Commercial vehicle cab roof strength simulation method and system

Abstract

The application discloses a kind of commercial vehicle cab top strength simulation methods, the method first determines the moment of separation after pendulum and cab impact and cab structure deformation recovery time, and in turn determines the failure time of pendulum and cab top contact and the effective time of top pressing plate and cab top contact, realizes the sequential simulation of dynamic preloading pendulum side impact and top pressure, the simulation method conforms to 2021 version GB 26512 national standard, can effectively identify risk, improve cab safety performance, applicable to the cab structure of different strength, and has strong versatility.The application also provides a kind of commercial vehicle cab top strength simulation system.

Description

Technical Field

[0001] This invention relates to a method and system for simulating the strength of the top of a commercial vehicle cab, belonging to the technical field of engineering machinery cabs. Background Technology

[0002] As a crucial means of transportation in logistics, the structural safety of the cab of commercial vehicles is paramount. The 2011 version of GB 26512, "Occupant Protection of Commercial Vehicle Cabs," only specified a top strength test, while the 2021 version imposes stricter requirements on the cab top strength: for trucks with a gross vehicle weight exceeding 7500 kg, a dynamic pre-loading test is added, namely a 20° side pendulum impact test with an impact energy of 17.6 kJ. After the side impact, a top strength test is conducted, with the loading force being the static load corresponding to the front axle load, with a maximum of 98 kN. In other words, for trucks with a gross vehicle weight exceeding 7500 kg, a dynamic pre-loading test with a side pendulum impact is required before the top steel plate is loaded to ensure sufficient strength in the cab during rollover to guarantee adequate survival space for the occupants. Therefore, during the development phase of commercial vehicle cabs, new simulation technologies are needed to assess the performance of the cab top strength and verify whether it meets the mandatory requirements of the national standard. Summary of the Invention

[0003] This invention aims to provide a method for simulating the strength of the top of a commercial vehicle cab. The method first determines the moment of separation of the pendulum after impact with the cab and the moment of deformation recovery of the cab structure. Based on this, it defines the failure moment of the pendulum contacting the top of the cab and the effective moment of the top pressure plate contacting the top of the cab. This ensures that the simulation sequence of dynamic preloaded pendulum side impact and top pressurization complies with the 2021 version of the national standard GB 26512. It is applicable to the simulation of different cab structures, effectively identifies risks, and improves the safety performance of the cab.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a method for simulating the strength of the cab roof, the method comprising:

[0005] Step 1: Establish a 3D digital model of the main structural components of the commercial vehicle;

[0006] Step 2: Based on the three-dimensional digital model of the main structural components of the commercial vehicle, establish a finite element model of the cab structure; the finite element model of the cab structure includes a partial frame and a cab assembly; the partial frame includes the cab suspension and the front axle leaf spring seat;

[0007] Step 3: Establish a finite element model of a dynamically preloaded pendulum so that the impact energy of the pendulum reaches the energy threshold W;

[0008] Step 4: Based on the finite element model of the cab structure, establish a finite element model of the top pressure plate, such that the loading speed of the top pressure plate satisfies that the ratio of kinetic energy to peak internal energy during the top pressurization process is less than a first threshold.

[0009] Step 5: Based on the position information of the driver's seat, associate the finite element dummy with the driver's seat; combine the finite element model of the cab structure, the finite element model of the dynamic preloaded pendulum, the finite element model of the top pressure plate, and the finite element dummy to generate a cab top strength simulation model, and set the contact action of the cab top strength simulation model;

[0010] Step 6: Fix the cab roof strength simulation model by constraining all degrees of freedom of the inner annular node connecting the front axle leaf spring seat and the leaf spring;

[0011] Parameters were set, and a side impact simulation of the pendulum was performed. The deformation results of the cab roof under the side impact of the pendulum were obtained by calculation using finite element dynamics analysis software. Based on the deformation results of the cab roof, the force curve between the pendulum and the cab roof and the internal energy change curve of the cab roof strength simulation model were obtained, and the pendulum release time t1 and the cab deformation recovery time t2 were determined.

