Design And 3D Printing Of Collapsible Energy-absorbing Composite Structure Helmet

The helmet is a common armor that protects the head.It is designed and manufactured to prevent injuries to the head due to impact during an accident,thus reducing the casualty rate caused by head injuries.Therefore,the most important part of the helmet design is the helmet lining that is close to the head.The quality of the helmet lining directly determines whether severe injuries can be avoided when the head is impacted.In recent years,practitioners in the manufacturing industry have designed a lattice structure by researching and designing more complex and innovative structures.This cyclically repeated structure will undergo stress during the process of external force collision.The energy is effectively attenuated,so applying the lattice structure to the helmet lining can effectively improve the helmet's mechanical properties and compressive ability.This topic selected the Selective Laser Sintering(SLS)technology to prepare the helmet lining.Firstly,the Solid-edge modeling software is used to design a lattice structure that meets the mechanical properties of helmet liners.Using ABAQUES finite element analysis software,the mechanical properties of the lattice structure are analyzed,and an appropriate lattice structure is obtained through optimization.Secondly,nylon PA2200 material is used to replace the traditional expanded polypropylene(EPP)and expanded polystyrene(EPS)to optimize the lattice structure.The mechanical tests of the lattice structure were performed,and the results after the finite element analysis were compared to select the appropriate lattice structure to complete the production.Finally,helmet linings with a lattice structure were manufactured using SLS technology.The research content and conclusions are as follows:(1)Using Solid edge three-dimensional modeling software to design four different lattice structure model,using material mechanics testing machine to test the material mechanical properties of the material PA2200,it is concluded that the material can meet the mechanical performance requirements of the helmet liner design,using the material to produce four Different lattice structure.(2)The body-centered cubic structure in the design structure is used to represent the unit structure model.The column is used as the adjustable beam structure.Basedon the geometric relationship,the relative density formula is derived.At the same time,the structural model beam structure thickness and surface structure wall thickness are controlled,and the unit structure volume is changed,thereby obtaining a lattice structure with adjustable porosity.(3)Through the compression simulation and mechanical testing of four different lattice structures,the two sets of experiments are cross-checked and contrasted.It is found that the body-centered cubic structure and the face-centered cubic structure are concentrated in the stress distribution at 82% porosity,and the compressive strength is weak and easily destroyed.The six-hole spherical structure and the minimally curved surface structure have even stress distribution and strong compressive strength and are not easily damaged.(4)According to the collapsible energy absorption design theory,the four kinds of lattice structures with different mechanical properties are combined in pairs to obtain a novel lattice structure for finite element mechanical simulation.According to the compressive strength and elastic modulus of the simulated structure,the outer surface with the best mechanical properties is the lattice structure with the body-centered cubic structure and the inner surface combined with the minimal curved surface structure as the helmet lining.Finally,the helmet lining with optimized lattice structure was manufactured by using SLS technology.