CN108563905B - Optimization design method for automobile B-column reinforcing plate carbon fiber reinforced composite material - Google Patents
Optimization design method for automobile B-column reinforcing plate carbon fiber reinforced composite material Download PDFInfo
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Abstract
The invention discloses an optimization design method of a carbon fiber reinforced composite material of an automobile B-column reinforcing plate, which aims to overcome the problems that the calculation time of a finite element whole automobile collision model is too long and the layering thickness, the layering angle and the layering sequence design of the carbon fiber reinforced composite material in the prior art are solved, and the optimization design method comprises the following steps: 1. decoupling the B pillar structure from the finished vehicle finite element model; 2. optimizing a B column reinforcing plate of the carbon fiber reinforced composite material: 1) establishing a static working condition of the B-column reinforcing plate; 2) the static working condition layer laying optimization of the carbon fiber reinforced composite material B-column reinforcing plate comprises (1) topology optimization; (2) optimizing the size; (3) optimizing the sequence; 3) and (3) verifying and calculating the optimization result of the B-column reinforcing plate under the dynamic working condition of the decoupling substructure: (1) improving a B column reinforcing plate; (2) carrying out analog simulation and analysis on the model with the optimized carbon fiber reinforced composite material B column reinforcing plate; (3) and checking the comparison data of the optimized B column and the B column in the original vehicle type.
Description
Technical Field
The invention relates to a design method in the field of automobile passive safety research, in particular to an automobile B-pillar structure decoupling and automobile B-pillar reinforcing plate carbon fiber reinforced composite material optimization design method.
Background
With the shortage of energy and the rise of new energy automobiles, light weight has become an indispensable research content in the current automobile industry. The lightweight design of the current main passenger car includes: structural design is carried out on vehicle body parts by adopting modes such as topology and the like, a large amount of high-strength steel is applied, and light metal, high polymer materials, ceramic materials, composite materials and other non-metal materials are used. The carbon fiber reinforced composite material has been primarily used in a composite material vehicle body structure by virtue of the advantages of low density, high specific strength, good manufacturability and the like, for example, a BMW i 7B column is locally added with the carbon fiber reinforced composite material at a key part of a metal structure to form a composite structure, so that the advantages of the carbon fiber reinforced composite material can be fully exerted, meanwhile, the cost can be reduced, the using amount can be reduced, and the carbon fiber reinforced composite material is a main application development direction for the carbon fiber reinforced composite material in the current independent brand automobile. In order to meet the requirements of higher crashworthiness and light weight required in the current social development, and with the continuous development of the forming technology of the carbon fiber reinforced composite material, the carbon fiber reinforced composite material can be more widely applied to an automobile body structure.
However, most of the current research on vehicle body light weight is simply replacing the traditional metal materials, and the parts with unsatisfactory impact resistance usually adopt the mode of increasing the plate thickness and the like to meet the requirements. However, this method does not fully utilize the designable performance of the composite material, and the effect of weight reduction is not significant, so that it is necessary to design the carbon fiber reinforced composite material in a material-structure integrated manner.
The B-pillar structure is a main energy-absorbing and force-bearing part of an automobile body in a side collision condition, is a part forming a force transmission path in the vertical direction, and can transmit force upwards to a roof longitudinal beam and then transversely transmit the force through a roof supporting cross beam. The anti-collision performance of the automobile is the most critical factor for determining the damage to human bodies under the side collision working condition, and the deformation condition of the B column can generate a certain amount of influence on the side direction structure of the whole automobile. Injuries to the human body during a side impact are primarily irreversible injuries caused by impact to the head, chest, spine and pelvic region. If the steel plate is not provided with enough rigidity, serious casualty conditions can be caused, and in the side collision condition, the steel plate has important significance for the research of the B column structure. The optimization of the carbon fiber reinforced composite material B column reinforcing plate aims to fully utilize the advantages of good specific strength, high specific modulus, corrosion resistance, fatigue resistance and the like of the fiber reinforced composite material, the thickness, angle and sequence of the laying layer of the carbon fiber reinforced composite material B column reinforcing plate are in a crucial relation to the material performance, and topology optimization, size optimization and sequence optimization are applied to the optimization of the carbon fiber reinforced composite material B column reinforcing plate to achieve the effect of light weight of an automobile.
On the other hand, at present, due to the limitation of computer performance, the calculation time of the whole vehicle collision model is too long, and the efficiency is influenced; and the fitting degree of the substructure model realized by the existing substructure decoupling method to the intrusion amount and intrusion speed curve in the whole vehicle is low. The decoupling method can accurately simplify the complex collision condition in the whole vehicle, greatly saves the calculation time and improves the calculation efficiency.
Similar decoupling and carbon fiber reinforced composite material B column reinforcing plate parameter optimization analysis methods are not found through relevant document retrieval at home and abroad.