[0012] Wherein, the pendulum detachment time t1 is the moment when the force between the pendulum and the top of the cab is zero, and the cab deformation recovery time t2 is the moment when the internal energy change curve of the strength simulation model of the cab top is horizontal;

[0013] Step 7: Set the failure time of the pendulum contacting the top of the cab as t1+Δt1, and the effective time of the top pressure plate contacting the top of the cab as t2+Δt2; Based on the failure time of the pendulum contacting the top of the cab and the effective time of the top pressure plate contacting the top of the cab, the cab top strength simulation model is simulated by pendulum side impact and top pressure plate loading in sequence. The deformation result of the cab after pendulum side impact and top pressure plate loading is obtained by finite element dynamic analysis software.

[0014] Step 8: Based on the cab deformation results in Step 7, determine whether the cab structure intrudes into the finite element dummy during the simulation. If so, change the internal structure of the cab and return to Step 5; if not, the top strength of the cab meets the requirements, and the simulation is complete.

[0015] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows:

[0016] In one preferred embodiment, step 3 specifically includes the following steps:

[0017] S31. Set the pendulum mass, pendulum geometry, and pendulum spatial placement.

[0018] S32. Assign an angular velocity ω to the pendulum so that the impact energy of the pendulum reaches the energy threshold W;

[0019] S33. Apply a gravitational field to the pendulum.

[0020] In one preferred embodiment, in step 4, the first threshold is not greater than 10%.

[0021] In one preferred embodiment, the formula for calculating the angular velocity ω in step S32 is: Where J = 2E0, and E0 is the kinetic energy of the pendulum calculated by finite element dynamics analysis software when the angular velocity is 1 rad / s.

[0022] Based on the same concept, the present invention also provides a commercial vehicle cab roof strength simulation system, the system including a memory and one or more processors; the memory stores one or more programs, which, when executed by the one or more processors, cause the one or more processors to implement the steps of the above method.

[0023] Compared with existing technologies, the beneficial effects of this invention are as follows: The commercial vehicle cab top strength simulation method provided by this invention, according to the dynamic preloading test requirements specified in the 2021 edition of GB 26512 national standard, first determines the moment of separation of the pendulum from the cab after impact and the moment of deformation recovery of the cab structure, and then determines the moment of failure of the pendulum contact with the cab top and the moment of effectiveness of the top pressure plate contact with the cab top, thus realizing the sequential simulation of dynamic preloading pendulum side impact and top pressurization. This simulation method complies with the 2021 edition of GB 26512 national standard, can effectively identify risks, improve cab safety performance, is applicable to cab structures with varying strengths, and has strong versatility. Attached Figure Description

[0024] Figure 1 This is a flowchart of a commercial vehicle cab roof strength simulation method according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram showing a cut-out of a three-dimensional digital model of a commercial vehicle main structural component according to an embodiment of the present invention; wherein, Figure 2 The image on the left is a schematic diagram of a complete commercial vehicle model. Figure 2 The image on the right is a partial schematic diagram of the vehicle frame;

[0026] Figure 3 This is a schematic diagram of a simulation model of the cab roof strength according to an embodiment of the present invention;

[0027] Figure 4 This is a front view of a simulation model of the cab roof strength according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the degree of freedom constraint of the inner annular node connecting the front axle leaf spring seat and the leaf spring according to an embodiment of the present invention;

[0029] Figure 6 This is a force curve diagram of the pendulum and the top of the cab, and an internal energy change curve diagram of the strength simulation model of the cab top, according to another embodiment of the present invention; wherein, Figure 6 The left figure shows the force curve between the pendulum and the top of the cab. Figure 6 The right figure shows the internal energy change curve of the simulation model of the cab roof strength.

[0030] Among them, 1 is the pendulum, 2 is the top pressure plate, 3 is the cab top structure, and 4 is the front axle leaf spring seat. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0032] Example 1

[0033] like Figure 1 As shown, Embodiment 1 of the present invention provides a method for simulating the strength of the top of a commercial vehicle cab. The specific implementation process is as follows:

[0034] Step 1: Establish a 3D digital model of the main structural components of the commercial vehicle;

[0035] The three-dimensional digital model of the main structural components of the commercial vehicle includes the commercial vehicle frame, front axle leaf spring seat, cab suspension, cab body-in-white, doors, seats, instrument crossbeams, etc.

