A system and method for performing quasi-static tests on a simulated structure in LS-DYNA

Abstract

The present invention discloses a system and method for performing a quasi-static test on a simulation structure in LS-DYNA. The system includes a creation module, a setting module, a control module, a calculation module, and a speed regulation module. The method includes: S1. The control module controls the loading block to start from the set loading position and uniformly displace towards the simulation structure at the initial loading speed; S2. The calculation module calculates the process force of the loading block and compares the magnitudes of the process force and the target force; S3. The speed regulation module calculates the required loading speed of the loading block; S4. The control module adjusts the loading speed of the loading block; S5. The calculation module calculates the process force of the loading block and compares the magnitudes of the process force and the target force. The speed regulation module generates a corresponding speed regulation instruction, and then returns to S4 until it is compared that the process force of the loading block is equal to the target force, then enters S6; S6. The control module controls the loading block to stop displacing. The present invention adjusts the loading speed of the loading block in real time according to the process force of the loading block, achieving high-efficiency and high-precision structural quasi-static simulation.

Description

Technical Field

[0001] The present invention belongs to the field of quasi-static tests, and particularly relates to a system and method for performing quasi-static tests on a simulation structure using LS-DYNA. Background Art

[0002] Generally, there are two methods for performing quasi-static tests on a simulation structure. The first method is to use implicit static solution, and each step of the loading process of the simulation structure can be balanced, but this method requires repeated debugging of the simulation structure to achieve a convergent result, with a high time cost. The second method is to use explicit dynamic solution, and by applying a relatively long loading time to the simulation structure, the dynamic effects caused by loading are reduced, making the entire loading process close to quasi-static. The second method has two loading paths. One is to use a continuously increasing force to load the simulation structure, but the loading process has obvious oscillations, and after the loading force increases to the target force, it needs to be maintained for a period of time. The other is to use displacement to load the simulation structure. This loading process has less oscillation, but it is impossible to judge the displacement to be loaded based on the target force before loading. In addition, for the case where multiple loading points need to be synchronously loaded onto the simulation structure, such as the static strength test of a seat headrest, multiple occupant positions need to be synchronously loaded. Due to the different structural rigidities of different loading points, conventional displacement loading cannot reach the same target force at the same time.

[0003] The patent with the patent number "CN202011496187.0" discloses a loading device, test method, and test data correction method for vehicle quasi-static tests, which can adjust the loading position according to the size of the test component and the working conditions, but the entire test process takes a long time. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and method for performing quasi-static tests on a simulation structure using LS-DYNA, to solve the problem in the background art that for the case where multiple loading points need to be synchronously loaded onto the simulation structure, such as the static strength test of a seat headrest, multiple occupant positions need to be synchronously loaded. Due to the different structural rigidities of different loading points, conventional displacement loading cannot reach the same target force at the same time.

[0005] To achieve the above-mentioned invention purpose, the technical solutions adopted by the present invention are as follows:

[0006] A system for performing quasi-static tests on a simulation structure using LS-DYNA includes a creation module, a setting module, a control module, a calculation module, and a speed regulation module;

[0007] The creation module is used to create the loading block and the simulation structure required for performing quasi-static tests;

[0008] The setting module is used to set the loading position, initial loading speed, and target force of the loading block, and send them to the control module;

[0009] The control module is used to control the displacement of the loading block towards the simulation structure according to the data sent by the setting module and the speed regulation module;

[0010] The calculation module is used to calculate the process force during the displacement of the loading block in real time, compare the magnitude of the calculated process force with the target force, and output the comparison result to the speed regulation module;

[0011] The speed regulation module is used to calculate the required loading speed of the loading block according to the comparison result output by the calculation module, and generate a corresponding speed regulation instruction to send to the control module.

[0012] When the present invention uses the LS-DYNA software to perform a quasi-static test on a simulation structure, by setting a calculation module and a speed regulation module, the loading speed of the loading block is adjusted in real time according to the process force of the loading block, so that the force exerted by the loading block on the simulation structure is always maintained at the level required for the quasi-static test, and this way of adjusting the loading speed can greatly reduce the time spent on the entire quasi-static test, achieving high-efficiency and high-precision structural quasi-static simulation; and for the case where multiple loading blocks need to be synchronously loaded onto the simulation structure, even if the rigidity of the simulation structure at the loading position of each loading block is different, the process force of each loading block can reach the same target force at the same moment.