Disclosure of Invention
The invention aims to solve the technical problems that the finite element whole vehicle collision model in the prior art is too long in calculation time and the problems of layering thickness, layering angle and layering sequence design of the carbon fiber reinforced composite material are solved, and provides an optimization design method of the carbon fiber reinforced composite material of an automobile B-column reinforcing plate.
In order to solve the technical problems, the invention is realized by adopting the following technical scheme: the method for optimally designing the automobile B-column reinforcing plate carbon fiber reinforced composite material comprises the following steps:
1) decoupling the B pillar structure from the finished vehicle finite element model:
(1) according to the original whole vehicle side collision model, parts connected with the B column are reserved to ensure the accuracy of the deformation condition of the B column, namely, the sill beam, the side coaming, the top cover beam, the tubular door collision-proof beam and the B column structure are used as a substructure model;
(2) adopting an area in a part connected with the B column, which is close to the connection position of the B column, and the foremost surface of the side collision trolley buffer honeycomb aluminum as a collision reference point, carrying out side collision finite element calculation, and extracting displacement-time curve data of the collision reference point through Ls-pre post-processing software;
(3) converting the extracted curve data into data information which can be identified by Ls-dyna simulation calculation software through MATLAB programming software, and introducing a simplified calculation k file which only keeps a B column and peripheral parts thereof and a sub-working condition model at the front end of the side collision trolley through a text editor, so that the side collision condition of the whole trolley can be accurately simulated;
2) optimizing a B column reinforcing plate of the carbon fiber reinforced composite material:
(1) establishing a static working condition of the B-column reinforcing plate;
(2) the static working condition layer laying optimization of the carbon fiber reinforced composite B-column reinforcing plate comprises the following steps:
A. topology optimization;
B. optimizing the size;
C. optimizing the sequence;
(3) and verifying and calculating the optimization result of the B-column reinforcing plate under the dynamic working condition of the decoupling substructure.
The establishment of the static working condition of the B-column reinforcing plate in the technical scheme is as follows:
(1) simple structure
Setting the thickness of the B-column reinforcing plate into a uniform initial thickness according to the geometric dimension of the structural shape of the existing B-column reinforcing plate, reserving shape and structure parameters in the original metal B-column reinforcing plate in the whole vehicle model, reserving a bolt fixing hole structure in a simplified structure, and checking the grid quality of the bolt fixing hole structure;
(2) establishment of carbon fiber reinforced composite material B column reinforcing plate
a. Changing the B-column reinforcing plate of the part to be optimized into a carbon fiber reinforced composite material, setting a layering angle, a layering sequence and a layering thickness according to experience, so that the original anti-collision performance can be kept in collision simulation, and taking the layering information as the initial parameter of the next optimization;
b. because the B-column reinforcing plates are all design areas, a ply-forming laminated plate structure is created by adopting an No. 8 anisotropic material model, PCOMPP is selected by attribute definition aiming at the design area, and because Optistruct optimization software can only thin the material without the function of thickening, a super layer with thicker initial thickness needs to be established, and the thickness of the super layer is set through initial optimization parameters;
(3) setting of load
Extracting the maximum relative displacement of the B-column reinforcing plate in the impact resistance simulation of the B-column model, calculating the numerical value of the required equivalent force, loading the numerical value into a B-column reinforcing plate structure optimization model in contact with a collision trolley, and carrying out average distribution loading on the equivalent force according to the number of loading points; reasonably neglecting and simplifying according to the magnitude of the force of the x, y and z axes, obtaining a better displacement fitting result of the static simulation model and the dynamic simulation model, and then carrying out static optimization simulation on the basis.
According to the technical scheme, the topology optimization means that:
a. defining a design variable, firstly creating a variable for topology optimization, defining two responses of quality and reference point displacement, and respectively using the two responses as an optimization response and a constraint response; creating constraint, using the reference point displacement response as constraint, setting a constraint upper limit value, and defining the minimum quality as an optimization target;
b. adjusting optimization control parameters including maximum allowable iteration times, a target tolerance value and an optimization step length;
c. defining a control card, wherein an OUTPUT card keyword needs to be defined as FSTOSZ in the control card part, and then storing or outputting a file;
d. and finally, checking, if no error information exists, starting optimization, checking a result file after the optimization is finished, and opening the thickness of an optimization result file checking unit in HyperView.
According to the technical scheme, the size optimization means that:
a. in order to ensure the correct transmission of the ply information, outputting the thickness information in a single direction in the form of the ply shape, resetting a control card, deleting an 'OMIT' card, and changing one type of keyword FSTOSZ into another type of keyword SZTOSH;
b. editing Laminate parameters, setting the form of the Laminate as Total, respectively defining size variables of each layer, ensuring that the upper limit of the thickness of each layer is modified, normalizing the thickness of each layer which cannot be modified into a similar integer, and still taking the displacement value of a reference point as a constraint condition to ensure that the optimization target is still the minimum quality;
c. the value of the workable thickness is specified, inspection optimization is performed after the optimization setting, and the thickness and the number of the layers are checked.
