Micro-Mechanics of Creep-Fatigue Damage in PB-SN Solder Due to Thermal Cycling—Part I: Formulation

2002 ◽  
Vol 124 (3) ◽  
pp. 292-297 ◽  
Author(s):  
Pradeep Sharma ◽  
Abhijit Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Damage Mechanics ◽  
Void Nucleation ◽  
Cyclic Creep ◽  
Diffusional Creep ◽  
Void Coalescence ◽  
Second Phase ◽  
Structural Stress ◽  
Damage Initiation ◽  
Creep Fatigue

This paper presents a micro-mechanistic approach for modeling fatigue damage initiation due to cyclic creep in eutectic Pb-Sn solder. Damage mechanics due to cyclic creep is modeled with void nucleation, void growth, and void coalescence model based on micro-structural stress fields. Micro-structural stress states are estimated under viscoplastic phenomena like grain boundary sliding, its blocking at second-phase particles, and diffusional creep relaxation. In Part II of this paper, the developed creep-fatigue damage model is quantified and parametric studies are provided to better illustrate the utility of the developed model.

Micro-Mechanics of Creep-Fatigue Damage in Pb-Sn Solder Due to Thermal Cycling

2000 ◽  
Author(s):  
Pradeep Sharma ◽  
Abhijit Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Damage Mechanics ◽  
Void Nucleation ◽  
Cyclic Creep ◽  
Diffusional Creep ◽  
Void Coalescence ◽  
Structural Stress ◽  
Damage Initiation ◽  
Mechanical Cycling ◽  
Creep Fatigue

Abstract This paper presents a micro-mechanistic approach for modeling fatigue damage initiation due to cyclic creep in eutectic Pb-Sn solder. Damage mechanics due to cyclic creep is modeled with void nucleation, void growth and void coalescence model based on micro-structural stress fields. Micro-structural stress states are estimated under viscoplastic phenomena like grain boundary sliding and its blocking at 2nd phase particles, and diffusional creep relaxation. A conceptual framework is provided to quantify the creep-fatigue damage due to thermo-mechanical cycling. Some parametric studies are provided to better illustrate the utility of the developed model.

Simulation of Damage Percolation Within Aluminum Alloy Sheet

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
O. S. Orlov ◽  
M. J. Worswick ◽  
E. Maire ◽  
D. J. Lloyd
Keyword(s):  
Aluminum Alloy ◽  
Void Nucleation ◽  
Phase Particle ◽  
Three Dimensional ◽  
Alloy Sheet ◽  
Void Coalescence ◽  
Second Phase ◽  
X Ray ◽  
Damage Initiation

A combined experimental and analytical approach is used to study damage initiation and evolution in three-dimensional second phase particle fields. A three-dimensional formulation of a damage percolation model is developed to predict damage nucleation and propagation through random-clustered second phase particle fields. The proposed approach is capable of capturing the three-dimensional character of damage phenomena and the three stages of ductile fracture, namely, void nucleation, growth, and coalescence, at the level of discrete particles. An in situ tensile test with X-ray tomography is utilized to quantify material damage during deformation in terms of the number of nucleated voids and porosity. The results of this experiment are used for both the development of a clustering-sensitive nucleation criterion and the validation of the damage percolation predictions. The evolution of damage in aluminum alloy AA5182 has been successfully predicted to match that in the in situ tensile specimen. Two forms of second phase particle field input data were considered: (1) that measured directly with X-ray tomography and (2) fields reconstructed statistically from two-dimensional orthogonal sections. It is demonstrated that the adoption of a cluster-sensitive void nucleation criterion, as opposed to a cluster-insensitive nucleation criterion, has a significant effect in promoting predicted void nucleation to occur within particle clusters. This behavior leads to confinement of void coalescence to within clusters for most of the duration of deformation followed by later development of a macrocrack through intracluster coalescence. The measured and reconstructed second phase particle fields lead to similar rates of predicted damage accumulation and can be used interchangeably in damage percolation simulations.

