Study On Mechanical Properties Of UHMWPE Weft - Knitted Composites

Using textile structure as reinforcing composite materials called textile composites. Because of its low cost, light quality, etc, it has been widely applied in many domains, such as safety protection, etc. As a kind of textile reinforced composite material, weft knitted fabric can give many advantages to the composite, such as good formability, drapability and extensibility, and it also has excellent performance of impact-resistance and energy absorption, etc. UHMWPE fiber is a king of optimization of composite fiber, with its excellent abrasion resistance, impact resistance and low friction coefficient, which is popular for people’s favor. The mechanical properties of UHMWPE fiber weft knitting composite materials were researched in this study, and the finite element method was used to simulate the impact performance. These studies can provide some experimental data and theoretical reference in the further discussion for safety protective materials.Using UHMWPE composite filament as the experimental material, weft plain-knitted fabric as enhancement, firstly this subject studies the theory of UHMWPE fiber in knitting machine weaving; then weft plain-knitted fabric can be weaven to meet the requirements of the test. VARTM molding process and the epoxy resin with low viscosity and good infiltration was selected as matrix to meet the technological requirements. The three different layers (4 layers,6 layers and 8 layers) of weft plain structure composite materials was prepared successfully by the way of vertical layer.Secondly, researching the mechanical performance of different layers of the weft knitted composite material through the analyzing the stress-strain curve, the results show that in the overall mechanical properties, the eight-layer composite material was the strongest, followed by six-layer, four-layer composite material was the worst, which shows layer number of composite materials has great effects on the mechanical properties of composite materials. From the damage of the sample and the scanning electron microscopic diagram observation found that composite materials have different degrees of damage, fiber fracture and slightly delamination. The research of composite materials on the same layer with different impact energies found that with the increase of impact energy, the sample damage more serious; and in the same energy, with the increase of the layer number, withstanding the impact force also increases, meaning the mechanical performance of eight-layer composite material was the strongest.Finally, used finite element simulation technology with ANSYS Workbench to complete low speed impact of four-layer weft plain-knitted composite. Through analyzing and comparing with experimental phenomenon, then found that both of the phenomena were similar. Some damages can be seen by eyes directly, however some internal damages can’t be found. Therefore the simulation to the impact performance of the composite material is necessary. The damage situation can be present by the simulation. It will play a basic role in the further research of protective materials.