[0036] Step 2: Based on the three-dimensional digital model of the main structural components of the commercial vehicle, establish a finite element model of the cab structure; specifically including the following steps:

[0037] S21. Based on the cab mount and the front axle leaf spring seat, a partial frame is cut out, the partial frame including the cab mount and the front axle leaf spring seat; wherein, the cab mount is used to connect the cab assembly and the frame beam, and the front axle leaf spring seat is used to fix and limit the model; the cab assembly includes the cab body-in-white, doors, seats, instrument beams, etc.

[0038] like Figure 2 As shown, the main load-bearing structure of a commercial vehicle is the frame beam, and a section of the frame that affects the structural strength response of the cab is cut from the frame beam. Figure 2 The image in the middle left is a schematic diagram of a complete commercial vehicle model. Figure 2 The image on the right is a partial schematic diagram of the vehicle frame.

[0039] S22. Perform finite element modeling on the extracted partial frame and cab assembly, and assemble them to form a complete and interconnected structural whole, thus completing the finite element modeling of the cab structure.

[0040] The finite element model of the cab structure is used for strength analysis of the cab top. The suspension springs are modeled as solids and the connecting bolts are represented by beam elements to accurately characterize the motion and deformation of the cab, which is suspended from the cab and mounted on the frame beam, under the action of side impact and top pressure load.

[0041] Step 3: Establish a finite element model of a dynamically preloaded pendulum so that the impact energy of the pendulum reaches the energy threshold W;

[0042] Step 4: Based on the finite element model of the cab structure, establish a finite element model of the top pressure plate, ensuring that the loading speed of the top pressure plate satisfies the requirement that the ratio of kinetic energy to peak internal energy during the top pressurization process is less than a first threshold; specifically including the following steps:

[0043] S41. A rigid wall of finite size is used to represent the top pressure plate, which can only move along the Z-axis; the other directions have 12456 degrees of freedom and are fully constrained.

[0044] S42. Apply a loading speed to the top pressure plate. The loading speed must ensure that the ratio of kinetic energy to peak internal energy during the top pressing process is less than a first threshold. When the ratio is not less than the first threshold, reduce the loading speed to avoid local deformation of the top of the cab caused by the excessively fast loading speed, which would distort the analysis results and ensure the credibility of the simulation results.

[0045] Step 5: According to GB26512, introduce a 50th percentile Hybrid III male finite element manipulator; and associate the finite element manipulator with the driver's seat based on the driver's seat position information; such as... Figure 3 and Figure 4 As shown, the cab structure finite element model, the dynamic preloaded pendulum finite element model, the top pressure plate finite element model and the finite element dummy are combined to generate the cab top strength simulation model, and the contact action of the cab top strength simulation model is set.

[0046] The contact action setting of the strength simulation model of the cab roof specifically includes the following steps:

[0047] S51, Define the cab component set, pendulum set, and top pressure plate set;

[0048] S52. The simulation model of the cab top strength is set to include three types of contact: self-contact of the cab body-in-white, when setting self-contact, only the cab component set is referenced; surface-to-surface contact between the pendulum and the cab top structure, when setting, the main surface references the pendulum set and the secondary surface references the cab component set; surface-to-surface contact between the top rigid pressure plate and the cab top structure, when setting, the main surface references the rigid pressure plate set and the secondary surface references the cab component set.

[0049] Step 6: Fix the cab roof strength simulation model by constraining all degrees of freedom of the inner annular node connecting the front axle leaf spring seat and the leaf spring to ensure simulation accuracy; Figure 5 As shown, the coordinate system is marked with constrained degrees of freedom;

[0050] Parameters, including calculation step size and termination time, are set in the simulation model of the cab top strength. Dynamic preloading of the pendulum side impact simulation is performed using finite element pre- and post-processing software. The finite element software solution document of the pendulum impact on the cab is output. The deformation result of the cab top under the pendulum side impact is obtained by finite element dynamic analysis software. Based on the deformation result of the cab top, the interaction force between the pendulum and the cab top and the internal energy change of the cab top strength simulation model are obtained. The interaction force curve between the pendulum and the cab top and the internal energy change curve of the cab top strength simulation model are plotted. The pendulum release time t1 and the cab deformation recovery time t2 are determined.