According to the technical scheme, the sequence optimization comprises the following steps: for a composite material, the layering sequence is closely related to the anisotropic mechanical property and the process feasibility of a laminated plate of the composite material, the change of the layering sequence of the composite material can influence the overall performance of the structure of the composite material, before the optimal layering sequence is calculated, manufacturing constraints are firstly set on variables of the layering sequence, and at most 2 layers of same layering can continuously appear in the layering in four directions of 0 degree, 90 degrees, 45 degrees and-45 degrees; the +45 degrees and-45 degrees appear in pairs to ensure symmetry, the generation of interlayer stress is avoided to the maximum extent, optimization constraint and optimization targets are unchanged, and finally layering sequence optimization is carried out; checking the output result file, and checking the layering sequence of each iteration step in a browser.
The verification calculation of the B-column reinforcing plate optimization result under the dynamic working condition of the decoupling substructure according to the technical scheme is as follows:
(1) carrying out regular partition according to the layering result to improve the B-column reinforcing plate;
(2) carrying out analog simulation calculation of the side impact trolley collision under the working condition of a decoupler on the model with the optimized carbon fiber reinforced composite material B column reinforcing plate;
(3) and checking the comparison data of the optimized B column and the B column in the original vehicle type, namely verifying the improvement degree of the performance of the B column reinforcing plate by comparing the intrusion amount of the reference point corresponding to the chest of the human body with the maximum value of the intrusion speed, and simultaneously obtaining the light weight effect of the B column reinforcing plate.
Compared with the prior art, the invention has the beneficial effects that:
1. referring to fig. 3, the optimized design method for the automobile B-pillar reinforcing plate carbon fiber reinforced composite effectively integrates the extracted displacement time curve of the relevant collision reference point of the whole automobile, and obtains a simplified decoupling B-pillar structure collision model after data processing.
2. The method for optimally designing the automobile B-column reinforcing plate carbon fiber reinforced composite material can accurately and quickly calculate the anti-collision performance of the designed carbon fiber reinforced composite material B column in the conceptual design stage of the automobile body anti-collision performance, and obtains the optimal B column parameter scheme by optimizing the angle, the thickness and the layering sequence of the novel material carbon fiber layering.
3. The optimal design method of the automobile B-column reinforcing plate carbon fiber reinforced composite material sequentially applies topology optimization, size optimization and sequence optimization to the lightweight design of the carbon fiber reinforced composite material B-column reinforcing plate. The design idea can be applied to material-structure integrated design of the composite material for the vehicle, unique material design of the composite material is realized, the designability advantage of the composite material compared with a metal material is fully utilized, and lightweight components meeting the performance requirements of the vehicle are designed quickly and efficiently.
Drawings
The invention is further described with reference to the accompanying drawings in which:
FIG. 1 is a block flow diagram of an optimized design method for a B-pillar reinforcing plate carbon fiber reinforced composite material of an automobile according to the present invention;
FIG. 2 is a decoupling B-pillar structure model of the automobile B-pillar reinforcing plate carbon fiber reinforced composite material optimization design method of the invention;
FIG. 3-1 is a fitting graph of the intrusion speed of a B-pillar structural model obtained by the method for optimally designing the carbon fiber reinforced composite material for the reinforcing plate of the B-pillar of the automobile, relative to a whole automobile model;
FIG. 3-2 is a fitting graph of the intrusion amount of a B-pillar structural model obtained by the method for optimally designing the carbon fiber reinforced composite material for the reinforcing plate of the B-pillar of the automobile, relative to the whole automobile model;
FIG. 4 is a model diagram of the shape structure parameters of a B-pillar reinforcing plate in the method for optimally designing the automobile B-pillar reinforcing plate carbon fiber reinforced composite material;
FIG. 5 is a schematic view of loading and constraint of a B-pillar reinforcing plate obtained by applying an equivalent static load method in the optimal design method of the automobile B-pillar reinforcing plate carbon fiber reinforced composite material of the present invention;
FIG. 6 is a schematic diagram of a part, where the thickness of a unit needs to be reduced, of a B-pillar reinforcing plate after topological optimization in the method for optimally designing the automobile B-pillar reinforcing plate carbon fiber reinforced composite material;
FIG. 7 is a sectional view of the optimization result of the B-pillar reinforcement plate in the method for optimally designing the automobile B-pillar reinforcement plate carbon fiber reinforced composite material of the present invention;
Detailed Description
The invention is described in detail below with reference to the attached drawing figures:
the optimal design method of the automobile B-pillar reinforcing plate carbon fiber reinforced composite material is divided into two stages, firstly, a B-pillar structure is decoupled from a finite element side collision model of a whole automobile, and subsequent calculation is carried out under the condition that the displacement-time curve fitting with a collision reference point positioned at the chest position of a human body in the whole automobile model is good, so that the computer running time is greatly reduced, and the calculation efficiency is improved; then, on the basis of the decoupled substructure model, modeling a lightweight B-pillar reinforcing plate structure according to test parameters of the carbon fiber reinforced composite material to obtain optimized initial data, namely an initial fiberboard layer and thickness; optimizing the ply angle, thickness and ply sequence of the carbon fiber B-pillar reinforcing plate by applying an equivalent static load method; and improving the B-column reinforcing plate according to the optimization result, and substituting the B-column reinforcing plate into a dynamic simulation model for calculation to verify the lightweight effect and the collision performance of the B-column reinforcing plate.
