Failure Analysis of Miniature Solder Specimen

2004 ◽  
Vol 126 (1) ◽  
pp. 100-105 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
H. E. Fang ◽  
M. K. Neilsen ◽  
T. J. Lim ◽  
...  
Keyword(s):  
Finite Element ◽  
Uniaxial Tension ◽  
Evolution Equations ◽  
Damage Model ◽  
Irreversible Thermodynamics ◽  
Tensile Creep ◽  
Tension Testing ◽  
Damage Theory ◽  
Inelastic Damage ◽  
Strain Space

The effects of specimen geometry size on the behavior of 63Sn-37Pb solder are investigated both experimentally in the laboratory and analytically with finite-element simulations. The simulations are achieved by developing a constitutive model for solder which couples viscoplasticity with a unified damage theory. The unified damage theory is characterized by a damage surface in strain space which separates fatigue damage from inelastic damage. The damage evolution equations are derived within the framework of irreversible thermodynamics. A series of uniaxial tension, tensile creep, and strain-controlled fatigue experiments are performed to obtain material parameters for the solder damage model. The solder damage model is then implemented into a finite element code and used to simulate a uniaxial tension test on a miniature specimen and on a standard ASTM specimen (ASTM Standards, 1999, “Tension Testing of Metallic Materials,” ASTM E8-78). Predictions from these simulations are then compared with each other and with experimental results in order to examine microstructure size effects.

Failure Analysis of Miniature Solder Specimen

2001 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
H. E. Fang ◽  
M. K. Neilsen ◽  
T. J. Lim ◽  
...  
Keyword(s):  
Finite Element ◽  
Uniaxial Tension ◽  
Evolution Equations ◽  
Damage Model ◽  
Irreversible Thermodynamics ◽  
Tensile Creep ◽  
Miniature Specimen ◽  
Damage Theory ◽  
Inelastic Damage ◽  
Strain Space

Abstract The effects of specimen geometry size on the behavior of 63Sn-37Pb solder are investigated both experimentally in the laboratory and analytically with finite-element simulations. The simulations are achieved by developing a constitutive model for solder which couples viscoplasticity with a unified damage theory. The unified damage theory is characterized by a damage surface in strain space which separates fatigue damage from inelastic damage. The damage evolution equations are derived within the framework of irreversible thermodynamics. A series of uniaxial tension, tensile creep, and strain-controlled fatigue experiments are performed to obtain material parameters for the solder damage model. The solder damage model is then implemented into a finite element code and used to simulate a uniaxial tension test on a miniature specimen and on a standard ASTM specimen (ASTM standards, 1999). Predictions from these simulations are then compared with each other and with experimental results in order to examine specimen size effects.

Nonlocal Damage Gradient Model for Fracture Characterization of Aluminum Alloy

2011 ◽  
Vol 20 (7) ◽  
pp. 1073-1093 ◽  
Author(s):  
Chi L. Chow ◽  
Jianghui Mao ◽  
Jie Shen
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Evolution Equations ◽  
Damage Model ◽  
Engineering Application ◽  
Material Model ◽  
Irreversible Thermodynamics ◽  
Nonlocal Damage ◽  
Regular Elements ◽  
Aluminum Alloy 2024

This article presents the development of a generalized nonlocal damage-coupled material model. The model introduces the concept of cumulative damage gradient through a set of damage evolution equations within the irreversible thermodynamics framework. The conventional damage-coupled plasticity models require either self-developed finite element codes or the mandatory use of regular elements. The proposed material model is implemented in a commercial finite element code ABAQUS (Version 6.5) via its UMAT subroutine. The implementation of this model on ABAQUS is described with a focus on the nonlocal treatment together with the derivation of the consistent tangent modulus (Jacobian). As a numerical example, the nonlocal damage model is applied to center-cracked specimen made of aluminum alloy 2024-T3. Comparison is made between the computed results and experimental ones. The validity of the proposed model is examined, and its effectiveness for engineering application is elucidated.

