Characterization of Cure-Dependent Viscoelastic Behavior for Molding Compound and Application to Package Warpage Simulation

2009 ◽  
Author(s):  
Tz-Cheng Chiu ◽  
Je-Li Kung ◽  
Yi-Shao Lai
Keyword(s):  
Finite Element ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Relaxation Modulus ◽  
Cure Kinetics ◽  
Constitutive Relationship ◽  
Element Analysis ◽  
Molding Compound ◽  
Modeling Methodology ◽  
Bga Package

In this study a process-dependent viscoelastic model is developed for considering the constitutive relationship of an epoxy molding compound. The process dependence is realized by incorporating the phenomenological models for the cure kinetics, the cure-dependent volume shrinkage, and the cure-dependent viscoelastic stress relaxation modulus into the constitutive model for the molding compound. The cure-dependent viscoelastic model is incorporated into numerical finite element analysis to simulate warpage of an overmolded chip scale ball grid array (BGA) package under uniform cooling from reflow to room temperature. The simulation results are compared to Shadow Moire´ experimental data for validating the modeling methodology. Additional finite element analyses are performed to investigate the influence of molding compound constitutive behavior (temperature-dependent elastic or viscoelastic) on the package warpage prediction, and to consider the package warpage evolution during the post-mold curing (PMC) process.

Nonlinear Viscoelastic Finite Element Analysis of Adhesive Joints

1988 ◽  
Vol 16 (3) ◽  
pp. 146-170 ◽  
Author(s):  
S. Roy ◽  
J. N. Reddy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Viscoelastic Behavior ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Adhesively Bonded Joints ◽  
Nonlinear Viscoelastic ◽  
Structural Failures ◽  
Updated Lagrangian

Abstract A good understanding of the process of adhesion from the mechanics viewpoint and the predictive capability for structural failures associated with adhesively bonded joints require a realistic modeling (both constitutive and kinematic) of the constituent materials. The present investigation deals with the development of an Updated Lagrangian formulation and the associated finite element analysis of adhesively bonded joints. The formulation accounts for the geometric nonlinearity of the adherends and the nonlinear viscoelastic behavior of the adhesive. Sample numerical problems are presented to show the stress and strain distributions in bonded joints.

scholarly journals Finite Element Analysis of the Nanomechanics of Hard Coatings on a Soft Polymer Substrate by a Spherical Indenter

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Chunlai Tian ◽  
Pengfei Duan
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Viscoelastic Model ◽  
Coating System ◽  
Element Analysis ◽  
Soft Polymer ◽  
Indentation Response

Composite has been widely used in various fields due to its advanced performance. To reveal the relation between the mechanical properties of the composite and that of each individual component, finite element analysis (FEA) has usually been adopted. In this study, in order to predict the mechanical properties of hard coating on a soft polymer, the response of this coating system during nanoindentation was modelled. Various models, such as a viscoelastic model and fitting model, were adopted to analyse the indentation response of this coating system. By varying the substrate properties (i.e., Young’s modulus, viscoelasticity, and Poisson’s ratio), Young’s modulus, energy loss, and the viscoelastic model of the coating system were analysed, and how the mechanical properties of the substrate will affect the indentation response of the coating system was discussed.

3-D Elastic-Plastic Constitutive Relationship of Mixed Hardening

2012 ◽  
Vol 249-250 ◽  
pp. 927-930
Author(s):  
Ze Yu Wu ◽  
Xin Li Bai ◽  
Bing Ma
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Kinematic Hardening ◽  
Constitutive Relationship ◽  
Isotropic Hardening ◽  
Element Analysis ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Mixed Hardening ◽  
Advantages And Disadvantages

In finite element calculation of plastic mechanics, isotropic hardening model, kinematic hardening model and mixed hardening model have their advantages and disadvantages as well as applicability area. In this paper, by use of the tensor analysis method and mixed hardening theory in plastic mechanics, the constitutive relation of 3-D mixed hardening problem is derived in detail based on the plane mixed hardening. Numerical results show that, the proposed 3-D mixed hardening constitutive relation agrees well with the test results in existing references, and can be used in the 3-D elastic-plastic finite element analysis.

