A New 3D Finite Element for Sandwich Beams With a Viscoelastic Core

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Kamel Amichi ◽  
Noureddine Atalla
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Boundary Conditions ◽  
Numerical Results ◽  
Sandwich Beams ◽  
3D Finite Element ◽  
Various Boundary Conditions ◽  
The Core ◽  
Viscoelastic Core ◽  
Displacement Approach

A sandwich finite element for laminated steels is presented. It is based on a discrete displacement approach and allows for both symmetrical and unsymmetrical configurations. The three-layer sandwich model is built assuming a Timoshenko hypothesis for the viscoelastic core and Euler–Bernoulli hypotheses for the elastic faces, but the latter is modified to account for the rotational influence of the transversal shearing in the core. The validity and accuracy of the presented element are assessed through comparisons with numerical results of sandwich beams and sandwich rings with a variety of geometrical and mechanical properties and various boundary conditions. The present results are also compared with analytical, finite element, and experimental solutions for various boundary conditions.

Comparison of Full Field and Single Inclusion Approaches to Homogenization of Composites with Non-Ellipsoidal Pores

2014 ◽  
Vol 627 ◽  
pp. 309-312
Author(s):  
Igor Tsukrov ◽  
Borys Drach ◽  
Anton Trofimov
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Boundary Conditions ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Numerical Results ◽  
Finite Element Simulations ◽  
Full Field ◽  
Representative Volume ◽  
Single Inclusion

This paper compares two approaches to predict the overall mechanical properties of solids with irregularly shaped pores. The first approach involves direct finite element simulations of representative volume elements containing arrangements of irregularly shaped pores subjected to periodic boundary conditions. The second approach utilizes numerical results for individual defect shapes in a micromechanical scheme. Several realizations of parallel and randomly oriented distributions of defects are considered. It is determined that the Mori-Tanaka micromechanical scheme provides good correlation with the full field finite element simulations.

Finite element modelling of sandwich panels with graded core under various boundary conditions

2012 ◽  
Vol 116 (1186) ◽  
pp. 1289-1314 ◽  
Author(s):  
M. Kashtalyan ◽  
B. Woodward
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Sandwich Panels ◽  
Stress Concentrations ◽  
Displacement Fields ◽  
Various Boundary Conditions ◽  
The Core ◽  
The Face ◽  
3D Elasticity ◽  
3D Finite Element Method

Abstract Sandwich panels are widely used in the aerospace industry instead of solid plates due to their high flexural stiffness-to-weight and flexural strength-to-weight ratios. However due to the mismatch of properties between the face sheets and the core, stress concentrations can occur at the face sheet/core interfaces, often leading to delamination. One possible solution to this problem is the introduction of a graded core — a core in which the properties vary gradually from the face sheets to the core centre, eliminating any abrupt changes in properties. In this paper a 3D finite element method, fully validated through comparison with results from the literature and a 3D elasticity solution, is applied to modelling of sandwich panels with graded core. The approach makes use of graded elements to study the effect of varying the boundary conditions on the elastic deformation of the panel subject to uniformly distributed loading. Comparative analysis of stress and displacement fields in sandwich panels with homogeneous and graded cores is carried out under various combinations of simply supported, clamped and free edges.

Finite element method and analytical analysis of static and dynamic pull-in instability of a functionally graded microplate

2020 ◽  
pp. 107754632098020
Author(s):  
Arang Pazhouheshgar ◽  
Yashar Haghighatfar ◽  
Amirhossein Moghanian
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Power Laws ◽  
Functionally Graded ◽  
Numerical Results ◽  
Damping Coefficient ◽  
Various Boundary Conditions ◽  
Crucial Effect ◽  
Fringing Field ◽  
Material Power

The static and dynamic pull-in phenomenon of a functionally graded Al/Al2O3 microplate, considering the damping coefficient and fringing field effects, has been analyzed because of its crucial effect in micro-electromechanical systems application, especially in microswitches. The nonlinear equation of motion of functionally graded microplate has been derived using Hamilton’s principle, and solved analytically. Furthermore, a finite element code has been developed to solve the problem. Comparing the theoretical and numerical results for specific boundary conditions demonstrates that the numerical solution predicts the pull-in phenomenon with the least errors; and it can be used for various material power laws, damping coefficients, and initial gaps between the microplate and the substrate. The numerical results for various boundary conditions demonstrate that by increasing the damping coefficient, the dynamic pull-in voltage is also increased, and pull-in time will slow down. Moreover, the effect of power law and applied voltage on the pull-in instability is investigated.