scholarly journals Characteristics of Creep Damage for 60 Sn-40 Pb Solder Material

1999 ◽  
Vol 123 (3) ◽  
pp. 278-283 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
H. E. Fang ◽  
M. K. Neilsen
Keyword(s):  
Damage Mechanics ◽  
Evolution Equations ◽  
Damage Model ◽  
Creep Damage ◽  
General Purpose ◽  
Tensile Creep ◽  
Finite Element Program ◽  
Solder Material ◽  
Phase Size ◽  
Element Program

This paper presents a viscoplasticity model taking into account the effects of change in grain or phase size and damage on the characterization of creep damage in 60 Sn-40 Pb solder. Based on the theory of damage mechanics, a two-scalar damage model is developed for isotropic materials by introducing the free energy equivalence principle. The damage evolution equations are derived in terms of the damage energy release rates. In addition, a failure criterion is developed based on the postulation that a material element is said to have ruptured when the equivalent damage accumulated in the element reaches a critical value. The damage coupled viscoplasticity model is discretized and coded in a general-purpose finite element program known as ABAQUS through its user-defined material subroutine UMAT. To illustrate the application of the model, several example cases are introduced to analyze, both numerically and experimentally, the tensile creep behaviors of the material at three stress levels. The model is then applied to predict the deformation of a notched specimen under monotonic tension at room temperature (22°C). The results demonstrate that the proposed model can successfully predict the viscoplastic behavior of the solder material.

Finite Element Modeling of Damage Formation in Rubber-Toughened Polymer

2005 ◽  
Vol 297-300 ◽  
pp. 1019-1024
Author(s):  
Mitsugu Todo ◽  
Yoshihiro Fukuya ◽  
Seiya Hagihara ◽  
Kazuo Arakawa
Keyword(s):  
Finite Element ◽  
Damage Zone ◽  
Damage Model ◽  
Crack Tip ◽  
Optical Microscope ◽  
Toughening Mechanism ◽  
Element Analysis ◽  
Zone Formation ◽  
Macro Scale ◽  
Rubber Toughened

Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.

scholarly journals Rock Failure Analysis Based on a Coupled Elastoplastic-Logarithmic Damage Model

2017 ◽  
Vol 62 (4) ◽  
pp. 753-774
Author(s):  
M. Abdia ◽  
H. Molladavoodi ◽  
H. Salarirad
Keyword(s):  
Constitutive Model ◽  
Plastic Flow ◽  
Mechanical Response ◽  
Damage Model ◽  
Yield Function ◽  
Irreversible Thermodynamics ◽  
Stiffness Degradation ◽  
Shear Stresses ◽  
Rock Materials ◽  
Damage Process

Abstract The rock materials surrounding the underground excavations typically demonstrate nonlinear mechanical response and irreversible behavior in particular under high in-situ stress states. The dominant causes of irreversible behavior are plastic flow and damage process. The plastic flow is controlled by the presence of local shear stresses which cause the frictional sliding. During this process, the net number of bonds remains unchanged practically. The overall macroscopic consequence of plastic flow is that the elastic properties (e.g. the stiffness of the material) are insensitive to this type of irreversible change. The main cause of irreversible changes in quasi-brittle materials such as rock is the damage process occurring within the material. From a microscopic viewpoint, damage initiates with the nucleation and growth of microcracks. When the microcracks length reaches a critical value, the coalescence of them occurs and finally, the localized meso-cracks appear. The macroscopic and phenomenological consequence of damage process is stiffness degradation, dilatation and softening response. In this paper, a coupled elastoplastic-logarithmic damage model was used to simulate the irreversible deformations and stiffness degradation of rock materials under loading. In this model, damage evolution & plastic flow rules were formulated in the framework of irreversible thermodynamics principles. To take into account the stiffness degradation and softening on post-peak region, logarithmic damage variable was implemented. Also, a plastic model with Drucker-Prager yield function was used to model plastic strains. Then, an algorithm was proposed to calculate the numerical steps based on the proposed coupled plastic and damage constitutive model. The developed model has been programmed in VC++ environment. Then, it was used as a separate and new constitutive model in DEM code (UDEC). Finally, the experimental Oolitic limestone rock behavior was simulated based on the developed model. The irreversible strains, softening and stiffness degradation were reproduced in the numerical results. Furthermore, the confinement pressure dependency of rock behavior was simulated in according to experimental observations.

