Isothermal Fatigue of 62Sn–36Pb–2Ag Solder

1991 ◽  
Vol 226 ◽  
Author(s):  
Semyon Vaynhan ◽  
Morris E. Fine
Keyword(s):  
Fatigue Life ◽  
Hold Time ◽  
Strain Range ◽  
Effect Of Temperature ◽  
Total Strain Range ◽  
Isothermal Fatigue ◽  
Tensile Hold ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Compressive Hold

AbstractThis paper discusses the effects of the most important variables during isothermal fatigue such as strain range, ramp time, tensile and compressive hold times, and temperature on fatigue life of near–eutectic 62Sn–36Pb–2Ag solder at strain ranges below 3.0%. The Coffin-Manson relation does not hold for 62Sn–36Pb–2Ag solder below 1% strain range. Decreasing frequency below 10-2 in no-hold tests reduces the number of cycles to failure. Tensile hold time or compressive hold time alone in the cycle dramatically reduce the number of cycles to failure. Increase of hold time over a few minutes leads to saturation of Nf. Combined tensile and compressive hold times affect the fatigue life of this solder less than either tensile or compressive hold alone. The effect of hold times on fatigue life is much stronger than the effect of ramp time. Practically no ramp time effect was observed in tests with tensile hold times. Very little effect of temperature over the range 25 to 80°C on fatigue life of 62Sn–36Pb–2Ag solder was observed when tested at total strain range of 1%.

Isothermal Fatigue of 63Sn-37Pb Solder

1990 ◽  
Vol 112 (2) ◽  
pp. 110-114 ◽  
Author(s):  
E. C. Cutiongco ◽  
S. Vaynman ◽  
M. E. Fine ◽  
D. A. Jeannotte
Keyword(s):  
Fatigue Life ◽  
Hold Time ◽  
Strain Range ◽  
Maximum Tensile Stress ◽  
Air Cooling ◽  
Maximum Strain ◽  
Total Strain Range ◽  
Plastic Strain Range ◽  
Isothermal Fatigue ◽  
Cycles To Failure

The effects of aging, strain range, hold time at maximum strain and temperature on the isothermal fatigue life of bulk 63Sn-37Pn solder samples over the total strain range (Δ εT) from 0.3 to 3.0 percent (tension-tension) and within the temperature range of 25° C to 100° C were studied. The cycles to failure (Nf) were defined as the number of cycles at which the ratio of the maximum tensile stress to the maximum compressive stress starts to drop appreciably. Fatigue life increases rapidly after a day or two of aging after heat treatment at 150° C for 2 hours followed by air cooling but levels off after a week. The log of fatigue life decreases linearly with increasing log of plastic strain range above Δ εT = 0.6 percent. Hold time at maximum strain dramatically decreases the cycles to failure, however, an increase of hold time more than a few minutes eventually leads to a constant Nf. Temperature variation from 25°C to 100° C was found to have little effect on the fatigue life of the solder in tests with and without hold time. Separation of Pb-rich and Sn-rich phases and cracking of the Sn-rich phases are the main modes of fracture under all conditions used. Damage is concentrated along crisscrossing shear bands oriented approximately 45 deg to the load direction.

Tensile and Fatigue Properties of Miniature Size Specimens of Sn-5Sb Lead-Free Solder

2016 ◽  
Vol 879 ◽  
pp. 2377-2382 ◽  
Author(s):  
Kyosuke Kobayashi ◽  
Ikuo Shohji ◽  
Hiroaki Hokazono
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Phase Boundary ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Total Strain ◽  
Effect Of Temperature ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Total Strain Range

Tensile and low cycle fatigue properties of Sn-5Sb (mass%) solder were investigated with miniature size tensile specimens. The effect of temperature and strain rate on tensile properties and the effect of temperature on low cycle fatigue properties were examined. Tensile strength increases with increasing strain rate regardless of temperature investigated. For elongation, the effect of temperature on it is negligible although it slightly increases with increasing strain rate. The low cycle fatigue life of Sn-5Sb obeys by the Manson-Coffin’s equation. The effect of temperature on the fatigue life is negligible in the temperature range from 25 oC to 150 oC. In the low cycle fatigue test with a high total strain range of 4%, cracking at phase boundary mainly occurs regardless of temperature investigated. In the case of a low total strain range of 0.4%, ductile fracture mainly occurs, and cracking at phase boundary with generation of grooves also occurs at high temperature.

