Study On Impact Resistance Of Folded Thin-walled Structures

Metallic thin-walled structures showed excellent energy absorption and mechanical properties and have been widely used in the fields of collision safety and engineering protection.Domestic and foreign studies have shown that adopting variable thickness or using multi-cell structure can significantly improve the crashworthiness of thin-walled structure.However,these methods have their limitations.It is relatively difficult to fabricate these structures or produce with high manufacturing costs.In this paper,the energy absorption characteristics of a kind of folded thin-walled structure are studied,which is characterized by its easy preparation,low cost,free in cross-sectional shapes and flexible geometric parameters.The folding method can not only make various types of single cell structures,but also prepare a variety of multi-cell structures.A series of folded thin-walled specimens with different cross-sectional shapes were prepared by folding the metal sheet.The quasi-static axial and lateral loading experiments were carried out using a universal material testing machine.The numerical simulations of the tests for different types of folded thin-walled structures were carried out by using nonlinear finite element software LSDYNA.Based on the validated numerical model,simulation with dynamic loads is performed for tubes with and without considering welding and those with different wall thickness and cross-sectional shapes.The effects of structural configurations,welding conditions and wall thickness on the energy absorption characteristics of tubes under axial loading are discussed and the effects of loading directions and structural configurations on the energy absorption characteristics of transverse loading are also analyzed.The results show that some of the folded thin-walled specimens spread during deformation under axial loading.There were some special deformation modes which are sensitive to manufacturing errors under the transverse loading.The simulations and the experimental tests show big difference in these two cases,but in other cases,the numerical simulations agree well with the experimental results.By comparing the energy absorption characteristics of the folded thin-walled structure with the traditional square tubes,it is found that the energy absorption performance of the folded single cell thin-walled structures is lower or close to that of the traditional thin-walled structures,but the performance of the folded multi-cell thin-walled structures is higher than that of traditional thin-walled structures.In addition,the energy absorption capacity and efficiency of the folded thin-walled structures can be further improved by spot welding connection.The energy absorption capacity of the folded thinwalled structure can be maximized by selecting an appropriate cross-sectional shape and loading direction.To conclude,it is possible to obtain a better energy absorption characteristic than the traditional single cell structure by simply folding the metal sheet,which has certain engineering application prospect.