繊維強化複合材料積層板の確率材料設計法の研究（第２報） 面内多軸荷重を受ける一方向繊維強化複合材料積層板のパラメータセンシティビティスタディ

Abstract

This paper deals with the sensitivity study on reliability or failure probability of uni-directional fibre reinforced composite laminates subjected to off-axial loads. Two kinds of new sensitivity measures, physical and stochastic sensitivity ones, were defined in the present first order reliability method (FORM). The former means the sensitivity measure which shows how the mean value of random parameters affect the safety index of laminates based on FORM. The latter is the variability sensitivity which is the measure how the standard deviations of random variables vary the failure probability of laminates. Both the sensitivities can be easily calculated analytically with safety index and standardised gradient coefficients on a design point by the present procedure. The proposed sensitivity measures have not only an advantage to be obtained analytically, but also to offer more information on reliability than the conventional numerical procedure. Numerical analysis of graphite epoxy uni-directional composites laminates was performed for the various combination of off-axial loads. These results are useful for a designer to evaluate the quantitative characters of design parameters which contribute the stochastic material design of composite materials.