Design properties of randomly reinforced fiber composites

The pseudoisotropic-laminate analogy is used in conjunction with fiber composite micro- and macromechanics to predict the thermal and mechanical properties of planar randomly reinforced fiber composites (PRRFC). Theoretical results are presented for boron/aluminum, boron/epoxy, Thornel-50/epoxy, and S-glass/epoxy PRRFC. The results show that the thermal and elastic properties depend on both constituent materials and the fiber volume ratio. The strength depends also on the type of applied stress. In general, no simple ratio exists between the properties of unidirectional fiber composites and those of PRRFC. The data are presented in convenient graphical form to serve as an aid for design and/or analysis and also for further research in PRRFC. The residual stresses and the impact resistance are also theoretically examined.