The method for optimally designing the automobile B-column reinforcing plate carbon fiber reinforced composite material comprises the following steps:
1. decoupling B pillar structure from finished vehicle finite element model
1) Referring to fig. 2, according to the original whole vehicle side collision model, the parts connected with the B-pillar are reserved to ensure the accuracy of the deformation conditions, namely, the sill beam, the side coaming, the top cover beam, the tubular door collision-proof beam, and the B-pillar structure is used as a substructure model.
2) And (3) performing side collision finite element calculation by using an area close to the connecting position of the B column in the component connected with the B column and the foremost surface of the side collision trolley buffer honeycomb aluminum as collision reference points, and extracting displacement-time curve data of the collision reference points through Ls-prepost post-processing software.
3) The extracted curve data is converted into data information which can be identified by Ls-dyna simulation calculation software through MATLAB programming software, and then a simplified calculation k file which only keeps a B column, surrounding parts of the B column and a sub-working condition model at the front end of the side collision trolley is led in through a text editor, so that the side collision condition of the whole trolley can be accurately simulated, the calculation time is greatly reduced, and the working efficiency is improved.
2. Optimization of carbon fiber reinforced composite material B column reinforcing plate
According to the invention, firstly, a metal B-column reinforcing plate is changed into a carbon fiber reinforced composite material in the B-column structure collision model obtained in the previous step, and simulation parameters are obtained through a composite material mechanical property test, including a tensile test and a shear test. The performance of the built carbon fiber reinforced composite material B-column reinforcing plate is ensured to be the same as that of the original metal B-column reinforcing plate through finite element collision simulation calculation, the laying sequence and the laying angle are set according to experience, and the laying is set as the initial parameters optimized later. Simplifying a geometric model of a B-column reinforcing plate of a passenger car, calculating a numerical value of required equivalent force according to the maximum relative displacement of the B-column reinforcing plate in the impact resistance simulation of the B-column model by adopting a method of applying equivalent static load, loading the numerical value at a B-column reinforcing plate structure optimization model contacted with a collision trolley, and carrying out average distribution loading on contact force according to the number of loading points. Carrying out topology, size and sequence optimization on the B-pillar reinforcing plate by utilizing Optistruct optimization software to obtain reasonable distribution, thickness, angle and sequence of the layer material; and finally, carrying out regional interpretation setting on the static layering optimization result and then bringing the result into Ls-Dyna simulation calculation software to verify whether the result meets the requirements under the dynamic working condition.
The carbon fiber reinforced composite material B column reinforcing plate optimization steps are as follows:
1) establishment of static working condition of B-pillar reinforcing plate
(1) Simple structure
Setting the thickness of the B-column reinforcing plate into a uniform initial thickness according to the geometric dimension of the structural shape of the existing B-column reinforcing plate, reserving shape and structure parameters in the original metal B-column reinforcing plate in the whole vehicle model, reserving a bolt fixing hole structure in a simplified structure, and checking the grid quality of the bolt fixing hole structure;
(2) establishment of carbon fiber reinforced composite material B column reinforcing plate
a. Firstly, changing a B-column reinforcing plate of a part to be optimized into a carbon fiber reinforced composite material, setting a layer laying angle, a layer laying sequence and a layer laying thickness according to experience, so that the original anti-collision performance can be kept in collision simulation, and taking the layer laying information as an initial parameter of the next optimization.
b. Because the B-pillar reinforcing plates are all design areas, a ply-laminated plate structure is created by adopting an 8 # anisotropic material model, PCOMPP (a material attribute form) is selected according to the attribute definition aiming at the design area, and because Optistruct optimization software can only thin the material without the function of thickening, a super layer with thicker initial thickness needs to be established. The thickness of the super layer is set by initial optimization parameters.
