E. Mahdi

Development of Short-Carbon-Fiber-Reinforced Polypropylene Composite for Car Bonnet

In this paper, short-carbon-fiber-reinforced polypropylene (SCF/PP) composites were prepared with melt blending and hot-pressing techniques. The tensile properties, flexural properties, hardness, and work of fracture (WOF) of this composite were investigated. Thermal stability of the composite was studied via the thermal gravimetric analysis (TGA). Finally, the mechanical properties of this composite were compared to mechanical properties of steel car bonnet in order to choose for car bonnet application. The properties of the composite prepared by 10% SCF/PP is comparable with the properties of carbon steel.

Effect of hybridisation on crushing behaviour of carbon/glass fibre/epoxy circular-cylindrical shells

Abstract This study concentrates on the effect of hybridisation on the crushing behaviour, energy absorption and failure mechanism and mode for composite cylinders. The static crushing behaviour of filament wound laminated (FWL) circular–cylindrical composite shell under uniform axial load has been investigated experimentally. Five different hybrids and non-hybrid FWL circular–cylindrical composite shell containing carbon and glass fibres were fabricated. Five types of composites were tested, namely, carbon fibre/epoxy, glass fibre/epoxy, carbon–glass–glass/epoxy, glass–carbon–glass/epoxy and glass–glass–carbon/epoxy. Failure modes were examined using the photographs taken during the different crushing stages for each specimen. Failure modes were highly dominated by the effect of hybridisation. The results also showed that the structure with material sequence of glass–carbon–glass/epoxy exhibited good energy absorption capability.

An experimental investigation into crushing behaviour of filament-wound laminated cone-cone intersection composite shell

Abstract This paper presents the effect of cone vertex angle on the crushing behaviour, energy absorption, failure mechanism and failure mode of filament-wound laminated (FWL) cone–cone intersection composite shell. The static crushing behaviour of FWL cone–cone intersection composite shell under uniform axial load is investigated experimentally. Two types of composites were tested, namely, carbon fibre/epoxy and glass fibre/epoxy. The cones vertex angles tested are 10°, 15°, 20° and 25°. Failure modes were examined using the photographs taken during crushing the specimens. The results showed that the initial failure was dominated by interfacial and shear failure, while the delamination and eventually fibre fracture dominated the failure mechanism after the initial first failure. The results also showed that the structure with vertex angles 20° and 25° exhibited good energy absorption capability. The volume reduction is obtained and found to be significant for these sets of angles.

Quasi-static axial crushing of segmented and non-segmented composite tubes

Abstract This paper examines the effect of segmentation on the crushing behaviour, energy absorption and failure mechanism of composite tubes. Quasi-static axial crushing behaviour of segmented and non-segmented composite tubes is investigated experimentally. The segmented composite tube consists of three different material regions, each with its own specific functions. Load–displacement curves and deformation histories of typical specimens are presented and discussed.The results showed that non-segmented composite tubes were found to be very brittle (i.e. the tissue mat glass fibre/epoxy tubes), or have low energy absorption capability (i.e. cotton fabric fibre/epoxy). On the other hand, segmented composite tubes including the tissue mat glass fibres were found to suffer from low energy absorption and the catastrophic failure mechanism initiated at the part made of tissue mat glass fibre/epoxy. Segmented composite tubes from carbon fabric fibre and cotton fabric fibres exhibited good energy absorption capability as well as stable load-carrying capacity.

Effect of Multi‐Wall Carbon Nanotubes on the Mechanical Properties of Natural Rubber

Abstract Multi‐walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Mechanical test results show an increase in the initial modulus for up to 12 times in relation to pure NR. In addition to mechanical testing, the dispersion state of the MWNTs into NR studied by Transmission Electron Microscopy (TEM) in order to understand the morphology of the resulting system

On the Collapse of Cotton/Epoxy Tubes under Axial Static Loading

Experimental quasi-static crushing tests and finite element analysis have been carried out for unidirectional filament wound laminated cotton/epoxy tubes. The work focuses on three main factors, which considerably affect the axial collapse load of unidirectional natural composite tubes. These factors are structural geometry, fibre diameter and fibre orientation. Cotton/epoxy tubes with different diameters (50, 70, 90, 110 and 130 mm) were examined and tested. The fibre orientation angles were 80 and 90°. The initial geometric imperfections are measured using the computerised Mistral coordinate measuring machine. The numerical prediction was obtained using commercially available finite element software. A limited agreement between the experimental and computational results was obtained. For all structures considered classical axial collapse eigenvalues were computed. The initial failure crush load computed from the finite element simulation model has been compared with the experiments.