[0051] Wherein, the pendulum disengagement time t1 is the moment when the force between the pendulum and the top of the cab is zero, and the cab deformation recovery time t2 is the moment when the internal energy change curve of the cab top strength simulation model is horizontal. When the force between the pendulum and the top of the cab is zero, it indicates that the pendulum has disengaged from the cab top, the cab is no longer subjected to the pendulum's force, and the elastically deformed cab begins to recover its shape; when the internal energy change curve of the cab top strength simulation model is horizontal, it indicates that the elastic deformation of the cab has been fully recovered, and subsequent simulation of top pressure plate loading can be performed.

[0052] Step 7: Based on the pendulum detachment time t1, determine the failure time of the pendulum contacting the top of the cab as t1 + Δt1. In this embodiment, Δt1 is set to 2ms. Based on the cab deformation recovery time t2, determine the effective time of the top pressure plate contacting the top of the cab as t2 + Δt2. In this embodiment, Δt2 is set to 2ms. When setting simulation parameters, the failure time of the pendulum contacting the top of the cab and the effective time of the top pressure plate contacting the top of the cab are introduced, so that the cab top strength simulation model performs pendulum side impact and top pressure plate loading simulations in sequence. The cab deformation results after pendulum side impact and top rigid pressure plate loading are obtained by finite element dynamics analysis software.

[0053] Step 8: Based on the cab deformation results in Step 7, analyze the spatial relationship between the cab structure and the finite element dummy during the simulation process when the top pressure plate force reaches the static load corresponding to the front axle load or the force reaches 98kN. Determine whether the cab structure intrudes into the finite element dummy during the simulation. If so, change the internal structure of the cab and return to Step 5; if not, the top strength of the cab meets the requirements, and the simulation is complete.

[0054] In this embodiment, the specific steps for establishing the finite element model of the dynamically preloaded pendulum include:

[0055] S31. According to GB26512, the mass of the pendulum is not less than 1500 kg. In this embodiment, the mass of the pendulum is set to 1500 kg. The geometric dimensions of the pendulum and the spatial placement of the pendulum are set according to GB 26512. The length of the suspension axis from the geometric center of the pendulum is not less than 3500 mm. In this embodiment, the length is set to 3500 mm. The suspension axis is fixed, and the pendulum is only freed from rotational freedom around the suspension axis.

[0056] S32. Assign an angular velocity ω to the pendulum so that the impact energy of the pendulum reaches the energy threshold W; in this embodiment, according to GB26512, the energy threshold W is 17.6kJ;

[0057] S33. Apply a gravitational field to the pendulum using the gravitational acceleration load of the finite element dynamics analysis software; simulate the pendulum's own gravity during the impact process to make the simulation conform to the real load scenario.

[0058] In this embodiment, the first threshold is no greater than 10%. The first threshold is the accuracy requirement for setting the loading speed of the top pressure plate, used to control the loading speed of the top pressure plate and ensure the authenticity and reliability of the simulation results.

[0059] In this embodiment, the formula for calculating the angular velocity ω is: The derivation of the calculation formula is as follows:

[0060] The formula for calculating the kinetic energy of a pendulum rotating about its suspension axis is:

[0061]

[0062] Where E is the kinetic energy of the pendulum, J is the moment of inertia of the pendulum about the suspension axis, and ω is the angular velocity of the pendulum about the suspension axis. When ω=1rad / s, the kinetic energy E0 of the pendulum calculated by the finite element dynamics analysis software can be obtained by formula (1) as J=2E0.

[0063] In the simulation test of the dynamically preloaded pendulum, the impact energy of the pendulum needs to reach the energy threshold W, i.e., E = W. This can be obtained by combining formula (1).

[0064]

[0065] According to GB26512, the energy threshold W required for a side pendulum impact is 17.6 kJ. Therefore,

[0066]

[0067] Example 2

[0068] Embodiment 2 of the present invention also provides a commercial vehicle cab roof strength simulation system, the system including a memory and one or more processors; the memory stores one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the steps of the simulation method described in Embodiment 1.

