“…The PD description, which uses integral differential equations (IDEs), converges to the traditional PDE theory where there are no discontinuities; in this sense, PD provides a generalization of the PDE theory that enables to directly simulate the fracture process and has capability of modeling crack initiation, propagation, bifurcation, coalescence, and separation. 16,17 In this view of point, nonlocal theory is a generalization of the traditional continuum theory and can resolve many problems that for the traditional theory is hard to handle. In recent years, nonlocal theory is in frontier research and undergoes a rapid development among the various research interests, for example, physical mechanics, 31,32 sociologies, 33,34 artificial intelligence 35,36 and medical images.…”