Energy Absorbing Simulation Research On Frustum Lattice Structure

In the crashworthiness design of rail vehicles,the installation of energy absorption device is an effective method to reduce the damage of collision accidents.During the collision accident,the energy absorbing device can use its own plastic deformation to absorb impact energy and protect the car body from excessive damage.During the collision,the energy absorbing device will sustain the complex loads from the longitudinal and vertical direction.Metal lattice material is a kind of porous material,which has connectivity between cells and diversity of design ability.Therefore,metal lattice material could have good longitudinal energy absorption ability and anti-bias load ability at the same time.At present,the researches on the energy absorption performance of metal lattice materials mainly focuses on the lattice sandwich structure.Compared with the lattice sandwich structure with panel,the block structure is more suitable for manufacturing energy absorbing device.However,the researches on lattice block energy absorbing are rare.In order to apply the lattice materials with functional characteristics to the passive safety protection of rail vehicles,the T-direction compression process of the frustum lattice block was studied by using the finite element simulation method.The compression and energy absorption of the frustum lattice materials was explored to provide reference information for the engineering design of the frustum lattice energy absorption device.The main contents of this paper are as follows:(1)The process of T-direction compression of frustum lattice block is analyzed by theoretical derivation.In order to meet the needs of the following simulation research,the relative density formula and the equivalent elastic modulus formula of the frustum lattice block are derived.The evaluation parameters which could compare the energy absorption capacity of lattice block are introduced.(2)By using Pam-crash software,the detailed shell element model of frustum lattice is established,and the simulation analysis of T-direction compression is carried out.Combined with the T-direction compression test data,the validity of the detailed shell element model is verified.Furthermore,by changing the geometric parameters of the lattice blocks,the influence of the geometric parameters of the cells on the energy absorption capacity of the lattice blocks is analyzed.(3)The anisotropic solid element is used to model the frustum lattice block,and the Tdirection compression simulation is carried out.Finally,the solid element model which is in good agreement with the lattice shell element fine model is obtained.At the same time,the element number of the solid element lattice block model is less.The solution time of the solid element lattice block model is less.And the solution efficiency of the solid element lattice block model is higher.(4)The finite element model of frustum lattice energy absorbing device is established with solid element.And it is applied to the driver’s cab model of an urban rail car to simulate the scene of collision against wall and offset collision.The frustum lattice energy absorbing device is verified.