Through-thickness reinforcement in the form of stitching, short fibrous or metallic rods (z-pins), or woven or braided tows suppresses delamination and may well offer a cost-effective approach to durable laminated structures. The through-thickness reinforcement acts as a crack bridging mechanism, with benefits of crack arrest or total suppression. However, certifying through-thickness reinforcement for delamination resistance has been impeded because delamination cracks do not behave according to Linear Elastic Fracture Mechanics (LEFM) in these composites. The bridging mechanism may act over quite long crack lengths, leading to so-called large scale bridging problems. Structural optimisation and the correct prediction of delamination, stiffness loss, and ultimate failure can therefore emerge only from correct fracture mechanics, which is not traditional LEFM, but involves fracture concepts that are new to most of the design community. Progress towards standardised design methods for these systems will be reviewed, including advances in modeling, the design of standard experiments, and the challenge of educating a generation of designers in simple but sound design practices.
Towards Standardization for Through-Thickness Reinforcement of Laminates
MASSABO', ROBERTA
2000-01-01
Abstract
Through-thickness reinforcement in the form of stitching, short fibrous or metallic rods (z-pins), or woven or braided tows suppresses delamination and may well offer a cost-effective approach to durable laminated structures. The through-thickness reinforcement acts as a crack bridging mechanism, with benefits of crack arrest or total suppression. However, certifying through-thickness reinforcement for delamination resistance has been impeded because delamination cracks do not behave according to Linear Elastic Fracture Mechanics (LEFM) in these composites. The bridging mechanism may act over quite long crack lengths, leading to so-called large scale bridging problems. Structural optimisation and the correct prediction of delamination, stiffness loss, and ultimate failure can therefore emerge only from correct fracture mechanics, which is not traditional LEFM, but involves fracture concepts that are new to most of the design community. Progress towards standardised design methods for these systems will be reviewed, including advances in modeling, the design of standard experiments, and the challenge of educating a generation of designers in simple but sound design practices.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
