Nabeel Almuramady

Planetary gear mechanisms (PGMs) are commonly employed in mechanical applications. Graph theory is a useful tool for synthesizing PGM structures to develop new transmission systems. The synthesis of 1- and 2-degree-of-freedom (DOF) planetary gear trains received a lot of attention. Nevertheless, the synthesis results are inconsistent because previous graph representations were insufficient for the synthesis processes. This paper proposes a graph model that improves upon earlier models, introducing the concept of type-2 pseudo-isomorphic graphs. The vertex levels are used to construct PGM-spanning trees and define geared graphs. This approach avoids pseudo-isomorphic graphs and maintains a one-to-one correspondence between PGM elements and the graph. The 6-link 2-DOF PGM synthesis demonstrated the current graph representation, yielding 24 non-isomorphic mechanisms of 11 or more than previously reported. Possible explanations for the inconsistency of synthesis results with earlier studies are investigated, and the advantages of the modified graph over existing approaches are discussed in detail.

The Rubber-carbon black composite material-based product is the main matrix used in domestic and industrial applications in the last decades. This study proposes replacing the reinforcing carbon with matrix-neutral rubber with epoxy resins to reduce the carbon footprint and lower the environmental impact while enhancing the product's mechanical properties. Five additive percentages of carbon--epoxy, starting from 100-50% Carbon-black and 0-50% Epoxy, were studied using a hybrid experimental-numerical approach. Experimentally, the extension fatigue, flexural fatigue, and elongation modulus testing were completed using the universal testing machines with a low loading rate (quasi-static process). Numerical, the finite element analysis by the commercial software ABAQUS-SAE within the built-in hyperelastic constitutive model was utilized to visualize the full-field stresses. The experimental nominal stress-strain data was used as input for the numerical model, and Ogden's formula was applied to simulate the mechanical response of the specimens. The stress field and stress concentration of different experimental tests are given. The effect of increasing the additive epoxy on the rubber-carbon mechanical response and the fatigue life under repeated loads were identified and discussed. Furthermore, the results show that a small amount of epoxy can be used as a reinforcing material for a rubber compound and it improves the mechanical properties. This along with more results are shown in the result section