An elastic–plastic stress analysis in a thermoplastic composite cantilever beam

In the present study an analytical elastic–plastic stress analysis is carried out for a low-density homogeneous polyethylene thermoplastic cantilever beam reinforced by Cr–Ni steel fibers. The beam is loaded by a constant single force at its free end. The expansion of the plastic region and the residual stress component of σx are determined for 0, 15, 30 and 45° orientation angles. Yielding begins for 0 and 45° orientation angles at the upper and lower surfaces of the beam at the same distances from the free end. However, it starts first at the upper surface for 15 and 30° orientation angles. The elastic–plastic analysis is carried out for both the plastic region which spreads only at the upper surface and the plastic region which spreads at the upper and lower surfaces together. The residual stress components are obtained after releasing the external force. The distributions of the residual stress components of σx and τxy are also determined. The intensity of the residual stress component is maximum at the upper and lower surfaces of the beam, but the residual stress component of τxy is maximum on or around the x-axis. The beam can be strengthened by using the residual stresses. The distance between the plastically collapsed points and the free end is calculated for the same load in the beam for 0, 15, 30 and 45° orientation angles.