When observing or describing the damage state in a composite material, often only Young's modulus or residual deformation are considered. Generally, however, the Poisson's ratio is more sensitive to damage than those properties. Rather than observing the Poisson's ratio as function of crack density, the evolution of the Poisson's ratio as function of the longitudinal strain was studied in part I of this research, where a peculiar shape of the evolution was observed and proven to be entirely due to the material itself, rather than the sensors used for the strain measurement. In this article, a theoretical explanation for the peculiar evolution of the Poisson's ratio as function of the longitudinal strain is presented. Based on this explanation, extra experiments were conducted for validation purposes. The material used for this study is a carbon fabric-reinforced PPS.
The relationship between the mechanical behaviour (i.e. Young’s modulus, Poisson's ratio and residual strain) of CFRP woven fabric laminates and the damage sustained during quasi-static loading has been investigated in two, four- and six-layer laminates. The laminate thickness is found to be an important parameter in determining the effect of matrix cracking and delaminations on the mechanical properties. The laminate behaviour has been modelled by a shear-lag analysis which takes into account delaminations at the crimp regions in the laminate where appropriate. Reasonable agreement is found between experiment and theory for the change in laminate properties as a function of damage accumulation.
Every function of n inputs can be efficiently computed by a complete network of n processors in such a way that: If no faults occur, no set of size t n /2 of players gets any additional information (other than the function value), Even if Byzantine faults are allowed, no set of size t n /3 can either disrupt the computation or get additional information. Furthermore, the above bounds on t are tight!