(3) Setting of load
Extracting the maximum relative displacement of the B-column reinforcing plate in the impact resistance simulation of the B-column model, calculating the numerical value of the required equivalent force, loading the numerical value into a B-column reinforcing plate structure optimization model in contact with a collision trolley, and carrying out average distribution loading on the equivalent force according to the number of loading points; reasonably ignoring and simplifying according to the magnitude of the forces of the x axis, the y axis and the z axis, obtaining a better displacement fitting result by the obtained static simulation model and the dynamic simulation model, and then carrying out static optimization simulation on the basis;
2) static working condition layer laying optimization of carbon fiber reinforced composite B column reinforcing plate
(1) Topology optimization
a. Defining a design variable, firstly creating a variable for topology optimization, defining two responses of quality and reference point displacement, and respectively using the two responses as an optimization response and a constraint response; creating constraint, using the reference point displacement response as constraint, setting a constraint upper limit value, and defining the minimum quality as an optimization target;
b. adjusting optimization control parameters including maximum allowable iteration times, a target tolerance value and an optimization step length;
c. defining a control card, wherein an OUTPUT card keyword needs to be defined as FSTOSZ (type keyword) in the control card part, and then saving or outputting a file;
d. checking, if no error information exists, starting optimization, checking a result file after the optimization is finished, and opening the thickness of an optimization result file checking unit in HyperView;
(2) size optimization
a. In order to ensure the correct transmission of the ply information, the thickness information in a single direction is output in the form of the ply shape, firstly, the control card is reset, the OMIT card is deleted, and FSTOSZ (one type of key words) is changed into SZTOSH (one type of key words);
b. editing Laminate parameters, setting the form of the Laminate as Total, respectively defining size variables of each layer, ensuring that the upper limit of the thickness of each layer is modified, normalizing the thickness of each layer into a similar integer which cannot be modified, still taking the displacement value of a reference point as a constraint condition, and still keeping the quality at the minimum;
c. appointing a machinable thickness value, carrying out inspection optimization after optimization setting, and checking the thickness and the number of the layers;
(3) sequence optimization
For the composite material, the layering sequence is closely related to the anisotropic mechanical property and the process feasibility of the laminated plate, and the change of the layering sequence of the composite material can influence the overall performance of the structure. Before calculating the optimal stacking sequence, firstly, setting manufacturing constraints on stacking sequence variables, and defining that at most 2 layers of same stacking can continuously appear in stacking in four directions of 0 degree, 90 degree, 45 degree and-45 degree; the +45 degrees and-45 degrees appear in pairs to ensure symmetry, the generation of interlayer stress is avoided to the maximum extent, optimization constraint and optimization targets are unchanged, and finally layering sequence optimization is carried out; checking the output result file, and checking the layering sequence of each iteration step in a browser;
3) verification calculation of B-column reinforcing plate optimization result under dynamic working condition of decoupling substructure
(1) Carrying out regular partition according to the layering result to improve the B-column reinforcing plate;
(2) carrying out analog simulation calculation of the side impact trolley collision under the working condition of a decoupler on the model with the optimized carbon fiber reinforced composite material B column reinforcing plate;
(3) and checking the comparison data of the optimized B column and the B column in the original vehicle type, namely verifying the improvement degree of the performance of the B column reinforcing plate by comparing the intrusion amount of the reference point corresponding to the chest of the human body with the maximum value of the intrusion speed, and simultaneously obtaining the light weight effect of the B column reinforcing plate.
Example (b):
referring to fig. 1, the invention will be described with reference to an example to use the optimized design method of the automobile B-pillar reinforcing plate carbon fiber reinforced composite material;
1. decoupling B pillar structure from finished vehicle finite element model
1) Referring to fig. 2, according to the original whole vehicle side collision model, the parts connected with the B-pillar are reserved to ensure the accuracy of the deformation conditions, namely, the sill beam, the side coaming, the top cover beam, the tubular door collision-proof beam, and the B-pillar structure is used as a substructure model.
2) And (3) performing side collision finite element calculation by using an area close to the connecting position of the B column in the component connected with the B column and the foremost surface of the side collision trolley buffer honeycomb aluminum as collision reference points, and extracting displacement-time curve data of the collision reference points through Ls-prepost post-processing software.
3) The extracted curve data is converted into data information which can be identified by Ls-dyna simulation calculation software through MATLAB programming software, and then a simplified calculation k file which only keeps a B column, surrounding parts of the B column and a sub-working condition model at the front end of the side collision trolley is led in through a text editor, so that the side collision condition of the whole trolley can be accurately simulated, the calculation time is greatly reduced, and the working efficiency is improved.
2. Optimization of carbon fiber reinforced composite material B column reinforcing plate
1) Establishment of static working condition of B-pillar reinforcing plate
(1) Simple structure
Referring to fig. 4, according to the original finished automobile finite element model, only the original metal B-pillar reinforcement plate shape model structure is retained, including the positions of the bolt holes in the B-pillar reinforcement plate finite element model located in the middle. The B-pillar reinforcing plate is set to be uniform and initially optimized in thickness, and is 2.5 mm. The two-dimensional grid quality inspection of the geometric surface of the three-dimensional grid is carried out, and the warp degree is more than 5, the aspect ratio is more than 5, the unit length is less than 7.5, and the Jacobian is less than 0.7.
