Study on the Single Scattering of Elastic Waves by a Cylindrical Fiber with a Partially Imperfect Bonding Using the Collocation Point Method

The single scattering of P- and SV-waves by a cylindrical fiber with a partially imperfect bonding to the surrounding matrix is investigated, which benefits the characterization of the behavior of elastic waves in composite materials. The imperfect interface is modelled by the spring model. To solve the corresponding single scattering problem, a collocation point (CP) method is introduced. Based on this method, influence of various aspects of the imperfect interface on the scattering of P- and SV-waves is studied. Results indicate that (i) the total scattering cross section (SCS) is almost symmetric about the axis α=π/2 with respect to the location (α) of the imperfect interface, (ii) imperfect interfaces located at α=0 and α=π highly reduce the total SCS under a P-wave incidence and imperfect interfaces located at α=π/2 reduce the total SCS most significantly under SV-incidence, and (iii) under a P-wave incidence the SCS has a high sensitivity to the bonding level of imperfect interfaces when α is small, while it becomes more sensitive to the bonding level when α is larger under SV-wave incidence.

The Strength of Dissimilar Fractal Joints

In this investigation, the influences of fractal geometry and material properties on the strength of dissimilar joints were studied. The fractal geometry explored was an iterative Koch curve. The interfacial layer joining two different materials was designed to be a Koch layer with three different numbers of iteration. The mechanical behaviors of the fractal dissimilar joints under both normal tensile traction and shear traction were simulated via finite element (FE) method. In the three-phase FE models, isotropic elasto-perfect-plastic material models with different stiffness and yielding strength were used for all three phases. By varying the stiffness and strength ratio of the Koch layer and the dissimilar materials, fractal dissimilar joints with both perfect bonding and imperfect bonding were simulated and compared. It was found that the fractal geometry plays a very important role in enhancing both the tensile and shearing strength of dissimilar joints, especially for the cases with imperfect bonding.