Elastic-plastic stress analysis of unidirectionally reinforced symmetric thermoplastic laminated beams loaded by bending moment

Elastic-plastic stress analysis is carried out on steel fiber reinforced thermoplastic matrix laminated beams loaded by bending moment. The beam is composed of four orthotropic layers, perfectly bonded and symmetrically arranged with respect to the x-axis. The orientation angles are chosen as (90 degrees/0 degrees)(s), (30 degrees/-30 degrees)(s), (45 degrees/-45 degrees)(s) and (60 degrees/-60 degrees)(s). The composite material is assumed to be linearly hardening, sigma(x) residual stress component is found to be highest at the upper and lower surfaces. However, when the applied bending moment is increased, the plastic region is further expanded towards middle plane from the upper and lower surfaces of the beam and so a, residual stress component is found to be highest at the elastic and plastic boundaries. The plastic flow is obtained to be maximum at the upper and lower surfaces for (30 degrees/-30 degrees)(s) orientation. The transverse displacement is obtained to be highest at the free end for (90 degrees/0 degrees)(s) orientation.