Impact and post impact behavior of layer fabric composites

A mechanical behaviour of plain-weave E-glass fabric/epoxy laminate composite plate exposed to ballistic impact is studied using a finite-element (FE) code Abaqus/Explicit. A ply-level FE model is developed, where a fabric-reinforced ply is modelled as a homogeneous orthotropic elastic material with potential to sustain progressive stiffness degradation due to fiber/matrix cracking, and plastic deformation under shear loading. The model is implemented as a VUMAT user subroutine. Ballistic experiments were carried out to validate the FE model. A parametric study for varying panel thickness is performed to compare impact resistance of the studied composite.

Advanced Composites Letters

In this study, the impact behaviours of glass/epoxy and hybrid (glass-carbon/epoxy) composite plates have been investigated experimentally. The increasing impact energy was performed on composite plates until complete perforation of samples. An energy profiling diagram, showing the relationship between impact energy and absorbed energy, was used together with load-deflection curves to determine the penetration and perforation thresholds of composite plates. The failure processes of damaged specimens for different impact energies were evaluated by comparing load-deflection curves and images of damaged samples taken from impacted sides and non-impacted sides. Cross-sections of damaged specimens for both plates were also inspected visually and discussed to assess the extent of damage, such as fibre fracture in layers, expansion of delaminations between adjacent layers. The perforation threshold of hybrid composite impacted from surface with carbon fibres was found approximately 30% and...

International Journal of Impact Engineering, 2012

Due to the improved impact performance characteristics, composites are widely used in engineering and military applications to absorb the impact energy. Determination of impact response of composite materials provides the engineer and the manufacturer with critical knowledge to understand the failure criteria, initiation of the first failure and damage growth through the laminates. This study covers the investigation of impact damage growth and determination of Hertzian failure and maximum force thresholds in three different types of composites. Unidirectional E-Glass, woven E-Glass and woven Aramid composite samples with dimensions of 100 Â 100 mm are subjected to low velocity impact with an instrumented impact test system. Rebound, onset of perforation and perforation limits of composites are found out. Also, energy profile diagrams of both unidirectional and plain weave E-Glass composites are obtained. According to test results, woven composites are found to be superior to unidirectional composites in the protection limit of low velocity impact. It is also observed that damage growth in woven composites is restricted within a smaller area. Impact tests conclude that strength of the composite materials under dynamic loading increases considerably compared to static loading case as a result of strain rate sensitivity.

2010

Abstract This paper presents the impact response of woven natural silk (WNS)/Epoxy composite. The composite specimens were prepared in configurations of 10, 15, 20, 25 and 30 ply of WNS. Drop weight impact test was carried out under varied impact energies of 32J, 48J and 64J. Examinations of load bearing capability, energy absorption capability and damage process from initiation of damage to final perforation, with regards to increasing number of WNS Ply and increasing impact loads were investigated.

International Journal of Engineering Applied Sciences and Technology

In this work, the synergistic effect of woven structure and asymmetric glass fiber epoxy composites on impact response was studied by experimental and numerical methods based on fiber orientation and number of layers. Three finite element models of G16, G26 and G4 (0/45/90)s, (+45/-45/90)s and (+45/-45)s respectively composites under low velocity impact were established in ABAQUS software and three samples was made same of samples on the finite element model to be tested on drop weight. All samples were manufactured by hand lay-up. Impacts with various energies 3, 9, and 15 J was applied to G16, G26 and G4. The FD curve obtained by simulation is well analyzed with the FD curve obtained by experiments, and the level of the higher values of force obtained from scalar is almost identical to the level of peak force values obtained from experimental tests with the difference in the level of displacement between them. In addition, the highest power obtained for the sample is G26, followed by G16, then G4.

