Lateral crushing in tightly packed arrays of thin-walled metal tubes

The plastic-collapse load and post-collapse behaviour of ductile, thin-walled tubes compressed between cylindrical indenters are analyzed for a complete range of indenter radii; experiments on steel, brass and aluminium alloy tubes show the usefulness of this analysis when deflections are large. The effect of shear force is considered; shear can develop when the sides of the tube are constrained against lateral expansion. While crushing by diametrically opposed indenters results in symmetrical modes of deformation, any shear in addition to the normally applied forces results in an asymmetrical mode of deformation which is more compliant than the symmetrical mode. The asymmetrical mode of deformation is initially unstable.