Developments of fracture mechanics in France in the last decades

International audienceThe purpose of the present paper is to give a survey on some developments of fracture mechanics in France in the last decades. Until about 1970, the subject was practically unknown at the universities. The topics were growing up rapidly, because of French industrial projects or programs in the fields of aeronautics, aerospace industries, nuclear reactor technology. In France, fracture mechanics became an important subject for engineers and researchers starting with the first Summer School (1970) devoted to fracture mechanics held at La Celle Saint Loup (France) (François & Joly 1972). At this meeting, engineers from the French Atomic Centre (CEA), Electricite de France, the Nuclear Vessel Builders (Framatome, Creusot-Loire) and from other industries gave lectures on linear elastic fracture mechanics, Griffith' s energy balance, Irwin's energy release rate G and Kies' stress intensity factors. Obviously, fracture mechanics is strongly motivated by industrial applications. Ten years after the first meeting at La Celle Saint Loup, scientists and engineers in France organised the ICF-5 conference in Cannes, in April 1981. Contributions to the experimental determination of toughness of different materials, the study of the int1uence of hydrostatic pressure on the toughness of aluminium alloys (Auger & François 1974), microscopic observations of cracks in metals, fatigue crack propagation (Lemaitre & Chaboche 1978) date back to the 1970's. But most of the papers in this period are devoted to computational aspects in linear and non-linear fracture mechanics with the emphasis on stress intensity factors calculations, 3D calculation of SIF by the weight function method (Labbens et al. 1976), path-independent integrals (Bui 1993), fatigue crack propagation and fatigue criterion (Dang Van 1973), crack tip plastic zones (Nguyen & Bui 1974). In the 1980's, studies in non-linear fracn1re mechanics were concerned with ductile fracture, with applications to nuclear energy technology (Rousselier 1981 ), crack initiation using damage mechanics (Bui & Ehrlacher 1980; Lemaitre & Chaboche 1985), thermodynamical aspects of fracture (Nguyen 1980; Ehrlacher 1985), homogenisation of periodic structures containing cavities or cracks (Marigo 1981, 1985; Sanchez-Palencia 1980; Suquet 1990). The contributions of Beremin, a pseudonym for a group of researchers from the Ecole des Mines de Paris, working in ductile fracture and the physics of metals (Mudry 1982; Pineau & Joly 1991; Pineau 1992) shall be mentioned in particular. Then, contributions on new subjects emerged since the mid 1980's: shear band localisation (Fressengeas & Molinari 1985, 1987; Benal1a1 et al. 1989, 1991, Doghri & Billardon 1995), stability analyses of systems of cracks (Nguyen et al. 1990), scale effects in micro-macro analyses (Leroy & Molinari 1993; Lalai & Sab 1996), delamination of composites (Allix & Ladeveze 1992, 1996; Allix et al. 1995), asymptotic analyses (Geymonat et al. 1986; Leguillon & Sanchez-Palencia 1987). inverse problems and identification of cracks (Bui 1993; Andrieux & Ben Abda 1992; Andrieux et al. 1997), weak singularities of stresses at interfaces such as the 'Epine' singularities (French word for the 'thorn' like shaped function characterised by its boundedness, discontinuity and unbounded gradient) (Bui & Taheri 1989; Deperrois & Dang Van 1 990; Leguillon 1992; Santacreu 1994), experimental approaches in dynamic fracture (Bui & Maigre 1988; Bui et al. 1992; Maigre & Riuel 1993) etc. In the sequel, some of these contributions will be discussed in more detail