Off-Axis Tensile Coupon Testing

Richards, Glendon Lee; Airhart, T.; Ashton, James E.

doi:10.1177/002199836900300322

Cited by 32 publications

(10 citation statements)

References 3 publications

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“…As has been mentioned previously many times, e.g. [7], the off-axis test is not sensitive to the value of F12 used in interpreting the results by means of the standard Tsai-Wu quadratic polynomial of Equation (1). It can easily be shown by calculation that the insensitivity is much deeper than that, and applies to a1 in general beyond an off-axis angle of about 5 ° .…”

Section: Discussionmentioning

confidence: 73%

“…The general failure stress quadratic formula given in Equation (1) can be inverted to give strains as the independent variables. While a1 is approximately zero in the present test specimens, this is not true of E1 due to the Poisson effect.…”

Section: Discussionmentioning

confidence: 99%

“…Early work [1][2][3][4][5][6][7] on determining a suitable failure criterion for advanced continuous fiber composites was often interpreted in the form of the Tsai-Wu tensor polynomial, given in its quadratic form for plane stress by [2]. A general result found is that this polynomial correlated various experimental results, particularly for off-axis tests [1,[3][4][5]7]. However, this polynomial does not directly indicate whether the predicted failure consists of fiber or matrix failure.…”

Section: Introduction Hile Fiber Composite Structures Are Designed Tomentioning

confidence: 99%

“…To this end, Hahn, Erikson, and Tsai [8] have suggested on the basis of the fracture mechanics of inherent flaws that matrix failure is governed by the expression which differs from Equation (1) by omission of the a1 terms. This raises two general questions; is matrix failure in fact insensitive to at, and does Equation (2) express the correct relationship between the inplane transverse and shear stresses.…”

Section: Introduction Hile Fiber Composite Structures Are Designed Tomentioning

confidence: 99%

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Failure of Carbon/Epoxy Lamina Under Combined Stress

Swanson

Messick

Tian

1987

Journal of Composite Materials

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It is well known that matrix failure in carbon/epoxy composites is influenced by multiaxial states of stress. However most of the experimental work to measure this interaction has not focused exclusively on matrix failure, and a general multiaxial stress criterion for matrix failure has not been established. To examine this question experimentally we have carried out a series of tests involving torsional shear combined with axial tension or compression of unidirectional hoop wound cylinders, using AS4/55A carbon/ epoxy lamina. The matrix failure stresses are seen to be well correlated with the Tsai-Wu quadratic polynomial. There is also a strong interaction between the strains at failure, with small amounts of transverse tension giving a significant reduction in the shear strain at failure. The effect of σ 2 on the nonlinear shear stress-strain curves is also presented.

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Section: Discussionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Introduction Hile Fiber Composite Structures Are Designed Tomentioning

confidence: 99%

Section: Introduction Hile Fiber Composite Structures Are Designed Tomentioning

confidence: 99%

See 2 more Smart Citations

Failure of Carbon/Epoxy Lamina Under Combined Stress

Swanson

Messick

Tian

1987

Journal of Composite Materials

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“…Rail shear tests have a number of disadvantages: it is very hard to produce a pure shear over the test section, and the test fixture introduces large stress concentrations. Coupon tests of the [ t 45]S specimen also have problems due to the fact that a state of combined The fourth test method uses off-axis coupon specimens of unidirectional composite [1][2][3][4][5]. This method seems ideal: easy specimen fabrication, very simple data reduction, requiring no special equipment.…”

Section: Introductionmentioning

confidence: 99%

A New End Tab Design for Off-Axis Tension Test of Composite Materials

Sun

Berreth

1988

Journal of Composite Materials

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A new end tab fabricated using a fiberglass knit in a silicon rubber matrix was used for off-axis tension tests on unidirectional composites. It was shown experimentally that this new tab allowed shear deformation of the specimen to occur in the hydraulic grips and, thus, produce a uniform state of strain in the specimen. Consequently, the shear modulus could be determined accurately using this new tab. Furthermore, due to the absence of stress concentrations, this procedure could also be used to determine shear strength.

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The effect of time and temperature on the mechanical behavior of epoxy composites

Moehlenpah

Ishai

Dibenedetto

1971

Polymer Engineering & Sci

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A crosslinked epoxy resin consisting of a 60/40 weight ratio of Epon 815 and Versamid 140 and composites of this material with glass beads, unidirectional glass fibers and air (foams) were tested in tension, compression and flexure to determine the effect of time and temperature on the elastic properties, yield properties and modes of failure. Unidirectional continuous fiber‐filled samples were tested at different fiber orientation angles with respect to the stress axis. Strain rates ranged from 10−4 to 10 in./in.‐min and the temperature from −1 to 107°C. Isotherms of tangent modulus versus strain rate were shifted to form master modulus curves. The moduli of the filled composites and the foams were predictable over the entire strain rate range. It was concluded that the time‐temperature shift factors for tangent moduli and the time‐temperature shift factors for stress relaxation were identical and were independent of the type and concentration of filler as well as the mode of loading. The material was found to change from a brittle‐to‐ductile‐to‐rubbery failure mode with the transition temperatures being a function of strain rate, filler content, filler type and fiber orientation angle, indicating that the transition is perhaps dependent on the state of stress. In the ductile region, an approximately linear relationship between yield stress and log strain is evident in all cases. The isotherms of yield stress versus log strain rate were shifted to form a practically linear master plot that can be used to predict the yield stress of the composites at any temperature and strain rate in the ductile region. The time‐temperature shift factors for yielding were found to be independent of the type, concentration and orientation of filler and the mode of loading. Thus, the composite shift factors seem to be a property of the matrix and not dependent on the state of stress. The compressive‐to‐tensile yield stress ratio was practically invariant with strain rate for the unfilled matrix, while fillers and voids raised this ratio and caused it to increase with a decrease in strain rate. The yield strain of the composites is less than the unfilled matrix and is a function of fiber orientation and strain rate.

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Off-Axis Tensile Coupon Testing

Cited by 32 publications

References 3 publications

Failure of Carbon/Epoxy Lamina Under Combined Stress

Failure of Carbon/Epoxy Lamina Under Combined Stress

A New End Tab Design for Off-Axis Tension Test of Composite Materials

The effect of time and temperature on the mechanical behavior of epoxy composites

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