Effect of material nonlinearity in unidirectional composites on the behavior of beam structures

The present study is made to investigate the e€ect of material nonlinearity in unidirectional composites on the behavior of beams, where the ®ber orientation is considered. The e€ect of these two factors on de¯ection, bending moment and external reactions is investigated. In order to achieve these objectives, a computer subroutine based on secant mechanical property is incorporated in a main computer program for beam and frame analysis. The program can solve structures made of unidirectional composite materials which exhibit general material nonlinearity. Several numerical examples including various beam structures having di€erent ®ber orientations are presented, for both linear and nonlinear analysis