Papers by Author: Madusudhanan R. Parlapalli

Abstract: In the present paper, effects of through-the-thickness stitching of delaminated glass/epoxy composite laminates with two different types of aramid threads, Kevlar® and Twaron® threads, on the buckling loads are studied. The buckling loads are predicted based on the Southwell, Vertical displacement and Membrane strain plot methods from the experimental data. Flexural modulus of the stitched and unstitched glass/epoxy composite laminates, knot tensile strength of Kevlar® and Twaron® stitching threads are obtained experimentally. From the Southwell, Vertical displacement and Membrane strain plot methods it is observed that stitching either by Kevlar® or Twaron® threads is effective in improving the buckling strength of glass/epoxy composite laminates when the delamination length is greater than 0.5L, L is the length of the laminate.

Abstract: In the present paper, new nondimensionalized parameters, namely, nondimensionalized axial and bending stiffnesses have been introduced to study analytically the buckling behavior of two-layer beams with separated delaminations. Numerical analysis has been carried out by using ANSYS software to validate the developed analytical model. Delaminations are modeled with gap elements in ANSYS. A detailed parametric study has been carried out and it is found that the buckling behavior strongly depends on these new nondimensionalized parameters. Another nondimensionalized parameter, effective-slenderness ratio is also introduced and it is found to be a controlling parameter of delamination buckling mode configurations.