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 Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 307
Author(s):  
Matthias Bruchhausen ◽  
Gintautas Dundulis ◽  
Alec McLennan ◽  
Sergio Arrieta ◽  
Tim Austin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Rate ◽  
Power Plants ◽  
Research Effort ◽  
Hold Time ◽  
Strain Range ◽  
Austenitic Steels ◽  
Mean Strain

A substantial amount of research effort has been applied to the field of environmentally assisted fatigue (EAF) due to the requirement to account for the EAF behaviour of metals for existing and new build nuclear power plants. We present the results of the European project INcreasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment (INCEFA-PLUS), during which the sensitivities of strain range, environment, surface roughness, mean strain and hold times, as well as their interactions on the fatigue life of austenitic steels has been characterized. The project included a test campaign, during which more than 250 fatigue tests were performed. The tests did not reveal a significant effect of mean strain or hold time on fatigue life. An empirical model describing the fatigue life as a function of strain rate, environment and surface roughness is developed. There is evidence for statistically significant interaction effects between surface roughness and the environment, as well as between surface roughness and strain range. However, their impact on fatigue life is so small that they are not practically relevant and can in most cases be neglected. Reducing the environmental impact on fatigue life by modifying the temperature or strain rate leads to an increase of the fatigue life in agreement with predictions based on NUREG/CR-6909. A limited sub-programme on the sensitivity of hold times at elevated temperature at zero force conditions and at elevated temperature did not show the beneficial effect on fatigue life found in another study.

Riveted single lap joints Part 2: Fatigue life prediction

1997 ◽  
Vol 211 (2) ◽  
pp. 123-128 ◽  
Author(s):  
C-P Fung ◽  
J Smart
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Effective Stress ◽  
Fatigue Testing ◽  
Strain Range ◽  
Lap Joints ◽  
Total Strain Range ◽  
Single Lap Joints ◽  
Data Points ◽  
Fretting Damage

Fatigue lives of snap and countersunk riveted single lap joints with either one-row or two- rows of rivets have been predicted with fatigue laws using either local total strain range or effective stress obtained from finite element analyses and data obtained from fatigue testing of plates with holes. The finite element models of the joints were subjected to an alternating cyclic load; plasticity and nonlinear geometry are considered. The failures have also been metallurgically examined and gave evidence of fretting damage. It was found that all the data points lie within a narrow band using the strain-life law although the band is wider when using the effective stress-life law, but it is impossible to predict the fatigue life from one kind of specimen to another using the conventional stress-life law.

Creep-Fatigue Properties of the Candidate Materials of 700°C-USC Boiler

2007 ◽  
Author(s):  
Keiji Kubushiro ◽  
Hiroki Yoshizawa ◽  
Takuya Itou ◽  
Hirokatsu Nakagawa
Keyword(s):  
Hold Time ◽  
Strain Range ◽  
Small Strain ◽  
Fatigue Tests ◽  
Holding Time ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Alloy 617 ◽  
Creep Fatigue ◽  
Cycles To Failure

Creep-fatigue properties of candidate materials of 700°C-USC boiler are investigated. The candidate materials are Alloy 230, Alloy 263, Alloy 617 and HR6W. Creep-fatigue tests were conducted at 700°C and the effect of both strain range and hold time were studied. Experimental results showed that at 1.0% strain range, cycles to failure with 60 min strain holding is about 10% of that without strain holding, but at 0.7% strain range, cycles to failure with 60 min strain holding decreases down to about 1% of without strain holding. It appears that cycles to failure is decreased by increasing strain holding time at all tested strain ranges, and the effect of holding time is emphasized at small strain range. These phenomena depend on the kind of alloys.

scholarly journals Determination of the Creep-Fatigue Interaction Diagram for Alloy 617

2016 ◽  
Author(s):  
J. K. Wright ◽  
L. J. Carroll ◽  
T.-L. Sham ◽  
N. J. Lybeck ◽  
R. N. Wright
Keyword(s):  
Fatigue Testing ◽  
Hold Time ◽  
Strain Range ◽  
Fatigue Tests ◽  
Alloy 617 ◽  
Interaction Diagram ◽  
Creep Fatigue ◽  
Intermediate Heat Exchanger ◽  
Cycles To Failure

Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor (VHTR). As part of evaluating the behavior of this material in the expected service conditions, creep–fatigue testing was performed. The cycles to failure decreased compared to fatigue values when a hold time was added at peak tensile strain. At 850°C, increasing the tensile hold duration continued to degrade the creep–fatigue resistance, at least to the investigated strain–controlled hold time of up to 60 minutes at the 0.3% strain range and 240 minutes at the 1.0% strain range. At 950°C, the creep–fatigue cycles to failure are not further reduced with increasing hold duration, indicating saturation occurs at relatively short hold times. The creep and fatigue damage fractions have been calculated and plotted on a creep–fatigue interaction D–diagram. Test data from creep–fatigue tests at 800 and 1000°C on an additional heat of Alloy 617 are also plotted on the D–diagram.

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