  A controllable crack propagation (CCP) strategy is suggested. It is well
known that crack always leads the failure by crossing the critical domain in
engineering structure. Therefore, the CCP method is proposed to control the
crack to propagate along the specified path, which is away from the critical
domain. To complete this strategy, two optimization methods are engaged.
Firstly, a back propagation neural network (BPNN) assisted particle swarm
optimization (PSO) is suggested. In this method, to improve the efficiency of
CCP, the BPNN is used to build the metamodel instead of the forward evaluation.
Secondly, the popular PSO is used. Considering the optimization iteration is a
time consuming process, an efficient reanalysis based extended finite element
methods (X-FEM) is used to substitute the complete X-FEM solver to calculate
the crack propagation path. Moreover, an adaptive subdomain partition strategy
is suggested to improve the fitting accuracy between real crack and specified
paths. Several typical numerical examples demonstrate that both optimization
methods can carry out the CCP. The selection of them should be determined by
the tradeoff between efficiency and accuracy.
