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The low-velocity impact perforation behavior of fiber-metal laminates (FMLs) is evaluated by analytical modeling. Four different FML layups consisting of glass fiber/epoxy layers and titanium alloy...

For crashworthiness applications, hollow composite tubes have been proposed and studied as impact-bearing members in earlier studies to replace metal tubes and beams which resisted impact by bending. This study focusses on the effect of the addition of hollow glass microballoons (GMB) in composite tubes for compressive loading. Epoxy containing 0 to 0.3 volume fraction of GMB is used with woven glass fabrics to fabricate the specimens. The mean load and energy absorbed while progressively crushing the tubes are experimentally obtained. The variation of these properties with the addition of GMB is analyzed. It is found that the compression properties improve with the addition of hollow glass particles. To explain the different modes of energy dissipation, the basic mechanical properties of the GMB-filled composites are obtained by various mechanical tests. These results are also used in an energy-based model to predict the properties of the tubes under compression.

In the present work, the neat epoxy and different orientations [0°, 45°, 90°, (45°/-45°/45°) s, (±45°/0°/90°) s] 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 CFRP composites which is required for 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.

Influence of interphase material and clay particle shape on the effective elastic properties of epoxy/clay nanocomposites (ECNs) containing randomly oriented exfoliated nanoclay particles is investigated by using the Mori–Tanaka method and a hybrid method. The effective particle concept is used to model the clay particle surrounded by the interphase material. Non-uniform distribution of the aspect ratio (AR) of clay particles is modelled by using the Gauss and rectangular distributions. The results indicate that the interphase thickness, interphase stiffness, clay AR distribution and clay particle shape have a significant influence on the Young's modulus of ECNs, but not on the Poisson's ratio. However, Poisson's ratio of the interphase material has a considerable influence on the Poisson's ratio of ECNs. Finally, a comparison of analytical and experimental results is presented.

The dynamic characteristics of the Polypropylene honeycomb (PPHC) sandwich composites have been investigated under various temperatures (30°,35°,40°,45°,50°,55°,60°, 65°,70°,75° and 80°C) and different orientations (0° and 90°) of the glass fibers in the composites. Since the thermal properties of the constituent materials (glass fiber, epoxy resin and PPHC core) of the PPHC sandwich composites are different and the in-plane effect of the composites varies with the two different orientations (0° and 90°) of the fibers, the variation of the loss factor under the various temperatures are also different for these orientations. A two stage layup technique has been used to fabricate the sandwich composite specimens. Impulse technique associated with the half power bandwidth method, has been used to evaluate the natural frequency and damping values of the sandwich composite under different temperatures.

Conventionally, shape memory programming involves deforming the material at a temperature higher than the glass transition (\(T_\mathrm {g}\)) and subsequently cooling the material below \(T_\mathrm {g}\) while holding the deformation to fix the temporary shape. Alternatively materials with reversible plasticity shape memory (RPSM) property can be programmed at temperatures well below the glass transition temperature which offers several advantages over conventional programing. Here, the RPSM property of multi-walled-carbon-nanotube (MWCNT) reinforced epoxy nanocomposites is investigated. A commercially available epoxy resin is tailored to realize RPSM effect and the properties are enhanced with the addition of nano-fillers in the epoxy matrix. This report systematically investigates the effect of MWCNT addition on the mechanical, thermal and RPSM properties of the epoxy matrix. The RPSM performance under different programming conditions like strain rate, strain level and stress relaxation time is studied. Results reveal that all samples show excellent shape memory properties under various programming conditions. The addition of MWCNT resulted in a significant improvement in mechanical and shape memory properties. Further the RPSM mechanism is explained using a thermo-viscoelastic-viscoplastic model and the model is used to predict the RPSM behavior of the nanocomposite under different programming conditions. As a result, this study shows that by varying the parameters like glass transition temperature, filler content and programming conditions the material can be designed for applications in self-healing systems and smart structures.