Partitioned Cyclic Fatigue Damage Evolution Model for PB-Free Solder Materials

2007 ◽  
Author(s):  
Leila J. Ladani ◽  
A. Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Creep Deformation ◽  
Damage Evolution ◽  
Evolution Model ◽  
Micro Scale ◽  
Elastic Plastic ◽  
Constitutive Properties ◽  
Free Solder ◽  
Cyclic Damage ◽  
Creep Deformations

This study presents an approach to predict the degree of material degradation and the resulting changes in constitutive properties during cyclic loading in viscoplastic materials in micro-scale applications. The objective in the modeling approach is to address the initiation and growth of distributed micro-damage, in the form of micro-cracks and micro-voids, as a result of cyclic, plastic and creep deformations of material. This study extends an existing micromechanics-based approach, developed for unified viscoplastic models [Wen, et al, 2001], which uses dislocation mechanics to predict damage due to distributed micro-scale fatigue crack initiation [Mura and Nakasone, 1990]. In the present study, the approach is extended to a partitioned viscoplastic framework, because the micro-scale mechanisms of deformation and damage are different for plastic and creep deformation. In this approach, the model constants for estimating cyclic damage evolution are allowed to be different for creep and plastic deformations. A partitioned viscoplastic constitutive model is coupled with an energy partitioning (E-P) damage model [Oyan and Dasgupta, 1992] to assess fatigue damage evolution due to cyclic elastic, plastic and creep deformations. Wen’s damage evolution model is extended to include damage evolution due to both plastic and creep deformations. The resulting progressive degradation of elastic, plastic and creep constitutive properties are continuously assessed and updated. The approach is implemented on a viscoplastic Pb-free solder. Dominant deformation modes in this material are dislocation slip for plasticity and diffusion-assisted dislocation climb/glide for creep. The material’s behavior shows a good correlation with the proposed damage evolution model. Damage evolution constants for plastic and creep deformation were obtained for this Pb-free solder from load drop data collected from the mechanical cycling experiments at different temperatures. The amount of cyclic damage is evaluated and compared with experiment.

scholarly journals Multiscale Damage Evolution Analysis of Aluminum Alloy Based on Defect Visualization

2019 ◽  
Vol 9 (23) ◽  
pp. 5251 ◽  
Author(s):  
Yuquan Bao ◽  
Yali Yang ◽  
Hao Chen ◽  
Yongfang Li ◽  
Jie Shen ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Accumulation ◽  
Evolution Model ◽  
Micro Computed Tomography ◽  
Fatigue Damage Accumulation ◽  
Macro Scale ◽  
Computed Tomography Scanning ◽  
Damage Data

The evaluation of fatigue life through the mechanism of fatigue damage accumulation is still a challenging task in engineering structure failure analysis. A multiscale fatigue damage evolution model was proposed for describing both the mesoscopic voids propagation in the mesoscopic-scale and fatigue damage evolution process, reflecting the progressive degradation of metal components in the macro-scale. An effective method of defect classification was used to implement 3D reconstruction technology based on the MCT (micro-computed tomography) scanning damage data with ABAQUS subroutine. The effectiveness was validated through the comparison with the experimental data of fatigue damage accumulation. Our results indicated that the multiscale fatigue damage evolution model built a bridge between mesoscopic damage and macroscopic fracture, which not only used the damage variable in the macro-scale to characterize the mesoscopic damage evolution indirectly but also understood macroscopic material degradation behavior from mesoscale with sufficient precision. Furthermore, the multiscale fatigue damage evolution model could offer a new reasonable explanation of the effect of load sequence on fatigue life, and also could predict the fatigue life based on damage data by nondestructive testing techniques.

Intergranular thermal fatigue damage evolution in SnAgCu lead-free solder

2008 ◽  
Vol 40 (10) ◽  
pp. 780-791 ◽  
Author(s):  
M. Erinc ◽  
P.J.G. Schreurs ◽  
M.G.D. Geers
Keyword(s):  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Damage Evolution ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder

A Mechanical Fatigue Damage Evolution Model for PB-Free Solder Materials

2008 ◽  
Author(s):  
Leila J. Ladani ◽  
Jafar Razmi
Keyword(s):  
Damage Evolution ◽  
Pure Shear ◽  
Damage Model ◽  
Energy Partitioning ◽  
Evolution Model ◽  
Ductile Material ◽  
Anisotropic Damage ◽  
Mechanical Fatigue ◽  
The Subject ◽  
Free Solder

Evaluating state of damage in a ductile material as it experiences mechanical fatigue and cyclic loading poses much complexity and has been the subject of many researches. This study revisits the anisotropic damage model developed by Lemaitre (1992) and proposes to use his model combined with a micro-mechanics and mechanism based damage evolution model (Energy Partitioning Damage Evolution (EPDE)) and also a Unified Creep Plasticity-based model to predict the state of damage. The model is examined for pure shear and is applied to Pb-free solder materials. New anisotropic damage model exponents are generated using experimental data for Pb-free solder for both EPDE and UPC-based models and are compared with exponents generated previously under the assumption of isotropic and homogenous damage evolution.

Successive Softening and Cyclic Damage in Viscoplastic Material

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Leila J. Ladani
Keyword(s):  
Finite Element ◽  
Damage Model ◽  
Damage Threshold ◽  
Propagation Path ◽  
Viscoplastic Material ◽  
Damage Propagation ◽  
Constitutive Properties ◽  
Successive Initiation ◽  
Free Solder ◽  
Cyclic Damage

A successive initiation finite element modeling approach is presented in which an empirical continuum damage model, energy partitioning damage evolution model, developed by the author is used to update state of damage and constitutive properties of the material under thermomechanical cyclic loading and accumulate damage in the elements. Plastic and viscoplastic damages are evaluated based on the plastic and viscoplastic work densities obtained through finite element. Constitutive properties are updated elementwise at each step of the process based on the state of damage in each element. The elements that have reached the damage threshold are removed from the structure to initiate and propagate fatigue crack. This successive initiation approach is used to model crack initiation and propagation in Pb-free solder material under thermomechanical loading. A case study is presented, damage propagation path and pattern are compared with typical experimental results, and the accuracy of the model was verified.

Cyclic Damage Evolution in a PMC Laminate

2007 ◽  
Vol 348-349 ◽  
pp. 33-36
Author(s):  
Alan Plumtree ◽  
M. Melo
Keyword(s):  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Life Stage ◽  
Crack Density ◽  
Stage I ◽  
Matrix Cracks ◽  
Minimum Stress ◽  
Stress Dependent ◽  
Cyclic Damage

Using damage mechanics, cyclic damage evolution has been described and evaluated in a non-crimped glass epoxy fabric composite. A fundamental fatigue study has been carried out by progressively monitoring the fatigue damage modulus and crack density throughout the life of an [0,+45,90,-45]2 (antisymmetric) laminate cycled at a stress ratio R (minimum stress/maximum stress) of 0.1. Development of damage can be separated into two main stages. Initially, damage increases very quickly during the first 10% of life (Stage I). Afterwhich, it increases more slowly at a relatively constant rate to failure (Stage II). The changes in the fatigue modulus and crack density both show the same behaviour. A large amount of damage in the form of transverse matrix cracks develops during the first cycle. These then remain constant throughout life. By contrast, the number of shear matrix cracks increase continually. The crack density is cycle, not stress dependent. This behaviour is reflected by changes in the fatigue modulus. Using damage mechanics, a representative equation has been applied to express the progressive evolution of damage. The significance of which is that the amount of fatigue damage at the end of Stage I for any stress level can be used to predict fatigue life and the stress-life diagram for the laminate.

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