Design Of Testing Machine For Dent Resistance Of Automotive Closure Parts And Numerical Simulation Analysis

Automotive Closure Parts will produce depression or even local deformation when it suffers static load such as artificial pressure and snow pressure or dynamic loads such as flying stones and flying sand’s collision,which will greatly affect the car’s appearance and safety.In the field of automobile manufacturing,the ability to withstand external loads and resist concave deflection and local dent distortion to maintain original shape is called dent resistance.With the development of the automobile industry and the constant consumption of non-renewable energy,in order to save energy and meet the stringent emission standards set by the state,car manufacturers have to use thinner steel as an external cover of the car.And the dent resistance of the covering parts is an important basis for evaluating whether the thinning of the covering parts and the suitability of the material substitution is suitable.Therefore,it is necessary to study the resistance of the automobile cover.This paper mainly studies and applies the anti-concave property of automobile panel from three aspects:theory,experiment and numerical simulation.Firstly,a typical rectangular hyperbolic shallow shell is selected as the studying project,then the finite displacement residual stiffness formula,the large displacement residual stiffness formula and the formula of critical energy for the residual deformation are deduced.The influencing factors of dent resistance for the hyperbolic shells,especially the factors of material properties and geometrical properties are studied,which lays a theoretical foundation for the study of the dent resistance.Then,the theory of dent resistance experiment is studied:The characteristics of the three stages of the depression of automobile panel are introduced;the three theoretical evaluation indexes of dent resistance are given and how the three theoretical evaluation indexes are used in engineering practice is introduced.This paper introduces the classification of the concave resistance test,divides into the successive loading method and one loading method,and introduces the loading-unloading step of the successive loading method and one loading method.Thirdly,a device for dent resistance measure was manufactured with the application of machinery and the Lab VIEW assembly program.The test device mainly consists of three parts-mechanical structure,electrical control system and software interface,the reality shows that the test device can measure the concave resistance of automotive panels well and could be a tool for a farther study of dent resistance.Finally,a rear car door which can better reflect the geometrical characteristics and stamping deformation characteristics of the automobile body cover is taken as the object of study.The dent resistance of the outer panel of the rear door is evaluated with numerical simulation method and proved by the test method.