Methods for the Simulation of Micro Components With Respect to the Grain Structure

2007 ◽  
Author(s):  
Albert Albers ◽  
Hans-Georg Enkler
Keyword(s):  
Polycrystalline Material ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Material Behavior ◽  
Grain Structure ◽  
Micromechanical Modeling ◽  
Element Analysis ◽  
Grain Structures ◽  
Process Effects ◽  
The One

The development of smaller and smaller micro components and systems is an ongoing process. Effects coming along with this process have to be investigated. A polycrystalline material consists of grains with different orientations. Therefore, a micromechanical model of a polycrystalline material for a Finite Element analysis should consider the grain structure. Studies show that with decreasing size of a micro component its grain structure and material anisotropy gain more and more influence on its stress, strain and flow of forces. In order to ensure a reliable dimensioning of micro components the influence of the grain structure and material’s anisotropy upon the stress and stress distribution has to be investigated. For this purpose, experimental work for characterizing materials’ properties is supplemented by numerical analyses. On the one hand, these analyses allow examining specific influences on the mechanical stress. On the other hand, micromechanical modeling has potential to increase the understanding of material behavior. Methods for modeling two- and three-dimensional micro components with complex grain structures including defects such as pores are presented and compared. The consideration of effects coming along with the grain structure makes a contribution to a reliable dimensioning of micro components with distinct grain structures.

Role of Out-of-Plane Coefficient of Thermal Expansion in Electronic Packaging Modeling

1999 ◽  
Vol 122 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Manjula N. Variyam ◽  
Weidong Xie ◽  
Suresh K. Sitaraman
Keyword(s):  
Thermal Expansion ◽  
Electronic Packaging ◽  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Dissimilar Materials ◽  
3D Models ◽  
Material Behavior ◽  
Element Analysis

Components in electronic packaging structures are of different dimensions and are made of dissimilar materials that typically have time, temperature, and direction-dependent thermo-mechanical properties. Due to the complexity in geometry, material behavior, and thermal loading patterns, finite-element analysis (FEA) is often used to study the thermo-mechanical behavior of electronic packaging structures. For computational reasons, researchers often use two-dimensional (2D) models instead of three-dimensional (3D) models. Although 2D models are computationally efficient, they could provide misleading results, particularly under thermal loading. The focus of this paper is to compare the results from various 2D, 3D, and generalized plane-deformation strip models and recommend a suitable modeling procedure. Particular emphasis is placed to understand how the third-direction coefficient of thermal expansion (CTE) influences the warpage and the stress results predicted by 2D models under thermal loading. It is seen that the generalized plane-deformation strip models are the best compromise between the 2D and 3D models. Suitable analytical formulations have also been developed to corroborate the findings from the study. [S1043-7398(00)01402-X]

Multiscale Modeling of Large Deformation Processes in Polycrystalline Metals

2003 ◽  
Author(s):  
Antoinette Maniatty ◽  
Karel Matous ◽  
Jing Lu
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Grain Structure ◽  
Current Work ◽  
Integration Scheme ◽  
Two Dimensional ◽  
Scale Bridging ◽  
Grain Structures ◽  
Backward Euler ◽  
Bulk Response

A mesoscale model for predicting the evolution of the grain structure and the mechanical response of polycrystalline aggregates subject to large deformations, such as arise in bulk metal forming processes, is presented. The gain structures modeled are either experimentally observed or are computer generated and statistically similar to experimentally observed grain structures. In order to capture the inhomogeneous deformations and the resulting grain structure characteristics, a discretized model at the mesoscale is used. This work focuses on Al-Mg-Si alloys. Scale bridging is used to link to the macroscale. Examples involving two-dimensional grain structures and current work on three-dimensional grain structures are presented. The present work provides a framework to model the mesoscopic behavior and interactions between grains during finite strains. The mesoscale is characterized by a statistically representative voluem element (RVE), which contains the grains of a polycrystal. Experimentally observed grain structures are used both as models directly (for two-dimensional cases) and to define statistical characteristics to verify the similarity of computer generated grain structures (for three-dimensional cases). A Monte Carlo method based on the Potts model is used to define three-dimensional grain structures. In order to make the representative grain structure appropriate for scale-bridging, we design them with periodicity. A three-field, updated Lagrangian finite element formulation with a kinematic split of the deformation gradient into volume preserving and volumetric parts is used to create a stable finite element method in the context of nearly incompressible behavior. A fully implicit two-level backward Euler integration scheme is derived for integrating the constitutive equations, and consistent linearization is used in Newton’s method to solve the resulting equations. In addition, the average of the boundary conditions and bulk response must match the macroscopically measured bulk response. To illustrate and verify the proposed model, we analyze examples involving two-dimensional grain structures and compare with results from a Taylor model. Current work on three-dimensional grain structures ara also presented.

scholarly journals A three - dimensional finite element study on the stress distribution pattern of two prosthetic abutments for external hexagon implants

