Mechanical properties of unidirectional organic-fiber-reinforced plastics under hydrostatic pressure

Zinoviev, Peter A.; Tsvetkov, S. V.

doi:10.1016/s0266-3538(97)00079-1

Cited by 27 publications

(21 citation statements)

References 17 publications

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“…The 2% offset yield strength and the compressive The results indicate that the strength is increased with increasing pressure in both pressure ranges. Improvements in the strength with increasing pressure have been found for polymers composites and other materials (Pae and Carlson, 1998;Hine et al, 2005;Shin and Pae, 1992;Zinoviev and Tsvetkov, 1998;Rabinowitz and Ward, 1970;Lankford et al, 1998;Paterson, 1970). Although there is considerable scatter in the yield strength data of Fig.…”

Section: Resultsmentioning

confidence: 99%

Pressure and friction dependent mechanical strength – cracks and plastic flow

Wiegand¹,

Redingius²,

Ellis

et al. 2011

International Journal of Solids and Structures

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a b s t r a c tThe mechanical properties of a polymer composite plastic bonded explosive, EDC37, have been investigated as a function of hydrostatic confining pressure between 0.1 and 138 MPa. The results indicate different failure processes in two pressure ranges, a low pressure range between about 0.1 and 7 MPa and a higher pressure range between about 7 and 138 MPa. In the low pressure range slow crack processes are important in failure while in the higher pressure range plastic flow dominates. The pressure dependence of the compressive strength in the low pressure range is attributed to coulomb friction between surfaces of closed shear cracks and from the observed linear increase of the strength with pressure and the angle of the fracture plane a friction coefficient is obtained. Friction coefficients can also be obtained from the ratio of the compressive to tensile strength and directly from the above angle. The friction coefficients obtained from these separate observations are in agreement and this is taken as strong evidence for the importance of this friction in determining strength and mechanical failure. These results clearly establish experimentally the role of friction in determining strength with or without applied pressure. An empirical relationship between strength, pressure and strain rate is also obtained for this pressure range and the failure strength of EDC37 is more sensitive to pressure than strain rate.Published by Elsevier Ltd.

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Section: Resultsmentioning

confidence: 99%

Pressure and friction dependent mechanical strength – cracks and plastic flow

Wiegand¹,

Redingius²,

Ellis

et al. 2011

International Journal of Solids and Structures

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“…It is thus necessary to seek an appropriate failure criterion that accounts for this variation. Based on the work of other researchers [3][4][5][6][7][8][9], the transverse stresses have been shown to have a role to play in determining the fibre-direction strength of a lamina. So it can be deduced that the failure is likely to have happened at a material point with some maximal combination of the three principal stresses.…”

Section: Fe Results and Failure Criterionmentioning

confidence: 99%

“…However there is still a paucity of reliable experimental data for biaxial or multiaxial load cases, especially for those involving through-thickness compression and in-plane tension, due to the cost and complexity of multiaxial testing. A number of works have investigated the unidirectional tensile strength of composites under hydrostatic pressure [3][4][5][6][7][8][9]. The results of these studies show that the strength and the failure mode of composites depend strongly on the magnitude of the hydrostatic pressure.…”

