A study of the influence of interfacial damage on stress concentrations in unidirectional composites

Qing-dun, Zeng; Wang, Zhili; Ling, Ling

doi:10.1016/s0266-3538(96)00115-7

Cited by 18 publications

(7 citation statements)

References 7 publications

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“…[6] A numerical model of composite with matrix defects of three different shapes, including square, circular and hexagonal, were investigated by Li et al [7] Fiedler et al studied stress amplification in multi-fiber model composites by using a fiber with a pre-existing crack in their model; [8] However, the presence of matrix cracks in this composite model was neglected, as in the study done by Van den Heuvel et al [9] Analysis of the initial interface debonding which occurs around fiber breaks during tensile load was investigated by Zhou et al, based on an energy balance model. [10] From an overview of the literature regarding the fibrous composites damage research, it appears that the present numerical studies have mostly been performed only on one special damage mode, namely the local load transfer at the interface between fiber and matrix and the local stress concentration due to fiber break or matrix crack, [11][12][13][14][15][16][17] while few studies have yet been performed on the propagation of cracks towards the interface. The stress field near the crack tip was studied excellently by these researchers using simplified symmetrical models subjected to simple loading conditions with pre-damage, but the propagation of the damage was ignored.…”

Section: Full Papermentioning

confidence: 99%

“…Microdamage analysis of fibrous composites has received considerable attention in recent years. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Herrera-Franco et al studied radial stresses at the interface during the fiber pulled out from the droplet using FEA analysis. [5] Sirivedin et al derived an analytical expression to estimate the…”

Section: Introductionmentioning

confidence: 99%

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Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

Sun

Jia

et al. 2008

Macro Materials & Eng

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Dynamic crack propagation routes in composites were investigated using numerical methods. The interfacial strength was characterized by means of the interfacial nodal constrained failure. Five different micro‐damage modes around a broken fiber and the corresponding stress/strain curves were obtained with the interfacial strength increasing. It was proved that the shear stress concentration region appears to be different as the interface varying from weak to strong and that the recovery of fiber load‐supporting with a strong interface is better than that with a weak interface. Experimental work has been done and the available results agree well with corresponding simulation results.

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Section: Full Papermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

Sun

Jia

et al. 2008

Macro Materials & Eng

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“…Interfacial shear fracture decreases the stress concentration on neighbouring fibers and reduces the notch effect of the crack tip followed up by the reduction of coordinated fiber cracks and clusters [4]. The matrix cracking with perpendicular propagation as a result of fiber fracture causes a higher stress concentration to the intact neighbouring fibers [5]. The notch stress induced by the fiber transverse crack propagation causes more likely coordinated fiber failure in adjacent fibers.…”

Section: Discussion Of the Failure Mechanismsmentioning

confidence: 99%

“…The notch stress induced by the fiber transverse crack propagation causes more likely coordinated fiber failure in adjacent fibers. In case multiple fiber fractures develop in the immediate vicinity the stress concentration steadily increases [5][6][7]. .…”

Section: Discussion Of the Failure Mechanismsmentioning

confidence: 99%

Fatigue behaviour of glasfiber‐thermosets; reasons and improvements

Schuermann¹

2011

Materialwissenschaft Werkst

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Dedicated to Prof. Holger Hanselka on the occasion of his 50 th birthday. H. SchuermannMechanisms are presented which occur in unidirectional fiber reinforced plastics due to fiber fracture and subsequent crack evolution. The 3-point-bending test was chosen as test method and the analyses are predominantly carried out by microscopy. It is shown that the matrix system, the fiber-matrix interface adhesion strength and the fiber volume fraction are of great importance for improving fatigue strength. The results can be transferred directly to high stressed bending structures such as leaf springs.Keywords: Unidirectional fiber reinforced plastics / bending fatigue tests / failure evolution / IntroductionIn comparison to other materials fiber reinforced plastics (FRP) exhibit outstanding stiffness and strength when stressed in fiber direction. Therefore FRPs are preferred for structures which are predominantly loaded by uniaxial normal stresses, e. g. tension/ compression-rods and slim bending structures such as leaf springs.In the last 15 years intensive research proofed leaf springs made of glass-fiber reinforced epoxies as superior to conventional steel leaf springs [1,2]. The failure developement of FRP leaf springs is known as absolutely forgiving. The high stress gradient in bending and the ply's crack stopper effect restricts the crack initiation to the boundary layers of the spring. In addition the cracks grow very slowly and are particularly detectable visually, Fig. 1. Of special interest is the high weight reduction only by changing the material from steel to fiber reinforced plastics.So a rear-axle spring of a 24t-truck made of steel weights 84 kg, the one made of FRP only 19 kg. This weight reduction of the rear-axle of totally 130 kg is hardly to achieve as simple with another approach.The ecological importance of the FRP-spring is even higher. In 2005 about 2.6 million trucks were registered in Germany. Mounting all these trucks with lightweight FRP leaf springs instead of steel springs would reduce the mass in the range of 52 000 t. Assuming an annual averaged driving performance of 50 000 km and a saving of 1.5 l fuel per 1 t mass-reduction per 100 km, the modification would yield to a fuel-saving of about 39 million litres per year. This is an extensive reduction of CO 2 emission. For this reasons it is indispensable to push ahead this lightweight approach consequently.However, till now the true mechanism of the failure on the micromechanical level, which leads to the good-natured failure, is unknown. The assumption is dominant, only the fatigue behaviour of the fiber counts for this, since the longitudinal load is almost totally born by the fibers. Hence the effect of the matrix on this fatigue case is classified as negligible. But distinct differences in the cyclic strength of the same fiber but different matrixsystems suggest a strong influence of the matrix.In a comprehensive research project of the institute Konstruktiver Leichtbau und Bauweisen at TU Darmstadt the failure mechanism due to cycli...

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“…Quin-Dun et al [14] defined T s * as a function of stress applied along fiber direction σ 11 and fiber/matrix properties:…”

Section: The Proposed Fatigue Damage Modelmentioning

confidence: 99%

A Stiffness Degradation Based Fatigue Damage Model for FRP Composites of (0/θ) Laminate Systems

Shirazi

Varvani‐Farahani

2009

Appl Compos Mater

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The present study develops a stiffness reduction-based model to characterize fatigue damage in unidirectional 0˚and θ°plies and (0/θ) laminates of fiber-reinforced polymer (FRP) composites. The proposed damage model was constructed based on (i) cracking mechanism and damage progress in matrix (Region I), matrix-fiber interface (Region II) and fiber (Region III) and (ii) corresponding stiffness reduction of unidirectional composite laminates as the number of cycles progresses. The proposed model enabled damage assessment of FRP (0/θ) composite laminates by integrating the fatigue damage values of 0˚and θ°plies. A weighting factor η was introduced to partition the efficiency of load carrying plies of 0°and θ°in the (0/θ) composite lamina. The fatigue damage curves of unidirectional FRP composite samples with off-axis angles of 0˚, 30˚, 45˚, and 90˚and composite laminate systems of (0˚/30˚), (0˚/45˚) and (0˚/90˚) predicted based on the proposed damage model were found in good agreement with experimental data reported at various cyclic stress levels and stress ratios in the literature.

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A study of the influence of interfacial damage on stress concentrations in unidirectional composites

Cited by 18 publications

References 7 publications

Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

Fatigue behaviour of glasfiber‐thermosets; reasons and improvements

A Stiffness Degradation Based Fatigue Damage Model for FRP Composites of (0/θ) Laminate Systems

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