Behavior of Lead-Free Solder Under Thermomechanical Loading

2004 ◽  
Vol 126 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
K. J. Lau ◽  
P. Vianco ◽  
H. E. Fang
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Base Alloy ◽  
Back Stress ◽  
General Purpose ◽  
Lead Free ◽  
Element Analysis ◽  
Different Temperatures ◽  
Free Solder

This paper presents an investigation of lead-free Sn-Ag base alloy, 95.5Sn-3.9Ag-0.6Cu, both experimentally and analytically. Experimentally, the deformation behavior of the material was measured for different temperatures (25°C and 1000°C) over a range of strain rates (10−5 to 10−3/s) under isothermal and thermomechanical conditions. Development of a unified viscoplastic constitutive model followed, taking into account the effects of the measured strain rate and temperature changes. The temperature rate effects are considered in the evolution equation of back stress. In order to include material degradation in the solder, the theory of damage mechanics is applied by introducing two damage variables in the viscoplastic constitutive model. Finally, the constitutive model is coded into a general-purpose finite element computer program (ABAQUS) through its user-defined material subroutine (UMAT). The damage-coupled finite element analysis (FEA) is then employed to monitor the condition of failure of a notched component. The predicted and measured maximum loads have been compared and found to be satisfactory. In addition, the calculated damage distribution contours enable the identification of potential failure site for failure analysis.

Progressive failure analysis of scarf-repaired composite laminate based on damage constitutive model

2016 ◽  
Vol 233 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Qiuyi Shen ◽  
Zhenghao Zhu ◽  
Yi Liu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Composite Laminate ◽  
Damage Mechanics ◽  
Cohesive Zone Model ◽  
Load Capacity ◽  
Three Dimensional ◽  
Zone Model ◽  
State Variables ◽  
Element Analysis

A three-dimensional finite element model for scarf-repaired composite laminate was established on continuum damage model to predict the load capacity under tensile loading. The mixed-mode cohesive zone model was adopted to the debonding behavior analysis of adhesive. Damage condition and failure of laminates and adhesive were subsequently addressed. A three-dimensional bilinear constitutive model was developed for composite materials based on damage mechanics and applied to damage evolution and loading capacity analyses by quantifying damage level through damage state variables. The numerical analyses were implemented with ABAQUS finite element analysis by coding the constitutive model into material subroutine VUMAT. Good agreement between the numerical and experimental results shows the accuracy and adaptability of the model.

Detailed Contact Analysis of the J-Tube Riser Pull-In Method

2011 ◽  
Author(s):  
Farzad Farid-Afshin ◽  
Christian Reva ◽  
Erlend R. Vistnes
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
General Purpose ◽  
Friction Model ◽  
Contact Analysis ◽  
Von Mises Stress ◽  
Contact Friction ◽  
Offshore Platforms ◽  
Element Analysis

J-tube method of riser installation is a conventional method of connecting the subsea pipelines to fixed offshore platforms which are abundant in the Norwegian and international waters. The integrity of the J-tube, its supports, riser itself and the platform has to be maintained during pull-in of a riser into a J-tube. To ensure this, it is required that the pull-in and reaction forces, in addition to the riser plastic strain and J-tube stresses should be established either by detailed finite element contact analysis or by simplified methods available in literature. With the advances made in the finite element procedures and tools in the past decades and due to the higher degree of accuracy that they can capture, the contact analysis is often the preferred approach. Various parameters contribute to the riser pull-in operation which should be represented accurately in a finite element analysis to provide reliable results. Among others, they include the riser back tension (lay tension, seabed friction, etc.), riser J-tube friction, riser material’s yield stress and constitutive model, riser and J-tube fabrication tolerances, boundary conditions, clearances, etc. In addition, there are numerical modeling parameters such as the friction model (contact friction-clearance/overclosure relationship) and the details of the material’s constitutive model which can affect the accuracy and convergence of the analyses. In this paper, the general trends of response are presented with respect to physical variations of these parameters. Pull-in force, J-tube equivalent von-Mises stress and riser plastic strain are the response indicators which are studied. Analyses are performed using ABAQUS general-purpose finite element package [1]. The conclusions based on the observed trends can help to decide these input parameters as every individual project (i.e. study, detailed phase, etc.) and client requires.

Damage Constitutive Model and Failure Mechanism of Lead-Free Solder in CBGA Package

2008 ◽  
Vol 44-46 ◽  
pp. 77-84
Author(s):  
Wei Na Hao ◽  
Guo Zhong Chai ◽  
J. Zhou
Keyword(s):  
Constitutive Model ◽  
Thermal Loading ◽  
Mechanical Response ◽  
Failure Process ◽  
Damage Model ◽  
Lead Free ◽  
Lead Free Solder ◽  
Element Analysis ◽  
Cyclic Thermal Loading ◽  
Free Solder

A viscoplastic constitutive model with void damage is developed to analyze the macroscopic mechanical response and damage mechanism of lead-free solder alloy in CBGA packaging under cyclic thermal loading. The constitutive model is implemented into ABAQUS through its user defined material subroutine. Two-dimensional nonlinear finite element analysis of a ceramic ball grid array(CBGA) package is conducted to simulate the viscoplastic deformation and damage failure process of the lead-free solder joint under cyclic thermal loading. The damage model is helpful for optimization and reliability of electronic package.

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