Study On Tensile Rupture Of PE/PE Laminates

Ultra high molecular weight polyethylene (UHMWPE) fiber is a kind of high performance organic fiber invented at the beginning of 1980s. UHMWPE fiber has a lot of excellent performance, such as small density, high tensile modulus and strength-to-weight ratio, good energy absorbance and damp. It is very fit for making bulletproof and impact resist material. It also has good electricity isolation, chemistry resist and ultraviolet radiation resist. So it can be used in a wide area such as national defence, aviation, navigation, chemistry engineering, architecture, gym and medical.In order to use composites more safely, we must know its mechanic property, rupture shape and rupture mechanism. Both occur and development of material's damage all have obvious acoustic emission(AE) property. This paper will study on tensile rupture of PE/PE laminate by AE technologyBy analysis of mechanic property and parameter of AE, the rupture shape and mechanism of PE/PE are studied. We tested tensile strength and rupture strain of component, single laminate and laminates. Meanwhile, tensile rupture property of different phases was discussed. Analysis of AE includes: wave velocity and attenuation of components, single laminate and laminates were tested;by clustering and discriminance, six different types of AE parameter and discriminant were established. Finally, we discussed tensile rupture mechanism and damage process of each phase.By analyzing testing datum, we draw a series of conclusions:Judged by numbers of AE signal, the AE's activity of matrix is the weakest, [90] is weaker, [0] is the strongest and [0/90] is between [0] and [90]. Judged by amplitude of AE signal, fiber rupture over 85dB, it is the most important effect of rupture, however the number of AE signal is smalland mostly produced at the end of rupture. The amplitude of matrix damage is about 45dB. It leads to a slight damage to laminate. The amplitude of interface damage is about 50-60 dB. Its number of AE signal is very big and its damage reaches to a certain degree. Judged by counts, crack of matrix is the smallest, interface damage is smaller and the rupture of fiber is the biggest. Matrix and fiber rupture all have a long duration and low frequency. Matrix crack and interface damage all have short duration and high frequency.Tensile rupture mechanism of [0] is: at the beginning of tensile, the specimen's damage takes place at original bug, then along with the load's increase, the damage of matrix and interface become more serious. This result leads to fiber's rupture at different time. Meanwhile, stress change accelerates matrix and interface damage. At the end of rupture, the weak interface leads to a bad synergetic effect between matrix and fiber. Finally, residual fibers rupture all together. Tensile rupture mechanism of [0/90] is: at the beginning of tensile, the main damage takes place at interface, then along with the load's increase, the damage of interface become more and more serious. At the middle of tensile, part of fibers begin to rupture at different time. This result leads to stress change and accelerates matrix and interface damage. The conglutinations among layers restrain fiber rupture. However its effect is very limited. At the end of rupture, the weak interface leads to a bad synergetic effect between matrix and fiber. Finally, residual fibers rupture all together.Wangxu(Textile engineering) Supervised by: Prof.Yanxiong...