Simulation of low energy impacts on composite structures is a key feature in
aeronautics. Unfortunately they are very expensive: on the one side, the structures of
interest have large dimensions and need fine volumic meshes (at least locally) in order to
capture damages. On the other side small time steps are required to ensure the explicit
algorithms stability which are commonly used in these kind of simulations [4]. Implicit
algorithms are in fact rarely used in this situation because of the roughness of the solutions
that leads to prohibitive expensive time steps or even to non convergence of Newtonlike
iterative processes. It is also observed that rough phenomenons are localized in
space and time (near the impacted zone). It may therefore be advantageous to adopt
a multiscale space/time approach by splitting the structure into several substructures
owning there own space/time discretization and their own integration schemes. The
purpose of this decomposition is to take advantage of the specificities of both algorithms
families: explicit scheme focuses on rough areas while smoother (actually linear) parts of
the solutions are computed with larger time steps with an implicit scheme. We propose
here an implementation of the Gravouil-Combescure method (GC) [1] by the mean of low
intrusive coupling between the implicit finite element analysis (FEA) code Z-set and the
explicit FEA code Europlexus. Simulations of low energy impacts on composite stiffened
panels are presented. It is shown on this application that time step ratios up to 5000 can be reached. However, computations related to the explicit domain still remain a
bottleneck in terms of cpu time
