Mechanical Behaviour and Structural Dynamics of Nanomaterials

Nanomaterials exhibit distinctive mechanical and structural properties that arise from their nanoscale dimensions, high surface-to-volume ratios, and size-dependent interactions. These characteristics influence their elastic modulus, hardness, strength, plasticity, deformation behavior, and dynamic response, distinguishing nanomaterials from their bulk counterparts. This review summarizes the principal classes of nanomaterials and examines the experimental techniques commonly used to characterize their structural and mechanical properties, including atomic force microscopy, scanning and transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Particular attention is given to size and shape effects, grain-boundary contributions, surface effects, and the mechanical behavior of nanowires, nanoplates, polymer nanocomposites, carbon-based nanomaterials, and metal nanoparticles. The review also discusses theoretical approaches used to describe nanoscale mechanical behavior, with emphasis on nonlocal elasticity, strain-gradient theories, couple-stress models, and stress-driven integral formulations. Wave propagation and vibration in nanobeams, nanotubes, and multilayer structures are considered in relation to their dynamic behavior and potential applications. Finally, current challenges and future research directions are outlined, emphasizing the development of reliable theoretical and computational frameworks for the design of advanced nano-enabled materials and devices.