Yousif A. Khalid

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.

Finite element analysis of corrugated web beams under bending

Abstract The effect of web corrugation on the beam’s strength is presented in this paper. Beams with plane web, vertically and horizontally corrugated webs were investigated using LUSAS finite element package. For the horizontally corrugated case, one arc and two arcs were studied, while half-circular wave corrugation was used for the vertical type. Half of circle corrugations of 22.41 mm mean radius and 3.44 mm thickness were used throughout this study. Non-linear elastic–plastic behaviour has been considered. Three different corrugation radii were taken for each type of the beam to investigate its effect on the beam’s strength. Ordinary I-beams, with plane web, were also tested experimentally. The comparison between the results obtained from both methods, for the plane web type, shows 3.1% to 7.1% differences. On the other hand, it is also found that beams with vertically corrugated web stands 38.8% to 54.4% higher moments than the horizontal type. The vertically corrugated web provides a stronger support against the flange buckling, compared to the plane and horizontally corrugated web types. It is found to be the same for the three radii taken. Moreover, corrugated web beams with larger corrugation radius could sustain higher bending moment and it is true for the sizes used throughout this investigation.

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.

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.