Research On The Response Characteristics Of UHMWPE Fiber Reinforced Thermoplastic Composites Under Low-velocity Impact

Because of the demand for lightweight,composite materials are widely used in the fields of aviation,automobile,military and sports goods.Although composite materials have the advantages of high strength and large modulus,they also show the weakness of fear of impact.Unlike the elastic-brittle of thermosetting composites,thermoplastic composites exhibit significant plastic deformation behavior.The low velocity impact response of thermoplastic composites is great different from that of thermosetting composites.The thermoplastic composites have obvious plastic deformation after being impacted.As a typical thermoplastic composite,UHMWPE fiber reinforced polymer has been applied to various kinds of shock resistance,and is often subjected to various forms of impact during its service.Therefore,it is very important to study the response characteristics of them under the low velocity impac t load.In this paper,the low-speed impact response characteristics of UHMWPE fiber reinforced composite materials are studied by means of experimental study combined with numerical simulation.First of all,this paper investigates the forming process of UHMWPE fiber reinforced composites,and determines the related molding process parameters.On this basis,three kinds of thickness laminates with 20,30 and 40 layers were prepared,and the low velocity impact tests were carried out based on ASTM D7136 test standard according to the modified Hopkinson pressure bar.The damage mechanism of laminate is analyzed after the impact.It is found that plastic deformation and delamination are the main damage forms of UHMWPE fiber laminates.In addition,the plastic deformation under constant impact load decreases with the increase of the number of laminates and presents a certain thickness effect.Then,based on the anisotropic elastic-plastic theory and cohesive element theory,the low velocity impact finite element model of UHMWPE fiber laminates corresponding to the test is established,and the impact process is simulated by LS-DYNA.The results of the numerical simulation are in good agreement with the test results,and the reliability of the finite element model is verified.By further analysis of the results,it is found that the UHMWPE fiber laminates exhibit excellent energy absorption characteristics during the impact process;delamination area is roughly peanut shaped,and the main axial direction of the interlayer layer between the two adjacent sub-layers is the same as that of the sublayer fibers that are separated from the impact surface in the two layers.Finally,this article based on the reliability of the finite element model are validated,applied the method of numerical simulation is an object with 20 layer thickness of laminated plates,respectively discusses the impact energy,layer and interface layer strength three factors of UHMWPE fiber reinforced composite material laminated plate shock response characteristics at low speed.It is found that the impact energy and layering mode and interfacial layer strength are the sensitive factors influencing dynamic response of UHMWPE fiber laminated plate.In 0°/90°orthogonal layer of UHMWPE fiber laminated plates with 45°,-45°sublayer of laminated plates after each performance have very big change,but the join position but has no effect on laminated plates performance;The strength of the interface layer directly affects the strength of laminated plate and t he degree of interlayer damage.As the strength of the interface layer increases,the impact resistance of laminated plate decreases first.