2013 ◽  
Vol 07 (04) ◽  
pp. 484-491 ◽  
Author(s):  
Wagner Moreira ◽  
Caio Hermann ◽  
Jucélio Tomás Pereira ◽  
Jean Anacleto Balbinoti ◽  
Rodrigo Tiossi
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
3D Fea ◽  
The One ◽  
Von Mises ◽  
Three Dimensional Finite Element

ABSTRACT Objective: The purpose of this study was to evaluate the mechanical behavior of two different straight prosthetic abutments (one- and two-piece) for external hex butt-joint connection implants using three-dimensional finite element analysis (3D-FEA). Materials and Methods: Two 3D-FEA models were designed, one for the two-piece prosthetic abutment (2 mm in height, two-piece mini-conical abutment, Neodent) and another one for the one-piece abutment (2 mm in height, Slim Fit one-piece mini-conical abutment, Neodent), with their corresponding screws and implants (Titamax Ti, 3.75 diameter by 13 mm in length, Neodent). The model simulated the single restoration of a lower premolar using data from a computerized tomography of a mandible. The preload (20 N) after torque application for installation of the abutment and an occlusal loading were simulated. The occlusal load was simulated using average physiological bite force and direction (114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial at an angle of 75° to the occlusal plan). Results: The regions with the highest von Mises stress results were at the bottom of the initial two threads of both prosthetic abutments that were tested. The one-piece prosthetic abutment presented a more homogeneous behavior of stress distribution when compared with the two-piece abutment. Conclusions: Under the simulated chewing loads, the von Mises stresses for both tested prosthetic-abutments were within the tensile strength values of the materials analyzed which thus supports the clinical use of both prosthetic abutments.

Comparison of Grain Structures and Textures in AA5754 Aluminum Alloy Sheets Processed by Room Temperature Rolling and Rolling with Liquid Nitrogen

2007 ◽  
Vol 558-559 ◽  
pp. 217-222 ◽  
Author(s):  
Hai Ou Jin ◽  
Pei Dong Wu ◽  
David J. Lloyd
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Electron Backscatter Diffraction ◽  
Optical Microscope ◽  
Grain Structure ◽  
Micro Hardness ◽  
Grain Structures ◽  
Room Temperature Rolling ◽  
The One ◽  
Backscatter Diffraction

Two AA5754 sheets have been processed by cold rolling with 83% thickness reduction, one at room temperature and another with liquid nitrogen as coolant. The sheets were subsequently annealed at 220-275°C for 1 hour. The development of grain structure and texture was studied by optical microscope, scanning electron microscopy (SEM), X-ray diffraction and electron backscatter diffraction (EBSD) in SEM, and the mechanical property by micro-hardness testing. It has been demonstrated that the as-rolled sheets have the same micro-hardness, but the grain structures and textures are very different. Compared to the sheet processed with liquid nitrogen, the one rolled at room temperature has stronger shear texture and finer grain structure.

Three-dimensional analyses of two high-speed trains crossing on a bridge

2003 ◽  
Vol 217 (2) ◽  
pp. 99-110
Author(s):  
H-T Lin ◽  
S-H Ju
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
High Speed ◽  
Three Dimensional ◽  
Dynamic Effect ◽  
Response Ratio ◽  
Element Analysis ◽  
Dynamic Finite Element Analysis ◽  
High Speed Trains ◽  
The One

This paper investigates the dynamic characteristics of the three-dimensional vehicle-bridge system when two high-speed trains are crossing on a bridge. Multispan bridges with slender piers and simply supported beams were used in the dynamic finite element analysis. A response ratio (RR) was defined in this study to represent the ratio of the vehicle-bridge interaction of two-way trains to that of a one-way train. The finite element results indicate that this ratio increases significantly when two-way trains run near the same speed, and the maximum value is approximately equal to or smaller than two for the vertical dynamic response. This means that the maximum dynamic response of the two-way trains is at most twice that of the one-way train. When the two-way train speeds are sufficiently different, the response ratio approaches one on average, which means that the dynamic effect of the two-way train is similar to that of the one-way train. Finite element results also indicate that the averaged response ratio in the three global directions is about 1.65 when the two-way trains run at the same speed.

Micromechanical Modeling of Viscoelastic Response of GMT Composite

2001 ◽  
Vol 35 (10) ◽  
pp. 849-882 ◽  
Author(s):  
Modris Megnis ◽  
Janis Varna ◽  
David H. Allen ◽  
Anders Holmberg
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Viscoelastic Properties ◽  
Micromechanical Model ◽  
Experimental Studies ◽  
Material Behavior ◽  
Micromechanical Modeling ◽  
Stress Concentrations ◽  
Concentric Cylinder ◽  
Fiber Orientation Distribution

