Assessment of Cyclic Load Induced Energy Dissipation and Damping on GFRP Composite Laminate
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ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version)
Assessment of Cyclic Load Induced Energy Dissipation and Damping on GFRP Composite Laminate T. G. Loganathan1*, K. Vinoth Kumar1, and R. Krishnamurthy2 1
Department of Mechanical Engineering, RMK College of Engineering Technology, Tamil Nadu 601206, India 2 Department of Manufacturing Engineering, IIT Madras, Tamil Nadu 600025, India (Received July 31, 2019; Revised January 10, 2020; Accepted January 19, 2020)
Abstract: Polymeric composites exhibit load sensitive stiffness unlike the case of homogeneous metallic material. Composites are widely used in dynamic loading environment and hence it is necessary to study their response in terms of structural properties. Behavioural changes of glass epoxy composite laminate on exposure to cyclic loading has been assessed in terms of energy dissipation (Ed) and Damping factor (DF) by hysteresis loop. GFRP composite specimens (UD-0, 0/30/60/ 0, 0/45/0/-45, 0/90/90/0, and 0/90/0/90) are exposed to low velocity constant amplitude cyclic loading using a laboratory arrangement (by an eccentric disc) at 4.6 Hz and 8.6 Hz frequencies. In fibre-reinforced composites apart from the fibre volume fraction, the fibre interaction angle significantly influences their dynamic properties on loading. Unidirectional (UD0) laminate exhibits low damping/energy dissipation, while 0/90/0/90 laminate with large fibre interaction angle shows highest damping/energy dissipation. Whereas, symmetric cross ply (0/90/90/0) laminate acts as a performance demarcation among the chosen laminates. Thus, optimum Ed/DF properties of GFRP laminate in dynamic environment is attributed to symmetric lay-up, smaller fibre orientation interaction angle in the lay-up sequence and 0 fibre layer at the boundary. Keywords: Cyclic loading, Energy dissipation, Damping, GFRP
fabrication, retention/residual and dissipation energy as in other materials like metals. Unlike the homogeneous materials, the design of energy absorbing composite materials is relatively challenging, owing to various damage mechanisms involved during loading such as matrix and fibre cracking, disturbance to the orientation, delamination, dislocations [10,11] and thermal effects acting simultaneously at varying magnitudes [12]. Upon cyclic loading, the imposed energy is transferred into the material that may be either dissipated in the form of heat affecting possibly the molecular chain of the matrix or consumed as stored energy. The stored energy in composite tends to disintegrate the resin/fibre system, inflicting matrix interface debonding and resulting in nonlinear response. Hysteresis loop is one of the methods suitable to study non- linear response of the composite materials in terms of energy dissipation and damping of the material through load/unload displacement plots. Hysteresis energy increases in the beginning, exhibiting a steady/ progressive rise, followed by a pointy/rapid rise at the final failure [13]. In contrast to homogeneous materials, composite materials have f
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