The hottest madymoautodoe in the occupant restrain

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The application of madymo/autodoe in the optimization of occupant restraint system

Abstract: the parameters of occupant restraint system are very important to the effect of occupant protection. This paper introduces the optimization of a folding safety belt system by madymo/autodo. The objective of optimization is to minimize occupant injury under gb11551 working condition. According to the actual situation, the safety belt elongation and folding length are selected as the optimization parameters. The optimization results show that the folding safety belt can change the movement posture of passengers and reduce the injury of passengers


madymo/autodo is an occupant safety analysis software. Autodo combines the characteristics of DOE (test design) and CAE analysis, and can automatically complete test design, simulation calculation and relevant data analysis according to user definitions. It greatly facilitates the engineering design, research and analysis of relevant aspects. The analysis process of autodo is shown in Figure 1

Figure 1 autodo analysis process

the folding safety belt overlaps a section of the webbing at the lap belt or shoulder belt and sews it up. After the load of the safety belt reaches the specified threshold, it will be torn off, reducing the webbing force to achieve the effect of protecting passengers (Figure 2). However, the use of this kind of safety belt will also lead to an increase in the forward displacement of passengers, causing greater injury to other parts such as legs

Figure 2 folding safety belt

this paper uses madymo/autodo to optimize the folding safety belt system of a certain vehicle model

model establishment

the occupant restraint system mainly includes:

1 Passenger space: floor, firewall and windshield

2. Restraint system: seat, safety belt, steering wheel, instrument panel

3. Steering system: steering column and steering wheel (Figure 3)

Figure 3 occupant restraint system model

the effectiveness of the model is verified through real vehicle tests

optimization of the model

according to the actual situation, two easily controlled parameters, the webbing elongation and the folding length, are selected to optimize the system. The selection of parameter level is shown in Table 1. Table 1 Why is the Jinan testing machine so good? Number and level

under the impact conditions required by gb11551, the dummy injury must meet the following requirements:

1 Head injury index (HIC) ≤ 1000, or "no head contact"

2. Thigh axial force FF ≤ 10000n

3. Sternum compression ≤ 75mm

the test and simulation results show that the sternum compression of the dummy in the collision is small, so it is not taken as a target value in the optimization process. Therefore, the objective of optimization is to find the minimum stable solution of HIC under the constraint that the thigh axial force is less than a certain value F0, that is:

draw the response surfaces of HIC and FF according to the calculation results of autodo (Fig. 4)

Figure 4 calculation results of autodo how much extra money will be spent when checking out

from the calculation results, it can be seen that properly increasing the folding length and elongation can reduce the HIC value, but it will increase the axial force of the thigh, and vice versa. The response of thigh force is approximately linear, while the response of HIC is strongly nonlinear. Therefore, the stability of the optimization results should be considered in the design

comparison of optimization results

the final optimized parameter value is:

1 The elongation of webbing is 14%

2. The folding length is 80mm

the comparison between the optimized results and the results of the original design (7% without folding) is shown in Figure 5. After optimization, the HIC is reduced by about 20%, and the axial force of the thigh is also limited to a reasonable range, which has achieved obvious results

Figure 5 Comparison of HIC before and after optimization


here, the optimization of the occupant restraint system only takes into account the parameters of the safety belt. In practice, it may also involve the optimization of many parameters such as airbag, knee bolster, seat, etc. the increase of parameters also increases the tension value that cannot record subtle changes, which increases the complexity of the system. The test design of autodo can greatly simplify the optimization steps, and clearly analyze the impact of various parameters on the occupant protection SEBS foam material is that the material can be recycled, so as to facilitate the optimization design of the occupant restraint system

thank you

thank Dr. liuxuejun of TNO for his support in the development of this project


1 Wang Xuan, lihongguang, Zhao hang, etc Modern automobile safety Beijing: People's Communications Press, 1998

2. MADYMO Reference Manual, Version 6.1, TNO Automotive, 2003.

3. A. C. Bosio, H. A. Lupker. Design of Experiments in Occupant Simulation. SAE 910891.

Author: songzhengchao


e-mail: Zhengchao_ song@(end)

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