The Statistic Analyses To The Strength Of Materials

The less uniform of compositions, construction, the flaws' size and distribution of in the materials would always lead to the scatter in the failure strength. The study on the statistic properties of strength has great meaning to understanding the mechanism of fracture, improving the materials performance and the reliability design. In this paper, the statistic properties of the yield and tensile strength of a Q235 steel and the bending strength of WC-Co hard alloy and the coatings were studied. Subsequently the scatter in the plasticity and toughness of UO2-Zr dispersing nuclear fuel sheet components was assessment by the Weibull statistics, and the fracture model was proposed by combining the Weibull statistics and fracture mechanics.The Weibull distribution adapted by the Bayesian statistics and the 4th Strength Laws can describe well the distribution of the yield strength of the Q235 steel, and the tensile strength follows the normal distribution and the three-parameter Weibull distribution, moreover it was found that the yield and tensile strength decrease with the samples length.The bending strength of cemented carbide would be affected by many factors, so only by statistics analysis it can be described well. The result shows that the bending strength can be adequately described using normal distribution,lognormal distribution and Weibull distribution at the same time. But for the goodness of fit, normal distribution is the best and Weibull distribution follow it. In this paper it also is discussed that how the size and uniformity of WC particles affect the bending strength. We can find that the bending strength increases and it's scatter decreases with the size decreasing and the uniformity meliorating. In this paper the possibility of Weibull application to the strength of coating is discussed. If it is possible to divide one system into independent constituting elements, a Weibull distribution will always be the asymptotic distribution of strength for those elements when its number tends to the infinity. The two-dimensional coating can satisfy these terms. The bending strength of the cemented carbide coatings was studied using the Weibull statistics.Finally, the bending strength, bending deflection and fracture energy of the UO2/Zrdispersing nuclear fuel sheet components and their pellets are measured by three-point-bending test. The scatter of these properties assessed with the Weibull module is to evaluate the reliability of the sheet components. Its fracture model was proposed by combining the Weibull statistics and fracture mechanics. From the model we can find that meliorating the distribution of UO2, improving the process and reducing the Oxygen content in the Zr-2 basis can all improve the fuel sheet components' properties and reliability.