This paper investigates the effect of fiber waviness on the behavior of carbon-epoxy composites. A theoretical elastic model is developed to predict lamina modulus of elasticity as a function of fiber waviness and is used in an incremental loading scheme to predict the general stress-strain response. This theoretical response is found to be nonlinear in the same fashion as the experimental, measured response.An optical procedure is employed to determine the magnitude of fiber waviness in a current material IM6/3501-6 system. A convincing correlation is demonstrated between measured fiber waviness and the degree of waviness necessary to match the experimental stress-strain curve.
In this paper, we study the interaction of a screw dislocation with a multi-layered interphase between a circularly cylindrical inclusion and a matrix. The layers are coaxial cylinders of annular cross-sections with arbitrary radii and different shear moduli. The number of layers may also be arbitrary. Continuity of traction and displacement across all interfaces is assumed. We extend Honein et al.Õs solution of circularly cylindrical layered media in anti-plane elastostatics to the case where all the singularities reside inside the inclusion core. The solution to this heterogeneous problem is given explicitly, for arbitrary singularities, as a rapidly convergent Laurent series, whose coefficients are expressed in terms of those of the complex potential of a corresponding homogeneous problem with the same singularities. We then consider the two particular cases of a screw dislocation, where, in the first instance, the dislocation resides inside the matrix, while, in the second instance, it is located in the inclusion core. In both instances, the Peach-Koehler force acting on the dislocation is calculated explicitly as a rapidly convergent series. We present several examples, where the effect of the layers on the material force is examined.
Abstract:In [10] the rst author used Lyapunov functionals and studied the exponential stability of the zero solution of nite delay Volterra Integro-di erential equation. In this paper, we use modi ed version of the Lyapunov functional that were used in [10] to obtain criterion for the stability of the zero solution of the in nite delay nonlinear Volterra integro-di erential equation
C(t, s)g(x(s))ds.
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