Mechanics of Micro- and Nano-Size Materials and Structures

For this reprint, we intend to cover theoretical as well as experimental works performed on small scale to predict the material properties and characteristics of any advanced and metamaterials. New studies on mechanics of small-scale structures such as MEMS/NEMS, carbon and non-carbon nanotubes (e.g., CNTs, Carbon nitride, and Boron nitride nanotubes), micro/nano-sensors, nanocomposites, macrocomposites reinforced by micro-/nano-fillers (e.g., graphene platelets), etc., are included in this reprint

Nonlinear Dynamic Behaviour of Solar Cells with Advanced Materials

The advanced solar structure (perovskite solar cell) (PSC) has fascinated both the scientific community and contemporary industry due to the high efficiency, low fabrication cost, abundant raw material, and distinguished electro-optic properties. Whereas, along the journey towards real-life implementation of the novel PSC, the mechanical performance and dynamic behaviour, as well as nonlinear stability of the structure are still not examined. Such investigation is tightly pertinent to device operating capacity and safety, and represents a key issue for commercial production. In addition, feasible reinforcement through advanced composite materials for the PSC is still an open problem, which is crucial for guaranteeing product serviceability. Moreover, the manifold practical influences within PSC’s working conditions are yet not fully explored, which can exert a critical impact on structural performance and dynamic attributes. Hence in this dissertation, an analytical framework is developed for analysing the mechanical capacity and nonlinear dynamic behaviour of the advanced solar panel and novel composite structures subjected to various realistic impulses. The innovative graphene platelets reinforced functionally graded porous stiffeners and oblique stiffeners have been involved to enhance the composite stiffness and stability. Moreover, different laminate plate theories have been incorporated to effectively handle thick to ultra-thin structures. The nonlinear motion equations are derived based on the Galerkin method. Then, the fourth-order Runge-Kutta method is leveraged to capture the mechanical performance and nonlinear response. Through comparing with results from finite element software and established benchmarks, the accuracy, effectiveness, and applicability of the developed framework have been verified. In addition, extensive practical effects, such as the damping, temperature alteration, wind load, elastic foundations, initial imperfection, active layer, blast impact, and multiple impulse loadings, on mechanical attributes and structure response under disparate support conditions have been identified systematically. By determining the optimal parameters of novel composite stiffeners, the dynamic performance and impact resistance of the PSC have been intensified. The proposed study will be beneficial to the modern design and practical deployment of energy-harvesting devices with improved mechanical capability, stability, and safety

The effect of plasma welding and carbides presence on the occurrence of cracks and micro-cracks

Presented in this paper is the effect of plasma welding (hardfacing) and carbides presence on the occurrence of cracks and micro-cracks in the welded layer. The reasons behind this phenomenon were analyzed and explained. In addition, the plasma welding technology with all the necessary data such as welding parameters is shown for the case of a non-damaged tooth of a machine used for milling of marble. Welded layer with a significant amount of tungsten-carbide was applied onto new, non-damaged tooth in order to improve the characteristics of the surface layer of the base material, by increasing its hardness which leads to increasing of wear resistance and impact toughness. After welding, tooth was cut using an electrical discharge machining (EDM) for the purpose of examinations of the ap-plied surface layer in different locations throughout welded joint. Macro and micro-structure analysis aided in determining the characteristics of the surface layer. The nature and causes of cracks and micro-cracks were analyzed, in order to provide a better solution to avoid cracks occurrences, as well as in determining of their potential effect on the integri-ty of the tooth as a whole