Design And Experimental Research Of The Test Device For Durability Of Vehicle Crash Test Dummy Skin

In recent years,the number of people in China killed in traffic accidents is always in the forefront of the world.Studying the protective effect of cars on occupants is becoming more and more urgent.Crash test dummy is an important tool in the research of vehicle crash safety,of which the skin plays an important role.in transmitting the impact to the sensors in each part and buffering the metal parts in the body.Its bionic characteristics are crucial to whether the dummy can truly reflect the protection effects of the vehicle on the occupant.Material of the skin is rubber-like,exhibiting elastic after-effect.Inelastic deformation will not completely disappear after being impacted.Long-term accumulation will inevitably influence the mechanical properties of the skin.Therefore,the study on the durability of the skin is important for the use and development of dummies.The material parameters of dummy skin are more complex.Material,thickness and hardness of the skin for various parts are different.The impact of the collision is also very complex.Therefore,the computational model existed is hard to be used for the study on the durability of the skin.In this paper,a test bench was designed to simulate the impact conditions of multiple parts of dummy,and many experiments on the durability of the skin were conducted.The main contents of this dissertation are shown as follows:1.The durability test project was designed,and the test objects were determined according to the situation of each part to be hit and the vulnerability of each part of the dummy.Based on the mechanical response curves in vehicle crash and regulatory requirements about the response of the dummy head and knee,the response peak was used as the impact characteristic to be simulated by the durability test device.The most common impact responses of the head and knee were obtained in the vehicle crash database respectively and the test procedure was determined.2.According to the requirements of the test bench to provide the reciprocating impact response,of which the size and position should be adjustable also,the mechanical structure of the durability test device was designed,whose core was the pneumatic technology.And the technical parameters of the cylinder,spring and so on were analyzed according to the maximum impact force required by the device.3.Taking STC89C52 as the main control chip,the control system of the device was designed,the hardware circuit built,the control strategy of the microcontroller designed.And the control system was developed according to the control strategy.4.Based on the durability test method of dummy skin,impact force adjustment tests and durability tests of the head and knee were conducted.And the effectiveness of the device was verified.For the same dummy part,several skin samples with different mechanical properties were tested.Durable impact times of the head skin in the condition of vehicle crash and calibration test were obtained respectively.Durable impact times of the knee skin in the condition of vehicle crash were also obtained.The results show that the overall trend of the peak value of the calibration test for the dummy parts become greater with the increase of the cumulative number of impact.Parts with low hardness skin show small response value in the first calibration test,and can withstand more durable impact times,showing stronger durability characteristics.By comparing the number of durable impact of the heads in vehicle crash condition and calibration test condition,the magnitude of the impact also has a great effect on the durability of the dummy skin.As the amplitude of impact force increases,the average increase magnitude of the resultant acceleration peak after each impact also increases,and the times of durable impact decrease.By comparing skins with different hardness,it is found that smaller hardness makes the average increase magnitude of the calibration test results also increase after each impact.By comparing the hardness of the skin before and after durability impact tests,the results show that the hardness increases after repeated impact.The different calibration test results of different samples with the same hardness indicate that there may be thickness and other factors that also affect the calibration results.