Progressive Crushing of Polymer Matrix Composite Tubular Structures: Review

The present paper reviews crushing process of fibre-reinforced polymer (FRPs) composites tubular structures. Working with anisotropic material requires consideration of specific parameter definition in order to tailor a well-engineered composite structure. These parameters include geometry design, strain rate sensitivity, material properties, laminate design, interlaminar fracture toughness and off-axis loading conditions which are reviewed in this paper to create a comprehensive data base for researchers, engineers and scientists in the field. Each of these parameters influences the structural integrity and progressive crushing behaviour. In this extensive review each of these parameters is introduced, explained and evaluated. Construction of a well-engineered composite structure and triggering mechanism to strain rate sensitivity and testing conditions followed by failure mechanisms are extensively reviewed. Furthermore, this paper has mainly focused on experimental analysis that has been carried out on different types of FRP composites in the past two decades.

Laminate Tailoring of Composite Tubular Structures to Improve Crashworthiness Design at Off-Axis Loading

This paper presents experimental and numerical investigation on the parameters effecting energy absorption capability of composite tubular structures at oblique loading to improve crashworthiness performance. Various inclined angles of 5°, 10°, 20° and 30° were selected for the study of off-axis loading. The results indicate that by increasing the lateral inclination angle the mean crushing force and also energy absorption capability of all tested sections decreased. From design perspective, it is necessary to investigate the parameters effecting this phenomenon. The off-axis loading effect that causes significant reduction in energy absorption was investigated and the effected parameters were improved to increase energy absorption capability. To establish this study, 10° off-axis loading was chosen to illustrate the obtained improvement in energy absorption capability. Five cases were studied with combinations of ply-orientation and flat trimming with 45° chamfer. This method was applied to the integrated 10° off-axis loading and the final results showed significant improvement in energy absorption capability of composite absorbers. Finite element model (FEM) was developed to simulate the crushing process of axial and off-axis composite section in LS-DYNA and the results were in good agreement with the experimental data.

Manufacturing of 3D Printed Laminated Carbon Fibre Reinforced Nylon Composites: Impact Mechanics

This paper presents the manufacturing development of laminated Carbon Fibre Reinforced Thermoplastics Polymer (CFRTP) specimens, which show significant improvement of mechanical properties in comparison with existing thermoplastic composites. There is a need to improve structural performance of thermoplastic composites by using a fully integrated chopped and continuous carbon fibre bundle into a thermoplastic resin matrix in a laminated shape with various stacking sequences. The developed manufacturing technique is capable to print components with various fibre orientations, which is spotted as the novelty of this research. The CFRTP specimens were tested under quasi-static tensile and low-velocity impact loading to proof the improvement of mechanical performance in both static and dynamic applications. Our results indicate a significant improvement in impact resistance and energy absorption capability of CFRTP composites in comparison with existing thermoplastic composites.

Effect of functionally-graded interphase on the elasto-plastic behavior of nylon-6/clay nanocomposites;a numerical study

In nanocomposites,the interphase thickness may be comparable to the size of nano-particles,and hence,the effect of interphase layers on the mechanical properties of nanocomposites may be substantial.The interphase thickness to the nano-particle size ratio and properties variability across the interphase thickness are the most important affecting parameters on the overall behavior of nanocomposites.In this study,the effect of properties variability across the interphase thickness on the overall elastic and elastoplastic properties of a polymeric clay nanocomposite(PCN)using a functionally graded(FG)interphase is investigated in detail.The results of the computational homogenization on the mesoscopic level show that Young’s modulus variation of the interphase has a significant effect on the overall elastic response of nanocomposites in a higher clay weight ratio(Wt).Moreover,strength variation through the interphase has a notable effect on the elasto-plastic properties of PCNs.Also,the increase or decrease in stiffness of interphase from clay to matrix and vice versa have a similar effect in the overall behavior of nanocomposites.

Transverse Impact Response Analysis of Graphene Panels: Impact Limits

Explicit numerical studies were conducted to determine the transverse impact response of graphene panels. Although the mechanical properties of graphene are well documented in both quasi-static and dynamic conditions via nano- and microscopic studies, the impact behaviour of the material at the macroscale has not yet been studied and would provide interesting and crucial insight in to the performance of the material on a more widely recognizable scale. Firstly, a numerical impact model was validated against an analytical impact model based on continuum mechanics which showed good correlation between contact-force histories. The performance of graphene panels subjected to impact was compared to the performance of panels composed of aerospace-grade aluminium and carbon fiber reinforced polymer (CFRP) composite. The graphene panel was found to exhibit lower specific energy than aluminium and CFRP at the low-energy range due to its inherently superior stiffness and intrinsic strength. On the other hand, the ballistic limit of 3 mm thick graphene panels was found to be 3375 m/s, resulting in an impact resistance 100 times greater than for aluminium or CFRP, making graphene the most suitable material for high-velocity impact protection.