[0069] Example 3

[0070] In the commercial vehicle cab roof strength simulation method provided in Example 1, in step 6, based on the cab roof deformation results of the pendulum side impact simulation, the interaction force between the pendulum and the cab roof and the internal energy change of the cab roof strength simulation model are obtained, and the interaction force curve between the pendulum and the cab roof and the internal energy change curve of the cab roof strength simulation model are plotted. The pendulum release time t1 and the cab deformation recovery time t2 are also determined. In this embodiment, as... Figure 6 As shown, t1 is 0.252s and t2 is 0.29s. The moment t1 when the pendulum detaches is the moment when the force between the pendulum and the top of the cab is zero, and the moment t2 when the cab deformation recovers is the moment when the internal energy change curve of the cab top strength simulation model is horizontal. When the force between the pendulum and the top of the cab is zero, it indicates that the pendulum has disengaged from the top of the cab, the cab is no longer subjected to the action of the pendulum, and the elastically deformed cab begins to recover its shape; when the internal energy change curve of the cab top strength simulation model is horizontal, it indicates that the elastic deformation of the cab has been fully recovered, and subsequent simulation of top pressure plate loading can be performed.

[0071] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present embodiments by those skilled in the art will fall within the scope defined by the appended claims.

Claims

1. A method for simulating the strength of the cab roof, characterized in that, The method includes: Step 1: Establish a 3D digital model of the main structural components of the commercial vehicle; Step 2: Based on the three-dimensional digital model of the main structural components of the commercial vehicle, establish a finite element model of the cab structure; the finite element model of the cab structure includes a partial frame and a cab assembly; the partial frame includes the cab suspension and the front axle leaf spring seat; Step 3: Establish a finite element model of a dynamically preloaded pendulum so that the impact energy of the pendulum reaches the energy threshold W; Step 4: Based on the finite element model of the cab structure, establish a finite element model of the top pressure plate, such that the loading speed of the top pressure plate satisfies that the ratio of kinetic energy to peak internal energy during the top pressurization process is less than a first threshold. Step 5: Based on the position information of the driver's seat, associate the finite element dummy with the driver's seat; combine the finite element model of the cab structure, the finite element model of the dynamic preloaded pendulum, the finite element model of the top pressure plate, and the finite element dummy to generate a cab top strength simulation model, and set the contact action of the cab top strength simulation model; Step 6: Fix the cab roof strength simulation model by constraining all degrees of freedom of the inner annular node connecting the front axle leaf spring seat and the leaf spring; Parameters were set, and a side impact simulation of the pendulum was performed. The deformation results of the cab roof under the side impact of the pendulum were obtained by calculation using finite element dynamics analysis software. Based on the deformation results of the cab roof, the force curve between the pendulum and the cab roof and the internal energy change curve of the cab roof strength simulation model were obtained, and the pendulum release time t1 and the cab deformation recovery time t2 were determined. Wherein, the pendulum detachment time t1 is the moment when the force between the pendulum and the top of the cab is zero, and the cab deformation recovery time t2 is the moment when the internal energy change curve of the strength simulation model of the cab top is horizontal; Step 7: Set the failure time of the pendulum contacting the top of the cab as t1+Δt1, and the effective time of the top pressure plate contacting the top of the cab as t2+Δt2; Based on the failure time of the pendulum contacting the top of the cab and the effective time of the top pressure plate contacting the top of the cab, the cab top strength simulation model is simulated by pendulum side impact and top pressure plate loading in sequence. The deformation result of the cab after pendulum side impact and top pressure plate loading is obtained by finite element dynamic analysis software. Step 8: Based on the cab deformation results in Step 7, determine whether the cab structure intrudes into the finite element dummy during the simulation. If so, change the internal structure of the cab and return to Step 5; if not, the top strength of the cab meets the requirements, and the simulation is complete.

2. The method for simulating the strength of the cab roof according to claim 1, characterized in that, Step 3 specifically includes the following steps: S31. Set the pendulum mass, pendulum geometry, and pendulum spatial placement. S32. Assign an angular velocity ω to the pendulum so that the impact energy of the pendulum reaches the energy threshold W; S33. Apply a gravitational field to the pendulum.

3. The method for simulating the strength of the cab roof according to claim 1, characterized in that, In step 4, the first threshold is no greater than 10%.

4. The method for simulating the strength of the cab roof according to claim 2, characterized in that, In step S32, the formula for calculating the angular velocity ω is: Where J = 2E0, and E0 is the kinetic energy of the pendulum calculated by finite element dynamics analysis software when the angular velocity is 1 rad / s.

5. A cab roof strength simulation system, characterized in that, The system includes a memory and one or more processors; the memory stores one or more programs, which, when executed by the one or more processors, cause the one or more processors to perform the steps of the method according to any one of claims 1 to 4.

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