Fumiko Sugiyama

Evaluations of the shear strength of advanced ceramic composite materials

The shear distributions of fibre–bonded ceramic composite were investigated using finite element analysis. The effect of notch distances on the shear stress distributions in a double notch shear (DNS) specimen was investigated under static and impact loading conditions. The stress concentration near the notch roots became larger as the notch distance increased. The effects of variations in the notch distances upon the shear strength of fibre bonded ceramics (FBC) and carbon–fibre reinforced silicon nitride (CFRSN) were experimentally investigated with static and impact tests. The shear strength decreased with an increase of the notch distance for both the static and impact tests, except that the notch distance was too small. The impact shear strength was larger than the static one regardless of notch distance. The shear strength evaluated by a DNS test was smaller than that obtained from a short beam bending (SBB) test.

Fracture Strength on Fiber-Bonded Ceramic Composite Subjected to Static and Dynamic Bending.

Finite-element analysis was performed to characterize the deformation behavior of ceramic composite material during static and dynamic bending. Normal and shearing stress distributions were clarified by FEM with respect to elastic anisotropy and the specimen height-to-span ratio, (H/L), and the tensile and shearing fracture behaviors were well understood in comparison with the predicted stress distributions. It is determined that well-ramped impact bending leads to almost identical stress distributions as static bending and, consequently, the fracture strength of brittle materials can be measured at a high deformation rate. Tensile and shearing strengths were significantly increased with the rise in the deformation rate.