A method for designing the strength of a lower swing arm mounting point

Abstract

The present application relates to the field of automobile safety technology, and discloses a strength design method of lower swing arm mounting point, comprising: constructing a finite element model; constructing a DOE analysis matrix composed of failure time of the lower swing arm mounting point, and obtaining optimal failure time of the lower swing arm mounting point according to the DOE analysis matrix; extracting force-time curve corresponding to the lower swing arm mounting point under the condition that the lower swing arm mounting point does not fail; obtaining force value corresponding to the optimal failure time according to the force-time curve corresponding to the lower swing arm mounting point, and taking the force value as initial failure strength of the lower swing arm mounting point; in the finite element model, verifying the initial failure strength by using finite element analysis, until actual failure time of the lower swing arm mounting point is located in the set fluctuation range of the optimal failure time, and obtaining design strength of the lower swing arm mounting point. The present application realizes strength design of the lower swing arm mounting point, is beneficial to realizing effective sequential deflection of the wheel, and gains more energy absorption space for the vehicle body structure before the vehicle body structure occurs large deformation under force.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile safety technology, in particular to a strength design method of a lower swing arm mounting point. BACKGROUND

[0002] With the continuous upgrading of the automobile driving safety regulations, the small offset collision condition is more and more concerned. The small offset collision condition is called the most severe collision condition, which is a great test for the vehicle body structure and the occupant protection. At present, the research on the occupant protection under the small offset collision condition is mostly concentrated in the strengthening of the occupant compartment and the optimization of the restraint system. The existing technology often adopts the methods of increasing the cross section of the door sill and the A-pillar, increasing the thickness of the door sill and the A-pillar, adding reinforcing members in the door sill and the A-pillar, and improving the material grade of the door sill and the A-pillar to increase the strength of the door sill and the A-pillar, improve the strength of the occupant compartment, and strengthen the protection of the occupant. However, increasing the strength of the door sill and the A-pillar may cause the A-pillar cross section to be too large to affect the field of view or cause the vehicle body cost and weight to exceed the standard. SUMMARY

[0003] In view of the above problems, the purpose of the present application is to provide a strength design method of a lower swing arm mounting point to solve the problem that increasing the strength of the occupant compartment under the small offset collision condition may cause the A-pillar cross section to be too large to affect the field of view or cause the vehicle body cost and weight to exceed the standard.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] The strength design method of the lower swing arm mounting point according to the present application comprises:

[0006] Step S1, constructing a finite element model of the connection between the wheel and the chassis connecting piece;

[0007] Step S2, constructing a DOE analysis matrix composed of the failure time of the lower swing arm mounting point in the finite element model, and obtaining the optimal failure time of the lower swing arm mounting point according to the DOE analysis matrix;

[0008] Step S3, extracting the force-time curve corresponding to the lower swing arm mounting point under the condition that the lower swing arm mounting point does not fail in the finite element model;

[0009] Step S4, obtaining the force value corresponding to the optimal failure time according to the force-time curve corresponding to the lower swing arm mounting point as the initial failure strength of the lower swing arm mounting point;

[0010] Step S5, verifying the initial failure strength by using finite element analysis in the finite element model until the actual failure time of the lower swing arm mounting point is within the set fluctuation range of the optimal failure time, and obtaining the design strength of the lower swing arm mounting point.

[0011] Preferably, the step S5 comprises:

[0012] Step S51, setting material parameters of the finite element model;

[0013] Step S52, obtaining the actual failure time of the lower arm mounting point according to the initial failure strength by finite element analysis, and judging whether the actual failure time is within the set fluctuation range of the optimal failure time, if the actual failure time is not within the set fluctuation range of the optimal failure time, then performing step S53;

[0014] Step S53, performing local strengthening or weakening treatment on the failure position of the lower arm mounting point to obtain the updated failure strength of the lower arm mounting point;

[0015] Step S54, obtaining the updated actual failure time of the lower arm mounting point according to the updated failure strength of the lower arm mounting point by finite element analysis, and judging whether the updated actual failure time is within the set fluctuation range of the optimal failure time;

[0016] Step S55, if the updated actual failure time is not within the set fluctuation range of the optimal failure time, then repeating steps S53 and S54 until the actual failure time of the lower arm mounting point is within the set fluctuation range of the optimal failure time, and obtaining the design strength of the lower arm mounting point.

[0017] Preferably, the set fluctuation range is within ±5ms of the optimal failure time.

[0018] Preferably, the lower arm mounting point comprises a front lower arm mounting point and a rear lower arm mounting point.

