Normal Flux Distribution at Step-Lap Joints of Si-Fe Wound Cores

2010 ◽  
Vol 670 ◽  
pp. 284-290 ◽  
Author(s):  
Themistoklis D. Kefalas ◽  
George Loizos ◽  
Antonios G. Kladas
Keyword(s):  
Finite Element ◽  
Flux Distribution ◽  
Computational Cost ◽  
Lap Joints ◽  
Accurate Estimation ◽  
Element Analysis ◽  
Lack Of Information ◽  
Simple Geometry ◽  
Flux Measurements ◽  
Low Computational Cost

Even though, the flux distribution at joints of stacked type transformer cores has been investigated thoroughly many issues remain unclear in the case of wound transformer cores. The paper addresses this lack of information by longitudinal and normal flux measurements at step-lap joints of Si-Fe wound cores. Flux measurements are verified by an original finite element analysis where the necessary excitation is performed by means of a pseudo-source. The advantage of the proposed technique is the accurate estimation of the flux distribution at step-lap joints, with a two dimensional model of simple geometry and low computational cost, by using any commercial finite element code.

Failure analysis of simple overlap bonding joints and numerical investigation of the adhered tip geometry effect on the joint strength

2021 ◽  
Vol 63 (11) ◽  
pp. 1007-1011
Author(s):  
İsmail Saraç
Keyword(s):  
Finite Element Analysis ◽  
Experimental Study ◽  
Finite Element ◽  
Reference Model ◽  
Lap Joints ◽  
Shear Stresses ◽  
Element Analysis ◽  
Single Lap Joints ◽  
Failure Loads ◽  
Previous Experimental Study

Abstract This study was carried out in two stages. In the first step, a numerical study was performed to verify the previous experimental study. In accordance with the previous experimental study data, single lap joints models were created using the ANSYS finite element analysis program. Then, nonlinear stress and failure analyses were performed by applying the failure loads obtained in the experimental study. The maximum stress theory was used to find finite element failure loads of the single lap joints models. As a result of the finite element analysis, an approximate 80 % agreement was found between experimental and numerical results. In the second step of the study, in order to increase the bond strength, different overlap end geometry models were produced and peel and shear stresses in the adhesive layer were compared according to the reference model. As a result of the analyses, significant strength increases were calculated according to the reference model. The strength increase in model 3 and model 5 was found to be 80 % and 67 %, respectively, relative to the reference model.

Failure Analysis of Bamboo Bolt Connection in Uniaxial Tension by FEM by Considering Fiber Direction

2021 ◽  
Vol 71 (1) ◽  
pp. 58-64
Author(s):  
Raviduth Ramful
Keyword(s):  
Finite Element ◽  
Uniaxial Tension ◽  
Failure Modes ◽  
Damage Mechanism ◽  
Field Analysis ◽  
Fiber Direction ◽  
Element Formulation ◽  
Element Analysis ◽  
Test Standards ◽  
Lack Of Information

Abstract Full-culm bamboo has been used for millennia in construction. Specific connections are normally required to suit its unique morphology and nonuniform structure. Presently, the use of full-culm bamboo is limited in the construction industry as a result of a lack of information and test standards about the use and evaluation of full-culm connections. This study aims to further explore this area by investigating the failure modes in bamboo bolt connections in uniaxial tension by considering fiber direction in finite element analysis. Three types of bolt configurations of varying permutations, namely, single, dual, and orthogonal, were investigated. An orthotropic material was used as a constitutive model in finite element formulation to capture the inhomogeneity prevailing in bamboo culm. From the strain-field analysis of a hollow-inhomogeneous model representing bamboo, shear-out failure was dominant, as a localized area equivalent to the bolt diameter was affected due to high material orthotropy with high axial strength but weak radial and tangential strength. Bearing failure is assumed to precede shear-out failure at the bolt–bamboo contact interface, as the embedding strength was affected by localized strain concentration. The strain distribution in various bolt arrangements was found to vary between bolted connections of inhomogeneous-hollow geometry of bamboo and the ones of inhomogeneous-solid geometry representing timber. The observation in this study highlights the need for alternative design criteria to specifically assess the damage mechanism in bamboo connections.

scholarly journals The Effect of Nanoparticles in Single Lap Joints Studied by Numerical Analyses

