Effects of climatic conditions changes on crack growth

International audienceFor fracture caused by stress concentrations in beams, a crack is often at the origin of final rupture. When air humidity variations occur, the small area around the crack tip (process zone), under high stresses is also directly submitted to these variations, which generally decrease the strength of the beam. To emphasize this phenomenon, crack growth tests are carried out under opening mode along the grain direction on modified Tapered double Cantilever Beams. The tests are realised in a climate room allowing variations of relative humidity. It has been found that air-drying gives a high increase of the crack velocity while air wetting gives a smaller increase. The effects of natural climate variation on crack propagation and on time to failure of notched beams under constant loading are also studies. The phenomenon is modelling by non linear fracture mechanics assuming that only process zone is sensitive to fast variations of relative humidity. Correct trend of experiments is obtained