On the behaviour of the residual strain produced by matrix cracking in cross-ply laminates

Bassam, F.; Boniface, L.; Jones, K.L.; Ogin, S.L.

doi:10.1016/s1359-835x(98)00037-2

Cited by 25 publications

(8 citation statements)

References 12 publications

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“…In composite materials, the residual strain (i.e. the strain that would be present if the load were to be reduced to zero) is often small [6][7][8]. Therefore, we neglect the residual strain, in which case the area O-C-D represents the dissipated energy.…”

Section: Dissipated Energy Densitymentioning

confidence: 99%

Predicting Failure in Composite Laminates Using Dissipated Energy

Huang

Springer

Christensen

2003

Journal of Composite Materials

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We present a method for evaluating the damage in and failure of fiber reinforced composite materials. The method is based on dissipated energy and has three major components: (i) a relationship between the strain in the material and the magnitude of the dissipated energy density, (ii) a model that relates the dissipated energy density to matrix damage and fiber failure inside the material, and, accordingly, reduces the elastic properties of the material, and (iii) a nonlinear finite element code for calculating the strain at each point in the material taking into account the degradation of the stiffness as damage occurs. The method provides the parameters of interest, namely, the regions of matrix damage and fiber failure, the load-displacement curve, the failure load, and the failure displacement. Tensile, shear, and four point bend tests were performed with S-glass/epoxy solid coupons as well as with coupons containing a central hole. The load-displacement curves, failure loads, and failure displacements were measured and compared to the results computed by the method. The data and the results of the method are in good agreement.

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Section: Dissipated Energy Densitymentioning

confidence: 99%

Predicting Failure in Composite Laminates Using Dissipated Energy

Huang

Springer

Christensen

2003

Journal of Composite Materials

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“…Bassam et al (1994) reported residual strains of up to 1000µɛ in cross-ply GFRP laminates due to the occurrence of matrix cracking. Bassam et al (1998) also investigating experimentally and analytically the residual strain due to matrix cracks in crossply glass epoxy laminates, using the shear-lag and variational approaches. The experimental results of the residual strains were found in reasonable agreement with both types of analysis.…”

Section: Introductionmentioning

confidence: 99%

Measurement of residual strains as a parameter of matrix cracking in CFRP laminates

Fikry

Ogihara

Vinogradov

2021

JAMDSM

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Matrix cracking in CFRP laminates results in degradation of mechanical properties of the material and appearance of residual strains. In this study, the residual strains are investigated experimentally and analytically for CFRP [0/75 6 ] s laminates. The typical stress-strain curves of cracked CFRP always show the presence of residual strain, a nonrecoverable strain in the laminates as the strain does not return to 0% even after being unloaded back to 0 MPa. This is a phenomenon where the matrix cracking in laminates increases the residual strain due to relaxation of curing stresses. Initially, the coefficients of thermal efficiency (CTE) of the laminates is measured to be used in the analysis to predict the residual strain due to the matrix cracks. The strain gauges were used in this study to measure the strains. Due to very small residual strains at the unloading condition, the residual strains were also measured at different stress levels for laminates with different crack densities and are compared with theoretical predictions. Time-dependent viscoelastic behavior of the material is also considered to accurately measure the residual strains due to the occurrence of matrix cracks. This was done by using the strain recovery test when the loads were stopped for 1-1.5 hours during unloading and the strain changes during these times were recorded. The experimental results of the residual strains are in reasonably good agreement with the theoretical predictions. The fiber non-linearity properties of the laminates may cause some experimental data to shift above the analytical line.

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“…(e.g., Bassam et al 1998;Harrison & Bader 1983). In this paper, we study damage formation and its effect on the mechanical properties of FRP laminates with various stacking sequences [θ m /φ n ] s prepared from two different CFRP prepregs and one GFRP prepreg materials.…”

Section: Introductionmentioning

confidence: 99%

The effect of matrix cracking on mechanical properties in FRP laminates

Fikry

Ogihara

Vinogradov

2018

Mech Adv Mater Mod Process

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Background: Fiber Reinforced Polymer (FRP) laminates have properties, which are highly dependent on the ply fiber orientations and which can be designed for optimum laminate performance. The purpose of this study is to investigate the effect of matrix cracking on the mechanical properties of FRP laminates with various off-axis angles, and to provide a critical test for an analytical solution using variational stress analysis. Methods: Carbon and glass fiber reinforced polymer laminates (CFRP and GFRP) are tested. FRP prepregs are cured by using autoclave method to form laminates with layups [θ m / φ n ] s . The laminates are then loaded monotonically and cyclically to obtain their mechanical properties and the effect of matrix cracks on the properties. Some of the effects include reduction of laminates' stiffness and residual strains after unloading. In order to obtain higher crack densities in specimens, artificial cracks method was introduced in this study, where notches were made at the edges of some specimens before tested in tension. Cracks observation for CFRP laminates is done by using the X-ray technique, while for GFRP laminates a DSLR camera is used.

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On the behaviour of the residual strain produced by matrix cracking in cross-ply laminates

Cited by 25 publications

References 12 publications

Predicting Failure in Composite Laminates Using Dissipated Energy

Predicting Failure in Composite Laminates Using Dissipated Energy

Measurement of residual strains as a parameter of matrix cracking in CFRP laminates

The effect of matrix cracking on mechanical properties in FRP laminates

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