Effect of Ply Thickness on Fracture of Notched Composite Laminates

Vaidya, Rajesh S.; Klug, John C.; Sun, C. T.

doi:10.2514/2.355

Cited by 22 publications

(13 citation statements)

References 12 publications

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“…Several studies have considered the effect of thickness on notched strength [e.g., 12,20,21]. However, a comprehensive study of scaled unnotched and open-hole tensile and compressive specimens independently varying thickness and in-plane dimensions has not been carried out before.…”

Section: Introductionmentioning

confidence: 99%

Scaling Effects in Notched Composites

Wisnom

Hallett

Soutis

2009

Journal of Composite Materials

141

108

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A program of scaled tests on unnotched and open-hole tension and compression specimens is summarized. Quasi-isotropic IM7/8552 carbon-fiber epoxy specimens have been tested using two different scaling techniques: sub-laminate-level ([45/90/ - 45/0]ns) and ply-level scaling ([45n/90 n/ - 45n/0n]s), independently varying the thickness and in-plane dimensions. Significant scaling effects are shown, with both strength and failure mechanisms changing with specimen size and the thickness scaling method having a particularly important effect. Failure mechanisms and scaling behavior are compared between tension and compression and models presented that predict the observed size effects from fundamental material parameters without any fitting factors.

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Section: Introductionmentioning

confidence: 99%

Scaling Effects in Notched Composites

Wisnom

Hallett

Soutis

2009

Journal of Composite Materials

141

108

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“…Jen et al investigated the interlaminar stresses at straight free edges [4] and around the centrally notched hole [5] in composite laminates. Vaidya et al first set up a failure criterion in notched thin laminates [6] and then studied the ply thickness effect on the criterion in notched composites [7]. Next, in consideration of notches in various composites, some references are selected.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties in Notched AS-4/PEEK APC-2 Composite Laminates at Elevated Temperature

Jen

Tseng

Chang

et al. 2006

Journal of Composite Materials

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The response of centrally notched AS-4/PEEK APC-2 composite laminates at elevated temperatures is investigated empirically and systematically. The failure mechanism and mechanical properties in notched cross-ply and quasi-isotropic laminates are perceived. First, the ultimate strength decreases seriously as the hole diameter increases, whereas the longitudinal stiffness changes irregularly. Next, combined with the effect of temperature elevation, the ultimate strength is accelerated to decay while the longitudinal stiffness is reduced slowly. Neglecting the increase in longitudinal stiffness, the worst case of both lay-ups as expected with the largest hole diameter and at the highest temperature still sustains at least 60% of ultimate strength. However, the reduction of strength in cross-ply laminates is more serious than that in quasi-isotropic laminates. Finally, a modified predictive model was proposed and found satisfactorily acceptable. It is also highlighted as a reliable, general, and simple model.

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“…As the strength is dependent on the actual damage preceding final failure, various methods based on damage parameters have been proposed to predict the notched strength of virgin and fatigue‐damaged laminates 13 –15 . These methods incorporate the presence of subcritical damage by directly modelling the physical mechanisms occurring around the hole; they therefore require a precise characterization of these mechanisms and a clear comprehension of their role in the failure and the overall response of the composite material.…”

Section: Introductionmentioning

confidence: 99%

Response of notched carbon/PEEK and carbon/epoxy laminates subjected to tension fatigue loading

Aymerich

Found

2000

Fatigue Fract Eng Mat Struct

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In this study a comparison is made between the tensile static and fatigue behaviours of quasi‐isotropic carbon/PEEK and carbon/epoxy notched laminates, selected as separate representatives of both tough and brittle matrix composites. Damage progression was monitored by various non‐destructive (ultrasonic scanning and x‐radiography) and destructive (deply and microscopic examinations) techniques, and by continuously measuring the change in stiffness, in order to identify the effect of damage on mechanical properties. The experimental observations indicated that fatigue damage in carbon/epoxy laminates consists of a combination of matrix cracks, longitudinal splitting and delaminations which attenuate the stress concentration and suppress fibre fracture at the notch; as a consequence, fatigue failure can be reached only after very high numbers of cycles while tensile residual strengths continuously increase over the range of lives investigated (103–106 cycles). Due to the superior matrix toughness and the high fibre‐matrix adhesion, the nature of fatigue damage in carbon/PEEK laminates strongly depends on the stress level. At high stresses the absence of early splitting and delaminations promotes the propagation of fibre fracture therefore resulting in poor fatigue performances and significant strength reductions; while at low stress levels damage modes are matrix controlled and this again translates into very long fatigue lives. These results indicate a strong influence of the major damage mechanisms typical of the two material systems on the behaviour of the laminates, with the nature, more than the amount, of damage appearing as the controlling parameter of the material response up to failure.

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Effect of Ply Thickness on Fracture of Notched Composite Laminates

Cited by 22 publications

References 12 publications

Scaling Effects in Notched Composites

Scaling Effects in Notched Composites

Mechanical Properties in Notched AS-4/PEEK APC-2 Composite Laminates at Elevated Temperature

Response of notched carbon/PEEK and carbon/epoxy laminates subjected to tension fatigue loading

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