Abstract
Compressive failure of fiber composites has been studied by many researchers, more so since the identification of these materials as potential candidates for use in aerospace structures around the early 1960s. The compressive strength of modern carbon fiber-reinforced plastics (CFRP) is generally 30–40% lower than the tensile strength due to microbuckling of the load bearing fibers aligned with the loading direction. It is further reduced by the presence of fastener holes and cut-outs used for joints and access. Currently, the static notched compressive strength is a significant limiting property when designing composite aerospace structures on the basis of strength.
This chapter describes the application of a cohesive zone model to predict the notched or open-hole compressive (OHC) strength of carbon fiber/epoxy laminates and study the level-ply scaling or ply blocking effect on notch sensitivity. The usual strategy is to replace the inelastic deformation associated with plasticity or microbuckling with a line crack and to assume some form of stress–displacement (σ–δ) bridging law across the crack faces. Here a plastic fiber kinking analysis and a linear reduced (softening) σ–δ relationship are used for the prediction of the unnotched and OHC strength; input data required and assumptions or simplifications made (in relation to the damage mode assumed) in the analytical models are explained since they have an impact on predictions. It is shown that the theoretical results when compared to experimental observations and measurements are in a good agreement (in some cases they differ less than 5%).
This chapter describes the application of a cohesive zone model to predict the notched or open-hole compressive (OHC) strength of carbon fiber/epoxy laminates and study the level-ply scaling or ply blocking effect on notch sensitivity. The usual strategy is to replace the inelastic deformation associated with plasticity or microbuckling with a line crack and to assume some form of stress–displacement (σ–δ) bridging law across the crack faces. Here a plastic fiber kinking analysis and a linear reduced (softening) σ–δ relationship are used for the prediction of the unnotched and OHC strength; input data required and assumptions or simplifications made (in relation to the damage mode assumed) in the analytical models are explained since they have an impact on predictions. It is shown that the theoretical results when compared to experimental observations and measurements are in a good agreement (in some cases they differ less than 5%).
Original language | English |
---|---|
Title of host publication | Comprehensive Composite Materials II |
Editors | Peter W.R. Beaumont, Carl H. Zweben |
Place of Publication | Amsterdam, The Netherlands |
Publisher | Elsevier BV |
Pages | 221-231 |
Number of pages | 11 |
Volume | 2 |
ISBN (Print) | 9780081005347 |
DOIs | |
Publication status | Published - 1 Jan 2017 |
Keywords
- cohesive zone
- compressive strength
- damage
- fiber microbuckling
- fracture mechanics
- laminates
- modeling
- open-hole compression
- ply blocking
- polymer composites
- shear strength