Composite Structures, 2003

In the current investigation, damage resistance of stitched/unstitched S2-glass/epoxy composites is studied. Five layer stitched/unstitched plain weave S2-glass woven fabric composite laminates were manufactured using toughened SC15 epoxy resin system. For stitching, two configurations: one with 25.4 mm grid and other with 12.7 mm grid, were used with 6 mm pitch. Damage resistance was evaluated by subjecting 100 × 100 mm samples to low velocity impact loading at energy levels ranging 10–80 J using DYNATUP Model 8210, an instrumented impact test system. Three samples were tested at each energy level. The extent of damage was evaluated using ultrasonic C-scan. Results of the study indicate that stitching confined the damage size. As the damage was low over most of the energy range, the study was further extended to determine the effect of repeated impact loading. Under this study, laminates were subjected to repeated impact loading up to maximum of 40 impacts at energy levels ranging from 10 to 50 J. Results of repeated impact study are reported in terms of peak load, absorbed energy and projected damage area. All the laminates, sustained repeated impact loading up to 30 J. Beyond 30 J, laminates failed to carry repeated loading beyond certain numbers, which depended on the laminate configuration.

2010

Response of fiberglass epoxy composite laminates under low velocity impact loading is investigated using LS-DYNA , and the results are compared with experimental analysis performed using an instrumented impact test setup (Instron dynatup 8250). The composite laminates are manufactured using H-VARTM c process with basket weave E-Glass fabrics. Epon 862 is used as a resin system and Epicure-W as a hardening agent. Composite laminates, with 10 layers of fiberglass fabrics, are modeled using 3D solid elements in a mosaic fashion to represent basket weave pattern. Mechanical properties are calculated by using classical micromechanical theory and assigned to the elements using ORTHOTROPIC ELASTIC material model. The damage occurred since increasing impact energy is incorporated using ADVANCED COMPOSITE DAMAGE material model in LS-DYNA . Good agreements are obtained with the failure damage results in LS-DYNA and experimental results. Main considerations for comparison are given to the impact load carrying capacity and the amount of impact energy absorbed by the laminates.

International Journal of Impact Engineering, 2013

This research is interested in the impact toughness of a reinforced composite face-sheet and cores materials used in lightweight sandwich panels. It investigated the degrees of damage inflicted on the contact surface, through thickness and rear surface of the sandwich panels. The sandwich specimens were prepared in configurations of natural silk (NS)/Epoxy/Foam, NS/Epoxy/Coremat, NS/Epoxy/Honeycomb and reinforced NS/Epoxy serving as referral. For all experiments, drop weight impact test was carried out under low velocity impact energies of 32 J, 48 J and 64 J. Parameters measured were load bearing capability, energy absorption capability and damage fragmentation of the specimen with regards to increasing impact loads. Dominant deformation modes were seen as upper face-sheet compression failure, lower face-sheet delamination and lower face-sheet tensile failure.

Composites Science and Technology, 2000

The behaviour of woven-fabric laminated composite plates has been studied under transverse central low-velocity point impact by using a modi®ed Hertz law and a 3D transient ®nite-element analysis code. The in-plane failure behaviour of the composites has been evaluated by means of a failure function based on the Tsai-Hill quadratic failure criterion. The eect of fabric geometry on the impact behaviour of woven-fabric composites has been studied. For comparison, the impact behaviour of balanced, symmetric, crossply laminates made of unidirectional layers and unidirectional composites has been included. The studies have been carried out with plate dimensions of 150 mmÂ150 mmÂ6 mm for a supported boundary condition. For these studies, incident impact velocities of 3 and 1 m/s and an impactor mass of 50 gm have been used. It is observed that the in-plane failure function is lower for wovenfabric laminates than for crossply laminates, indicating that woven-fabric laminates are more resistant to impact damage.

Composite Structures, 2013

In this study, the effect of stacking sequence on the impact behavior of sequentially stacked woven/knit fabric glass/epoxy hybrid composites was investigated. 2D (double layer) fabric was used as a woven fabric and rib and milano fabrics were used as knitted fabrics. Woven and knit fabric layers were sequentially stacked in six different variations to fabricate eight ply woven/knit fabric hybrid composites. The composite laminates were processed by hand lay-up technique using 3 mm thick spacers and cured under pressure of 8 MPa for 100 min. at 100°C, followed by cooling at room temperature under same pressure. The impact and post-impact (CAI) behavior of hybrid composites at various impact energies were investigated. FEA results were compared with experimental results. Results show that specimens having outer layer of woven fabric exhibited better impact properties than that of the specimens having outer layer of knitted fabric. The worst performance in terms of impact resistance was observed in knit/ knit composites. FEA analysis was in a good agreement with the experimental results.