Abstract

A numerical simulation method is used here for the design and quality control of a material subject to normal gradual stress sigma or a cyclic stress sigma, having fixed cumulative probability F and the number of cycles l; capable of achieving a given mechanical property such as yield point, elastic limit stress, fracture strength, etc., as well as the admissible tolerance deltaF the presence of such property is to be accepted with. With F and deltaF, the stress of the design cc can be determined, as well as the variations deltam, deltasigma(0) and deltasigma(L) of Weibull's parameters m, sigma(0) and sigma(L), respectively, that the tolerance deltaF admits. When cyclic stresses arise, other parameters must be introduced, k(1), k(2) and p, which produce variations deltak(1), deltak(2), and deltap, respectively. The determination of the necessary number of samples to be tested in order to carry out the quality control of the material, with a given probability of effectiveness, is obtained with variations deltam, deltasigma(0), deltasigma(L), deltak(1), deltak(2), and deltap, with the parameter dispersion estimated by numerical simulation, and with the help of a property deduced from the Fischer's matrix to obtain the parameter dispersion. (C) 2003 Elsevier Ltd. All rights reserved.