[0013] Preferably, the system for performing a quasi-static test on a simulation structure by LS-DYNA further includes a stop module;

[0014] The stop module is used to obtain the comparison result output by the calculation module, and generate or not generate a stop instruction to the control module according to the comparison result;

[0015] The control module is further used to receive the stop instruction generated by the stop module, and stop controlling the displacement of the loading block.

[0016] The present invention also provides a method for performing a quasi-static test on a simulation structure by LS-DYNA, which is applied to the system for performing a quasi-static test on a simulation structure by LS-DYNA as described above; the method for performing a quasi-static test on a simulation structure by LS-DYNA includes the following steps:

[0017] Step S1. The control module controls the loading block to start from the set loading position and move uniformly towards the simulation structure at the initial loading speed until it contacts the simulation structure;

[0018] Step S2. The calculation module calculates the process force of the loading block when it contacts the simulation structure, compares the process force with the target force, and outputs the comparison result;

[0019] Step S3. The speed regulation module calculates the required loading speed of the loading block according to the comparison result and generates a corresponding speed regulation instruction;

[0020] Step S4. The control module adjusts the loading speed of the loading block according to the speed regulation instruction. The loading block displaces at the adjusted loading speed and transmits the process force to the simulation structure;

[0021] Step S5. The calculation module calculates the process force of the loading block after transmitting the process force to the simulation structure, compares the process force with the target force, and outputs the comparison result; the speed regulation module calculates the required loading speed of the loading block according to the comparison result and generates a corresponding speed regulation instruction, and then returns to Step S4 until it is compared that the process force of the loading block is equal to the target force, then enter Step S6;

[0022] Step S6. The control module controls the loading block to stop displacing.

[0023] Preferably, the Step S1 further includes: a setting module sets the loading position of the loading block, the initial loading speed v 0 , and the target force F 目标 .

[0024] Preferably,

[0025] In the Step S5, the calculation module calculates the process force F of the loading block after transmitting the process force to the simulation structure 过程 , and compares the process force F 过程 with the target force F 目标 , and outputs the comparison result; the output comparison result includes F 目标 ≥F 过程 , F 目标 <F 过程 <2F 目标 , 2F 目标 ≤F 过程 .

[0026] Preferably, in the Step S5, the speed regulation module calculates the required loading speed v of the loading block according to the comparison result, including the following formula:

[0027]

[0028] Preferably, the initial loading speed v 0 is 0.1 - 1 m / s.

[0029] Preferably, the method for performing a quasi-static test on a simulation structure by LS-DYNA further includes: starting from the contact between the loading block and the simulation structure, the calculation module calculates the process force F of the loading block every Δt seconds. 过程 ; Δt is 10-7 to 10-6 seconds.

[0030] Preferably, the method for performing a quasi-static test on a simulation structure by LS-DYNA further includes: every time the calculation module calculates the process force F of the loading block. 过程 After that, the calculation module compares the process force F 过程 with the target force F 目标 and outputs the comparison result.

[0031] Preferably, the method for performing a quasi-static test on a simulation structure by LS-DYNA further includes: every time the calculation module outputs the comparison result, the speed regulation module calculates the required loading speed of the loading block in real time according to the comparison result and generates a corresponding speed regulation instruction.

[0032] Beneficial effects:

[0033] A system and method for performing a quasi-static test on a simulation structure by LS-DYNA according to the present invention, when using LS-DYNA software to perform a quasi-static test on a simulation structure, by setting a calculation module and a speed regulation module in combination with the test method, the loading speed of the loading block can be adjusted in real time according to the process force of the loading block, so that the force exerted by the loading block on the simulation structure is always maintained at the level required for the quasi-static test, and this way of adjusting the loading speed can greatly reduce the time spent on the entire quasi-static test, realizing high-efficiency and high-precision structural quasi-static simulation; and for the case where multiple loading blocks need to be synchronously loaded onto the simulation structure, even if the rigidity of the simulation structure at the loading position of each loading block is different, the process forces of each loading block can reach the same target force at the same moment. Description of the drawings

[0034] Figure 1 Shown is a structural block diagram of a system for performing a quasi-static test on a simulation structure by LS-DYNA in Embodiment 1;

[0035] Figure 2 Shown is a flowchart of a method for performing a quasi-static test on a simulation structure by LS-DYNA in Embodiment 2;

[0036] Figure 3 Shown is a judgment logic diagram of a method for performing a quasi-static test on a simulation structure by LS-DYNA in Embodiment 2;

[0037] Figure 4The figure shows the relationship diagram of the process force and time of a method for performing a quasi-static test on a simulation structure using LS-DYNA in the second embodiment. Detailed implementation manners

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation manners of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings and other implementation manners can be obtained.

