In this paper, the response of sandwich panels (Glass/Epoxy/PU Foam) to projectile impact in the velocity range of 30-100 m/s was studied. Three sets of sandwich plates (WRM/Epoxy/Foam, CSM/Epoxy/Foam, and WRM/CSM/Epoxy/Foam) were used. A piston-type gas gun setup was used to accelerate a cylindro-conical mild steel projectile of mass 558.6 g. From the experimental results, the ballistic limit, residual velocity, and the energy absorption were found. The ballistic limit decreased as the trend moved from WRM to CSM. Debonding was observed in pure WRM/Foam laminates, whereas this was not the case for the other two sets of panels. Plugging occurred when the projectile struck CSM/Foam sandwich panels, which was not observed in the other two sets. A mathematical model was proposed to predict the ballistic limit, residual velocity, and the energy absorption based on the energy-balance principle. The experimental results were compared with the proposed model, which showed good agreement. © Woodhead Publishing Ltd.

R. Velmurugan

Department of Aerospace Engineering

Energy absorption

Mathematical models

Projectiles

Sandwich structures

Ballistic limit

CHOPPED STRAND MAT

ENERGY ABSORPTION AND MATHEMATICAL MODELING

Polyurethane foam

SANDWICH PANELS

WOVEN ROVING MAT

Crashworthiness

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

International Journal of Crashworthiness

In this study, the glass/epoxy composite laminate is layered with polyurethane foam/ polyurethane sheet and silicon carbide to analyse their response during high mass and low velocity impact. The silicon carbide is layered in two forms, one is as plate and the other is as inserts. The target materials are prepared in various combinations and the bonding of layers is done by using epoxy. Effectiveness of silicon carbide inserts and plates are compared in terms of their energy absorbing capacities. The numerical simulation is also carried for the target material with the same experimental conditions. The experimental results are compared with the numerical results for validation and a reasonably good agreement is found. Further, the validated numerical model is extended to understand the ballistic performance of the target material. It is observed that the introduction of silicon carbide as front layer improves both the structural and ballistic performance. Also, the damage in case of samples with silicon carbide inserts is localized as opposed to that of silicon carbide plate. © 2018, Brazilian Association of Computational Mechanics. All rights reserved.

Fulltext

Latin American Journal of Solids and Structures

Numerical study on multi layered target material subjected to impact loading

In the present work, an analytical model is proposed to obtain the damage area of the composite laminates at below ballistic limit velocities. The model is based on the fact that total kinetic energy of the projectile is absorbed by different energy absorbing mechanisms taking place in laminates during impact. Depending upon the projectile velocity, some or all energy absorbing mechanisms observed are; fibre breakage, deformation of fibres, delamination, matrix cracking and cone formation on the back face of the laminates. The accuracy of the model is then assessed by comparing its predictions for damage area and specific energy absorption with the experimental values for two different types of fibres (glass and kevlar) as well as glass/kevlar hybrid combinations. Experimental results are also used to quantify and compare the specific energy absorption capacity of the glass/epoxy, kevlar/epoxy and glass/kevlar/epoxy laminates. It is observed that the glass/kevlar/epoxy laminates in which kevlar percentage is 27.5% w/w showed 20% improvement in specific energy absorption as compared to the glass/epoxy laminates. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Effect of velocity and fibres on impact performance of composite laminates–Analytical and experimental approach

Kevlar/epoxy composite laminates are subjected to impact loading and the energy absorbing capacity of the laminates is studied. In the present study, laminates with four different orientations and thickness values are considered. It is found that cross-ply laminates are most efficient in ballistic resistance when compared with the laminates of other orientations. It is also noticed that the energy absorbing capacity is decreasing with increase in velocity of the projectile for a given lay-up and thickness value. © 2017 Elsevier Ltd. All rights reserved.

Materials Today: Proceedings

FE Analysis of Impact on Kevlar/Epoxy Laminates with Different Orientations and Thicknesses

Composite laminates are made of glass woven roving mats of 610gsm, epoxy resin and nano clay which are subjected to projectile impact. Nano clay dispersion is varied from 1% to 5%. Impact tests are conducted in a gas gun setup with a spherical nose cylindrical projectile of diameter 9.5 mm of mass 7.6 g. The energy absorbed by the laminates when subjected to impact loading is studied, the velocity range is below ballistic limit. The effect of nano clay on energy absorption in vibration, delamination and matrix crack is studied for different weight % of nano clay and for different thickness values of the laminates. The natural frequencies and damping factors are obtained for the laminates during impact and the effect of nano clay is studied. The results show considerable improvement in energy absorption due to the presence of nano clay. © 2015, Brazilian Association of Computational Mechanics. All rights reserved.

Vibration and energy dissipation of nanocomposite laminates for below ballistic 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

Major Accomplishments in Composite Materials and Sandwich Structures

Damage Tolerance of Naval Sandwich Panels

Energy partition for ballistic penetration of sandwich panels

Composite Structures

Low velocity impact damage characteristics of Z-fiber reinforced sandwich panels — an experimental study

The penetration energy of sandwich panel elements under static and dynamic loading. Part I

Journal of Pressure Vessel Technology

Penetration and Perforation of Composite Sandwich Panels by Hemispherical and Conical Projectiles

Projectile impact on sandwich panels

Journal	International Journal of Crashworthiness
ISSN	13588265
Open Access	No