Commercial vehicle cab top strength simulation method and system

Abstract

The invention discloses a commercial vehicle cab top strength simulation method, which comprises the following steps of: firstly, determining a separation moment after a pendulum bob collides with a cab and a cab structure deformation recovery moment, and then determining a failure moment when the pendulum bob is contacted with the top of the cab and an effective moment when a top pressure plate is contacted with the top of the cab according to the separation moment and the cab structure deformation recovery moment; sequential simulation of dynamic preloading swing-out side impact and top pressurization is realized; the simulation method accords with 2021 edition GB 26512 national standard regulations, can effectively identify risks and improve the safety performance of the cab, is suitable for cab structures with different strengths, and is high in universality. The invention further provides a commercial vehicle cab top strength simulation system.

Description

Technical Field

[0001] The invention relates to a commercial vehicle cab top strength simulation method and system, belonging to the technical field of engineering machinery cabs. Background Art

[0002] As an important means of transportation for logistics and transportation, the structural safety of the cab of commercial vehicles is of vital importance. The 2011 version of GB26512 "Occupant Protection of Commercial Vehicle Cabs" only stipulates the top strength test, while the 2021 version of GB 26512 "Occupant Protection of Commercial Vehicle Cabs" puts forward stricter requirements for the strength of the cab top: for trucks with a total mass of more than 7500kg, a dynamic preload test is added, that is, a 20° impact test of the cab side pendulum with an impact energy of 17.6kJ. After the side impact, the top strength test is carried out. The loading force of the top strength test is the static load corresponding to the front axle load, with a maximum of 98kN. That is, for trucks with a total mass of more than 7500kg, a dynamic preload test of the side pendulum impact is required first, and then the top steel plate is loaded to ensure that the cab has sufficient strength during the rolling process to ensure that the occupants have enough living space. Therefore, in the development stage of the commercial vehicle cab, it is necessary to use new simulation technology to conduct a performance survey of the cab top strength to verify whether it meets the mandatory requirements of the national standard. Summary of the invention

[0003] The present invention aims to provide a method for simulating the strength of the top of a commercial vehicle cab. The method first determines the separation moment of the pendulum and the cab after the collision and the deformation recovery moment of the cab structure, and defines the failure moment of the contact between the pendulum and the top of the cab and the effective moment of the contact between the top pressure plate and the top of the cab based on this, ensuring the order of the dynamic preloading pendulum side impact and top pressurization simulation, which complies with the provisions of the 2021 version of GB 26512 national standard, is suitable for the simulation of different cab structures, effectively identifies risks, and improves the safety performance of the cab.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: a cab top strength simulation method, the method comprising:

[0005] Step 1: Establish a three-dimensional digital model of the main structural parts of a commercial vehicle;

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

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

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

[0009] Step 5: Associating a finite element dummy with the driver's seat according to the position information of the driver's seat; combining the cab structure finite element model, the dynamic preload pendulum finite element model, the top pressure plate finite element model and the finite element dummy to generate a cab top strength simulation model, and setting the contact effect of the cab top strength simulation model;

[0010] Step 6, fixing the cab roof strength simulation model by constraining all degrees of freedom of the inner annular surface nodes connected to the front axle leaf spring seat and the leaf spring;

[0011] Setting parameters, performing pendulum side impact simulation, and calculating by finite element dynamics analysis software to obtain the deformation result of the cab top under the pendulum side impact; obtaining the force curve between the pendulum and the cab top and the internal energy change curve of the cab top strength simulation model according to the deformation result of the cab top, and determining the pendulum detachment time t1 and the cab deformation recovery time t2;

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

[0013] Step 7, setting the failure time of the pendulum contacting the top of the cab to t1+Δt1, and the effective time of the top pressure plate contacting the top of the cab to t2+Δt2; according to 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 sequentially performs pendulum side impact and top pressure plate loading simulation, and calculates through finite element dynamics analysis software to obtain the deformation result of the cab after the pendulum side impact and then the top pressure plate loading;

[0014] Step 8: According to the cab deformation result in step 7, determine whether the cab structure invades the finite element dummy during the simulation process. 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 completed.

[0015] According to the embodiments of the present invention, the present invention can be further optimized. The following is the technical solution formed after optimization:

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

[0017] S31, setting the mass of the pendulum, the geometric dimensions of the pendulum and the spatial placement position of the pendulum;

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

[0019] S33, applying a gravitational field effect to the pendulum.