[0019] Preferably, the failure time of the front lower arm mounting point is 20ms-60ms, and the interval between the failure times of the front lower arm mounting point and the rear lower arm mounting point is 10ms-60ms.

[0020] Preferably, the matrix elements of the DOE analysis matrix include the failure times of the front lower arm mounting point and the rear lower arm mounting point.

[0021] Preferably, in the step S4, the initial failure strength includes a first initial failure strength of the front lower arm mounting point and a second initial failure strength of the rear lower arm mounting point.

[0022] Preferably, in the finite element model, the failure strength of the connection point between the lower arm and the steering knuckle is greater than the larger one of the first initial failure strength and the second initial failure strength.

[0023] Compared with the prior art, the strength design method of the lower swing arm mounting point has the beneficial effects that:

[0024] The strength design method of the lower swing arm mounting point constructs a DOE analysis matrix according to the failure time of the lower swing arm mounting point, obtains the optimal failure time and the initial failure strength of the lower swing arm mounting point through a finite element analysis method, obtains the final design strength of the lower swing arm mounting point through repeated verification on the initial failure strength, realizes the strength design of the lower swing arm mounting point, is conducive to realizing the sequential effective deflection of the vehicle wheel, and ensures more energy absorption space for the vehicle body structure before the vehicle body structure is subjected to large deformation, thereby reducing the pressure on the vehicle body structure and improving the grade of the vehicle body structure. In the case of a small increase in cost and weight, the grade target of the vehicle body structure in the small offset collision condition is realized without the need to improve the passenger compartment strength, thereby avoiding the problems of an excessively large A-pillar section that affects the field of view or causes the vehicle body cost and weight to exceed the standard, and facilitating the lightweight of the vehicle body. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flowchart of the strength design method of the lower swing arm mounting point according to the embodiment of the present application;

[0026] Figure 2 is a schematic diagram of the connection between the vehicle wheel and the chassis connecting piece in the embodiment of the present application Figure 1 ;

[0027] Figure 3 is a schematic diagram of the connection between the vehicle wheel and the chassis connecting piece in the embodiment of the present application Figure 2 ;

[0028] In the figure, 1 is a lower swing arm front mounting point; 2 is a lower swing arm rear mounting point; 3 is a vehicle wheel and steering system connection point; 4 is a vehicle wheel and transmission system connection point; 5 is a lower swing arm and steering knuckle connection point; 6 is a vehicle wheel and transverse stabilizer bar connection point; 7 is a vehicle wheel and front suspension connection point; and 8 is a vehicle wheel. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application will be further described in detail below in combination with the drawings and embodiments. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0030] As shown in Figure 1 , the strength design method of the lower swing arm mounting point according to the embodiment of the present application comprises:

[0031] Step S1, constructing a finite element model of the connection between the vehicle wheel 8 and the chassis connecting piece, wherein the chassis connecting piece comprises a lower swing arm, a steering knuckle, a transmission system, a transverse stabilizer bar, a front suspension and the like, as shown in Figure 2 ;

[0032] Step S2, in the finite element model, a DOE (Design of Experiment) analysis matrix composed of the failure time of the lower swing arm mounting point is constructed, and the optimal failure time of the lower swing arm mounting point is obtained according to the DOE analysis matrix;

[0033] Step S3, in the finite element model, the force-time curve corresponding to the lower swing arm mounting point under the condition that the lower swing arm mounting point does not fail is extracted;

[0034] Step S4, the force value corresponding to the optimal failure time is obtained according to the force-time curve corresponding to the lower swing arm mounting point, and the force value corresponding to the optimal failure time is taken as the initial failure strength of the lower swing arm mounting point;

[0035] Step S5, in the finite element model, the initial failure strength is verified by using finite element analysis, until the actual failure time of the lower swing arm mounting point is located in the set fluctuation range of the optimal failure time, and the design strength of the lower swing arm mounting point is obtained.