Optimization-Based Inverse Finite Element Analysis for Material Parameter Identification of a Biphasic Viscoelastic Hydrogel

2008 ◽  
Author(s):  
Kaifeng Liu ◽  
Brian Thomas ◽  
J. Craig Fryman ◽  
Jeff Bischoff ◽  
Timothy Ovaert ◽  
...  
Keyword(s):  
Finite Element ◽  
Solid Phase ◽  
Polymer Network ◽  
Viscoelastic Model ◽  
Optimization Method ◽  
Creep Testing ◽  
Material Parameter Identification ◽  
Element Analysis ◽  
Biphasic Model ◽  
Material Parameters

Hydrogels are a cross-linked network of polymer swollen with a liquid, and are promising replacements for diseased or damaged load bearing tissues such as articular cartilage [1]. Recently, a linear biphasic model, developed originally for cartilage [2], has been applied to characterize the mechanical behavior of hydrogels [3, 4]. However, the linear elastic assumption for the solid phase ignores the intrinsic viscoelasticity of the polymer network [3, 4]. Some attempts have been made in the literature to simulate hydrogels with a biphasic viscoelastic model using a self-developed finite element code [5]. This study is aimed at simulating hydrogels with a biphasic viscoelastic model and investigating an inverse finite element (FE) technique to identify material parameters of hydrogels via combined creep testing and FE modeling. Creep testing of hydrogels is simulated in the commercial software ABAQUS, which makes this approach easy to adapt to other test geometries. Material parameters are identified by fitting the FE results to the experimental results using an optimization method.

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.

Study on Mechanism of L-Shaped Concrete-Filled Steel Tubular Columns Subjected to Axial Compression

2012 ◽  
Vol 476-478 ◽  
pp. 2463-2468 ◽  
Author(s):  
Ji Cheng Zhang ◽  
Jun Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Axial Compression ◽  
Constitutive Relations ◽  
Steel Tube ◽  
Constitutive Relationship ◽  
Steel Tubes ◽  
Element Analysis ◽  
Relationship Of ◽  
Deformation Relationship

In this paper, a constitutive relationship of the concrete core restrained by L-Shaped steel tube is put forward based on referring to the constitutive relations of core concrete in concrete-filled square steel tube columns, which takes the restraint of steel tube to concrete as an equivalent confinable effect coefficient . Load-deformation relationship of L-Shaped concrete-filled steel tubular column subjected to axial compression is analyzed by finite element analysis (using ABAQUS software). The predicted load versus deformation relationship cures are in good agreement with those of tests based on the finite element analysis, loads carried by steel tubes and concrete respectively during the loading process, as well as interactions between them are analyzed. Finally, influences of length-width ratio and width-thickness ratio on the interaction between steel tubes and concrete are investigated.

MICRO-CONSTITUENT BASED VISCOELASTIC FINITE ELEMENT ANALYSIS OF BIOLOGICAL CELLS

2010 ◽  
Vol 02 (02) ◽  
pp. 229-249 ◽  
Author(s):  
F. CHENG ◽  
G. U. UNNIKRISHNAN ◽  
J. N. REDDY
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Reaction Force ◽  
Experimental Studies ◽  
Viscoelastic Model ◽  
Material Model ◽  
Outer Cortex ◽  
Element Analysis ◽  
Actin Cortex

A viscoelastic analysis of the biological cell considering the microcellular material properties is carried out in this work. Three separate regions of the cell: the actin cortex, cytoplasm and nucleus are considered. The outer cortex and cytoplasm are modeled using standard linear viscoelastic model (SLS) and standard neo-Hookean viscoelastic solid, and a linear elastic material model is considered for the nucleus. The effect of the material properties of cytoplasm and actin cortex on the derivable parameters from three major experimental studies of magnetic twisting cytometry (MTC) and atomic force microscopy (AFM) and micropipette aspiration (MPA) are analyzed using the finite element method. The bead center displacement for the MTC, reaction force for AFM, and aspiration length ratio for the MPA are the major quantities derived from the finite element analysis. A number of parametric studies are also conducted and it is observed that SLS and SnHS models predict nearly identical results for the material constants.

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