Study On Crashworthiness Of Concave Tube For Vehicle Passive Safety Under Multiangle Collision

With the increase of vehicle quantity,vehicle collision increases inevitably,the number of casualties caused by vehicle crashes is also increasing,there is an urgent need to improve the passive safety of vehicle.In the event of a collision,the energy absorbing structure of the vehicle plays a major role in protecting the passengers,so it is significant to study the crashworthiness of the energy absorbing structure of the vehicle to improve the passive safety of the vehicle.Thin-walled structures have been widely used as energy absorption structures of vehicles which can be controlled to convert the kinetic energy into plastic deformation energy to protect passengers during crash process.The crashworthiness of thin-walled structures is closely related to their cross-section shape,geometric size and collision conditions.In this paper,the crashworthiness of concave polygonal tubes under multiangle collision is studied systematically:1.Based on the quasi-static compression test,the deformation and energy absorptioncharacteristics of concave tubes are studied.The influence of angle element on deformationand energy absorption of concave tubes is analyzed by numerical simulations,and theresults show that the mean force of concave tube decreases with the increase of angleelement,and the concave tube has better energy absorption than the square tube.Theformula of the mean force of concave tube is obtained through theoretical analysis.2.Parametric analysis is carried out on the structural parameters of concave tube undemultiangle collision,such as diameter D,thickness t,height H and angle element?,and thefinal deformation distribution diagram of concave tube is given.The influence of structuralparameters on the crashworthiness of concave is analyzed,the results show that the diameteris the main factor affecting the deformation of concave tube.The relationship between themean force and thickness is used to verify the simulation results.3.The deformation and energy characteristics of aluminum foam under multiangle collisionare analyzed by means of experiment,theory and simulation.A foam-filled tube composedof aluminum foam and concave tube is presented,the results show that angle element?,foam density?_f and thickness t are important parameters affecting energy absorptioncharacteristics of the foam-filled tube,and the foam density has the best effect on improvingthe crashworthiness of the foam-filled tube.The negative poisson's ratio effect brought bythe concave angle element has obvious improvement on the energy absorption of the foam-filled tube,and the interaction between the concave tube and aluminum foam is enhancedin the meanwhile.4.The star-shaped section is applied to the designs of tapered tubes,the parametric analysisof tapered angleand thickness t is carried out,the results show that the tapered angle isthe main factor affecting the deformation and energy absorption.The tapered angle canavoid the overall bending deformation of the star-shaped tube under multiangle collision,so as to maintain a high anergy absorption capacity.Based on the influence of tapered angleon energy absorption,a spline curve tapered star-shaped tube is presented.Taking the splinecurve contour as the optimization target,the multi-objective optimization is carried outbased on the proxy model,optimization results show that SEA increases by 9.87%in aconstant F_max.