Glass/epoxy, carbon/epoxy and hybrid (glass-carbon/epoxy) composites are subjected to quasi-static to high strain rate (542 s−1) studies to obtain the tensile strength. The two-parameter Weibull distribution is employed to measure the variability of the tensile strength of cross ply laminates. The Weibull parameters are obtained using the linear curve fit method. The theoretical tensile strength values are determined for the GFRP, CFRP and hybrid composites. The experimental and theoretical strength values are in good agreement. Using Hitachi scanning electron microscope instrument, the failure mechanisms are investigated in the fracture surfaces of glass/epoxy, carbon/epoxy and hybrid specimens, and discussed. © 2016 Elsevier Ltd

Shankar Krishnapillai

Department of Mechanical Engineering

R. Velmurugan

Department of Aerospace Engineering

Kakur S. Naresh

Fiber reinforced plastics

Fractography

Fracture

FRACTURE MECHANICS

Glass

Laminated composites

Laminates

Scanning electron microscopy

Strain rate

Weibull distribution

Cross-ply laminate

Failure mechanism

Fiber reinforced polymers

Fracture surfaces

High strain rates

THEORETICAL STRENGTH

THEORETICAL TENSILE STRENGTHS

WEIBULL PARAMETERS

Tensile strength

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

Thin-Walled Structures

Examination of stacking sequence effect is essential in optimising the properties of synthetic fibre reinforced hybrid polymer composites for protecting the aircraft structure from the barely visible impact damage during low-velocity impact (LVI) events. It is important to know the quasi-static mechanical properties of polymer composites before analysing the LVI damage. Therefore, in this study, both quasi-static mechanical (tensile, flexural and punch-shear) and LVI properties of epoxy reinforced woven roving, E-glass and three different interply hybrid fabric (S-glass-E-glass, Carbon-E-glass and Kevlar-E-glass) composites are investigated. In all these hybrid composites, E-glass fabric layers are placed in the interior. Analysis of LVI properties indicated a 7.5% increase in the maximum energy absorption for laminates having Kevlar fibre as surface layers as against 3.4% decrease in energy absorption and 13.5% for laminates with carbon fibre and S-glass fibre as surface layers, respectively, compared to the E-glass/epoxy composite. An X-ray computed tomography is used for observing the layer-wise damage mechanisms of the LVI tested specimens from damage initiation to final perforation, which predicts that the bottommost layers of the plate are subjected to more damage. The damage area for each layer of the composite plates are measured using Image J software. Carbon-E-glass/epoxy composites are found to have more damage area than the other laminates. The delamination and damage zone of the plates are detected using the ultrasonic C-scan. The scanning electron microscopy is used to examine the fractured surfaces of tensile, flexural and punch-shear tested specimens. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

International Journal of Crashworthiness

Layer-wise damage prediction in carbon/Kevlar/S-glass/E-glass fibre reinforced epoxy hybrid composites under low-velocity impact loading using advanced 3D computed tomography

In the present work, the neat epoxy and different orientations (0°, 45°, (45°/-45°/45°)s, (±45°/0°/90°)s and 90°) of unidirectional carbon/epoxy composites are experimentally studied under tensile and impact loading. The notched impact tests are performed using the Izod impact machine to obtain the energy absorption of neat epoxy and different Carbon Fiber Reinforced Polymer (CFRP) composites which are required for the effective design of bullet proof jackets and military vehicles. The micro mechanical analysis is employed to determine the shear properties of a matrix using the tensile properties. Using classical laminate theory (CLT), the theoretical tensile properties are determined. The SEM fractography analysis is used to observe the damage mechanisms of neat epoxy and different orientations of CFRP composites subjected to tension and impact loading. © 2017 Trans Tech Publications, Switzerland.

