Search results for " Structural"
showing 10 items of 1751 documents
Digital simulation of wind field velocity
1998
Abstract In this paper some computational aspects on the generation procedure of n -variate wind velocity vectors are discussed in detail. Decompositions of the power spectral density matrix are also discussed showing the physical significance of eigenquantities of this matrix.
Size effects of small-scale beams in bending addressed with a strain-difference based nonlocal elasticity theory
2019
Abstract A strain-difference based nonlocal elasticity model devised by the authors elsewhere (Polizzotto et al., Int. J. Solids Struct. 25 (2006) 308–333) is applied to small-scale homogeneous beam models in bending under static loads in the purpose to describe the inherent size effects. With this theory —belonging to the strain-integral nonlocal model family, but exempt from anomalies typical of the Eringen nonlocal theory— the relevant beam problem is reduced to a set of three mutually independent Fredholm integral equations of the second kind (each independent of the beam’s ordinary boundary conditions, only one depends on the given load), which can be routinely solved numerically. Appl…
Independent friction-restitution approach to analyze anomalies in normal kinematic restitution in oblique impact
2021
Abstract Oblique impact between rigid bodies is usually described in terms of the coefficients of normal and tangential restitution. When the contact between bodies occurs under elasto-plastic conditions, the normal coefficient of restitution can be ordinarily taken as essentially constant. Several anomalous results reported by Louge and Adams (Anomalous behavior of normal kinematic restitution in the oblique impacts of a hard sphere on an elasto-plastic plate. Phys. Rev. E 65 (2002) 021303), however denoted a significant variation of this coefficient with the incidence angle under certain conditions. This anomalous behavior is interpreted here within the independent friction and restitutio…
Fractional Tajimi–Kanai model for simulating earthquake ground motion
2014
The ground acceleration is usually modeled as a filtered Gaussian process. The most common model is a Tajimi–Kanai (TK) filter that is a viscoelastic Kelvin–Voigt unit (a spring in parallel with a dashpot) carrying a mass excited by a white noise (acceleration at the bedrock). Based upon the observation that every real material exhibits a power law trend in the creep test, in this paper it is proposed the substitution of the purely viscous element in the Kelvin Voigt element with the so called springpot that is an element having an intermediate behavior between purely elastic (spring) and purely viscous (dashpot) behavior ruled by fractional operator. With this choice two main goals are rea…
Measurements of integrated direct, diffuse and global ultraviolet-B radiation
2015
Abstract We present the first multiyear set of simultaneous measurements of the global ultraviolet-B radiation and its two components: direct and diffuse. The measurements have been taken with four YES-UVB-1 radiometers: two radiometers to measure the diffuse radiation, one provided with a shadow band and the other with a shadow disk on a Sun tracker; a radiometer to measure the global horizontal radiation; and a Sun-tracking radiometer to measure the direct radiation with an especially designed radiance collimator. The diffuse minute-values measured with both instruments agree within a coefficient correlation of 1.00. The diffuse component represents at least 50% of the global UVB (ultravi…
An extended Ritz formulation for buckling and post-buckling analysis of cracked multilayered plates
2018
Abstract An extended Ritz formulation for the analysis of buckling and post-buckling behaviour of cracked composite multilayered plates is presented. The formulation is based on: (i) the First-order Shear Deformation Theory to model the mechanics of the multilayered plate; (ii) the von Karman’s theory to account for geometric non-linearities ; (iii) the use of an extended set of approximating functions able to model the presence of an embedded or edge crack and to capture the crack opening fields as well as the global behaviour within a single cracked domain. The numerical results of the buckling analyses and the equilibrium paths in the post-buckling regime are compared with the results fr…
Non-smooth modelling of billiard- and superbilliard-ball collisions
2008
Abstract A description of billiard-ball collisions using a ‘discontinuous’ model is presented considering a two-step situation corresponding to the ball–ball interaction followed by ball-supporting surface interaction. It is applied to the inelastic impact of a cue ball having arbitrary pivotment and ‘English’ spins against an object ball initially at rest. This formulation provides a simplified approximation to the ‘continuous’ models of impact and considers two different regimes of impact: gross slip, and slip–stick, described in terms of coefficients of friction and restitution. As a result, the angles of scattering of the balls just after the impact (post-collision angles) and when the …
Discussion of "preliminary Study of Surface Hydraulic Jumps" by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam
2020
In this paper the results of Preliminary Study of Surface Hydraulic Jumps” by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam are discussed
Measuring longitudinal wave speed in solids: two methods and a half
2006
Three methods to analyse longitudinal wave propagation in metallic rods are discussed. Two of these methods also prove to be useful for measuring the sound propagation speed. The experimental results, as well as some interpretative models built in the context of a workshop on mechanical waves at the Graduate School for Pre-Service Physics Teacher Education, Palermo University, are described. Some considerations about observed modifications in trainee teachers' attitudes to utilizing physics experiments to build pedagogical activities are discussed.
Advanced models for nonlocal magneto-electro-elastic multilayered plates based on Reissner mixed variational theorem
2019
In the present work, nonlocal layer-wise models for the analysis of magneto-electro-elastic multilayered plates are formulated. An Eringen non-local continuum behaviour is assumed for the layers material; in particular, as usual in plate theories, partial in-plane nonlocality is assumed whereas local constitutive behaviour is considered in the thickness direction. The proposed plate theories are obtained via the Reissner Mixed Variational Theorem, assuming the generalized displacements and generalized out-of-plane stresses as primary variables, and expressing them as through-the-thickness expansions of suitably selected functions, considering the expansion order as a free parameter. In the …