STATISTICAL PROPERTIES OF THE TENSILE-STRENGTH OF B/AL COMPOSITES AT ELEVATED-TEMPERATURES

Tensile tests of a 10 vol% boron-aluminum composite were carried out at room temperature, 150 degrees C and 300 degrees C, in order to investigate the validity of the finite-element simulation proposed in the previous report which can evaluate the tensile strength of fiber-reinforced metals. The simulated average strengths were in good agreement with the experimental results, though the scatter of strength was somewhat underestimated. The fiber stress distributions around a broken fiber were analyzed by FEM, by taking into account the matrix constitutive equation at each temperature, From the results of analysis and the stochastic model based on a Markov chain theory, the relation between the fiber stress distributions and the statistical properties of composite strength obtained in the experiment and the simulation was discussed. It was pointed out that, consequently, the statistical properties of room temperature strength would be maintained to some degree at elevated temperatures, unless the fibers were degraded severely. Additionally, the effect of thermal stresses occurring in the composite on the tensile strength was investigated.