Life Prediction of Solder Joints by Damage and Fracture Mechanics

1996 ◽  
Vol 118 (4) ◽  
pp. 193-200 ◽  
Author(s):  
S. H. Ju ◽  
B. I. Sandor ◽  
M. E. Plesha
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Damage Mechanics ◽  
Solder Joints ◽  
Continuum Damage Mechanics ◽  
Computer Time ◽  
Initial Crack ◽  
Continuum Damage ◽  
Growth Path

Much research has been done on Surface Mount Technology (SMT) using the Finite Element Method (FEM). Little of this, however, has employed fracture mechanics and/or continuum damage mechanics. In this study, we propose two finite element approaches incorporating fracture mechanics and continuum damage mechanics to predict time-dependent and temperature-dependent fatigue life of solder joints. For fracture mechanics, the J-integral fatigue formula, da/dN = C(δJ)m, is used to quantify fatigue crack growth and the fatigue life of J-leaded solder joints. For continuum damage mechanics, the anisotropic creep-fatigue damage formula with partially reversible damage effects is used to find the initial crack, crack growth path, and fatigue life of solder joints. The concept of partially reversible damage is especially novel and, based on laboratory tests we have conducted, appears to be necessary for solder joints undergoing cyclic loading. Both of these methods are adequate to predict the fatigue life of solder joints. The advantage of the fracture mechanics approach is that little computer time is required. The disadvantage is that assumptions must be made on the initial crack position and the crack growth path. The advantage of continuum damage mechanics is that the initial crack and its growth path are automatically evaluated, with the temporary disadvantage of requiring a lot of computer time.

Numerical estimation of fretting fatigue life of bolted joints using continuum damage mechanics and SEAM Tool

2020 ◽  
Vol 23 (11) ◽  
pp. 2486-2499
Author(s):  
Xinhao Lin ◽  
Yazhou Xu ◽  
Hui Zhang ◽  
Qianqian Ren ◽  
Junqi Yu
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Initial Crack ◽  
Bolted Joints ◽  
Propagation Path ◽  
Continuum Damage ◽  
Tightening Torque

For fretting fatigue, micro-slipping often causes initial micro-cracks in the contact surfaces, which gradually propagate and eventually result in fracture failure. However, it is difficult to directly observe and measure the crack initiation and propagation processes of single-lap bolted joints due to the obstacle of testing technique. Therefore, this article presents an elastic analysis–based method, in which the total fretting fatigue lifetime is divided into initiation life predicted by continuum damage mechanics and propagation life calculated by SEAM Tool in combination with Paris’s law. Since the initiation life model implicitly reflects the result of damage process, one can directly calculate the initiation life based on the elastic stress analysis. The predicted fretting fatigue life, initial crack location, and propagation path are in reasonable agreement with the fretting fatigue test and scanning electron microscope observation results. In addition, it is found that among the main factors affecting fretting fatigue of steel single-lap bolted joints, the initial life is affected by cyclic stress, friction coefficient, and tightening torque, and the propagation path is mainly influenced by tightening torque.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

scholarly journals A Review on Fatigue Life Prediction Methods for Metals

2016 ◽  
Vol 2016 ◽  
pp. 1-26 ◽  
Author(s):  
E. Santecchia ◽  
A. M. S. Hamouda ◽  
F. Musharavati ◽  
E. Zalnezhad ◽  
M. Cabibbo ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Fatigue Life Prediction ◽  
Continuum Damage ◽  
Metallic Materials ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

Metallic materials are extensively used in engineering structures and fatigue failure is one of the most common failure modes of metal structures. Fatigue phenomena occur when a material is subjected to fluctuating stresses and strains, which lead to failure due to damage accumulation. Different methods, including the Palmgren-Miner linear damage rule- (LDR-) based, multiaxial and variable amplitude loading, stochastic-based, energy-based, and continuum damage mechanics methods, forecast fatigue life. This paper reviews fatigue life prediction techniques for metallic materials. An ideal fatigue life prediction model should include the main features of those already established methods, and its implementation in simulation systems could help engineers and scientists in different applications. In conclusion, LDR-based, multiaxial and variable amplitude loading, stochastic-based, continuum damage mechanics, and energy-based methods are easy, realistic, microstructure dependent, well timed, and damage connected, respectively, for the ideal prediction model.

Sign in / Sign up

Export Citation Format

Share Document