Analysis of Multi-Axial Creep–Fatigue Damage on an Outer Cylinder of a 1000 MW Supercritical Steam Turbine

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Weizhe Wang
Keyword(s):  
Steam Turbine ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Hydrostatic Stress ◽  
Fatigue Behavior ◽  
Axial Stress ◽  
Outer Cylinder ◽  
Continuum Damage Mechanics ◽  
Transfer Coefficients ◽  
Creep Fatigue

A multi-axial continuum damage mechanics (CDM) model was proposed to calculate the multi-axial creep–fatigue damage of a high temperature component. A specific outer cylinder of a 1000 MW supercritical steam turbine was used in this study, and the interaction of the creep and fatigue behavior of the outer cylinder was numerically investigated under a startup–running–shutdown process. To this end, the multi-axial stress–strain behavior of the outer cylinder was numerically studied using Abaqus. The in-site measured temperatures were provided to validate the heat transfer coefficients, which were used to calculate the temperature field of the outer cylinder. The multi-axial mechanics behavior of the outer cylinder was investigated in detail, with regard to the temperature, Mises stress, hydrostatic stress, multi-axial toughness factor, multi-axial creep strain, and damage. The results demonstrated that multi-axial mechanics behavior reduced the total damage.

Micro-Mechanics of Creep-Fatigue Damage in PB-SN Solder Due to Thermal Cycling—Part II: Mechanistic Insights and Cyclic Durability Predictions From Monotonic Data

2002 ◽  
Vol 124 (3) ◽  
pp. 298-304 ◽  
Author(s):  
Pradeep Sharma ◽  
Abhijit Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Practical Interest ◽  
Cyclic Creep ◽  
Ramp Rate ◽  
Cyclic Durability ◽  
Creep Fatigue ◽  
Parametric Studies ◽  
Hydrostatic Stresses ◽  
Monotonic Test

This paper illustrates the micromechanics approach to cyclic creep-fatigue damage of Pb-Sn, developed by the authors with the help of a simple case study. It is demonstrated that durability predictions can be made based solely on monotonic test data. Various parametric studies of practical interest are conducted to obtain mechanistic insights into various aspects of damage in solders e.g., effect of hydrostatic stresses, grain size, ramp rate, etc.

Application of the Three-Dimensional Damage Percolation Model and X-Ray Tomography for Damage Evolution Prediction in Aluminium Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 1011-1016 ◽  
Author(s):  
O. Orlov ◽  
Éric Maire ◽  
Jérôme Adrien ◽  
Michael J. Worswick ◽  
David J. Lloyd
Keyword(s):  
Tensile Test ◽  
Damage Evolution ◽  
Void Nucleation ◽  
Sheet Material ◽  
Three Dimensional ◽  
Percolation Model ◽  
Second Phase ◽  
Material Damage ◽  
X Ray ◽  
Damage Initiation

A three-dimensional damage percolation model, which captures the effect of microstructural heterogeneity on damage evolution, has been developed to model damage initiation and propagation in materials containing second phase particles. It considers the three phenomena preceding ductile rupture of the material: void nucleation, growth, and coalescence. Threedimensional X-ray tomography is used to obtain measured three-dimensional second phase particle distributions in aluminum alloy sheet. Material damage evolution is studied within a tensile test simulation and compared to measured damage from an in situ tensile test utilizing X-ray tomography. Experimental and simulation results for material damage initiation and evolution are in good agreement.

A Study of Microdeformation and Creep-Fatigue Damage using Acoustic Emission Technique

1988 ◽  
Vol 142 ◽  
Author(s):  
Yunxu Liu ◽  
Xingren Li
Keyword(s):  
Plastic Deformation ◽  
Fatigue Damage ◽  
High Performance ◽  
Damage Mechanics ◽  
High Strength Steels ◽  
High Strength ◽  
Optical Microscope ◽  
Plastic Deformation Behavior ◽  
Creep Fatigue ◽  
Theory Of Damage

AbstractThis paper deals with the relationship between the plastic deformation damage and microstructure by means of Acoustic Emmission. The plastic deformation behavior of AISI 4340 steel of various microstructures was investigated in both the tensile and creep-fatigue testings with a view to providing new insights into properties of high performance steel. Based on Theory of Damage Mechanics, a creep-fatigue law was derived and formulated. The reason of early failure and the service life prophecy of high strength steels was studied.The damage micromechanism of four stages was studied by the optical microscope, scanning electron microscope, and microhardness tester. It seems that the nucleation and the growth of the voids at the martensiteferrite interface is the dominant mechanism of damage. The monitoring of Acoustic Emmission indicated that the plastic deformation did not appear in the circulating hardening stage. But in the circulating softening stage, the accumulation of the plastic deformation and the creep-fatigue damage become more and more severe. The total energy of Acoustic Emmission was successfully applied to measure the degree of the damage caused by the plastic deformation.

