Search results for "Finite element method"
showing 10 items of 746 documents
Electromechanical characterization of a bimorph piezo for Energy Harvesting applications in road infrastructures
2012
Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources used to operate certain types of sensors/actuators, telemetry, and MEMS devices. However, the energy produced by these materials is, in many cases, far too small to directly power an electrical device. In the present study, piezoelectric devices will be investigated and experimentally tested to determine each of their abilities to transform ambient vibration into electrical energy. Tested piezoel…
Layer thickness optimisation in a laminated composite
1997
Abstract The paper describes a method to optimise the thickness balance within a composite laminate with layers oriented according to a limited set of angles. The laminate must be symmetric, balanced and loaded in-plane. The optimisation process is particularly suited to be used in conjunction with a finite element program. It provides the designer with the optimal overall engineering characteristics anda list of all the possible orientation combinations ranked with respect to their safety factor. The optimisation method is based on the first order gradient optimum search method and operates iteratively in the engineering elastic characteristics field. The cost function implemented up to no…
From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials
2014
In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters a…
Micro-Meso Scale Model of Electrospun Poly (Ester Urethane) Urea Scaffolds
2009
Soft tissue engineering applications require accurate descriptions of native and engineered tissue microstructure and their contributions to global mechanical behavior [1–6]. Moreover, micro scale based mechanical models can be used to: (1) guide tissue engineering scaffold design, (2) provide a better understanding of cellular mechanical and metabolic response to local micro-structural deformations, and (3) investigate structural changes as a function of deformation across multiple scales. We present a novel approach to automatically collect micro-architectural data (fibers overlaps, fiber connectivity, and fiber orientation) from SEM images of electrospun poly (ester urethane) urea (PEUU)…
Time Dependent Case
1999
This chapter is devoted to finite element approximations of scalar time dependent hemivariational inequalities. We start with the parabolic case following closely Miettinen and Haslinger, 1998. At the end of this chapter we discuss, how the results can be extended to constrained problems. Our presentation will follow the structure used for the static case in Chapter 3. First, we introduce an abstract formulation of a class of parabolic hemivariational inequalities (see Miettinen, 1996, Miettinen and Panagiotopoulos, 1999).
Numerical study of the components positioning influence on the stability of a reverse shoulder prosthesis
2014
Aim of this paper is to setup a novel procedure able to analyze performances of a reverse shoulder prosthesis when different geometrical configurations are assumed. Nowadays, such a prosthesis is widely used but, because of its novelty, data in literature give poor information about performances and limits to its applicability. The activity has been divided into the following steps. At the beginning the shape of the prosthesis has been digitally acquired via a 3D scanner. Then, CAD models of all prosthetic components have been geometrically optimized in a way to obtain final entities suitable for numerical simulations. After that, CAD assemblies have been created between prosthetic componen…
On the Measurement and Prediction of the Out-of-Plane Displacement Surrounding Cold-Expanded Holes
2010
Experimental measurements of the out-of-plane displacement surrounding cold-expanded holes in a 6082-T6 aluminum alloy were made with a 3D optical scanner using the technique of the encoded light-pattern projection in white light. The measured surface profiles have shown the thickness discontinuity along the hole edge due to the effect of the split in the sleeve. An analytical–numerical solution of the out-of-plane displacement is presented based on existing analytical models. Thus, the results given by the analytical model were then compared with the experimental data and with a finite element (FE) model that simulates the cold-expansion process. The location of the elastic–plastic boundar…
Postprocessing of a Finite Element Scheme with Linear Elements
1987
In this contribution we first give a brief survey of postprocessing techniques for accelerating the convergence of finite element schemes for elliptic problems. We also generalize a local superconvergence technique recently analyzed by Křižek and Neittaanmaki ([20]) to a global technique. Finally, we show that it is possible to obtain O(h4) accuracy for the gradient in some cases when only linear elements are used. Numerical tests are presented.
An optimum design of the magnetic circuit of a PM linear electrical generator for the exploitation of sea waves.
2006
In this paper an approach to the optimization of the magnetic design of a Permanent Magnet (PM) linear generator for the exploitation of the energy contained in sea waves is presented. This approach consists of a two step procedure: the first one takes into account the stochastic features of the sea wave motion and describe the working condition of the machine under this motion by adopting a lumped parameter model. In this step the objective function is the energy production. The second step optimizes the generator by using the results obtained in the first step as the constraints that must be fulfilled by a design based on a Finite Element Method (FEM) analysis. Furthermore, the approach i…
Optimization of cogging force in a linear permanent magnet generator for the conversion of sea waves energy
2015
In this paper an approach to the optimization of cogging force in a linear permanent magnet generator for the conversion of sea waves energy is presented. We have optimized the cogging force of a linear permanent magnet generator by using a 3D FEM parametric simulation. Several possible design solutions have been computed. A generator has been built and the results of the minimization procedure has been experimentally validated.