THE EFFECT OF DAMAGE AT AN ENSEMBLE OF MICROSTRUCTURE POINTS ON THE MARGIN OF SAFETY IN STRUCTURALLY HETEROGENEOUS MATERIALS

Fracture concentration regions are considered in a microstructure under loading. A mathematical model of a micro-heterogeneous medium with random properties of elements is used for the calculations. The initial data in the problem includes the characteristics of the distributions of random elastic moduli and ultimate strengths in the microstructure elements. The microstructure strength condition is a difference between stresses and ultimate strengths for a multitude of points of a given configuration. The probability of stress simultaneously exceeding the ultimate strength in a given set of elements determines the probability of fracture in this ensemble of points and relative damage at the micro level. A multidimensional normal distribution is used to calculate damage. The structure of the correlation matrix of distribution takes into account the kind of the damage concentration region. The relationship between critical microstructure damage and the margin of safety is determined. Examples of calculating the probability of fracture in two, three, and four microstructure elements are given.