(2) Establishment of carbon fiber reinforced composite material B column reinforcing plate
a. Firstly, a laminated plate structure is created by adopting an anisotropic material model No. 54-55 in Ls-dyna simulation calculation software. The material parameters are shown in table 1. The single-layer thickness is 0.25mm, and the total thickness is 2.5mm by layering at angles of 0 degree, 45 degrees, -45 degrees and 90 degrees respectively. The stacking sequence was set to [0/45/-45/90/45/45/90/-45/45/0] according to experience. After sub-working condition side collision simulation calculation, the performance of the original metal B-pillar reinforcing plate can be met, namely, the invasion speed and the invasion amount of the metal B-pillar reinforcing plate at the breast reference point of a human body are ensured not to be increased, and the weight is reduced from 1.034kg to 0.2881kg and is reduced by 72.14%.
TABLE 1
| RHO | EA | EB | μ21 | GAB | GBC |
| 1.75e-9 | 145200 | 8100 | 0.002 | 4400 | 1530 |
| GCA | Xt | Xc | Yt | Yc | S |
| 1530 | 2455 | 2455 | 35 | 35 | 61 |
b. In Optistruct optimization software, a B-column reinforcing plate adopts an 8 # anisotropic material model to create a layer and layer laminated plate structure, and material parameters are shown in Table 1. Because the software can only thin the paving layer but does not have the function of thickening, a super layer with thicker thickness needs to be designed. And taking the layering information of the carbon fiber reinforced composite material meeting the collision performance obtained in the previous step as an initial optimization parameter. Property definitions were set to PCOMPP (a material property form) for the design area, setting 4 ply directions, 0 degrees, 45 degrees, -45 degrees, and 90 degrees, with each layer thickness of 0.5mm, 1mm, 0.5mm, and a total thickness of 2.5 mm.
(3) Setting of load
Referring to fig. 5, a method for applying an equivalent static load is adopted, a numerical value of required equivalent force is calculated according to the maximum relative displacement of the B-pillar reinforcing plate in the impact resistance simulation of the B-pillar model, the numerical value is loaded at a structural optimization model of the B-pillar reinforcing plate in contact with the collision trolley, and the contact force is evenly distributed and loaded according to the number of loading points. Since X, Z the two-axis direction is far different from the Y-axis contact force peak value, X, Z the two-axis contact force is negligible, and only the Y-axis peak force is extracted for equivalent analysis. 8 parts of 1N concentrated force is uniformly loaded on a part, which is in contact with the collision trolley, of the B-column structural optimization model and is used as uniform force to perform simulation calculation, and analysis calculation is performed on the basis of a defined B-column reinforcing plate structure, so that the relative displacement which is the same as that in the collision model can be realized, and the relative displacement is 37.317 mm.
2) Static working condition layer laying optimization of carbon fiber reinforced composite B column reinforcing plate
(1) Topology optimization
a. First, a design variable Topo (defined variable name) is defined, and a layer of the design space is selected. And defining a mass response M and a displacement response D as an optimization target response and a constraint response respectively. And (4) creating a constraint, setting the displacement response D as the constraint, setting the upper limit value to be 37.35mm, and setting the minimum mass response M as an optimization target.
b. The optimization control parameters were adjusted with a maximum allowed number of iterations of 80, a minimum value of 0.005 for the target tolerance value and 0.5 for the optimization step size.
c. Defining a control card, where it is necessary to define the OUTPUT card key as FSTOSZ (a type of key) in the control card section, and then save or OUTPUT the file.
d. Finally, checking is carried out, and optimization is carried out if no error information exists. And viewing the result file after the optimization is finished, opening the thickness of the optimized result file checking unit in HyperView, and mainly reducing the thickness of the B-pillar reinforcing plate as shown in FIG. 6.
(2) Size optimization
a. Firstly, setting a card, changing FSTOSZ (one type of key word) into SZTOSH (one type of key word), and deleting OMIT (one type of key word) to ensure the correct transmission of the layer information, namely outputting the thickness information in a single direction in the form of the layer shape.
b. The Laminate parameters were edited and the Laminate form was set to Total (Total). And defining a Size design variable Size, modifying the upper limit of the thickness of each layer to be 0.5mm which is twice the thickness of the single layer, wherein each layer needs to be updated, and the layers which cannot be modified are regularly integrated into a similar integer. The optimization goal is still quality minimization.
c. The thickness of the work piece is specified to be 0.25mm, and optimization is performed if no error information exists after inspection. And viewing the result file after the optimization is finished, viewing the thickness and the number of the layers, wherein 16 layer items are total, and the thickness of a single layer is 0.25 mm.