Effect of Material and Geometry on Crushing Behaviour of Laminated Conical Composite Shells

This paper examines the effects of the material and structural geometry on the crushing behaviour, energy absorption, failure mechanism and failure mode of circular conical composite shell. The static crushing behaviour of circular conical composite shell under uniform axial compressive load has been investigated experimentally. The cone vertex angles used were 0, 6, 12 and 18 degrees. The cone vertical length and bottom outer diameter were kept for all the cases as 100 and 110 mm, respectively. Failure modes were examined using several photographs taken during the crushing stages for each specimen. Results obtained from this investigation showed that the initial failure was dominated by the interfacial and shear failure, while the delamination and eventually fibre fracture were dominated the failure mechanism after the initial failure. It has also found that the static crushing behaviour of the circular conical shell is very sensitive to the change in the vertex angle. Reinforcement type greatly affects the energy absorption of the circular conical and cylindrical shells.

Effect of residual stresses in a filament wound laminated conical shell

Abstract This paper examines the effect of residual fabrication stresses on the crushing behaviour, energy absorption, failure mechanism and failure mode of a filament wound laminated conical composite shell. The static crushing behaviour of the conical composite shell under uniform axial compressive load is investigated experimentally. The cone vertex angles were 0°, 6°, 12° and 18°. The numerical result shows that residual stresses developed have been concentrated at the small ends of cones. Experimental results obtained from this investigation show that the initial failure was dominated by interfacial and shear failure, while the delamination and eventually fibre fracture were dominated by the failure mechanism after the initial failure. It is also found that the static crushing behaviour of the conical shell is highly sensitive to the change in cone vertex angle, which strongly dominates the residual fabrication stress development. It can be deduced that as the axial residual stress increases, the initial failure load decreases.

Axial and lateral crushing of the filament wound laminated composite curved compound system

In this paper, experimental and numerical investigations into the crushing behaviour of the filament wound laminated curved compound system have been conducted. The structure being investigated is composed of a complete and semi-circular cone-cylinder-cone system. The conical parts of the structure were symmetric. The cone vertex angle and the cylindrical part height were 15 degrees and 10 mm, respectively. Load–displacement curves and deformation histories of typical specimens are presented and discussed. The experimental data are correlated with predictions from finite element model. Numerical results show that for curved systems under lateral load, local stress has been concentrated at the junctions between the cylinder and cones as well as the edge of the systems, while for the curved systems under axial load, the stress concentration is slightly clear at the loaded end of the curved systems. Experimental results show that the axial loaded curved systems are crushed into a progressive failure mode and exhibit high-energy absorption capability. Results also show that the debonding at the fibre–matrix interface is influenced by the load–displacement relationship for the lateral loaded curved systems. On the other hand, the fragmentation failure mode is dominated by the load–displacement relationship for the axial loaded curved systems.

Ellipticity ratio effects in the energy absorption of laterally crushed composite tubes

A comprehensive experimental investigation of woven roving glass/epoxy laminated composite elliptical tubes subjected to quasi-static lateral loading has been carried out. To this end a series of experiments were conducted for tubes with ellipticity ratio a/b ranging from 0.5 to 2. Typical deformation histories of the tubes are presented and influences thereon of ellipticity ratio are discussed. It was found that for a/b > 1, two fracture lines developed, whereas for a/b < 1 only one fracture line was observed to develop. Modes of energy dissipation mechanisms are identified and analysed on the basis of micro and macro failure levels. Ellipticity ratio significantly affected the energy absorption capability of the tubes.