Scale Effects in the Response and Failure of Fiber Reinforced Composite Laminates Loaded in Tension and in Flexure

Abstract

The feasibility of using scale model testing for predicting the full-scale behavior of flat composite coupons loaded in tension and beam-columns loaded in flexure is examined. Classical laws of similitude are applied to fabricate and test replica model specimens to identify scaling effects in the load response, strength, and mode of failure. Experiments were performed on graphite-epoxy composite specimens having different laminate stacking sequences and a range of scaled sizes. From the experiments it was deduced that the elastic response of scaled composite specimens was independent of size. However, a significant scale effect in strength was observed. In addition, a transition in failure mode was observed among scaled specimens of certain laminate stacking se quences. A Weibull statistical model and a fracture mechanics based model were applied to predict the strength scale effect since standard failure criteria cannot account for the in fluence of absolute specimen size on strength.

Defect controlled transverse compressive strength of polyethylene fiber laminates

“…While cross-ply CFRPs loaded in through thickness compression also fail by fiber tensile rupture (Gan et al, 2014;Kim et al, 2010), the dependence of this strength upon sample thickness has not been ascertained. Studies by Jackson et al (1992) and Kellas and Morton (1992) and a review by Sutherland et al (1999) show a decrease in the tensile and flexural strength with increasing sample size. Weakestlink' statistical models (i.e.…”

Size Effect and Fracture Characteristics of Composite Laminates

“…tions by random particle models also agree with this law; Bazant and Tabbara (1990), Bazant and Jinisek (1995). With regard to the statistical approach to size effect, the recent study by Jackson et al (1992) of the size effect of graphite/epoxy composites under tension and flexure deserves mention. Geometrically similar specimens of size ratios I :2:3:4 were used and the results were analyzed on the basis of Weibull's statistical theory based on a distribution function of random material strength.…”

Measuring the notched compressive strength of composite laminates: Specimen size effects

“…Although there is a significant, but inconclusive, amount of evidence that there is a size effect in composites under tensile and flexural load [2][3][4][5][6][7], scaling of composite strength is not well documented or understood. Most of the research to date has looked at the size effect on the unnotched rather than notched strength under unidirectional tensile [4][5][6][7] or compressive loading [8][9][10]. The results show the importance of ply thickness and the interactions between delamination and matrix cracking with the fibre direction failure modes.…”