[0036] In the small offset collision condition, the vehicle collides with the barrier, and the barrier generates a reaction force on the vehicle, which can reduce the pressure on the upper vehicle body through the force transmission of the lower vehicle body. Under the condition of the same cost weight, it is beneficial to obtain a better vehicle body structure rating. The wheel deflection has an important influence on the vehicle body structure in the small offset collision condition. The wheel deflection can provide more energy-absorbing space for the passenger compartment, reduce the force and energy transmitted to the cabin, and the wheel without deflection can transmit force to the lower vehicle body earlier, absorb more collision energy through the lower vehicle body, and reduce the deformation of the upper vehicle body. Therefore, the time point of controlling the wheel deflection needs to be controlled. For example Figure 2 and Figure 3As shown, the chassis connecting member is connected with the wheel 8 to form a plurality of connecting points, including a wheel and steering system connecting point 3, a wheel and transmission system connecting point 4, a lower swing arm and steering knuckle connecting point 5, a wheel and transverse stabilizer connecting point 6, a wheel and front suspension connecting point 7, a lower swing arm mounting point, a plurality of connecting points form a constraint on the deflection of the wheel 8, wherein the wheel and transverse stabilizer connecting point 6, the wheel and steering system connecting point 3, and the wheel and transmission system connecting point 4 all form a Y-direction constraint on the wheel 8; the wheel and front suspension connecting point 7 and the lower swing arm mounting point form an X, Y, Z three-direction constraint on the wheel 8. Failure of the wheel and front suspension connecting point 7 can cause fluctuation of the wheel 8 Z-direction movement, and failure of the lower swing arm mounting point can realize stable deflection of the wheel 8 around the Z-axis. Therefore, controlling the failure of the lower swing arm mounting point is an effective way to control the time point of wheel deflection. The present application controls the strength of the lower swing arm mounting point, which is beneficial to realize the sequential and effective deflection of the wheel, and to gain more energy absorption space for the vehicle body structure before the vehicle body structure is subjected to large deformation under stress, thereby reducing the pressure on the vehicle body structure and improving the level of the vehicle body structure. In the case of small cost and weight increase, the level target of the vehicle body structure in the small offset collision working condition is realized, which can avoid simply strengthening the vehicle body structure to cope with the small offset collision working condition, and is beneficial to the lightweight of the vehicle body.

[0037] As Figure 3 shown, the lower swing arm mounting point includes a lower swing arm front mounting point 1 and a lower swing arm rear mounting point 2, and further, the matrix elements of the DOE analysis matrix include the failure time of the lower swing arm front mounting point 1 and the failure time of the lower swing arm rear mounting point 2. Correspondingly, in the step S4, the optimal failure time includes the optimal failure time of the lower swing arm front mounting point 1 and the optimal failure time of the lower swing arm rear mounting point 2; the initial failure strength includes the first initial failure strength of the lower swing arm front mounting point 1 and the second initial failure strength of the lower swing arm rear mounting point 2.

[0038] In the finite element model, according to the time point of the collision force transmission, the time when the collision force is transmitted to the front mounting point 1 of the lower swing arm is about 20 ms later, and the collision force is transmitted to the passenger compartment through the wheel 8 after 60 ms, if the front mounting point 1 of the lower swing arm fails after 60 ms, it is basically equivalent to that the wheel 8 is not deflected, therefore, the failure time of the front mounting point 1 of the lower swing arm is 20 ms-60 ms, for example, it can be set to 20 ms, 30 ms, 40 ms, 50 ms, 60 ms. The interval between the failure time of the front mounting point 1 of the lower swing arm and the rear mounting point 2 of the lower swing arm is 10 ms-60 ms, for example, the failure interval can be set to 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 60 ms. In the present application, the matrix elements in the DOE analysis matrix are set to 30, and the optimal solution in 30 different failure times is extracted, the optimal failure time of the front mounting point 1 of the lower swing arm is recorded as T1, and the optimal failure time of the rear mounting point 2 of the lower swing arm is recorded as T2. In step S4, the first initial failure strength is recorded as F1, and the second initial failure strength is recorded as F2. In order to ensure that the connecting point 5 of the lower swing arm and the steering knuckle does not fail, the failure strength of the lower swing arm and the steering knuckle mounting point in the finite element model is greater than the larger value of F1 and F2.

[0039] In the present embodiment, the step S5 comprises:

[0040] Step S51, set the material parameters of the finite element model, so that the simulation of the model is more in line with the engineering practice;

[0041] Step S52, using finite element analysis, obtaining the actual failure time of the lower swing arm mounting point according to the initial failure strength, and judging whether the actual failure time is located in the set fluctuation range of the optimal failure time, if the actual failure time is not located in the set fluctuation range of the optimal failure time, then step S53 is performed;

[0042] Step S53, local strengthening or weakening treatment is made at the failure position of the lower swing arm mounting point to obtain the updated failure strength of the lower swing arm mounting point;

[0043] Step S54, using finite element analysis, obtaining the actual failure time of the updated lower swing arm mounting point according to the updated failure strength of the lower swing arm mounting point, and judging whether the updated actual failure time is located in the set fluctuation range of the optimal failure time;

[0044] If the updated actual failure time is not located in the set fluctuation range of the optimal failure time, steps S53 and S54 are repeated until the actual failure time of the lower swing arm mounting point is located in the set fluctuation range of the optimal failure time, and the design strength of the lower swing arm mounting point is obtained. Preferably, the set fluctuation range is ±5 ms of the optimal failure time, and specifically, the failure time of the front lower swing arm mounting point 1 is located in ±5 ms of T1, and the failure time of the rear lower swing arm mounting point 2 is located in ±5 ms of T2.

