Significant efforts have been made in the past decades to unravel the influence of material heterogeneities on the failure behavior of composites. The apparent fracture properties of brittle composites are strongly controlled by the various local failure mechanisms involved at the crack tip during the interaction of the crack with microscopic material heterogeneities. The competition between these local mechanisms, as well as their ultimate contribution to material reinforcement, is usually well-described by the Linear Elastic Fracture Mechanics (LEFM) theory.
A major pitfall of LEFM is that it does not take into account the influence of some ubiquitous spatially extended weakening dynamics near the crack tip, that can emerge from, e.g., cavitation and fibrillation in soft elastomers, crazing in polymers, micro-cracking and particle bridging in concrete and rocks. As such, no meaningful length scale associated with the failure process is taken into account in LEFM. However, in a realistic modeling of fracture in heterogeneous materials, one expect the dynamics to depend on the interplay between the material heterogeneities (of size w ) and the spatially extended dissipative zones. The typical scale on which such spatially extended dissipation occurs is ƒ, characteristic of the so-called process zone. The construction of a dearly missing framework to describe fracture properties in heterogeneous materials necessarily builds on a description of the failure processes around w ~ ƒ.
To fill this gap, the candidate will perform experiments of adhesive peeling of a soft elastomer from a micro-patterned interface. Imaging techniques will be deployed to monitor the failure process involved during the interaction of a peeling front with heterogeneities of adhesion of size ranging below and above the process zone. The failure mechanisms observed in the experiments and the associated toughening of the interface will be compared to that predicted by recent models developed in our group.Offer Requirements Specific Requirements
Ph.D. in Physics or Mechanical Engineering, or in another relevant Solid Mechanics discipline (applicants who have submitted their PhD thesis and are awaiting their PhD award are also encouraged to apply). Experience in experiments of adhesion or fracture of polymers is required.Contact Information