Creep-Fatigue Damage: An International Perspective

2007 ◽  
Author(s):  
David W. Gandy ◽  
Jonathan Parker
Keyword(s):  
Fatigue Damage ◽  
Impact Damage ◽  
International Perspective ◽  
Test Methods ◽  
Future Research ◽  
International Expert ◽  
Damage Initiation ◽  
Cyclic Operation ◽  
Creep Fatigue ◽  
Expert Workshop

Improved knowledge of creep and fatigue interactions is necessary today more than ever as power-generating plants are exposed to cyclic operation. Understanding factors that impact damage initiation and propagation, as well as technologies to predict accumulation of damage in systems and components are required. This paper summarizes the primary results of an International Expert Workshop on Creep-Fatigue Damage Interaction that was held in Amsterdam in July 2006. The purpose of the Expert Workshop was to bring together key industry experts from around the world to do the following: • Assess and document current creep-fatigue test methods; • Evaluate analytical methodologies with respect to crack initiation and growth; • Discuss life prediction methodologies for different applications; • Assess deficiencies that exist in the area of creep-fatigue damage; • Identify future research and development requirements. The International Expert Workshop resulted in 16 action items which are delineated in this paper. Updates will be provided on progress made to date toward addressing these 16 items.

Damage Mechanics-Finite Element Full-Couple Method to Predict the Fatigue Life of Metallic Material

2014 ◽  
Vol 707 ◽  
pp. 390-396
Author(s):  
Xian Min Chen ◽  
Di Guan ◽  
Feng Ping Yang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Fatigue Tests ◽  
Damage Initiation ◽  
Strain Threshold ◽  
Couple Method

A damage accumulation model is presented for fatigue life prediction of metallic structures. Based on the energy theory and material fatigue test data, the plastic strain threshold for damage initiation was modified for HCF and LCF respectively. The damage evolution parameters were determined according to the fatigue test results of standard specimens. A damage mechanics-finite element full-couple method was adopted to simulate the process of fatigue damage evolution, incorporating elastic modulus reduction due to fatigue damage. Comparisons are made with the fatigue tests of 2A12-T4 open-hole plates and good agreement was obtained.

Damage mechanics characterization on the fatigue behaviour of a solder joint material

2001 ◽  
Vol 215 (8) ◽  
pp. 883-892 ◽  
Author(s):  
C. L. Chow ◽  
F Yang ◽  
H. E. Fang
Keyword(s):  
Solder Joint ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Internal State ◽  
Damage Effect ◽  
Irreversible Processes ◽  
State Variables ◽  
Solder Material ◽  
Damage Initiation ◽  
Joint Material

This paper presents the first part of a comprehensive mechanics approach capable of predicting the integrity and reliability of solder joint material under fatigue loading without viscoplastic damage considerations. A separate report will be made to present the comprehensive damage model describing life prediction of the solder material under thermomechanical fatigue (TMF) loading. The method is based on the theory of damage mechanics, which makes possible a macroscopic description of the successive material deterioration caused by the presence of microcracks/voids in engineering materials. A damage mechanics model based on the thermodynamic theory of irreversible processes with internal state variables is proposed and used to provide a unified approach in characterizing the cyclic behaviour of a typical solder material. With the introduction of a damage effect tensor, the constitutive equations are derived to enable the formulation of a fatigue damage dissipative potential function and a fatigue damage criterion. The fatigue evolution is subsequently developed on the basis of the hypothesis that the overall damage is induced by the accumulation of fatigue and plastic damage. This damage mechanics approach offers a systematic and versatile means that is effective in modelling the entire process of material failure, ranging from damage initiation and propagation leading eventually to macrocrack initiation and growth. As the model takes into account the load history effect and the interaction between plasticity damage and fatigue damage, with the aid of a modified general-purpose finite element program, the method can readily be applied to estimate the fatigue life of solder joints under different loading conditions.

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