Section: Introductionmentioning

confidence: 99%

Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

Gan

Wisnom

Hallett

2014

Composites Science and Technology

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The fibre-direction tensile strength of carbon/epoxy laminates under the influence of throughthickness compressive stresses has been experimentally investigated. In a unidirectional (UD) laminate, the through-thickness compressive stresses will cause premature longitudinal fibresplitting, masking the effect of transverse stresses on the fibre-direction strength. Here a cross-ply laminate has been used. With the addition of 90° plies preventing the 0° fibres from splitting, it effectively allows the dependence of fibre-direction tensile strength on high through-thickness stresses to be studied. The severity of the through-thickness loads has been varied using cylindrical indenters of different radii, up to the loads near the through-thickness compressive failure stress of the cross-ply laminate. The results show that there is a linear decrease in fibre-direction strength with the mean through-thickness stress. In all the test cases, the specimens failed in a catastrophic brittle manner, with scanning electron micrography showing primarily a fibre tensile fracture mode. The detailed stress state in the specimens has been calculated via finite element analysis. Two failure criteria are proposed, which can be used as conservative design criteria concerning fibre-dominated failures in multiaxial load scenarios. IntroductionWith the increasing use of composite materials replacing metals in aerospace applications, the need to consider complex load conditions is also increasing. Highly localised throughthickness stresses can often be seen in components where localised contact conditions exist, such as in bolted joints. These stresses may interact with co-existing primary in-plane tensile loading in the fibre-direction, leading to earlier failure. when he studied through-thickness compressive loading on unidirectional and cross-plied carbon/epoxy AS4/8552 laminates. The through-thickness stresses that interact with the unidirectional composite fibre direction strength found in the literature are mostly in the form of hydrostatic pressure, at most up to moderate values of ~700 MPa. The current study is a detailed expansion of initial results presented in [12]. In this work, a biaxial test method is developed to apply highly localised through-thickness compressive stress (locally as high as -1700 MPa, as calculated by linear elastic finite element analysis) on a simple cross-plied carbon/epoxy tensile test specimen.The high through-thickness compressive strength of a cross-plied laminate allows the interaction between a broad range of through-thickness compression and in-plane tensile strength to be examined. Multiple experimental load cases are presented and finite element models have been used to study the stresses within the specimens so that a simple failure criterion can be proposed for engineering design purposes. Experimental Specimen preparation and rig setupThe material under consideration is Hexcel's carbon epoxy pre-preg system, IM7/8552 with a nominal ply thickness of 0.125 mm. Four identical panels wi...

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“…Hine et al (1999) found that the tensile strength of dry carbon fibre tows decreases with an increase in superimposed pressure. Similarly, the in-plane tensile strength of carbon, glass and Kevlar composites (in an epoxy matrix) decreases with increasing superimposed pressure, see for example Wronski (1985, 1986), Sigley et al (1991), Zinoviev Tsvetkov (1998 and Hine et al (1999Hine et al ( , 2005. The precise reason for this weakening effect is unclear but the effect is widely recognised, and we shall include it in our analysis.…”

mentioning

confidence: 90%

“…He concluded that the yield strength of the epoxy matrix is pressure-dependent. Collings' work motivated a number of studies on the transverse compression of UD plies with superimposed hydrostatic pressure, see for example Hine et al (1999Hine et al ( , 2005, Pae and Rhee (1995) and Zinoviev and Tsvetkov (1998).…”

mentioning

confidence: 99%

The effect of matrix shear strength on the out-of-plane compressive strength of CFRP cross-ply laminates

Khaderi

Deshpande

et al. 2018

International Journal of Solids and Structures

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The failure mechanism of 'indirect tension' is explored for cross-ply IM7/8552 carbon fibre/epoxy laminates subjected to quasi-static, out-of-plane compressive loading. The sensitivity of compressive response to strain rate and to the state of cure is measured, motivated by the hypothesis that the out-of-plane compressive strength is sensitive to the matrix shear strength. A pressure-sensitive film is placed between specimen and loading platen, and reveals that a shear lag zone of reduced compressive traction exists at the periphery of the specimen, giving rise to a size effect in compressive strength. The width of the shear lag zone reduces with increasing shear strength of the matrix. The laminates fail by the indirect tension mechanism: out-of-plane compressive loading generates tension in the fibre direction for each ply and ultimately induces fibre tensile failure. Finite element (FE) simulations and an analytical model are developed to account for the effect of matrix shear strength, specimen geometry, and strain rate on the out-of-plane compressive strength. Both the FE simulations and the analytical model suggest a recipe for increasing the through-thickness compressive strength.

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Mechanical properties of unidirectional organic-fiber-reinforced plastics under hydrostatic pressure

Cited by 27 publications

References 17 publications

Pressure and friction dependent mechanical strength – cracks and plastic flow

Pressure and friction dependent mechanical strength – cracks and plastic flow

Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

The effect of matrix shear strength on the out-of-plane compressive strength of CFRP cross-ply laminates

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