Actuation Fatigue Life Prediction of Notched Shape Memory Alloy Members

2019 ◽  
Vol 86 (6) ◽  
Author(s):  
Md Mehedi Hasan ◽  
Theocharis Baxevanis
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fatigue Damage ◽  
Life Prediction ◽  
Notch Root ◽  
Fatigue Life Prediction ◽  
Critical Plane ◽  
Plane Model ◽  
Root Region

The efficiency of the critical plane model of Smith, Watson, and Topper in estimating fatigue life for loaded notched shape memory alloy members undergoing thermal cycling is demonstrated. The field intensity approach is adopted, which characterizes fatigue damage over a critical notch root region rather than at a critical point.

Fatigue Behaviour of Lead-Free Solder Interconnections in Life Prediction of Trilayer Structures Subjected to Thermal Cycling

2015 ◽  
Author(s):  
Alireza Shirazi ◽  
Hua Lu ◽  
Ahmad Varvani-Farahani
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Life Prediction ◽  
Damage Parameter ◽  
Fatigue Life Prediction ◽  
Lead Free Solder ◽  
Critical Plane ◽  
Trilayer Structure ◽  
Fatigue Damage Parameter ◽  
Free Solder

Trilayer structures such as flip chip plastic ball grid array (FC-PBGA) packages are bodies made of a large variety of dissimilar materials. Due to the coefficients of thermal expansion (CTE) mismatches between and temperature gradients within the layers, thermally induced interaction becomes a typical type of the loads for the joint layer made of lead-free solder joint interconnections. Thermal stresses and strains at the interfaces of solder joints and neighboring adhesive layers are the cause for solder joint fatigue failures, which account for the most common package failures. The current study puts forward a fatigue life prediction method for a trilayer structure using the critical plane-energy fatigue damage parameter in combination with the modified Coffin-Manson life model. The proposed method of calculated fatigue damage parameter for the samples of study, along with their experimental life (Nf50%) under two different thermal conditions is presented. The values of life in (0–100°C) condition and (25–125°C) with the same temperature ramp rate and dwell conditions are found to differ by a factor of 1.3 where the structures tested under (0–100°C) condition show lower lives. The present study further correlated the fatigue damage parameters with the Coffin-Manson type equation to calculate/predict the fatigue life of structures under (25–125°C) condition. The results of the Nf50 fatigue life prediction versus the experimental cycles show that the predicted lives of samples with SAC305 solder joints fall apart with a factor ranging from (1.24)∼(−1.45). The advantage of the proposed method in comparison with the existing methods in life prediction of the trilayer structure with solder alloy is that there are no empirical parameters involved in energy-critical plane damage parameter in life prediction of the trilayer structure. Parameters within the proposed approach purely involves mechanical and fatigue properties of the midlayer alloy.

scholarly journals A sectional critical plane model for multiaxial high-cycle fatigue life prediction

2020 ◽  
Author(s):  
Xinxin Qi ◽  
Tianqi Liu ◽  
Xinhong Shi ◽  
Jiaying Wang ◽  
Jianyu Zhang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Plane Model

A weight function method for multiaxial low-cycle fatigue life prediction under variable amplitude loading

2018 ◽  
Vol 53 (4) ◽  
pp. 197-209 ◽  
Author(s):  
Xiao-Wei Wang ◽  
De-Guang Shang ◽  
Yu-Juan Sun
Keyword(s):  
Fatigue Life ◽  
Weight Function ◽  
Life Prediction ◽  
Function Method ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Variable Amplitude ◽  
Weight Function Method

A weight function method based on strain parameters is proposed to determine the critical plane in low-cycle fatigue region under both constant and variable amplitude tension–torsion loadings. The critical plane is defined by the weighted mean maximum absolute shear strain plane. Combined with the critical plane determined by the proposed method, strain-based fatigue life prediction models and Wang-Brown’s multiaxial cycle counting method are employed to predict the fatigue life. The experimental critical plane orientation and fatigue life data under constant and variable amplitude tension–torsion loadings are used to verify the proposed method. The results show that the proposed method is appropriate to determine the critical plane under both constant and variable amplitude loadings.

scholarly journals Strain energy-based rubber fatigue life prediction under the influence of temperature

2018 ◽  
Vol 5 (10) ◽  
pp. 180951 ◽  
Author(s):  
Jingnan Zhang ◽  
Fengxian Xue ◽  
Yue Wang ◽  
Xin Zhang ◽  
Shanling Han
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Fatigue Damage ◽  
Strain Energy ◽  
Life Prediction ◽  
Least Square ◽  
Fatigue Life Prediction ◽  
Uniaxial Tensile ◽  
Influence Of Temperature ◽  
Different Temperatures

Aiming at the problem of the fatigue life prediction of rubber under the influence of temperature, the effects of thermal ageing and fatigue damage on the fatigue life of rubber under the influence of temperature are analysed and a fatigue life prediction model is established by selecting strain energy as a fatigue damage parameter based on the uniaxial tensile data of dumbbell rubber specimens at different temperatures. Firstly, the strain energy of rubber specimens at different temperatures is obtained by the Yeoh model, and the relationship between it and rubber fatigue life at different temperatures is fitted by the least-square method. Secondly, the function formula of temperature and model parameters is obtained by the least-square polynomial fitting. Finally, another group of rubber specimens is tested at different temperatures and the fatigue characteristics are predicted by using the proposed prediction model under the influence of temperature, and the results are compared with the measured results. The results show that the predicted value of the model is consistent with the measured value and the average relative error is less than 22.26%, which indicates that the model can predict the fatigue life of this kind of rubber specimen at different temperatures. What's more, the model proposed in this study has a high practical value in engineering practice of rubber fatigue life prediction at different temperatures.

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