the reverse compensation of the node displacement, so that a basis is provided for the optimal design of the forming tool.
In addition, the invention can realize the displacement compensation of profile nodes with different processes and structures, can obtain accurate optimal design in simulation and experiments, reduces errors caused by setting rebound value design by relying on experience in the past, can directly obtain the compensated molding surface of the molding die, provides a method for controlling solidification deformation, and has good practical value. .
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail herein, but rather is provided for the purpose of enabling those skilled in the art to make and use the embodiments described herein.
Claims (8)
1. A composite material part curing deformation compensation design method based on finite element simulation is characterized by comprising the following steps of: the geometric model of the composite material part and the forming tool thereof is established, finite element simulation calculation is carried out by assigning values to the material characteristics of the composite material part and the forming tool thereof, the compensation design is carried out on the profile nodes of the composite material part by a node displacement method according to the finite element calculation result, and the geometric profile of the compensated die is directly calculated, so that the precise compensation design of the composite material profile is realized.
2. The method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 1, wherein the method comprises the following steps: the method comprises the following steps:
step one, building a three-dimensional model
Establishing a three-dimensional model of a composite material workpiece in three-dimensional software, extracting a molding surface of the composite material workpiece, and designing a molding tool of the composite material workpiece according to the molding surface to form a three-dimensional model of the molding tool;
step two, establishing a finite element model
Leading a three-dimensional model of a composite material part and a three-dimensional model of a forming tool thereof established by three-dimensional software into finite element software, defining the interaction relation of contact surfaces, and assembling the finite element model for curing analysis;
step three, solidification simulation
Assigning a value to the finite element model structure according to the material characteristics of the composite material part and the forming tool thereof, setting a curing temperature field and boundary conditions, and performing curing simulation on the composite material part according to a curing process;
step four, profile compensation calculation
According to the finite element software, a composite material workpiece curing simulation calculation result is obtained, and a composite material workpiece demolding rebound profile node is obtained; leading out the node of the rebound molding surface, comparing the rebound surface with a theoretical molding surface, and reversely compensating the node to form a compensation molding surface of the molding tool;
step five, verifying the compensation result
And (3) manufacturing a molding tool of the composite material part according to the molded surface compensation calculation result, paving the material, curing and molding the composite material part by adopting an autoclave, and verifying the compensation calculation result and optimizing the compensation coefficient by detecting the molded surface of the prepared composite material part.
3. The finite element simulation-based composite material part curing deformation compensation design method is characterized by comprising the following steps of: the software used to build the three-dimensional model is CATIA.
4. The method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 2, wherein the method comprises the following steps: before the three-dimensional model is imported into the finite element software, a preprocessing step is further provided, namely, the built three-dimensional model of the composite material part and the forming tool thereof is subjected to grid division by adopting software, and then finite element analysis software is imported.
5. The method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 4, wherein the method comprises the following steps: the software for carrying out grid division on the three-dimensional model of the composite material part and the forming tool of the composite material part is Hypermesh; the finite element analysis software is PAM-COMPOSITS.
6. The method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 2, wherein the method comprises the following steps:
when the composite material part is a C-section frame type part, the preparation material value of the composite material part is T800/epoxy resin prepreg, and the material value of a forming tool is Q235 steel;
the set curing temperature field and boundary conditions are as follows: the pressure maintaining pressure of the autoclave is 0.6MPa, the pressure maintaining time is 150min, the heat preservation temperature is 180 ℃, and the temperature rising and reducing speed is 2 ℃/min.
7. The method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 2, wherein the method comprises the following steps: the node reverse compensation is performed to form a compensation molding surface, and the specific algorithm is as follows:
setting:
P n representing an initial position of a composite member node n; wherein, n=1, 2,3 · N is the same as the sum of the values of N, N is the total number of nodes of the original molded surface of the composite material component;
A nk representing the position of solidification deformation of the node n after k times of compensation; wherein, k=0, 1,2 · the flow rate of the product is as follows, representing the number of compensations experienced by the composite member node n when it reaches the ideal profile; when k=0, the node n of the composite material component is not subjected to node profile compensation, and the position of the node n is calculated for the first finite element; when k=m, the composite member node n undergoes m times of compensation;
C nk representing the position of the node n after the kth compensation;
P n A nk representing the displacement vector of the node n relative to the reference point after k times of compensation;
P n C nk representing the position vector of the node n after k times of compensation;
C nk A n(k+1) representing the compensation displacement vector of the node n in k+1 times;
then: the initial state of the node n of the composite material component is P n After curing at the initial position, the deformed position is A n0 The deformation vector is P n A n0 ；
The reverse compensation algorithm defining any node of the composite member is as follows:
the reverse compensation direction is along the normal direction of the curved surface where the node is located at the node and is opposite to the deformation direction; the compensation step length is as follows:
||C n(k-1) C nk ||＝||P n B nk ||＝||λP n A nk || (1)；
the compensation step length of the initial deformation is as follows:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (2)；
wherein B is nk The position of the compensation for the Kth time relative to the previous compensation result; lambda is a compensation coefficient, and the value is 1;
if the deformation simulation value after compensation is still greater than the precision requirement of the composite member, the composite member is required to be assembled according to the node group C n0 Performing secondary reverse compensation on the new composite material component molded surface;
after the second deformation simulation is finished, the deformation vector of the node n is C n0 A n1 At this time, the deformation position is opposite to the reference point P n The deformation of (C) is P n A n1 The corresponding compensation step size that can be found according to equation (1) is:
||P n C n0 ||＝||P n B n0 ||＝λ||P n A n0 || (3)；
thus, the reverse compensation quantity of the node n relative to the reference point can be obtained as follows;
P n C n1 ＝P n C n0 +C n0 C n1 ＝P n C n0 +λP n A n1 (4)；
and so on, after k times of compensation, the deformation vector of the node n is C nk A n(k+1) The deformation amount of the deformation position relative to the reference datum point is P n A n(k+1) The deformation compensation vector of the node n is P n B n(k+1) ；
Note that the set of nodes within the composite member is p= (P) 1 ,P 2 ,P 3 ···P n ···P N ) The deformation quantity set X= { X of each node relative to the theoretical profile after each step of compensation can be obtained by performing the compensation calculation on all the nodes 1 ,x 2 ,x 3 ···x N }；
The condition for the end of the deformation compensation is that after the kth compensation, all nodes in the node deformation set X satisfy the following inequality:
x nk ＝||P n A n(k+1) || max ＜ε(x nk ∈X k ) (5)。
8. the method for compensating the solidification deformation of the composite material part based on finite element simulation according to claim 2, wherein the method comprises the following steps: the surface detection of the prepared composite material part is carried out by adopting three-coordinate detection equipment.
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