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

[0021] In one preferred embodiment, in S32, the calculation formula of the angular velocity ω is: Where J = 2E 0 , E 0 It 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, which includes a memory and one or more processors; one or more programs are stored on the memory, 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 above method.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the commercial vehicle cab top strength simulation method provided by the present invention, according to the dynamic preloading test requirements specified in the 2021 version of GB 26512 national standard, first determines the separation moment after the pendulum hits the cab and the deformation recovery moment of the cab structure, and then determines the failure moment of the pendulum contacting the cab top and the effective moment of the top pressure plate contacting the cab top, thereby realizing the sequential simulation of the dynamic preloading swinging out of the side impact and the top pressurization. The simulation method complies with the provisions of the 2021 version of GB 26512 national standard, can effectively identify risks, improve the safety performance of the cab, is applicable to cab structures of different strengths, and has strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0028] Figure 5 It 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 one embodiment of the present invention;

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

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

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[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, and the specific implementation process is as follows:

[0034] Step 1: Establish a three-dimensional digital model of the main structural parts of a commercial vehicle;

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

[0036] Step 2: Building a cab structure finite element model based on the three-dimensional digital model of the main structural parts of the commercial vehicle; specifically comprising the following steps:

[0037] S21. According to the cab suspension and the front axle leaf spring seat, a partial frame is cut, wherein the partial frame includes the cab suspension and the front axle leaf spring seat; wherein the cab suspension 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 cross beam, etc.;

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

[0039] S22. Perform finite element modeling on the intercepted partial vehicle frame and cab assembly, and assemble them to form a complete structural whole that is interconnected with each other, thereby completing the finite element modeling of the cab structure.

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

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

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

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

[0044] S42, applying a loading speed to the top pressure plate, the loading speed needs to satisfy that the ratio of kinetic energy to peak internal energy during the top pressure process is less than a first threshold value; when the ratio is not less than the first threshold value, the loading speed is reduced to avoid the simulation result of the top pressure loading causing local deformation of the cab top due to the excessively fast loading speed, which causes distortion of the analysis result, so as to ensure the credibility of the simulation result.

[0045] Step 5: According to GB26512, a 50 percentile Hybrid III male finite element dummy is introduced; and according to the position information of the driver's seat, the finite element dummy is associated with the driver's seat; Figure 3 and Figure 4 As shown, the cab structure finite element model, the dynamic preload pendulum finite element model, the top pressure plate finite element model and the finite element dummy are combined to generate a cab top strength simulation model, and the contact effect of the cab top strength simulation model is set;

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

[0047] S51, defining a cab component set, a pendulum set, and a top pressure plate set;

[0048] S52. Setting the cab top strength simulation model to include three types of contacts: self-contact of the cab body-in-white. When setting the 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 slave surface references the cab component set; and 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 slave surface references the cab component set.

[0049] Step 6: Fix the cab top strength simulation model by constraining all degrees of freedom of the inner annular nodes connecting the front axle leaf spring seat and the leaf spring to ensure simulation accuracy; Figure 5 As shown, the degrees of freedom are constrained at the coordinate system mark;

[0050] Setting parameters in the cab top strength simulation model, including calculation step length, termination time, etc., performing dynamic preload pendulum side impact simulation settings through finite element pre- and post-processing software, outputting a finite element software solution document of the pendulum impact cab simulation, and calculating through finite element dynamics analysis software to obtain the deformation result of the cab top under the pendulum side impact; according to the deformation result of the cab top, obtaining the force between the pendulum and the cab top and the internal energy change of the cab top strength simulation model, and drawing the force curve between the pendulum and the cab top and the internal energy change curve of the cab top strength simulation model, and determining the pendulum detachment time t1 and the cab deformation recovery time t2;

[0051] The pendulum separation moment t1 is the moment when the force between the pendulum and the cab top is zero, and the cab deformation recovery moment 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 cab top is zero, it indicates that the pendulum has been separated from the cab top, the cab is no longer affected by 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 the top pressure plate loading simulation can be performed later.

[0052] Step 7, according to the pendulum detachment moment t1, determine the failure moment of the pendulum contacting the top of the cab as t1+Δt1, in this embodiment, Δt1 is set to 2ms; according to the cab deformation recovery moment t2, determine the effective moment of the top pressure plate contacting the top of the cab as t2+Δt2, in this embodiment, Δt2 is set to 2ms; when setting the simulation parameters, introduce 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, so that the cab top strength simulation model performs pendulum side impact and top pressure plate loading simulation in sequence; calculate through finite element dynamics analysis software to obtain the cab deformation result after the pendulum side impact and then the top rigid pressure plate loading;

[0053] Step 8. According to the deformation result of the cab in step 7, by analyzing the spatial position relationship between the cab structure and the finite element dummy during the simulation process, when the force of the top pressure plate reaches the static load corresponding to the front axle load or the force reaches 98kN, it is determined whether the cab structure invades the finite element dummy during the simulation process. 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 completed.

[0054] In this embodiment, the specific steps of establishing the dynamic preload pendulum finite element model include:

[0055] S31. According to GB 26512, 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 in accordance with 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 only releases the rotational freedom around the suspension axis.