2020 ◽  
Vol 5 (10) ◽  
pp. 1288-1293
Author(s):  
Panagiotis J. Charitidis
Keyword(s):  
Finite Element ◽  
Failure Load ◽  
Tensile Loading ◽  
Lap Joints ◽  
Von Mises Stress ◽  
Adhesive Material ◽  
Element Analysis ◽  
Single Lap Joints ◽  
Epoxy Adhesives ◽  
Von Mises

The present study concerns with the finite element investigation of balanced aluminium single lap joints subjected to tensile loading. Epoxy adhesives were used for bonding having different nanoparticles rate in the epoxy resin (0.5, 1.0, 1.5 and to 2 wt. %, respectively). Two-dimensional (2D) finite element analysis has been employed to determine the peeling stress, von Mises stress, and the shear strain distribution across the midplane of the joints. The results mainly prove that the nanoparticles rate in the adhesive material directly affects the joint tensile strength. Nanocomposite adhesives present a higher failure load than that of neat adhesives. Furthermore, nanocomposite adhesive with 0.5 wt. % of nanoparticles generated strengths (shear and peeling strengths) more than neat adhesives, after which decreased by further addition of the nanoparticles.

scholarly journals Nonlinear Structural Dynamic Finite Element Analysis Using Ritz Vector Reduced Basis Method

1996 ◽  
Vol 3 (4) ◽  
pp. 259-268 ◽  
Author(s):  
M.S. Yao
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Computational Cost ◽  
Finite Amplitude ◽  
Basis Vector ◽  
Reduced Basis ◽  
Ritz Vector ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Nonlinear Equations Of Motion

The large number of unknown variables in a finite element idealization for dynamic structural analysis is represented by a very small number of generalized variables, each associating with a generalized Ritz vector known as a basis vector. The large system of equations of motion is thereby reduced to a very small set by this transformation and computational cost of the analysis can be greatly reduced. In this article nonlinear equations of motion and their transformation are formulated in detail. A convenient way of selection of the generalized basis vector and its limitations are described. Some illustrative examples are given to demonstrate the speed and validity of the method. The method, within its limitations, may be applied to dynamic problems where the response is global in nature with finite amplitude.

Radial basis function surrogate model-based optimization of guardrail post embedment depth in different soil conditions

2019 ◽  
Vol 234 (2-3) ◽  
pp. 739-761
Author(s):  
Sedat Ozcanan ◽  
Ali Osman Atahan
Keyword(s):  
Finite Element ◽  
Radial Basis Function ◽  
Basis Function ◽  
Computational Cost ◽  
Critical Parameters ◽  
Crash Test ◽  
Soil Conditions ◽  
Embedment Depth ◽  
Element Analysis ◽  
Radial Basis

For guardrail designers, it is essential to achieve a crashworthy and optimal system design. One of the most critical parameters for an optimal road restraint system is the post embedment depth or the post-to-soil interaction. This study aims to assess the optimum post embedment depth values of three different guardrail posts embedded in soil with varying density. Posts were subjected to dynamic impact loads in the field while a detailed finite element study was performed to construct accurate models for the post–soil interaction. It is well-known that experimental tests and simulations are costly and time-consuming. Therefore, to reduce the computational cost of optimization, radial basis function–based metamodeling methodology was employed to create surrogate models that were used to replace the expensive three-dimensional finite element models. In order to establish the radial basis function model, samples were derived using the full factorial design. Afterward, radial basis function–based metamodels were generated from the derived data and objective functions performed using finite element analysis. The accuracy of the metamodels were validated by k-fold cross-validation, then optimized using multi-objective genetic algorithm. After optimum embedment depths were obtained, finite element simulations of the results were compared with full-scale crash test results. In comparison with the actual post embedment depths, optimal post embedment depths provided significant economic advantages without compromising safety and crashworthiness. It is concluded that the optimum post embedment depths provide an economic advantage of up to 17.89%, 36.75%, and 43.09% for C, S, and H types of post, respectively, when compared to actual post embedment depths.

