Application of coefficient of variation in reliability-based mechanical design and manufacture

This paper deals with an application of the method of coefficient of variation to the characteristic analysis of the statistical distributions of material properties, including ultimate strength or fatigue limit, failure rates and structural/material reliability. The coefficient of variation, which is defined as the ratio of the standard deviation to the mean, can be used in both the reliability-based design of mechanical systems or components and in the evaluation of an existing product. The complicated functional relationship may be transformed into simple form by using the concept of coefficient of variation. The concept simplifies greatly the calculation of statistical parameters and the results obtained are very close to those derived directly from the original functional relation. By determining the simplified relation between coefficient of variation and statistical parameters, one can analyze the characteristics of statistical distributions by means of coefficient of variation. By means of a numerical example, it is shown that the method of the coefficient of variation can give an identical result to that of the Taylor expansion method. However, the method of the coefficient of variation has the advantage that it is much simpler to use than the Taylor expansion method.