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Bioinspired materials that act like living tissues and can repair internal damage by themselves, i.e. self-healing materials, are an active field of research. Here a methodology for experimental testing of self-healing ability of soft polymer materials is described. The methodology is applied to a recently synthesized polyurethane material Smartpol (ADHTECH Smart Polymers & Adhesives S.L., Alicante,...
Growing biological media develop residual stresses to make compatible elastic and inelastic growth-induced deformations, which in turn remodel the tissue properties modifying the actual elastic moduli and transforming an initially isotropic and homogeneous material into a spatially inhomogeneous and anisotropic one. This process is crucial in solid tumor growth mechanobiology, the residual stresses...
A systematic investigation is presented that explores band gap properties of periodic micro-structures architected for maximum auxeticity. The design of two-dimensional auxetic cells is addressed using inverse homogenization. A non-convex optimization problem is formulated that is solved through mathematical programming. Different starting guesses are used to explore local minima when distributing...
Protein mechanical vibrations play a pivotal role in biological activity. In particular, low-frequency (terahertz) modes are related to protein conformational changes, which represent the foundations for a correct protein functionality. Relying on the fact that such low-frequency motions involve large protein portions, thus modeling of local details is not necessary, coarse-grained models have proven...
Combining a series of atomistic simulations with fracture mechanics theory, we systematically investigate the crack growth stability of graphene under tension and indentation, with a pre-existing crack made by two methods: atom removal and (artificial) bonding removal. In the tension, the monotonically increasing energy release rate $$G$$ G is consistent with the unstable crack growth. In contrast,...
The acoustic dispersion properties of monodimensional waveguide filters can be assessed by means of the simple prototypical mechanical system made of an infinite stack of periodic massive blocks, connected to each other by elastic joints. The linear undamped dynamics of the periodic cell is governed by a two degree-of-freedom Lagrangian model. The eigenproblem governing the free propagation of shear...
Recent research has shown that hierarchical laminated composites can be profitably employed to improve the actuation performance of electrically-activated soft dielectric transducers. This note focuses on two types of rank-two layouts composed of ideal dielectric phases which follow nonlinear hyper-elastic mechanical behaviour and aims at providing a simplified set of solving equations for voltage-controlled...
Lattices composed of cubic and triangular prismatic unit cells with polymeric Sarrus linkage rib elements are designed, fabricated via 3D printing and studied experimentally. Size effects in these lattices are observed experimentally; slender specimens appear more rigid in torsion and in bending than expected via classical elasticity. Effects are analyzed via Cosserat elasticity. The magnitude of...
In this paper a metamaterial sheet constituted by a periodic pattern of square tensegrity cells (T-bar) subjected to a uniform equibiaxial pressure is studied. In particular, a minimal mass lattice is analytical determined by imposing stability and material failure conditions. Interestingly, the shear stiffness of this optimized lattice is very small in comparison to the other moduli and exhibits...
In this work, we propose an inertial amplified resonator (IAR) as a building block of a tunable locally resonant metasurface. The IAR consists in a mass–spring resonator coupled with two inerters, realized by two inclined rigid links connected to an additional mass. The IAR has a static behaviour equivalent to that of a standard mass–spring oscillator whereas its dynamic response can be controlled...
We report on a numerical experiment by which we investigated the propagation of an erosion pipe in a water saturated granular soil. The simulation was performed with a two-dimensional implementation of the coupling between the discrete element method and the lattice Boltzmann method. A synopsis of the numerical scheme is provided. The specimen and testing conditions were designed as representative...
With the increasing research in the field of contact mechanics, different types of contact models have been investigated by many researchers by employing various complex material models. To ascertain the orthotropy effect and modeling parameters on a receding contact model, the double frictional receding contact problem for an orthotropic bilayer loaded by a cylindrical punch is taken into account...
The nonlinear dynamics of self-organising bubble departures from twin nozzles in engine oils was analysed. Air bubbles were generated from twin brass nozzles with an inner diameter equal to 1 mm. The flow of bubbles in bubble chains was recorded using high-speed camera. The time series of air pressure oscillations and signal from laser–phototransistor identifying the presence of bubbles over the nozzles...
Understanding of the elastic deformation behaviours of recently synthesised carbon nanorings (CNRs) is crucial in guiding their future applications, because the strain engineering provides an efficient means to modify their physical and chemical properties. In this paper, by using molecular dynamics simulations and nonlocal continuum mechanics models, we study the elastic deformations of CNRs with...
Present work investigates the biaxial buckling of three-phase, angle-ply laminates reinforced with graphene platelets and carbon or glass fibres. The analysis is based on Classical Plate Theory with the shear effect neglected. The laminate is defined as a three-ply symmetric laminate with simply supported boundary conditions and with different graphene and fibre contents in the surface and middle...
Nonlinear forced vibrations of a fractional viscoelastic pipe conveying fluid exposed to the time-dependent excitations is investigated in the present work. Attention is focused in particular on the primary and secondary resonances with the Kelvin–Voigt fractional order constitutive relationship model. The nonlinear geometric partial differential equations due to stretching effect have been expressed...
This paper investigates the linear free vibration of axially moving simply supported thin circular cylindrical shells with constant and time-dependent velocity considering the effect of viscous structure damping. Classical shell theory is employed to express strain-displacement relation. Linear elasticity theory is used to write stress–strain relation considering Hook’s Law. Governing equations in...
The focus of this paper is on the development of a novel and simple linear modeling to interpret the (asymptotic) instability conditions for laminar channel (Poiseuille) flow, thereby giving insight on the major length and time scales of the subsequent mean turbulent regime. Although this is an old problem, recently there has been a renewed effort to understand how information on the wall turbulence...
An analytical model for the textured infinitely long slider is developed to study the influence of cross-hatched texture on hydrodynamic lubrication by considering the mass-conserving boundary condition. The three-dimensional morphology of the cross-hatched texture is characterized by a series of mathematical formulas. By using multigrid method and Gauss–Seidel iteration, the hydrodynamic pressure...
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