Papers by Author: Cheng Yan

Abstract: The mechanical strength and failure behavior of two photonic crystal silica optical fibers with different diameters were investigated using tensile test. The effect of polymer coating on the failure behavior was also studied. The results indicated that all fibers failed in a brittle manner and the failure normally initiated from fiber surfaces. The failure loads observed in the coated fibers are higher than that in bare fibers and the reason is explained by the apparent delamination between the fiber and the polymer coating when loaded on the fiber surfaces. The relationship between a characteristic parameter measured on the fracture surfaces and the failure stress was examined.

Abstract: This work investigated the post buckling strength and failure behavior of advanced grid stiffened structures (AGS) under thermal-mechanical load using a finite element method. Based on the first order shear deformation theory (FSDT), Von Karman non-linear deformation assumption, and a progressive failure criterion, the buckling, large deformation，local failure modes in the AGS were studied. The thermal effect was also analyzed. By some numerical examples, the failure characteristics of the AGS were discussed.

Abstract: The deformation and failure behavior of an AM60 magnesium alloy was investigated using tensile test on circumferentially notched specimens with different notch radii. The strain and stress triaxiality corresponding to the failure point were evaluated using both analytical and finite element analyses. Combining with systematical observations of the fracture surfaces, it is concluded that deformation and failure of AM60 magnesium alloy are notch (constraint) sensitive. The failure mechanisms change from ductile tearing to quasi cleavage with the increase of constraint.