Analytical and Experimental Studies of Short-Beam Interlaminar Shear Strength of G-10CR Glass-Cloth/Epoxy Laminates at Cryogenic Temperatures

Abstract

Cryogenic interlaminar beam tests in the form of three-point flexure are examined both experimentally and analytically. The use of the short-beam shear test for measuring the interlaminar shear strength of glass-cloth/epoxy laminates at low temperatures is evaluated first. The interlaminar shear tests were carried out with short-beam shear specimens at room temperature, 77 K and 4 K to evaluate the interlaminar shear strength of G-10CR glass-cloth/epoxy laminates. Each specimen was placed on two roller supports that allow lateral motion and a load was applied directly at the center of the specimen. These tests were conducted in accordance with ASTM, 1984, “Standard Test Method for Apparent Interlaminar Shear Strength of Parallel Fiber Composites by Short-Beam Method,” Designation D2344-84. The effects of temperature, specimen width, and span-to-thickness ratio on the apparent interlaminar shear strength are shown graphically. Photomicrographs (scanning electron micrographs, optical micrographs) of actual failure modes were utilized to verify the failure mechanisms. A three-dimensional finite element analysis was also performed to investigate the effects of specimen width and span-to-thickness ratio on the shear stress distribution in the mid-plane. Effective elastic moduli were determined under the assumption of uniform strain inside the representative volume element. The numerical findings are then correlated with the experimental results.

Cryogenic Damage and Fracture Behaviors of G-11 Woven Glass-Epoxy Laminates

“…Effective elastic moduli are determined under the assumption of uniform strain inside the representative volume element. Verification of the RVE method for predicting effective elastic moduli for woven glass-epoxy laminates are presented in previous paper (20), (21) . The elastic properties of the matrix (epoxy) and fiber (E-glass) were approximated by the exponential functions (22) , and the elastic properties of the composite yarns were calculated using equations of Hashin (23) .…”

Effect of Mixed-Mode Ratio on Cryogenic Interlaminar Fracture Toughness of Woven Fabric Glass/Epoxy Laminates

“…The apparent interlaminar shear strength at liquid nitrogen temperature (77 K) and liquid helium temperature (4 K) depended on specimen geometry, and decreased with an increase in notch separation. A three-dimensional finite element analysis of the test procedure showed that the maximum shear stress near the notch tip was nearly independent of notch separation variations and appeared to be a true indication of the interlaminar shear strength of the double-notched specimen [5] also characterized the cryogenic interlaminar shear strength of G-10CR by both snort-beam test and three-dimensional finite element method. Observation of failed specimens showed a complex failure mechanism in the cryogenic short-beam-shear tests.…”

“…The critical total strain energy release rate GfJ(MMB) is obtained by adding equation (5), as follows:…”

Cryogenic through-thickness tensile characterization of plain woven glass/epoxy composite laminates using cross specimens: Experimental test and finite element analysis

“…In addition, efficient utilization of composites requires a thorough understanding of their performance in a variety of conditions. Our research group studied both experimentally and numerically the interlaminar shear behavior of woven GFRP laminates [5,6], hybrid composite laminates consisting of woven GFRP composites and polyimide films [7,8], and woven CFRP laminates [9] at cryogenic temperatures.…”