[0039] The technical solutions of the present invention will be introduced in detail below with specific embodiments.

[0040] Embodiment 1

[0041] As Figure 1 shown, a system for performing a quasi-static test on a simulation structure using LS-DYNA in this embodiment includes a creation module, a setting module, a control module, a calculation module, and a speed regulation module;

[0042] The creation module is used to create a loading block and a simulation structure required for performing a quasi-static test;

[0043] The setting module is used to set the loading position, initial loading speed, and target force of the loading block and send them to the control module;

[0044] The control module is used to control the displacement of the loading block towards the simulation structure according to the data sent by the setting module and the speed regulation module;

[0045] The calculation module is used to calculate the process force in real time during the displacement of the loading block, compare the calculated process force with the magnitude of the target force, and output the comparison result to the speed regulation module;

[0046] The speed regulation module is used to calculate the required loading speed of the loading block according to the comparison result output by the calculation module and generate a corresponding speed regulation instruction to send to the control module.

[0047] A system for performing quasi-static tests on a simulation structure using LS-DYNA in this embodiment. When performing quasi-static tests on a simulation structure using LS-DYNA software, by setting a calculation module and a speed regulation module, the loading speed of the loading block is adjusted in real time according to the process force of the loading block, so that the force exerted by the loading block on the simulation structure is always maintained at the level required for quasi-static tests. Moreover, this way of adjusting the loading speed can greatly reduce the time spent on the entire quasi-static test, achieving high-efficiency and high-precision structural quasi-static simulation. And for the case where multiple loading blocks need to be synchronously loaded onto the simulation structure, even if the rigidities of the simulation structures at the loading positions of each loading block are different, the process forces of each loading block can reach the same target force at the same moment.

[0048] Preferably, the system for performing quasi-static tests on a simulation structure using LS-DYNA further includes a stop module;

[0049] The stop module is used to obtain the comparison result output by the calculation module and generate or not generate a stop instruction to the control module according to the comparison result;

[0050] The control module is further used to receive the stop instruction generated by the stop module and stop controlling the displacement of the loading block.

[0051] Specifically, the loading block in this embodiment applies a load to the simulation structure through a displacement load.

[0052] Embodiment Two

[0053] As Figures 2 to 4 shown, a method for performing quasi-static tests on a simulation structure using LS-DYNA of the present invention is applied to the system for performing quasi-static tests on a simulation structure using LS-DYNA in Embodiment One. The method for performing quasi-static tests on a simulation structure using LS-DYNA includes the following steps:

[0054] Step S1. The control module controls the loading block to start from the set loading position and displace uniformly towards the simulation structure at the initial loading speed until it contacts the simulation structure;

[0055] Step S2. The calculation module calculates the process force of the loading block when it contacts the simulation structure, compares the process force with the target force, and outputs the comparison result;

[0056] Step S3. The speed regulation module calculates the required loading speed of the loading block according to the comparison result and generates a corresponding speed regulation instruction;

[0057] Step S4. The control module adjusts the loading speed of the loading block according to the speed regulation instruction, and the loading block displaces at the adjusted loading speed and transmits the process force to the simulation structure;

[0058] Step S5. The calculation module calculates the process force of the loading block after transferring the process force to the simulation structure, compares the magnitudes of the process force and the target force, and outputs the comparison result; the speed regulation module calculates the required loading speed of the loading block according to the comparison result, generates a corresponding speed regulation instruction, and then returns to step S4 until it is compared that the process force of the loading block is equal to the target force, and then enters step S6;

[0059] Step S6. The control module controls the loading block to stop displacement.

[0060] Preferably, step S1 further includes: a setting module sets the loading position of the loading block, the initial loading speed v 0 , the target force F 目标 .

[0061] Preferably,

[0062] In step S5, the calculation module calculates the process force F of the loading block after transferring the process force to the simulation structure 过程 , and compares the magnitudes of the process force F 过程 and the target force F 目标 , and outputs the comparison result; the output comparison result includes F 目标 ≥F 过程 , F 目标 <F 过程 <2F 目标 , 2F 目标 ≤F 过程 .

[0063] Preferably, in step S5, the speed regulation module calculates the required loading speed v of the loading block according to the comparison result, including the following formula:

[0064]

[0065] Preferably, the initial loading speed v 0 is 0.1 to 1 m / s.