Solid State Phenomena

Comparative study of a neat epoxy and unidirectional carbon/epoxy composites under tensile and impact loading

In this study, the Interlaminar Shear Strength (ILSS) and flexural properties for five different laminate orientations (0°, 45°, (45°/-45°/45°)s, (±45°/0°/90°)s and 90°) of unidirectional carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) composites are investigated and compared. The different approach is used by applying the tensile load on double notched specimens for measuring the inter-laminar shear strength. The theoretical flexural properties are obtained using the Classical Laminate Theory (CLT). The good agreement is obtained between the theoretical model and experimental results. The results indicate that the flexural strength and stiffness are higher for 0° laminates whereas flexural strain is higher for (45°/-45°/45°)s laminates as compared to other laminates. The scanning electron microscopy is used to observe the fracture surface of all laminate orientations of CFRP and GFRP composites. © 2017 Trans Tech Publications, Switzerland.

Effect of fiber orientation on carbon/epoxy and glass/epoxy composites subjected to shear and bending

Composites are efficient to deal with tensile loads than metals. Now-a-days, metals are replaced with composites owing to their higher strength to weight ratio and are extensively used in aircraft wing and fuselage structures. These structures are subjected to high strain rates during impact loadings, such as bird hit or run-way debris impact. In order to design robust composite structures, it is important to understand the strain-rate-dependent behavior of composite materials. In this study, influence of strain rate on the tensile properties of glass/epoxy, carbon/epoxy and hybrid (glass-carbon/epoxy) composites are experimentally and theoretically investigated in the range of strain rates from 0.0016&nbsp;s−1 to 542&nbsp;s−1. Drop mass setup is used for high strain rate tests. Quasi-static tests are performed on Instron universal testing machine in accordance with ASTM D638. The results indicate that the tensile strength and tensile modulus of GFRP and hybrid composites increase and percentage of failure strain for GFRP, CFRP and Hybrid composites decreases with the increase in strain rate, whereas tensile strength and tensile modulus of CFRP composites remains approximately constant. The scanning electron microscopy is used for analyzing the failure modes of the failed region (surface) of the tested specimens. Non contact DIC system is used to capture the strain field with the help of high speed camera. © 2016 Elsevier Ltd

Composites Part B: Engineering

Effect of high strain rate on glass/carbon/hybrid fiber reinforced epoxy laminated composites

As polymers are rate sensitive to mechanical properties, dynamic tensile tests are carried out on drop mass setup, to obtain medium strain rate stress-strain response which fills the gap between quasi-static strain rate (&lt;10 s-1) and split Hopkinson pressure bar (SHPB) technique (&gt;1000 s-1). The present research work is to study the effect of medium strain rate on tensile behavior of epoxy/clay nanocomposites. Neat epoxy and nanocomposites containing 1.5, 3 and 5 wt% clay content are fabricated using mechanical stirrer. The dispersion of nanoclay in epoxy is examined using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The digital image correlation (DIC) technique is employed for evaluating full-field strain and strain rate using high speed CCD camera, which captures about 100,000 frames per second. Stress-strain measurements are reported for epoxy/clay nanocomposites for strain rates ranging from 0.008 to 450 s-1. The results reveal that the tensile strength and modulus increase with increase in strain rate for epoxy and its clay nanocomposites. The fracture surfaces of tensile specimens are investigated using scanning electron microscopy (SEM). © 2015 Elsevier Ltd. All rights reserved.

Polymer

High strain rate sensitivity of epoxy/clay nanocomposites using non-contact strain measurement

Probabilistic strength based matrix crack evolution in multi-directional composite laminates

Construction and Building Materials

Tensile behavior of glass fiber reinforced composite at different strain rates and temperatures

Polymers

Modified Weibull Distribution for Analyzing the Tensile Strength of Bamboo Fibers

Statistical analysis of the tensile strength of GFRP, CFRP and hybrid composites

Journal	Data powered by TypesetThin-Walled Structures
Publisher	Data powered by TypesetElsevier Ltd
ISSN	02638231
Open Access	No