A Study On The UHMWPE/LDPE Composite Laminates Under Quasi-Ststic Penetration And Drop Hammer Impact

UHMWPE/LDPE composite has been used in many high-performance fields. It improved and enhanced much the mechanical properties and physical properties of conventional materials, and can solve many key problems which conventional materials can not. However, the future composite materials will not play the role in one side. So it is very important to test UHMWPE/LDPE composite in various aspects. The optimized process of UHMWPE/LDPE composite laminates has been obtained by using orthogonal method. In the processes of preparation, temperature is the most influencing factor. High temperature can enhance the mobility of matrix and the strength of the interface, but it will also make fiber relax and result in the decline of fiber strength. It is necessary to control the temperature within a certain range. Extending hours and increasing pressure can make full spread of the matrix macromolecules and tangle with the fibers, so that the composites achieve good overall performance. In this paper, the UHMWPE/LDPE composite laminates are prepared with fiber overlayed in vertical,[0/±60/0/±60/0]_S,[0/+45/0/±45/0]_S. The same fiber overlayed laminates are divided into two groups separately under quasi-static penetration and drop hammer tests. Experimental data obtained under quasi-static penetration of laminate damage are broadly divided into four phases: phase bending, stretching stage, tiered stage, fiber breakage stage. The drop hammer impact tests are roughly divided into three stages: Tensile stage, shear stage, stratified stage. By comparing the data, the properties of UHMWPE/LDPE composite laminates with fiber overlay different perspectives as fallowing:1. With the increasing of the fiber laying angle, the properties of laminates increases;2. With the increasing of the fiber laying angle, from the laminates' maximum yield strength to the load when the laminates are punctured, the amplitude of load is more obvious;3. In drop hammer impact test, with the increasing of the fiber laying angle, stress fluctuations are more obvious when stress is increasing; after reaching maximum stress, the stress fluctuations of laminates gradually release.By comparing and analyzing of the data tested under quasi-static penetration and drop hammer impact, a simple load - deflection curve is drawn. The curve is same as the theoretical load - basically curve, so the quasi-static penetration and drop hammer impact test on the UHMWPE/ LDPE composites materials damage basically in the same way. Through the calculated data, a conclusion that has little difference between static performance and penetration of the quasi-static properties on UHMWPE / LDPE composite laminates is drawn.Momentum and shear stress are different in quasi-static penetration and drop hammer impact test. According to the definition of momentum, a relation of total energy, the work done by the load and loss of energy in laminate delaminating is drawn. In the process of quasi-static penetration and drop hammer tests, shear stress leads to delamination. By calculating, the shear stress on laminates tested by quasi-static penetration is far lower than it tested by drop hammer impact. The delamination is mainly caused by shear stress and loss of the former energy much lower than that of the latter.