Robust characterization of crack propagation in 3D woven composites and evidences of size dependency

High temperature translaminar fracture of woven-ply thermoplastic laminates in tension and in compression

“…Damage growth is characterized by the resistance curve (R-curve), which represents the evolution of the critical strain energy release rate as a function of the macroscopic crack length. There are different specimens geometries to induce stable crack growth and to measure the translaminar fracture toughness: Compact Tension (CT) and Compact Compression (CC) [3][4][5][6]8,[10][11]14,[16][17][19][20], three-/four-point bending [7,9,12,15,19] and "Eccentrically loaded Single-Edge-notch Tensile" (ESET) [18,[22][23].…”

“…The resistance of a laminate to translaminar crack initiation and propagation are characterized by a resistance curve, called the Rcurve. The first point of the R-curve can be defined as the critical energy release rate related to crack initiation G C I , while the propagation values G C I during propagation generally tend towards an asymptote [3,[5][6][7][8][9][10][11]14,[17][18][19]. Here, the ASTM-399 test standard is only applied to determine the value of the critical initiation energy release rate, the critical load associated with crack initiation was identified using digital image analysis.…”

“…It depends on the stacking sequence of the laminate [6,[10][11]20], the loading conditions and the architecture of the reinforcement. Most of the studies dealing with translaminar mode I (opening) failure of multidirectional laminates are based on the quantification of the fracture toughness of unidirectional-ply laminates [3,[5][6][7][8][9][10][11][12][13][14], while very few studies are dealing with woven-ply laminates [4,[15][16][17][18][19].…”

Failure prediction of a new sandwich panels based on flax fibres reinforced epoxy bio-composites

“…Compact Tension (CT) tests have been realized for yarns (warp and weft direction) Gf identification using the same samples as described by Pinho [34]. A precedent study [35] concerning 3D woven composites shows us that the area method is the more robust method to determine Gf. We use the same experimental approach to determine Gf in the warp direction of our flax woven composite.…”