The objective of this paper is to study the vibrational damping characteristics during medium velocity impact of nanoclay filled glass fiber reinforced epoxy hybrid laminates. A series of laminates with varying degree of nanoclay concentration (0-5 wt.%) and fiber weight fraction (25-75 wt.%) were prepared by vacuum assisted resin infusion molding (VARIM) method. The laminates were subjected to medium velocity projectile impact using in-house built gas gun set-up and the ballistic limit of laminates series was determined. The result indicated that during impact, the laminate undergoes vibrational damping. This damping property is a function of fiber weight fraction and orientation, nanoclay concentration and nanocomposite structure. A 42% increase of ballistic limit was observed for 5 wt.% nanoclay filled hybrid (50 wt.% fiber) when compared with unfilled composite. Structural and modal analysis of hybrids showed that the increased ballistic limit of nanoclay filled hybrids is due to the nanocomposite structure and improved damping and fracture properties. © 2015 Elsevier Ltd.

R. Velmurugan

Department of Aerospace Engineering

Ballistics

Damping

Fibers

Modal analysis

Nanocomposites

Nanostructured materials

Nanostructures

PAPER LAMINATES

B. VIBRATION

DAMPING CHARACTERISTICS

GLASS FIBER-REINFORCED EPOXY

IMPACT BEHAVIOR

NANO-COMPOSITE STRUCTURE

NANOCLAY CONCENTRATIONS

VACUUM ASSISTED RESIN INFUSION MOLDINGS

VIBRATIONAL DAMPING

Laminates

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Composites Part B: Engineering

This paper investigates the influence of homogenous and super hybrid external patches based on plain weave woven glass fabric and aluminium alloy sheet (2024) on low velocity impact and quasi-static tensile after impact (TAI) response of adhesively bonded external patch repairs in damaged glass/epoxy composite laminates. The intent of using super hybrid external patches is to combine the excellent high displacement to failure property of aluminium as a ductile reinforcement with the superior mechanical property of glass fiber as a brittle reinforcement. The undamaged normal specimens were taken as the standard specimen for evaluation of residual mechanical properties. Four various types of external patches with different contents of glass (100%, 50% with two different lay-up configuration, and 0%) were used for performing the repair. In all hybrid patches, the proportion of aluminium and glass fiber were equal (i.e. 50% of aluminium and 50% of glass by volume fraction), while lay-up configuration were different. This further allows studying the associated effects of hybridization and lay-up configuration on low velocity impact and TAI response of the repaired laminates. The effect of glass/aluminium content on impact response and TAI response was investigated at various nominal impact energy levels, namely 2, 4, 6 and 8 J. Results show that super hybridization and lay-up configurations of the external patches play a significant role on low velocity impact and post impact response (i.e. absorbed energy, peak contact force, ultimate load, stiffness, residual deformation, displacement to failure and damage pattern) of the repaired specimens. Results indicate that repaired specimens having external patches with outer layer of aluminium and inner layer of glass fiber exhibited better impact properties and damage tolerance capability than that of the specimens conventionally repaired using homogeneous glass patches. Damage profile analysis was in a good correlation with the experimental results. © 2017 Elsevier Ltd

Composite Structures

The role of adhesively bonded super hybrid external patches on the impact and post-impact response of repaired glass/epoxy composite laminates

Composite laminates, made of glass/epoxy using compression molding technique, were subjected to impact loading. The ballistic limit and energy absorption capacity of the laminates were obtained. Experiments were carried out to study the effect of fiber orientation and thicknesses on ballistic limit and energy absorption of the laminates, by using a rigid conical bullet having 9.5 mm diameter and mass of 7.5 g in an air gun. Analytical expressions were obtained to find the ballistic limit, residual velocity and energy absorption capacity of the laminates. The expressions obtained by considering the various damage modes, which were involved in penetration, when laminates subjected to impact loading. The values obtained from analysis were compared with experimental results and good agreement was found. The strain rate sensitivity of the glass/epoxy composites was considered for analysis. © 2013 Elsevier Ltd. All rights reserved.

Influence of fiber orientation and thickness on the response of glass/epoxy composites subjected to impact loading

Composite laminates made of glass/epoxy with and without nano fillers were subjected to projectile impact. The laminates of different thicknesses were prepared by hand lay-up and compression molding processes. Laminates were made from glass woven roving mats of 610 gsm, epoxy resin and nano clay of 1-5 wt.% of matrix. A piston type gas gun setup was used to impact a spherical nose projectile of diameter 9.5 mm and mass of 7.6 g, on the nanocomposite laminates at impact velocities in the range of their ballistic limit and above. The energy absorbed during penetration and ballistic limit of the nanocomposite laminates were studied both experimentally and analytically. The analytical model also predicts the energy absorbed in various failure modes due to tensile failure of primary fibers, deformation of secondary fibers, delamination and matrix crack. Mechanical properties like tensile modulus, stress-strain function, shear modulus, and strain energy release rate were used as input to the analytical model. Laminates of three, five and eight layers have been considered for the analysis. The effect of clay dispersion in the matrix for different failure modes is discussed. Ballistic limit obtained from the model is validated with experimental results and good agreement is found. © 2014 Elsevier Ltd. All rights reserved.

International Journal of Impact Engineering

Energy absorption and ballistic limit of nanocomposite laminates subjected to impact loading

This paper presents the experimental study of free vibration and damping characteristics of hybrid nanocomposite laminates by reinforcing short fibre chopped strand mat and organically modified montmorillonite clay (0, 1, 3 and 5 wt.%) in the vinyl ester matrix by hand lay-up technique. Theoretical study is also carried out to study the vibration and damping characteristics of hybrid nanocomposites. Dynamic result shows that the second phase nanoscale dispersion in the matrix and E-glass fibre significantly enhances the internal damping of hybrid composites. © 2007 Elsevier B.V. All rights reserved.

Materials Letters

Effect of nanoclay addition on vibration properties of glass fibre reinforced vinyl ester composites

Thermo-mechanical vibration analysis of nonlocal temperature-dependent FG nanobeams with various boundary conditions

Flexural strength of bidirectional hybrid epoxy composites reinforced by E glass and T700S carbon fibres

Damping characteristics of nanoclay filled hybrid laminates during medium velocity impact

Journal	Data powered by TypesetComposites Part B: Engineering
Publisher	Data powered by TypesetElsevier Ltd
ISSN	13598368
Open Access	No