Experimental studies have been performed to obtain creep compliance functions of polypropylene (PP) and Glass Mat reinforced Thermoplastics (GMT) with PP matrix. It was found that both GMT and PP in the considered loading region may be considered as linear viscoelastic materials. The obtained viscoelastic compliance functions were successfully used to describe material behavior in the stress relaxation test. A micromechanical model based on the correspondence principle in the Laplace domain was developed to describe the viscoelastic behavior of GMT. This model considers the GMT composite with a given fiber orientation distribution function as consisting of an infinite number of unidirectional layers with orientations corresponding to this distribution function. The viscoelastic properties of the unidirectional layer are calculated using Hashin's concentric cylinder model that uses the experimentally determined viscoelastic properties of PP matrix. The predictions for GMT have been compared with experimental data. The model predicts rather good initial properties of GMT but it gives slightly less time dependence than compared to experimental data for both relaxation functions and compliance. The cause of the difference (debonding) between matrix and fiber, nonuniform fiber spatial distribution, stress concentrations etc.) is discussed.

scholarly journals A Micromechanical Model of Additively Manufactured Aluminum Alloys

2019 ◽  
Vol 221 ◽  
pp. 01016
Author(s):  
Evgeniya Emelianova ◽  
Varvara Romanova ◽  
Olga Zinovieva ◽  
Ruslan Balokhonov ◽  
Aleksandr Zinoviev ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Plastic Anisotropy ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Face Centered Cubic ◽  
Melt Pool ◽  
Grain Structures ◽  
Face Centered ◽  
Three Dimensional Models ◽  
Packing Method

A micromechanical model is developed to predict the deformation behavior of additively manufactured aluminum alloys. Three-dimensional models of grain structures typical for different microregions of the melt pool are generated by the step-by-step packing method. A crystal plasticity-based constitutive model accounting for the elastic-plastic anisotropy of face-centered cubic crystals is employed to simulate the microscale deformation in an additively manufactured aluminum alloy under loading. The grain shape and texture effects on the plastic strain localization patterns are analyzed.

scholarly journals Study of one-dimensional cure simulation applicable conditions for thick laminates and its comparison with three-dimensional simulation

2018 ◽  
Vol 25 (6) ◽  
pp. 1197-1204 ◽  
Author(s):  
Mingfa Ren ◽  
Qi Wang ◽  
Jie Cong ◽  
Xin Chang
Keyword(s):  
Computational Cost ◽  
Three Dimensional ◽  
Cure Kinetics ◽  
Transient Heat Conduction ◽  
Material System ◽  
Element Analysis ◽  
One Dimensional ◽  
Dimensional Simulation ◽  
The One ◽  
Three Dimensional Finite Element

AbstractThe comparison of one- and three-dimensional cure simulation of thick thermoset matrix laminates was conducted in this study. The applicable conditions of one-dimensional cure simulation were investigated. The transient heat conduction equation coupled to the cure kinetics was solved numerically using one- and three-dimensional finite element analysis. The evolution of temperature and degree of cure of the laminates during the curing process obtained by the simulation agreed well with the published experimental results. The results indicate that a wider one-dimensional analysis applicable region around the center point will be obtained in the laminate with a higher span-to-thickness ratio and in a less anisotropic material system. In the applicable region, the accuracy of the one-dimensional cure simulation can satisfy the engineering request and save the computational cost. While beyond the region, there is a steep increase in deviation of the one- and three-dimensional simulation results.

Surface Cracks in Round Bars under Cyclic Tension or Bending

2008 ◽  
Vol 378-379 ◽  
pp. 341-354 ◽  
Author(s):  
Andrea Carpinteri ◽  
Sabrina Vantadori
Keyword(s):  
Three Dimensional ◽  
Fatigue Behaviour ◽  
Surface Cracks ◽  
Displacement Method ◽  
Element Analysis ◽  
Cyclic Tension ◽  
Step Procedure ◽  
Dimensional Finite Element ◽  
The One ◽  
Three Dimensional Finite Element

The fatigue growth of a surface crack in a metallic round bar under cyclic tension or bending is analysed. The stress-intensity factor (SIF) along the crack front is computed through a three-dimensional finite element analysis and the one-quarter point displacement method. The results are compared with those presented by other Authors. Then, the fatigue behaviour of the cracked bar is numerically determined by a step-by-step procedure.

The Effect of Carbon Nanotubes on the Natural Frequencies of Microcantilever Beams

2010 ◽  
Author(s):  
Hossein Rokni D. T. ◽  
Abbas S. Milani ◽  
Rudolf J. Seethaler ◽  
Jonathan Holzman
Keyword(s):  
Carbon Nanotubes ◽  
Natural Frequencies ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Distribution Patterns ◽  
Mode Shapes ◽  
Test Case ◽  
Element Analysis ◽  
Multi Wall Carbon Nanotubes ◽  
Three Dimensional Finite Element

In this study, the natural frequencies and mode shapes of carbon nanotube (CNT) reinforced polymer composite microcantilever beams are investigated by means of a micromechanical model and the three-dimensional finite element analysis. Microcantilever beams are made of Poly vinyl chloride (PVC) and reinforced with multi-wall carbon nanotubes (MWCNTs). MWCNTs can be distributed along the length/width/thickness of the nanocomposite beam. To validate the accuracy and effectiveness of the model, a direct comparison of results is made with an analytical solution for a test case. Next, various material types of the nanocomposite microcantilever beam are introduced and the effect of different distribution patterns and the weight-percents (wt%) of MWCNTs on the first six natural frequencies and mode shapes is found.

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