Numerische Abbildung von Beton mit einem plastischen Schädigungsmodell – Grundlegende Untersuchungen zu Normalbeton und UHPC/Finite element simulation of concrete with a plastic damage model – Basic studies on normal strength concrete and UHPC

Bauingenieur ◽  
2015 ◽  
Vol 90 (06) ◽  
pp. 252-264 ◽  
Author(s):  
Dominik Kueres ◽  
Alexander Stark ◽  
Martin Herbrand ◽  
Martin Classen
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Damage Model ◽  
Normal Strength Concrete ◽  
Numerische Simulation ◽  
Plastic Damage ◽  
Element Simulation ◽  
Finite Elemente ◽  
Normal Strength ◽  
Basic Studies

Die numerische Simulation des Tragverhaltens von Beton- und Stahlbetonkonstruktionen mit nicht-linearen Finite-Elemente-Modellen gewinnt in der konstruktiven Ingenieurpraxis zunehmend an Bedeutung. In kommerziellen Finite-Elemente-Programmen stehen dem Anwender unterschiedliche Möglichkeiten zur Abbildung des Betonverhaltens in Form von plastischen Materialmodellen zur Verfügung. Zur Anwendung dieser Materialmodelle ist dabei in der Regel die Kenntnis des Betontragverhaltens unter einaxialer Druck- und Zugbeanspruchung erforderlich. Im vorliegenden Beitrag werden verschiedene Ansätze zur mathematischen Beschreibung dieser konstitutiven Beziehungen für Normalbeton und ultrahochfesten Beton (UHPC) vorgestellt und im Hinblick auf ihre Anwendbarkeit in plastischen Materialmodellen untersucht. Darauf aufbauend werden numerische Simulationen mit einem plastischen Schädigungsmodell unter Verwendung eines einheitlichen Parametersatzes durchgeführt und mit den Ergebnissen experimenteller Untersuchungen verglichen. Die Untersuchungen umfassen hierbei Materialprüfungen an Normalbeton und UHPC unter verschiedenen ein- und mehraxialen Spannungszuständen. Durch die Wahl geeigneter konstitutiver Beziehungen kann für die untersuchten Spannungszustände eine gute Übereinstimmung zwischen simuliertem und experimentell ermitteltem Betontragverhalten erreicht werden.

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.

Comparison of Two Time-Integration Algorithms for an Anisotropic Damage Model Coupled with Plasticity

2015 ◽  
Vol 784 ◽  
pp. 292-299 ◽  
Author(s):  
Stephan Wulfinghoff ◽  
Marek Fassin ◽  
Stefanie Reese
Keyword(s):  
Evolution Equations ◽  
Damage Model ◽  
Time Integration ◽  
Three Dimensional ◽  
Anisotropic Damage ◽  
Euler Scheme ◽  
The Finite Element Method ◽  
Time Step ◽  
Implicit Euler Scheme ◽  
Integration Algorithms

In this work, two time integration algorithms for the anisotropic damage model proposed by Lemaitre et al. (2000) are compared. Specifically, the standard implicit Euler scheme is compared to an algorithm which implicitly solves the elasto-plastic evolution equations and explicitly computes the damage update. To this end, a three dimensional bending example is solved using the finite element method and the results of the two algorithms are compared for different time step sizes.

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