[0066] Preferably, the method for performing a quasi-static test on the simulation structure by LS-DYNA further includes: starting from the contact between the loading block and the simulation structure, the calculation module calculates the process force F of the loading block every △t seconds 过程 ; △t is 10-7 to 10-6 seconds.

[0067] Preferably, the method for performing a quasi-static test on the simulation structure by LS-DYNA further includes: every time the calculation module calculates the process force F of the loading block 过程 , the calculation module compares the magnitudes of the process force F 过程 and the target force F 目标 and outputs the comparison result.

[0068] Preferably, the method of the LS-DYNA for performing a quasi-static test on a simulation structure further includes: each time the calculation module outputs a comparison result, the speed regulation module calculates in real time the loading speed required for the loading block according to the comparison result and generates a corresponding speed regulation instruction.

[0069] Specifically, in this embodiment, a quasi-static simulation of the stiffness of the seat backrest frame is performed based on the LS-DYNA solver, and the target force F 目标 applied to the loading block is required to be a load of 147 N, and the specific implementation steps are as follows:

[0070] The loading block created in this embodiment is a rigid body, and the loading position is directly above the seat backrest frame. The degrees of freedom required for displacement loading are released from the loading position in a direction perpendicular to the seat backrest frame, and at the same time, the degrees of freedom in other directions are constrained so that the loading block can move uniformly to the middle position at the upper end of the seat backrest frame.

[0071] Further, the keyword *CONTACT is used to establish the contact between the loading block and the seat backrest frame; the keyword *BOUNDARY_PRESCRIBED_MOTION is used to apply a displacement load to the loading block so that the initial speed of the loading block is 0.5 m / s. After the loading block contacts the seat backrest frame, the force is transmitted to the seat backrest frame through the contact.

[0072] Further, the keyword *SENSOR_DEFINE_FORCE is used to establish a contact force sensor SENSID_1 between the loading block and the seat backrest frame to monitor the process force F 过程 of the loading block in real time; the keyword *SENSOR_SWITCH is used to establish 3 judgment sensors: SWITID_1, SWITID_2, SWITID_3, which are respectively activated when the conditions F 目标 ≥F 过程 , F 目标 <F 过程 <2F 目标 , 2F 目标 ≤F 过程 are satisfied. When they are activated, the feedback logic judges TRUE, otherwise it judges FALSE. The monitoring interval of each sensor is the time step △t = 4×10 -7 seconds of the display dynamics calculation. The correction process of the process force F 过程 of the loading block at the △t time interval is as shown in Figure 4 .

[0073] Further, three control sensors, CNTLID_1, CNTLID_2, and CNTLID_3, are established using the keyword *SENSOR_CONTROL. They are respectively controlled by the logical judgments fed back by SWITID_1, SWITID_2, and SWITID_3. When the feedback is TRUE, the corresponding control is activated; otherwise, it is not. CNTLID_1, CNTLID_2, and CNTLID_3 respectively control different loading speeds. The specific process force F 过程 corresponds to the target force F 目标 in different loading speeds as Figure 3 shown.

[0074] Further, the control condition for ending the calculation is established using the keyword *TERMINATION_SENSOR. When the process force F 过程 reaches 147N of the target force F 目标 , that is, when the force monitored by the contact force sensor SENSID_1 is equal to the target force F 目标 , the calculation is automatically stopped and the entire analysis process ends. Otherwise, return to step S4 and repeat the subsequent process.

[0075] Specifically, the actual loading time of the existing structural quasi-static test is generally from several seconds to several hundred seconds. Using implicit static analysis requires a long model debugging time, and even because of large deformations, non-convergent calculation results may be obtained. Using explicit dynamics calculation, if loaded according to the real test time, the calculation time is about several hundred to several thousand hours. Generally, in simulation analysis, the quasi-static simulation results are obtained by shortening the loading time and turning off the material strain rate effect. However, when using force loading, because the loading process is unbalanced, a loading time of 1 - 2 seconds is required to obtain a relatively stable loading process. For the method of conducting quasi-static tests on a simulated structure using LS-DYNA of the present invention, the difference between the process force F 过程 and the target force F 目标 is determined for each calculation step, and the loading speed is adjusted according to the size of the difference, reducing the impact of the rigid structure of the simulated structure on the unbalanced loading process. Compared with using force loading, the loading time can be shortened by more than 50%.

