1,721,026 research outputs found
Buckling analysis of functionally graded nanobeams via surface stress-driven model
No full textThe manuscript investigates the buckling behaviour of Bernoulli-Euler nanobeams composed of Functionally-Graded (FG) materials with different cross-sectional shapes. This analysis is conducted using the surface stress-driven model of elasticity. The nonlocal governing equations for the elastostatic buckling problem are derived employing the principle of virtual work. The study also includes a parametric investigation, presenting and discussing the main results while varying the nonlocal parameter, material gradient index, the cross-sectional shapes and the constraints at the ends of the FG nanobeams. Critical loads are numerically calculated and compared with those obtained by other authors using the classical stress-driven model elasticity
Free vibration analysis of functionally graded nanobeams based on surface stress-driven nonlocal model
No full textA surface stress-driven nonlocal model is employed in this manuscript to study the coupled effects of the long-range interaction and surface energy on the free vibrations of nano-beams made of metal-ceramic functionally graded material. The nanobeam theory is formulated based on the Bernoulli-Euler kinematics and surface effects include surface elasticity, surface residual stresses, surface density and rotary inertia. Hamilton's principle is applied to derive the size-dependent governing equation. The main results of a parametric investigation, carried out considering four different kinematic boundary conditions, i.e. Cantilever, Simply-Supported, Clamped-Pinned and Doubly-Clamped, are also presented and discussed, varying the nonlocal parameter and the material gradient index. The results show how the proposed model is able to capture surface energy effects on the overall dynamic behavior of functionally graded Bernoulli-Euler nanobeams and provides a cost-effective method for the design and the optimization of nano-scaled structures
A numerical analysis on the effects of washer size on the pin-bearing failure load of glass fibre polymer laminates
No full textAn Experimental Investigation on the Behavior of Web-Flange Junctions of GRP Pultruded Profiles
No full textMechanical behavior of web-flange junctions of thin-walled pultruded I-profiles: an experimental and numerical evaluation
Full text linkThis paper presents experimental and numerical results of the first phase of a multi-phase comprehensive joint research program between University of Salerno, Italy, and the University of California, Irvine, USA, on investigating one of the major structural issues that defines the strength limit-state of pultruded fibre-reinforced polymer (PFRP) profiles.
Specifically, the strength and stiffness of the web-flange junction (WFJ) of the majority of commercially-produced pultruded composite profiles. A summary of experimental results for twentyeight full-scale pull-out tests are presented and typical modes failure are identified. Moreover, the influence of the pull-out load distance (d) from the edge of the specimens on the failure strength of the web-flange junction has been investigated and a new definition for an "influence zone" is proposed that is found to be dependent on the loaded length, with a maximum value equal to approximately the PFRP member's depth. This proposed zone was observed in all laboratory tests and its existence was confirmed by the results of FEM numerical analysis. 3-D finite element models were also developed to predict the behavior of these specimens. The results from the numerical models were compared to those obtained from the experimental program and found to be satisfactory
A note on torsion of nonlocal composite nanobeams
Full text linkThe Eringen elastic constitutive relation is used in this paper in order to assess small-scale effects in nanobeams. Structural behavior is studied for functionally graded materials in the cross-sectional plane and torsional loading conditions. The governing boundary value problem has been formulated in a mixed framework. Torsional rotations and equilibrated moments are evaluated by solving a first-order differential equation of elastic equilibrium with boundary conditions of kinematic-type. Benchmarks examples are briefly discussed, enlightening thus effectiveness of the proposed methodology
On bending of bernoulli-euler nanobeams for nonlocal composite materials
Full text linkEvaluation of size effects in functionally graded elastic nanobeams is carried out by making recourse to the nonlocal continuum mechanics. The Bernoulli-Euler kinematic assumption and the Eringen nonlocal constitutive law are assumed in the formulation of the elastic equilibrium problem. An innovative methodology, characterized by a lowering in the order of governing differential equation, is adopted in the present manuscript in order to solve the boundary value problem of a nanobeam under flexure. Unlike standard treatments, a second-order differential equation of nonlocal equilibrium elastic is integrated in terms of transverse displacements and equilibrated bending moments. Benchmark examples are developed, thus providing the nonlocality effect in nanocantilever and clampled-simply supported nanobeams for selected values of the Eringen scale parameter
Nonlinear Dynamic Behavior of Porous and Imperfect Bernoulli-Euler Functionally Graded Nanobeams Resting on Winkler Elastic Foundation
No full textNonlinear free vibrations of functionally graded porous Bernoulli–Euler nano-beams resting
on an elastic foundation through a stress-driven nonlocal elasticity model are studied taking into
account von Kármán type nonlinearity and initial geometric imperfection. By using the Galerkin
method, the governing equations are reduced to a nonlinear ordinary dierential equation. The closed
form analytical solution of the nonlinear natural flexural frequency is then established using the
Hamiltonian approach to nonlinear oscillators. Several comparisons with existing models in the
literature are performed to validate the accuracy and reliability of the proposed approach. Finally,
a numerical investigation is developed in order to analyze the eects of the gradient index coecient,
porosity volume fraction, initial geometric imperfection, and theWinkler elastic foundation coecient,
on the nonlinear flexural vibrations of metal–ceramic FG porous Bernoulli–Euler nano-beams
Preliminary results of an experimental investigation on the improvement of axial flexibility and strength of web-flange junctions of gfrp pultruded I-beams
No full textThis paper presents a summary of preliminary results obtained from an experimental investigation on the behavior of web-flange junctions of pultruded glass fibre-reinforced polymer (GFRP) I-profiles. In particular, the aim of the study is to suggest simple stiffening and strengthening element to improve the axial flexibility and strength of the junctions. Digital image correlation technique was used to capture in plane displacements and strains of the specimens
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