The analysis of two-factor rolling contact fatigue test results

Experiments conducted at all combinations of the levels of two or more factors are called factorial experiments. Factorial experiments have been shown to be more efficient in exploring the effects of external factors on a response variable than nonfactorial arrangements of factor levels. This paper presents a methodology for the analysis of life test results obtained at all combinations of the levels of two factors. Item life is assumed to follow the two-parameter Weibull distribution with a shape parameter that, although unknown, does not vary with the factor levels. The purpose of the analysis is to compute interval estimates of the common shape parameter and to assess whether either factor has an effect on the Weibull scale parameter and hence on any percentile of the fatigue life distribution which might be used as rating life.