The Influence of Test Fixture Design on the losipescu Shear Test for Fiber Composite Materials

Abdallah, M.G.; Gascoigne, HE

doi:10.1520/stp10030s

Cited by 12 publications

(5 citation statements)

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“…All 90 degree specimens exhibited a similar failure mode, in that fracture occurred within the gauge section of the specimen and ran from notch tip to notch tip. The failure plane of the 90 degree specimens was always normal to the specimen longitudinal direction thus helping to verify that no out-of-plane bending existed as reported by Abdallah and Gascoigne [15].…”

Section: Experimental Results For Final Test Proceduressupporting

confidence: 68%

“…The actual shimming procedures were based upon judgment and a pre-loading was required to verify the gauge readings prior to the actual testing. If the above care was taken then this fixture did not produce in-plane or out-of-plane bending when loaded as suggested by Abdallah and Gascoigne [15]. The necessity for shimming is eliminated in the revised University of Wyoming test fixture [7], however, it is still recommended that the four loading faces be ground parallel in the assembled fixture.…”

Section: Evaluation Of Testing Techniquesmentioning

confidence: 99%

“…He also recommended that the strain readings from ±45 degree oriented strain gages in the test section be monitored separately to verify that a pure shear-strain field exists in the test section. Abdallah and Gascoigne [15] conducted a very comprehensive experimental study in which they evaluated the influence of the two University of Wyoming fixtures and the asymmetric four-point bend (AFPB) fixture [16] on a number of aspects associated with the determination of the in-plane shear response. One of their major conclusions was that both of the University of Wyoming fixtures suffered alignment problems that could not be controlled and that both fixtures induced both in-plane and out-of-plane bending resulting in large scatter in the results.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Testing Techniques for the losipescu Shear Test for Advanced Composite Materials

Lee

Munro

1990

Journal of Composite Materials

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The purpose of the study was to explore and subsequently establish experimental techniques for the losipescu shear test method for advanced composite materials. For the preparation of notches in the Iosipescu specimens it was found that conventional machine cutting tools could be used provided that the base of the notch was inspected for micro-damage. The occurrence of a pure shear strain field in the test section was evaluated by separately monitoring the readings from the tension and compression strain gauges. Grinding of the four loading surfaces of the original University of Wyoming test fixture was required to eliminate in-plane or out-of-plane bending or twisting of the specimen. A state of pure shear strain (as defined by equal readings from the tension and compression gauges) can be produced in 90 degree but not 0 degree original Iosipescu specimens when tested in the original University of Wyoming fixture (when the loading surfaces were ground smooth and parallel). In terms of analysis of the results for the 90 degree specimens for IM6/1806, IM6/F584 and IM6/5245C material systems, the determination of the in-plane shear modulus by the tangent method had lower scatter than by initial modulus or secant methods.

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Section: Experimental Results For Final Test Proceduressupporting

confidence: 68%

Section: Evaluation Of Testing Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of Testing Techniques for the losipescu Shear Test for Advanced Composite Materials

Lee

Munro

1990

Journal of Composite Materials

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“…(1987) showed that the margin of the discrepancy depending on the degree of the anisotropy of the material rnight reach 40%. Abdallah and Gascoigne (1989) reponed that the best results for shear modulus could be obtained from [0"/90°] and [0°/k450/900] specimens. This fact was also reflected in ASTM D5379-93.…”

Section: Strain Gages 7 1'mentioning

confidence: 99%

“…This problem, beside the nonunifonnity of the shear stress in the gage section, promotes a premature failure of the specimen. The finite element analyses conducted by Herakovich and Bergner ( 1980) and Abdallah et. al.…”

Section: Strain Gages 7 1'mentioning

confidence: 99%

A New Test Method for Measuring the Longitudinal and Shear Moduli of Fiber Reinforced Composites

Jalali¹,

Taheri‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

1999

Journal of Composite Materials

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A new test method for the simultaneous evaluation of the longitudinal and the shear moduli of fiber reinforced plastic composites (FRPC) is introduced. Under the proposed method, specimens with different span to depth ratios (Llh) are subjected to three-point bending. Therefore, we name the method the "Varying Span Method" (VSM). The method builds on the inherent low shear modulus characteristics of FRPC. This characteristic leads to a flexural modulus which is a function of LMh. Eliminating the effect of local deformation from the test results, the flexural modulus (beside the geometry of the specimen) is a function of the longitudinal and the through-the-thickness shear moduli. These moduli can be obtained from the results of at least two tests on specimens with different Llh. For this, two distinctly different theories are introduced. A special apparatus is used to eliminate the effect of local deformations. The factors that may affect the accuracy and efficiency of the results are investigated and discussed. The validity of the proposed method is demonstrated by theoretical and experimental evaluations. The moduli of graphite/epoxy and Kevlar/epoxy composites, as measured by VSM, are reported. The measured values were found to be in very good agreement with the values evaluated by other standard methods.

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An evaluation of the arcan specimen for determining the shear moduli of fiber-reinforced composites

Hung

Liechti

1997

Experimental Mechanics

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ABSTRACT--Moir6 interferometry was used to examine the strain distributions in Arcan-type specimens under shear loading. The compact geometry allowed longitudinal and transverse shear behavior to be considered. The best results for longitudinal moduli were obtained with fibers running from notch to notch. As with the Iosipescu configuration, strain averaging or correction factors were required for modulus determination in all fiber orientations. None of the bending problems that have been encountered in the Iosipescu specimen were observed. Some twisting was noticed, but its extent (less than 2 percent) was much less than has been noted in shear testing with Iosipescu specimens.

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The Influence of Test Fixture Design on the losipescu Shear Test for Fiber Composite Materials

Cited by 12 publications

References 0 publications

Evaluation of Testing Techniques for the losipescu Shear Test for Advanced Composite Materials

Evaluation of Testing Techniques for the losipescu Shear Test for Advanced Composite Materials

A New Test Method for Measuring the Longitudinal and Shear Moduli of Fiber Reinforced Composites

An evaluation of the arcan specimen for determining the shear moduli of fiber-reinforced composites

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