Nonlinear Static Finite Element Analysis Research Articles

Nonlinear finite element analysis of functionally graded plates integrated with patches of piezoelectric fiber reinforced composite

In this paper, a nonlinear static finite element analysis of simply supported smart functionally graded (FG) plates in the presence/absence of the thermal environment has been presented. The substrate FG plate is integrated with the patches of piezoelectric fiber reinforced composite (PFRC) material which act as the distributed actuators of the plate. The material properties of the FG substrate plate are assumed to be temperature dependent and graded along the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The derivation of this nonlinear thermo-electro-mechanical coupled finite element model is based on the first order shear deformation theory and the Von Karman type geometric nonlinearity. The numerical solutions of the nonlinear equations of the finite element model are obtained by employing the direct iteration method. The numerical illustrations suggest the potential use of the distributed actuator made of the PFRC material for active control of nonlinear deformations of smart FG structures. The effects of volume fraction index of the FG material of the substrate plates and the locations of the PFRC patches on the control authority of the patches are investigated. Emphasis has also been placed on investigating the effect of variation of piezoelectric fiber orientation angle in the PFRC patches on their actuation capability for counteracting the large deflections of FG plates.

Buckling analysis of cylindrical shells with cutouts including random boundary and geometric imperfections

In this paper, the effect of random geometric imperfections on the critical load of isotropic, thin-walled, cylindrical shells under axial compression with rectangular cutouts is presented. Second moment characteristics of geometric imperfections are estimated by data of available measurements, a simulation procedure based on the Karhunen–Loève expansion is applied for generating realizations of geometric imperfections. Nonlinear static finite-element analyses are carried out for the calculation of the response statistics of the critical load of the cylindrical shells. Cumulative distribution functions of the critical load as obtained by direct Monte Carlo simulation are presented. Furthermore, the individual and combined effects of random boundary and geometric imperfections on the limit loads of isotropic, thin-walled, cylindrical shells under axial compression are also treated. Again, second moment characteristics of these imperfections are estimated by data of available measurements of imperfections, a simulation procedure also based on the Karhunen–Loève expansion is applied for generating realizations of both boundary and geometric imperfections. A nonlinear static finite-element analysis using the general purpose code STAGS [C.C. Rankin, F.A. Brogan, W.A. Loden, H.D. Cabiness. STAGS (STructural Analysis of General Shells) User Manual, LMSC P032594, Version 3.0. Lockheed Martin Missiles and Space Co., Inc., Palo Alto, CA, USA, 1998] is carried out for the calculation of the buckling response of the cylindrical shells. Finally, the cumulative distribution functions of the limit load using direct Monte Carlo simulation are shown.

Simulation of Motor-Scooter Drop Testing by a Multi-Body Finite Element Integrated Approach

The drop test is employed in the motor-scooter industry for evaluating the frame performance under particularly severe conditions. In this work, a numerical procedure developed for simulating the test is presented. The procedure includes a multi-body model for the evaluation of the maximum loads acting on the scooter frame during impact at ground. Such loads were then employed in a non-linear static finite element analysis in order to obtain the permanent frame deformation. The experimental activity carried out for vehicle characterization and the experimental apparatus set up for tests are also presented in detail. The multi-code approach appeared versatile and straightforward, and furnished results in satisfactory agreement with experiments.

Numerical analysis and parameter study of a mechanical damper for use in long slender endmills

A mechanical damper has been introduced to reduce tool vibration during the high-speed milling process. The mechanical damper is composed of multi-fingered cylindrical inserts placed in a matching cylindrical hole in the center of a standard end-milling cutter. Centrifugal forces during high-speed rotation press the flexible fingers against the inner surface of the tool. Bending of the tool/damper assembly due to cutting forces or chatter vibration causes relative axial sliding between the tool inner surface and the damper fingers, and dissipates energy in the form of friction work. In this paper, a simple numerical method is presented to estimate the amount of friction work during tool bending. Non-linear static finite element analysis is used to estimate normal and frictional contact forces due to centrifugal forces and cutting forces, and calculate the amount of frictional work dissipated by the damper. The numerical results are compared with analytical results, and show a similar trend. Parameter studies are also carried out using the numerical model to identify the best configuration to maximize the amount of friction work.

Stress Singularity Effect on Beam Flanges in Moment Connections

The ductility capacity of the directly welded flange connection was found to be insufficient after the 1994 Northridge earthquake. The Enlarged End Section (EES) connection which considers the stress singularity effect on beam flanges can be utilized as a means to improve the performance of welded moment connections. The corner of a steel plate contains stress singularities (unbounded stresses) when the corner is bounded by free-free edges and when the angle of the corner is larger than 180°. Also, the corner of a steel plate contains stress singularities when the corner is bounded by fixed-free edges and when the angle of the corner is larger than 61.3°. Nonlinear static finite element analyses of two types of beam-to-column moment connections were conducted. These two types of connections are (1) the constant-beam-section connection, and (2) the Enlarged End Section connection. The result of the finite element analyses shows that the Enlarged End Section connection exhibits much higher strength and ductility capacities.

Nonlinear static finite element analysis of reinforced masonry walls in tall buildings

AbstractA finite element computer program or code, FEM/I, has been developed for the nonlinear, static analysis of reinforced masonry building components subjected to in‐plane loading. The masonry is represented by a material with bimodular orthotropy, and includes tension stiffening, compression softening, and strain softening, as well as a degrading unloading rule. The masonry model incorporates a tension crack orientation adjustment approach, where the orientation of the final cracks can be different from the initial cracks. The model also includes a compressive strength reduction after tensile cracking normal to the principal compressive strains. Additionally, the model includes a compressive strength increase due to lateral compressive confinement. The reinforcement is represented by an orthotropic material with a bilinear stress‐strain relationship and includes unloading. The FEM/I code is operational on IBM compatible personal computers, such as the 286/386/486 systems. This capability makes the developed technology available to a large group of engineers and researchers, since a large main frame computer is not required to operate the program. The computer program is expected to be particularly useful to designers of tall reinforced masonry buildings that contain components with unusual configurations. These components can be analyzed to properly assess their structural performance.