An Elastic-Plastic Stress Analysis on a Thermoplastic Composite Beam of Arbitrary Orientation Supported from Two Ends Acted upon with a Force at the Midpoint

An analytical elastic-plastic stress analysis is presented for a low density polyethylene thermoplastic composite reinforced by woven steel fibers supported at the ends acted upon with a force at the midpoint. The expansion of the plastic region and the residual stress component of σ _x are determined for θ = 0°, 15°, 30° and 45° orientation angles. Plastic yielding occurs for 0° and 45° orientation angles on the lower and upper surfaces of the beam at the same distances from the midpoint. But, it starts first at the lower surface for 15° and 30° orientation angles. The residual stress components are obtained after releasing the external force. The residual stress component of σ _x is maximum at the lower and upper surfaces. However, the intensity of the residual stress component τ _xy is maxiumu on or around the x axis of the beam. The beam can be strengthened by using the residual stresses.