(3) Sequence optimization
Before optimizing the optimal stacking sequence, manufacturing constraints are set first, defining that at most 2 layers of 0 degree, 90 degree, 45 degree and-45 degree oriented stacking can occur continuously, and that +45 degree and-45 degree pairs occur in pairs. The optimization constraints and optimization objectives are still the displacement and mass minimum objectives in the last step of size optimization. Checking the output result file, and checking the layering sequence of each iteration step in a browser.
3) Verification calculation of B-column reinforcing plate optimization result under dynamic working condition of decoupling substructure
(1) And performing engineering interpretation on the B-pillar reinforcing plate according to the layering optimization result, and dividing the integration into four areas, as shown in FIG. 7. Zone 1 having a thickness of 2.5mm, 10 plies were laid in the order [45/-45/0/0/45/-45/0/0/90/90 ]; 2 areas with the thickness of 0.5mm are paved into 2 layers, and the paving sequence is [45/-45 ]; the thickness of 3 areas is 1mm, 4 layers are laid, and the laying sequence is [45/-45/90/90 ]; the thickness of the zone 4 is 1 mm; 4 layers are laid, and the laying sequence is [0/0/45/-45 ].
(2) Carrying out analog simulation calculation of the side impact trolley collision under the working condition of a decoupler on the model with the optimized carbon fiber reinforced composite material B column reinforcing plate;
(3) looking at the simulation calculation result data, the performance is improved compared with the original structure, namely the relative invasion amount of the reference point corresponding to the chest of the human body on the B-pillar reinforcing plate is reduced, as shown in the table 2. The mass of the original metal B-column reinforcing plate is 1.034kg, the mass of the carbon fiber reinforced composite material B-column reinforcing plate before optimization is 0.2881kg, the mass of the carbon fiber reinforced composite material B-column reinforcing plate after layering optimization can be 0.2174 kg, the weight reduction proportion before and after optimization can reach 24.54%, the weight reduction proportion can be finally achieved to be 78.97% compared with the original metal material, and the weight reduction effect is obvious.
TABLE 2
In conclusion, the B-pillar structure decoupling and carbon fiber reinforced composite material B-pillar reinforcing plate optimization analysis method provided by the invention has the advantages that the finite element analysis calculation is carried out through the structural simplification of the substructure decoupling, the calculation time is greatly saved under the condition of excellent fitting degree, and the calculation efficiency is improved; then, performing layer optimization of the static working condition of the B-column reinforcing plate on the basis, wherein the layer optimization comprises three parts, namely topology optimization, size optimization and sequence optimization; and finally, carrying out verification simulation on the improved carbon fiber reinforced composite material B column reinforcing plate under a dynamic working condition. The invention fully utilizes the designable performance of the composite material compared with the metal material, and has obvious lightweight effect on the basis of ensuring the anti-collision performance of the B column.
Claims (6)
1. The optimal design method of the automobile B-column reinforcing plate carbon fiber reinforced composite material is characterized by comprising the following steps of:
1) decoupling the B pillar structure from the finished vehicle finite element model:
(1) according to the original whole vehicle side collision model, parts connected with the B column are reserved to ensure the accuracy of the deformation condition of the B column, namely, the sill beam, the side coaming, the top cover beam, the tubular door collision-proof beam and the B column structure are used as a substructure model;
(2) adopting an area in a part connected with the B column, which is close to the connection position of the B column, and the foremost surface of the side collision trolley buffer honeycomb aluminum as a collision reference point, carrying out side collision finite element calculation, and extracting displacement-time curve data of the collision reference point through Ls-pre post-processing software;
(3) converting the extracted curve data into data information which can be identified by Ls-dyna simulation calculation software through MATLAB programming software, and introducing a simplified calculation k file which only keeps a B column and peripheral parts thereof and a sub-working condition model at the front end of the side collision trolley through a text editor, so that the side collision condition of the whole trolley can be accurately simulated;
2) optimizing a B column reinforcing plate of the carbon fiber reinforced composite material:
(1) establishing a static working condition of the B-column reinforcing plate;
(2) the static working condition layer laying optimization of the carbon fiber reinforced composite B-column reinforcing plate comprises the following steps:
A. topology optimization;
B. optimizing the size;
C. optimizing the sequence;
(3) and verifying and calculating the optimization result of the B-column reinforcing plate under the dynamic working condition of the decoupling substructure.
