Evolution of the strain energy release rate during ductile or brittle failure in woven‐ply reinforced thermoplastic laminates under high temperature conditions

Abstract

Depending on laminates' stacking sequence, the contribution of matrix behavior to the strain energy release rate is evaluated during failure in brittle and ductile composite laminates subjected to high temperature conditions (T > T g ) when matrix toughness is enhanced. The purpose of this work is therefore to investigate the strain energy released along with crack growth in 5harness satin weave carbon fabric reinforced polyphenylene sulfide (PPS) structures with a Single Edge Notch. The crack growth appears to be self-similar in quasi-isotropic (QI) laminates, and nonself-similar in angle-ply (AP) laminates. Based on fracture mechanics concepts, semianalytical representations of the translaminar failure are combined with an Acoustic Emission (AE) technique to correlate the cumulative AE energy to the strain energy release rate. The experimental results reveal that the fracture toughness increases with increasing precrack length in QI laminates, whereas the effect of increase in precrack length exhibits reduced fracture toughness in AP laminates. The energy released during a non-self-similar crack growth is all the more significant than the stress concentration factor is reduced. A small defect (e.g., precrack) means a larger portion of the mechanical energy brought to the specimen to be dissipated during failure by means of large plastic deformations. With respect to QI laminates, the contribution of PPS matrix toughness to the fracture energy released is more significant in highly ductile AP laminates, resulting in higher fracture toughness. POLYM. COMPOS., 00:000-000,

Fracture mechanics of hybrid composites with ductile matrix and brittle fibers: Influence of temperature and constraint effect

“…In addition, temperature promotes local crushing (resulting from compression) in the contact area, and exacerbates ductility at T > T g . 11,15 It therefore contributes to the retardation of the crack extension and the increase in the fracture toughness as will be further discussed in section ''Influence of constraint effect on G-R curves''.…”

“…9 The question is still open when it comes to evaluate the influence of temperature and constraint effect on the translaminar fracture toughness of ductile thermoplastic (TP)-based composites with brittle fibers. 8,10,11 When a notched laminate is loaded in tension, a Fracture Process Zone (FPZ) is observed at the notch tip, 12 and gradually grows with increasing load (Figure 1). Depending on stacking sequence and constitutive materials, the crack path observed in fiberreinforced polymer laminates is often complex.…”

Experimental research on the high‐temperature compression mechanical properties of carbon/phenolic composites in rapid carbonization conditions

“…Tensile tests were carried out at 120 C in combination with an acoustic emission test, and it was considered that the best use state of polymer matrix composites was the glass state. [24] The components of polymer matrix composites change dynamically at high temperatures, which also causes changes in their mechanical properties. [25,26] Considering the influence of dynamic changes (for various parameters) on the properties of composites during pyrolysis, the stress-strain relationship can be obtained by averaging different phase parameters.…”

Study of thermomechanical coupling in carbon fibers woven‐ply reinforced thermoplastic laminates: Tensile behavior under radiant heat flux

“…Research on the fire performance of composite materials began at the end of the 1970s, in parallel with their development in the aerospace industry, especially for high-temperature applications. [1][2][3][4][5][6][7][8][9][10][11] Classically, there are two main families of heat sources. The first consists of the sources producing a real flame by means of gas burners.…”