Reduced Material Model of Composite Laminates for 3D Finite Element Analysis

2014 ◽  
Author(s):  
Goldy Kumar ◽  
Vadim Shapiro
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Composite Laminates ◽  
Substantial Reduction ◽  
Computational Cost ◽  
Material Model ◽  
Basis Functions ◽  
Constitutive Relationship ◽  
Element Analysis ◽  
3D Fea

Laminate composites are widely used in automotive, aerospace, medical, and increasingly in consumer industries, due to their reduced weight, superior structural properties and cost-effectiveness. However, structural analysis of complex laminate structures remains challenging. 2D finite element methods based on plate and shell theories may be accurate and efficient, but they generally do not apply to the whole structure, and require identification and preprocessing (dimensional reduction) of the regions where the underlying assumptions hold. Differences in and limitations of theories for thin/thick plates and shells further complicate modeling and simulation of composites. Fully automated structural analysis using 3D elements with sufficiently high order basis functions is possible in principle, but is rarely practiced due to the significant increase in computational integration cost in the presence of a large number of laminate plies. We propose to replace the actual layup of the laminate structure by a simplified material model, allowing for a substantial reduction of the computational cost of 3D FEA. The reduced model, under the usual assumptions made in lamination theory, has the same constitutive relationship as the corresponding 2D plate model of the original laminate, but requires only a small fraction of computational integration costs in 3D FEA. We describe implementation of 3D FEA using the reduced material model in a meshfree system using second order B-spline basis functions. Finally, we demonstrate its validity by showing agreement between computed and known results for standard problems.

Application of Regional Strain Energy in Topology Optimization With Inertia Relief Analysis

2013 ◽  
Author(s):  
Wei Song ◽  
Hae Chang Gea ◽  
Ren-Jye Yang ◽  
Ching-Hung Chuang
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Strain Energy ◽  
Computational Cost ◽  
Structure Design ◽  
Protective Structure ◽  
Element Analysis ◽  
Regional Strain ◽  
Unbalanced Loads ◽  
Energy Formulation

In finite element analysis, inertia relief solves the response of an unconstrained structure subject to constant or slowly varying external loads with static analysis computational cost. It is very attractive to utilize it in topology optimization to design structures under unbalanced loads, such as in impact and drop phenomena. In this paper, regional strain energy formulation and inertia relief is integrated into topology optimization to design protective structure under unbalanced loads. For background, the equations of inertia relief are introduced and a commonly used solving method is revisited. Then the regional strain energy formulation for topology optimization with inertia relief is proposed and its sensitivity is derived from the adjoint method. Based on the solving method, the sensitivity is evaluated term by term to simplify the results. The simplified sensitivity can be calculated easily using the output of commercial finite element packages. Finally, the effectiveness of this formulation is shown in the first example and the proposed regional strain energy formulation for topology optimization with inertia relief are presented and discussed in the protective structure design examples.

Finite Element Analysis of Electroactive and Magnetoactive Coupled Behaviors in Multi-Field Origami Structures

2017 ◽  
Author(s):  
Wei Zhang ◽  
Anil Erol ◽  
Saad Ahmed ◽  
Sarah Masters ◽  
Paris von Lockette ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Smart Materials ◽  
Electromechanical Coupling ◽  
Material Selection ◽  
Constitutive Relations ◽  
Computational Cost ◽  
Constitutive Models ◽  
Element Analysis ◽  
The Impact

Active origami designs, which incorporate smart materials such as electroactive polymers (EAPs) and magnetoactive elastomers (MAEs) into mechanical structures, have shown good promise in engineering applications. In this study, finite element analysis (FEA) models are developed using COMSOL Multiphysics software for two configurations that incorporate a combination of active and passive material layers, namely: 1) a single-notch unimorph folding configuration actuated using only external electric field and 2) a bimorph configuration which is actuated using both electric and magnetic (i.e. multifield) stimuli. Constitutive relations are developed for both electrostrictive and magnetoactive materials to model the coupled behaviors directly. Shell elements are adopted for their capacity of modeling thin films, reduction of computational cost and ability to model the intrinsic coupled behaviors in the active materials under consideration. A microstructure-based constitutive model for electromechanical coupling is introduced to capture the nonlinearity of the EAP’s relaxor ferroelectric response; the electrostrictive coefficients are then used as input in the constitutive modeling of the coupled behavior. The magnetization of the MAE is measured by experiment and then used to calculate magnetic torque under specified external magnetic field. The objective of the study is to verify the effectiveness of the constitutive models to simulate multi-field coupled behaviors of the active origami configurations. Through quantitative comparisons, simulation results show good agreement with experimental data, which is a good validation of the shell models. By investigating the impact of material selection, location, and geometric parameters, FEA can be used in design, reducing trial-and-error iterations in experiments.

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