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Failure Analysis of Thick Composite Beams: A Comparative Study of Various Failure Theories

Garella, Satish and Kizhakkinan, Umesh and Harursampath, Dineshkumar (2016) Failure Analysis of Thick Composite Beams: A Comparative Study of Various Failure Theories. In: International Workshop on Mechanical Behavior of Thick Composites, MAR 14-15, 2016, Montreal, CANADA, pp. 77-85.

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Thick composite beams are used as primary structural members in various engineering applications, for example, composite flex beams in a hinge less rotor system of modern helicopters. One end of the flex beam yoke is connected to the rotor hub through joints and the other end is connected similarly to the rotor blade. A flex beam yoke has to support rotating loads, vibratory bending loads and torsional loads. It should be strong enough to hold the blade yet flexible enough to allow for the flapping motion. Hence, it is essential to understand the mechanism of stress development, crack initiation and propagation in a bolted thick composite beam, which is subjected to axial and flexural loads. A unidirectional glass/epoxy thick composite beam is considered in this study. A common engineering practice is to use bolted joints to attach two structural members and the bolts are pre-tensed. Buffer pads are attached to the composite beam to avoid localized damage. To simulate the real life situation, a CAD model is generated using ABAQUS 1] consisting of a thick composite beam with eight bolt holes, buffer pads, steel clamping blocks, steel washers and steel bolts. The composite beam is attached to a rigid block using a clamping block, washers and bolts. The finite element mesh is generated using 3-D continuum elements, C3D8I. Nonlinear stress analysis is performed for bolt pre-tension and bending loads with material and contact nonlinearity. The numerical results depend on the element type in finite element analysis. Parametric study for element selection between SC8, C3D8 and C3D20 is carried out. The finite element analysis results are compared with the experimental values. Different failure criteria are considered to study the failure behavior of the thick composite beam: Tsai-Wu, Christensen, and Puck, Hashin and quadratic delamination failure criteria. These failure criteria are coded in ABAQUS through user subroutines. The bolt holes act as stress concentration regions in the beam, where the failure behavior is studied utilizing the above criteria. The effect of different loading, such as bolt pre-tension, bending on the failure of the composite thick beam are investigated.

Item Type: Conference Proceedings
Additional Information: Copy right for this article belongs to the DESTECH PUBLICATIONS, INC, 439 DUKE STREET, LANCASTER, PA 17602-4967 USA
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering (Formerly, Aeronautical Engineering)
Date Deposited: 30 Dec 2016 06:11
Last Modified: 30 Dec 2016 06:11
URI: http://eprints.iisc.ernet.in/id/eprint/55624

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