2. The optimal design method of the automobile B-column reinforcing plate carbon fiber reinforced composite material according to claim 1, wherein the establishment of the static working condition of the B-column reinforcing plate is as follows:
(1) simple structure
Setting the thickness of the B-column reinforcing plate into a uniform initial thickness according to the geometric dimension of the structural shape of the existing B-column reinforcing plate, reserving shape and structure parameters in the original metal B-column reinforcing plate in the whole vehicle model, reserving a bolt fixing hole structure in a simplified structure, and checking the grid quality of the bolt fixing hole structure;
(2) establishment of carbon fiber reinforced composite material B column reinforcing plate
a. Changing the B-column reinforcing plate of the part to be optimized into a carbon fiber reinforced composite material, setting a layering angle, a layering sequence and a layering thickness according to experience, so that the original anti-collision performance can be kept in collision simulation, and taking the layering information as the initial parameter of the next optimization;
b. because the B-column reinforcing plates are all design areas, a ply-forming laminated plate structure is created by adopting an No. 8 anisotropic material model, PCOMPP is selected by attribute definition aiming at the design area, and because Optistruct optimization software can only thin the material without the function of thickening, a super layer with thicker initial thickness needs to be established, and the thickness of the super layer is set through initial optimization parameters;
(3) setting of load
Extracting the maximum relative displacement of the B-column reinforcing plate in the impact resistance simulation of the B-column model, calculating the numerical value of the required equivalent force, loading the numerical value into a B-column reinforcing plate structure optimization model in contact with a collision trolley, and carrying out average distribution loading on the equivalent force according to the number of loading points; reasonably neglecting and simplifying according to the magnitude of the force of the x, y and z axes, obtaining a better displacement fitting result of the static simulation model and the dynamic simulation model, and then carrying out static optimization simulation on the basis.
3. The optimal design method of the automobile B-pillar reinforcing plate carbon fiber reinforced composite material according to claim 1, characterized in that the topological optimization is as follows:
a. defining a design variable, firstly creating a variable for topology optimization, defining two responses of quality and reference point displacement, and respectively using the two responses as an optimization response and a constraint response; creating constraint, using the reference point displacement response as constraint, setting a constraint upper limit value, and defining the minimum quality as an optimization target;
b. adjusting optimization control parameters including maximum allowable iteration times, a target tolerance value and an optimization step length;
c. defining a control card, wherein an OUTPUT card keyword needs to be defined as FSTOSZ in the control card part, and then storing or outputting a file;
d. and finally, checking, if no error information exists, starting optimization, checking a result file after the optimization is finished, and opening the thickness of an optimization result file checking unit in HyperView.
4. The method for optimally designing the automobile B-pillar reinforcing plate carbon fiber reinforced composite material according to claim 1, wherein the size optimization is as follows:
a. in order to ensure the correct transmission of the ply information, outputting the thickness information in a single direction in the form of the ply shape, resetting a control card, deleting an 'OMIT' card, and changing one type of keyword FSTOSZ into another type of keyword SZTOSH;
b. editing Laminate parameters, setting the form of the Laminate as Total, respectively defining size variables of each layer, ensuring that the upper limit of the thickness of each layer is modified, normalizing the thickness of each layer which cannot be modified into a similar integer, and still taking the displacement value of a reference point as a constraint condition to ensure that the optimization target is still the minimum quality;
c. the value of the workable thickness is specified, inspection optimization is performed after the optimization setting, and the thickness and the number of the layers are checked.
5. The method for optimally designing the automobile B-pillar reinforcing plate carbon fiber reinforced composite material according to claim 1, wherein the sequential optimization is as follows:
for a composite material, the layering sequence is closely related to the anisotropic mechanical property and the process feasibility of a laminated plate of the composite material, the change of the layering sequence of the composite material can influence the overall performance of the structure of the composite material, before the optimal layering sequence is calculated, manufacturing constraints are firstly set on variables of the layering sequence, and at most 2 layers of same layering can continuously appear in the layering in four directions of 0 degree, 90 degrees, 45 degrees and-45 degrees; the +45 degrees and-45 degrees appear in pairs to ensure symmetry, the generation of interlayer stress is avoided to the maximum extent, optimization constraint and optimization targets are unchanged, and finally layering sequence optimization is carried out; checking the output result file, and checking the layering sequence of each iteration step in a browser.
6. The method for optimally designing the automobile B-column reinforcing plate carbon fiber reinforced composite material according to claim 1, wherein the verification calculation of the B-column reinforcing plate optimization result under the dynamic working condition of a decoupling substructure refers to the following steps:
(1) carrying out regular partition according to the layering result to improve the B-column reinforcing plate;
(2) carrying out analog simulation calculation of the side impact trolley collision under the working condition of a decoupler on the model with the optimized carbon fiber reinforced composite material B column reinforcing plate;
(3) and checking the comparison data of the optimized B column and the B column in the original vehicle type, namely verifying the improvement degree of the performance of the B column reinforcing plate by comparing the intrusion amount of the reference point corresponding to the chest of the human body with the maximum value of the intrusion speed, and simultaneously obtaining the light weight effect of the B column reinforcing plate.
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