On dynamic fracture along curved planes of weakness

Abstract

The wave field generated by dynamic fracture in elastic solids varies considerably depending on the Mach numbers, i.e. the ratios between the speed of the propagating fracture tip and the longitudinal (P) and shear (S) wave speeds. However, the wave field itself is symmetric with respect to the fracture plane as long as the fracture propagates in a straight manner. This symmetry is held even when fracture propagates straightly along a plane of weakness (interface) between identical solids, and therefore, in order to break the symmetry, usually, fracture propagation along an interface between dissimilar solids is considered. Here, another possibility to break the symmetry, namely, fracture propagation along a curved interface between identical solids, is investigated. As simply expected, two-dimensional finite difference numerical simulations of fracture (an energy source) moving dynamically along a circular or an arc-shaped loose interface show that the wave field becomes indeed asymmetric with respect to the interface, and the induced waves can be strongly confined to specific regions on the convex side of the interface regardless of the Mach numbers. Possible influences of this asymmetric wave confining or focusing due to the existence of curved interfaces are considered by treating real phenomena found in the event of the 2024 Noto Peninsula, Japan, earthquake.