[0045] In summary, the embodiment of the present application provides a strength design method of a lower swing arm mounting point, which constructs a DOE analysis matrix based on the failure time of the lower swing arm mounting point, obtains the optimal failure time and the initial failure strength of the lower swing arm mounting point through a finite element analysis method, obtains the final design strength of the lower swing arm mounting point through repeated verification of the initial failure strength, realizes the strength design of the lower swing arm mounting point, is conducive to realizing the sequential effective deflection of the wheel, and gains more energy absorption space for the vehicle body structure before the vehicle body structure is subjected to large deformation, thereby reducing the pressure on the vehicle body structure and improving the level of the vehicle body structure. In the case of a small increase in cost and weight, the level of the vehicle body structure in the small offset collision condition is realized without the need to improve the strength of the passenger compartment, thereby avoiding the problem of an excessively large A-pillar section that affects the field of view or leads to an excessive cost and weight of the vehicle body, and being conducive to the lightweight of the vehicle body.

[0046] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, several improvements and replacements can be made without departing from the technical principles of the present application, and these improvements and replacements should be considered as the protection scope of the present application.

Claims

1. A method of designing the strength of a lower swing arm mounting point, characterized by, The method comprises the following steps: S1, constructing a finite element model of a wheel and a chassis connecting piece; S2, in the finite element model, constructing a DOE analysis matrix composed of failure time of lower arm mounting points, and obtaining optimal failure time of the lower arm mounting points according to the DOE analysis matrix; the lower arm mounting points include a front lower arm mounting point and a rear lower arm mounting point, and matrix elements of the DOE analysis matrix include failure time of the front lower arm mounting point and failure time of the rear lower arm mounting point; S3, in the finite element model, extracting force-time curves corresponding to the lower arm mounting points under the condition that the lower arm mounting points do not fail; S4, obtaining a force value corresponding to the optimal failure time according to the force-time curves corresponding to the lower arm mounting points as initial failure strength of the lower arm mounting points; S5, in the finite element model, verifying the initial failure strength by using finite element analysis until actual failure time of the lower arm mounting points is located in a set fluctuation range of the optimal failure time, and obtaining design strength of the lower arm mounting points.

2. The method of designing the strength of a lower swing arm mounting point according to claim 1, wherein, The step S5 comprises: S51, setting material parameters of the finite element model; S52, obtaining actual failure time of the lower arm mounting points according to the initial failure strength by using finite element analysis, and judging whether the actual failure time is located in the set fluctuation range of the optimal failure time, if the actual failure time is not located in the set fluctuation range of the optimal failure time, then performing step S53; S53, performing local strengthening or weakening treatment on a failure position of the lower arm mounting points to obtain updated failure strength of the lower arm mounting points; S54, obtaining updated actual failure time of the lower arm mounting points according to the updated failure strength of the lower arm mounting points by using finite element analysis, and judging whether the updated actual failure time is located in the set fluctuation range of the optimal failure time; S55, if the updated actual failure time is not located in the set fluctuation range of the optimal failure time, then repeating steps S53 and S54 until the actual failure time of the lower arm mounting points is located in the set fluctuation range of the optimal failure time, and obtaining design strength of the lower arm mounting points.

3. The method of designing the strength of a lower swing arm mounting point of claim 2, wherein, The set fluctuation range is within ±5 ms of the optimal failure time.

4. The method of designing the strength of a lower swing arm mounting point of claim 1, wherein, The failure time of the front lower arm mounting point is 20 ms to 60 ms, and an interval between the failure time of the front lower arm mounting point and the failure time of the rear lower arm mounting point is 10 ms to 60 ms.

5. The method of designing the strength of a lower swing arm mounting point of claim 1, wherein, In the step S4, the initial failure strength includes first initial failure strength of the front lower arm mounting point and second initial failure strength of the rear lower arm mounting point.

6. The method of hemline arm mounting point strength design according to claim 5, wherein, In the finite element model, failure strength of a lower arm and a steering knuckle connecting point is greater than a larger value of the first initial failure strength and the second initial failure strength.

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