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

[0057] S33. Apply a gravity field effect to the pendulum through the gravity acceleration load of the finite element dynamics analysis software; and make the simulation conform to the real load scenario by simulating the gravity effect of the pendulum itself during the impact process.

[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 pressing plate, and is used to control the loading speed of the top pressing plate to ensure the authenticity of the simulation results.

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

[0060] For a pendulum rotating around a suspension axis, the kinetic energy is calculated as:

[0061]

[0062] Where E is the kinetic energy of the pendulum, J is the moment of inertia of the pendulum around the suspension axis, and ω is the angular velocity of the pendulum around the suspension axis. When ω = 1 rad / s, the kinetic energy of the pendulum E calculated by the finite element dynamics analysis software is 0 , from formula (1) we can get J = 2E 0 .

[0063] In the dynamic preload pendulum simulation test, the impact energy of the pendulum needs to reach the energy threshold W, that is, E = W. Combining formula (1), we can get

[0064]

[0065] According to GB26512, the energy threshold W that the side pendulum impact energy needs to reach is 17.6 kJ, so

[0066]

[0067] Example 2

[0068] Embodiment 2 of the present invention further provides a commercial vehicle cab roof strength simulation system, the system comprising a memory and one or more processors; one or more programs are stored on the memory, 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 top strength simulation method provided in Example 1, in step 6, the force between the pendulum and the cab top and the internal energy change of the cab top strength simulation model are obtained according to the cab top deformation result of the pendulum side impact simulation, and the force curve between the pendulum and the cab top and the internal energy change curve of the cab top strength simulation model are plotted, and the pendulum separation time t1 and the cab deformation recovery time t2 are determined. In this embodiment, Figure 6As shown, t1 is 0.252s, and t2 is 0.29s. The pendulum disengagement moment t1 is the moment when the force between the pendulum and the cab top is zero, and the cab deformation recovery moment 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 cab top is zero, it indicates that the pendulum has been separated from the cab top, the cab is no longer affected by 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 the top pressure plate loading simulation can be performed later.

[0071] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A cab roof strength simulation method, characterized in that: The method comprises: Step 1: Establish a three-dimensional digital model of the main structural parts of a commercial vehicle; Step 2: Based on the three-dimensional digital model of the main structural parts of the commercial vehicle, a cab structure finite element model is established; the cab structure finite element model includes a partial frame and a cab assembly; the partial frame includes a cab suspension and a front axle leaf spring seat; Step 3: Establish a finite element model of a dynamic preloaded pendulum so that the impact energy of the pendulum reaches an energy threshold value W; Step 4: Based on the cab structure finite element model, a top pressure plate finite element model is established, so that the loading speed of the top pressure plate satisfies that the ratio of kinetic energy to peak internal energy during top pressurization is less than a first threshold value; Step 5: Associating a finite element dummy with the driver's seat according to the position information of the driver's seat; combining the cab structure finite element model, the dynamic preload pendulum finite element model, the top pressure plate finite element model and the finite element dummy to generate a cab top strength simulation model, and setting the contact effect of the cab top strength simulation model; Step 6, fixing the cab roof strength simulation model by constraining all degrees of freedom of the inner annular surface nodes connected to the front axle leaf spring seat and the leaf spring; Setting parameters, performing pendulum side impact simulation, and calculating by finite element dynamics analysis software to obtain the deformation result of the cab top under the pendulum side impact; obtaining the force curve between the pendulum and the cab top and the internal energy change curve of the cab top strength simulation model according to the deformation result of the cab top, and determining the pendulum detachment time t1 and the cab deformation recovery time t2; The pendulum separation moment t1 is the moment when the force between the pendulum and the cab top is zero, and the cab deformation recovery moment t2 is the moment when the internal energy change curve of the cab top strength simulation model is horizontal; Step 7, setting the failure time of the pendulum contacting the top of the cab to t1+Δt1, and the effective time of the top pressure plate contacting the top of the cab to t2+Δt2; according to 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 sequentially performs pendulum side impact and top pressure plate loading simulation, and calculates through finite element dynamics analysis software to obtain the deformation result of the cab after the pendulum side impact and then the top pressure plate loading; Step 8: According to the cab deformation result in step 7, determine whether the cab structure invades the finite element dummy during the simulation process. 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 completed.

2. The cab roof strength simulation method according to claim 1, characterized in that: The step 3 specifically comprises the following steps: S31, setting the mass of the pendulum, the geometric dimensions of the pendulum and the spatial placement position of the pendulum; S32, giving an angular velocity ω to the pendulum so that the impact energy of the pendulum reaches an energy threshold value W; S33, applying a gravitational field effect to the pendulum.

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

4. The cab roof strength simulation method according to claim 2, characterized in that: In S32, the calculation formula of the angular velocity ω is: Wherein, 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 top strength simulation system, characterized in that: The system includes a memory and one or more processors; one or more programs are stored in the memory, 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 method according to any one of claims 1 to 4.

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