On the optimization of the mechanical behavior of a class of composite systems under both quasi-static and dynamic loading

This paper is concerned with the optimization, with the inclusion of the microstructure, of the mechanical behavior of fiber-reinforced polymeric composites under both quasi-static and dynamic loading. Analytical models pertaining to both continuous- and discontinuous-fiber composites are investigated. In the first part of the presentation, the effects of microstructural parameters, such as fiber-aspect ratio, fiber off-axis angle and fiber-volume fraction, on the damping and stiffness of a fiber-composite system are examined. Quasi-static models are, then, developed by using a “forced balance approach” to define the mechanical response properties of discontinuous fiber-reinforced composites. Subsequently, simultaneous optimization of the damping, stiffness and specific weight is carried out by using the so-called “inverted utility function methods”. The obtained results show that discontinuous fiber-reinforced composites have superior design flexibility and damping properties as compared with those pertaining to continuous fiber-reinforced composites. In the second part of the presentation, the determination of the impact response of a composite laminate is dealt with. In this context, the “first shear deformation theory (FSDT)” is employed to deal with the transit wave-propagation phenomenon. The “correspondence principle” is, then, utilized to extend the obtained elastic solutions to a corresponding viscoelastic problem. The obtained results emphasize the importance of including material viscoelasticity in the analysis concerning the prediction of the mechanical response of laminated composites under impact loading.