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

scholarly journals Applicability of a Three-Layer Model for the Dynamic Analysis of Ballasted Railway Tracks

Vibration ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 151-174
Author(s):  
André F. S. Rodrigues ◽  
Zuzana Dimitrovová
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Shear Stiffness ◽  
Shear Resistance ◽  
Railway Track ◽  
Fe Model ◽  
Inertial Effects ◽  
Layer Model ◽  
3D Finite Element

In this paper, the three-layer model of ballasted railway track with discrete supports is analyzed to access its applicability. The model is referred as the discrete support model and abbreviated by DSM. For calibration, a 3D finite element (FE) model is created and validated by experiments. Formulas available in the literature are analyzed and new formulas for identifying parameters of the DSM are derived and validated over the range of typical track properties. These formulas are determined by fitting the results of the DSM to the 3D FE model using metaheuristic optimization. In addition, the range of applicability of the DSM is established. The new formulas are presented as a simple computational engineering tool, allowing one to calculate all the data needed for the DSM by adopting the geometrical and basic mechanical properties of the track. It is demonstrated that the currently available formulas have to be adapted to include inertial effects of the dynamically activated part of the foundation and that the contribution of the shear stiffness, being determined by ballast and foundation properties, is essential. Based on this conclusion, all similar models that neglect the shear resistance of the model and inertial properties of the foundation are unable to reproduce the deflection shape of the rail in a general way.

ON THE PROTECTION CAPABILITY OF THE FLYING PLATE AGAINST TO LONG-ROD PENETRATORS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1285-1290
Author(s):  
STANISLAV ROLC ◽  
JAROSLAV BUCHAR ◽  
ZBYNEK AKSTEIN
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Numerical Results ◽  
Finite Element Code ◽  
Plate Material ◽  
3D Finite Element ◽  
Plate Velocity ◽  
Long Rod ◽  
Protection Capability

The interaction of the flying plate with the Long-rod penetrator has been studied both experimentally and numerically using the LS DYNA 3D finite element code. The influence of the plate velocity and plate material on this interaction has been investigated in details. Numerical results show that there was a relatively large damage of the projectiles. The extent of this damage well agree with our experimental foundings. The numerical simulation of the damaged projectiles with some targets has been also performed

scholarly journals Prediction of Mechanical Properties of Graphene Oxide Reinforced Aluminum Composites

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1077 ◽  
Author(s):  
Dasari ◽  
Brabazon ◽  
Naher
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Graphene Oxide ◽  
Load Transfer ◽  
Theoretical Models ◽  
Element Model ◽  
Current Approach ◽  
Numerical Results ◽  
Al Matrix Composites ◽  
Al Matrix

Estimating the effect of graphene oxide (GO) reinforcement on overall properties of aluminum (Al) matrix composites experimentally is time-consuming and involves high manufacturing costs and sophisticated characterizations. An attempt was made in this paper to predict the mechanical properties of GO/Al composites by using a micromechanical finite element approach. The materials used for prediction included monolayer and multilayer GO layers distributed uniformly on the spherical Al matrix particles. The estimation was done by assuming that a representative volumetric element (RVE) represents the composite structure, and reinforcement and matrix were modeled as continuum. The load transfer between the GO reinforcement and Al was modeled using joint elements that connect the two materials. The numerical results from the finite element model were compared with Voigt model and experimental results from the GO/Al composites produced at optimized process parameters. A good agreement of numerical results with the theoretical models was noted. The load-bearing capacity of the Al matrix increased with the addition of GO layers, however, Young’s modulus of the GO/Al composites decreased with an increase in the number of layers from monolayer to 5 layers. The numerical results presented in this paper have demonstrated the applicability of the current approach for predicting the overall properties of composites.

Finite Elements for Curved Sandwich Beams

1977 ◽  
Vol 28 (2) ◽  
pp. 123-141 ◽  
Author(s):  
P J Holt ◽  
J P H Webber
Keyword(s):  
Finite Elements ◽  
Stiffness Matrix ◽  
Test Cases ◽  
Sandwich Beams ◽  
Honeycomb Core ◽  
The Core ◽  
The Face ◽  
Core Thickness ◽  
Displacement Approach ◽  
Circular Sandwich Ring

SummaryThe formulation of curved finite elements to represent a two-dimensional circular sandwich ring with honeycomb core and laminated faces is investigated. Assumed stress hybrid and equilibrium methods are found to be easier to employ in this case than the displacement approach. Using these methods, an element stiffness matrix is developed. The approximations of membrane faces and an infinite core normal stiffness are then used to develop simpler elements. Test cases show that these assumptions may become invalid, but that they are adequate for most practical cases where the core thickness to radius ratio and the face thickness to core thickness ratio are both low.

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