Papers by Keyword: Statistic Distribution

Abstract: The brittle is crippling the application of bioceramic. The compound bioceramic is a new biomaterial being widely applied in medical treatments and its fracture toughness is an important mechanical behaviors. In this paper, we introduce the manufacturing method of the compound bioceramic and experiment facilities for its fracture toughness, investigate its probability distribution for the experimental data and conduct the test for fit. We conclude that the experimental data for the toughness fracture of the compound bioceramic obey the two-parameter Weibull distribution, introduce the analyzing method for the upper confidence limit curve and lower confidence limit curve and study the reliability and confidence level of the fracture toughness of the compound bioceramic.

Abstract: The dependence of strength on notch radii of ceramic components is presented. The strength is exponential decay as the notch radius decrease, the smooth specimen that corresponds to the infinity notch radius topped the fracture strength, but the lowest value relys on the micro feature of the materials. Plotted the strengths on Weibull and Normal probability paper, the fitness coefficients reveal that the strength of smooth specimen, as the past literatures indicated, follows Weibull distribution, but the strength of notched specimen follows Normal distribution better. Such result is due to the fact that the decreasing notch radius reduces and limits the effective original fracture volume, when the notch becomes a slim crack, the weakest link place becomes deterministic.

Abstract: Butt-fusion welding is the main technology to join high-density polyethylene (HDPE) plastic pipes, which are widely used in transport the water, gas and corrosive liquid. Investigation shows that one of the failure modes of HDPE pipe is the crack slowly grows across the thick direction and leads to failure at last, so that it is very important to study the resistance to crack initiation of HDPE pipe and its butt-fusion welded joint. In this study, the elastic-plastic fracture mechanics parameter, crack opening displacement (COD) is used to describe the fracture initiation behaviors for the HDPE materials and its butt-fusion welded joints. The resistance to initiation fracture of HDPE pipe materials and butt-fusion welded joints were investigated at different temperature by using multiple specimen resistance curve method and silicon-rubber replica method. The results show that saturation initial crack COD- δis of HDPE pipe materials and butt-fusion welded joints decreases with the decreasing temperature. The δis of butt-fusion welded joints is lower than that of HDPE pipe materials. Investigation also proved that the silicon-rubber replica method is more suitable for HDPE engineering material than the multiple specimen method. At the same time the statistic distribution of the δis of HDPE butt-fusion welded joint was conducted. The results show that the value of the δis has the statistic variance inherently. The optimum fitting distribution of COD is Weibull distribution with three parameters.