After retiring in the 1980s, he started an intense research activity in Granular Matter, and contributed to settle the so-called Moreau-Jean event-capturing (or time-stepping) numerical scheme. The Moreau-Jean scheme may be seen as an extension of the implicit Euler method, originating from the (second order) sweeping process formalism of the Lagrange dynamics with unilateral constraints and impacts, which is a specific Measure Differential Inclusion (i.e., a differential inclusion whose solutions are measures). The Moreau-Jean scheme has inspired several groups of researchers in Europe and the USA for the simulation of non-smooth mechanical systems, and is available in open-source software packages like the INRIA SICONOS platform or the LMGC90 platform.
