Citation:
Abstract:
Second-order cone interior-point method for quasistatic and moderate dynamic cohesive fracture by S. Vavasis, K. Papoulia, M. R. Hirmand
Cohesive fracture is among the few techniques able to
model complex fracture nucleation and propagation
with a sharp (nonsmeared) representation
of the crack. Implicit time-stepping schemes are often favored
in mechanics due to their ability to take larger time steps in
quasistatic and moderate dynamic problems. Furthermore,
initially rigid cohesive models are typically preferred when
the location of the crack is not known in advance, since
initially elastic models artificially lower the material stiffness.
It is challenging to include an initially rigid
cohesive model in an implicit scheme because
the initiation of fracture corresponds
to a nondifferentiability of the underlying potential. In
this work, an interior-point method is proposed for implicit time
stepping of initially rigid cohesive
fracture. It uses techniques developed for convex second-order
cone programming for the nonconvex problem at hand. The underlying cohesive model
is taken from Papoulia (2017) and is based on a nondifferentiable
energy function. That previous work proposed an algorithm based on successive
smooth approximations to the nondifferential objective for solving
the resulting optimization problem. It is argued herein that cone
programming can capture the nondifferentiability without smoothing,
and the resulting cone formulation is amenable to interior-point
algorithms. A further benefit of the formulation is that other
conic inequality constraints are straightforward to incorporate.
Computational results are provided showing that certain contact
constraints can be easily handled and that the
method is practical.