On (Non-)Monotonicity and Phase Diagram of Finitary Random Interlacement

In this paper, we study the evolution of a Finitary Random Interlacement (FRI) with respect to the expected length of each fiber. In contrast to the previously proved phase transition between sufficiently large and small fiber length, for all d≥3, FRI is NOT stochastically monotone as fiber length increases. At the same time, numerical evidence still strongly supports the existence and uniqueness of a critical fiber length, which is estimated theoretically and numerically to be an inversely proportional function with respect to system intensity.

Mechanical Properties of Randomly Oriented Calotropis Gigantea Fiber-Reinforced Phenol Formaldehyde Biocomposites

Mechanical properties such as tensile, flexural and impact, of randomly oriented Calotropis Gigantea Fiber (CGF) -reinforced Phenol Formaldehyde (PF) biocomposites were studied based on the five different fiber loadings (10, 20, 30, 40, and 50 vol%) and three different fiber lengths (3, 9, and 15 mm). The critical fiber length and optimum fiber loading were identified with the maximum level of mechanical properties in this composite. The fractured surfaces of composites after testing were studied by scanning electron microscope (SEM). The results revealed that the addition of CGFs is improving the mechanical properties of the PF composite. The properties of composites reach the properties of the neat resin sample at 20 vol% of all the cases. The critical fiber length and the optimum fiber loading to obtain the maximum mechanical properties were identified as 9 mm and 40 vol% respectively. Experimental tensile property values were compared with theoretical values and found to be in good agreement.

Carbon Fiber Reinforced Cement and Mortar

Although carbon fibers have high tensile strengths and are chemically inert, their application in cementitious composites is limited due to their brittleness. An image analysis technique employed to determine the length distribution of the reinforcing fibers before and after mixing in cement paste and mortar matrices indicates that substantial fiber breakage occurs during mixing. In paste mixtures, the average fiber length after mixing remains above the critical fiber length, but in mortar mixes the average fiber length falls below the critical fiber length resulting in no significant enhancement of composite flexural properties.

Longitudinal Relaxation of a Thermally Stressed Fiber by Prismatic Dislocation Punching

ABSTRACTA model predicting the number of prismatic loops dislocation punched at the ends of a cylindrical fiber by thermal mismatch stresses is presented and compared to another based on a mismatching ellipsoid. The longitudinal stress in the fiber and the interfacial shear stress are derived by adapting a shear-lag model to the plastic portion of the interface. In certain cases, the central part of the fiber is strained by plastic and elastic interfacial shear until it exhibits no mismatch with the matrix. This leads to a critical fiber length above which the number of punched loops is constant.