[0076] The above has elaborated in detail the embodiments of the system and method for conducting quasi-static tests on a simulated structure using LS-DYNA provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An LS-DYNA system for quasi-static testing of a simulation structure, characterized in that, it includes a creation module, a setting module, a control module, a calculation module, and a speed regulation module; The creation module is used to create a loading block and a simulation structure required for quasi-static testing; The setting module is used to set the loading position, initial loading speed, and target force of the loading block, and send them to the control module; The control module is used to control the displacement of the loading block towards the simulation structure according to the data sent by the setting module and the speed regulation module; The calculation module is used to calculate the process force during the displacement of the loading block in real time, compare the calculated process force with the magnitude of the target force, and output the comparison result to the speed regulation module; The speed regulation module is used to calculate the required loading speed of the loading block according to the comparison result output by the calculation module, and generate a corresponding speed regulation instruction to send to the control module; The calculation module calculates the process force F of the loading block after the process force is transmitted to the simulation structure 过程 , and compares the process force F 过程 with the target force F 目标 , and outputs the comparison result; the output comparison result includes F 目标 ≥F 过程 , F 目标 <F 过程 <2F 目标 , 2F 目标 ≤F 过程 ; The speed regulation module calculates the required loading speed v of the loading block according to the comparison result, including the following formula:

2. The LS-DYNA system for quasi-static testing of a simulation structure according to claim 1, the LS-DYNA system for quasi-static testing of a simulation structure further includes a stop module; The stop module is used to obtain the comparison result output by the calculation module, and generate or not generate a stop instruction to the control module according to the comparison result; The control module is further used to receive the stop instruction generated by the stop module, and stop controlling the displacement of the loading block.

3. An LS-DYNA method for quasi-static testing of a simulation structure, characterized in that, it is applied to the LS-DYNA system for quasi-static testing of a simulation structure according to claim 2; the LS-DYNA method for quasi-static testing of a simulation structure includes the following steps: Step S1. The control module controls the loading block to start from the set loading position and move uniformly towards the simulation structure at the initial loading speed until it contacts the simulation structure; Step S2. The calculation module calculates the process force of the loading block when it contacts the simulation structure, compares the process force with the target force, and outputs the comparison result; Step S3. The speed regulation module calculates the required loading speed of the loading block according to the comparison result, and generates a corresponding speed regulation instruction; Step S4. The control module adjusts the loading speed of the loading block according to the speed regulation instruction, and the loading block moves at the adjusted loading speed and transmits the process force to the simulation structure; Step S5. The calculation module calculates the process force of the loading block after transmitting the process force to the simulation structure, compares the process force with the target force, and outputs the comparison result; the speed regulation module calculates the required loading speed of the loading block according to the comparison result, and generates a corresponding speed regulation instruction, then returns to Step S4 until it is compared that the process force of the loading block is equal to the target force, then enters Step S6; Step S6. The control module controls the loading block to stop moving.

4. The LS-DYNA method for quasi-static testing of a simulation structure according to claim 3, characterized in that, The step S1 further includes: a setting module sets the loading position of the loading block and the initial loading speed v 0 , the target force F 目标 .

5. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 4, characterized in that, In the step S5, the calculation module calculates the process force F of the loading block after the process force is transmitted to the simulation structure 过程 , and compares the process force F 过程 with the target force F 目标 , and outputs the comparison result; the output comparison result includes F 目标 ≥F 过程 , F 目标 <F 过程 <2F 目标 , 2F 目标 ≤F 过程 .

6. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 5, characterized in that, in step S5, the speed control module calculates the required loading speed v of the loading block according to the comparison result, including the following formula:

7. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 6, characterized in that, The initial loading speed v 0 is 0.1 to 1 m / s.

8. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 7, characterized in that, The method for performing a quasi-static test on the simulation structure by LS-DYNA further includes: starting from the contact between the loading block and the simulation structure, the calculation module calculates the process force F of the loading block every △t seconds 过程 ; where △t is 10-7 to 10-6 seconds.

9. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 8, characterized in that, The method of the LS-DYNA for performing a quasi-static test on a simulation structure further includes: each time the calculation module calculates the process force F of the loading block 过程 after that, the calculation module will compare the process force F 过程 and the target force F 目标 in terms of magnitude and output the comparison result.

10. The method for performing a quasi-static test on a simulation structure in LS-DYNA according to claim 9, characterized in that, the method for performing a quasi-static test on a simulation structure in LS-DYNA further includes: each time the calculation module outputs a comparison result, the speed control module calculates the required loading speed of the loading block in real time according to the comparison result and generates a corresponding speed control instruction.

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