Axial compression of empty and foam filled composite conical shells

Experimental and theoretical studies of axial compression of both empty and foam filled glass fibre/polyester resin truncated conical shells are presented. An analysis is carried out to determine the mean crushing load and the crush length, i.e., the shell length crushed in a cycle of progressive crushing of the shell. The mean crushing load is obtained by equating the total energy involved in a crush cycle to the work done by the applied load. The expression for crush length is obtained by minimizing the total potential energy with respect to the crush length. The shells were made of short, randomly oriented glass fibre mats with polyester resin, and their cone angles were 9.5 degrees, 14 degrees, 18.4 degrees, 21 degrees and 45 degrees. These were subjected to axial compression in the Instron machine at a cross head velocity of 2 mm/min. Their typical deformation histories, load-deformation behaviour and energy absorption characteristics are presented and influence thereon of the infill foam is discussed. Standard tensile specimens were made with the same lay up sequence and number of layers as in the actual conical shells. These were subjected to uni-axial tension test in Instron machine to obtain their tensile properties. The analytical results obtained compared well with the experimental results.