Mechanical and physical properties of water hyacinth and cogon grass fiber reinforced epoxy resin composites

In this paper, the study investigates the mechanical and physical properties of water hyacinth and cogon grass fiber reinforced epoxy resin hybrid composites. Hand lay-up technique was used to fabricate the composites. Water absorption, microstructure, tensile properties, flexural properties, and impact strength tests for total fiber contents, 15 wt %, and different water hyacinth and cogon grass fiber ratios (10/0, 8/2, 6/4, 4/6, 2/8, and 0/10) were used to evaluate the investigation’s effects. The addition of water hyacinth and cogon grass fiber into epoxy improves tensile, flexural, and impact properties while decreasing water absorption, according to the findings. Using a scanning electron microscope (SEM), the microstructure of the composites was analyzed, and surface fracture behavior and the void between the fiber and matrix were observed.

Modeling of Surface Fracture in Friction Interaction of Fiber Composites

The model of the frictional interaction of a fiber composite material with a rigid non- wearing body is proposed, which makes it possible to study the effect of the mechanical and strength characteristics of the fiber and matrix materials and the composite structure on its stress state, in particular, at the fiber-matrix interface. Analysis of the stress distribution in the subsurface layers of the composite was carried out for different values of the ratio of matrix to fiber materials hardness, the sliding friction coefficient and the distance between the fibers. For the known failure criteria of fiber composites, the conclusions about the effect of the structure and relative strength properties of a fiber (fiber bundle) and matrix on the pattern of subsurface fracture of the composite under sliding friction conditions are made

Glass Fracture during Micro-Scratching

The regularity of glass surface fracture and resistance to destruction were investigated by the methods of progressive and static microscratching with the Berkovich indenter. The research hardware was the original nanoindentation/microscratching devices and a non-contact interference profilometer for studying the morphology of the formed microscratches. The regularities of the fracture stages and the cracks growth along the microscratch were established depending on the indenter applied load. Based on analysis of the microcracks profile formed at various loads on the indenter immediately after the process of applying these scratches and after several hours of rest, it was found that the process of crack propagation along the scratch continues for a long time. Taking into account this established fact, a discrete-statistical method of the cracks formation for a long time is proposed. In accordance with this method, scratching is carried out with a constant load on short and separated tracks. The load on the indenter in each track increases discretely with a certain step. The influence of the medium on the scratching process is analyzed. The breaking mechanism in the glasses scratching process is formulated as the load on the indenter increases, and a model of the glass fracture stages is proposed.