Effect of Cyclic Strain-Hardening Exponent on Fatigue Ductility Exponent for Sn Based Alloy

2011 ◽  
Author(s):  
Yoshihiko Kanda ◽  
Yuji Oto ◽  
Yusuke Shiigi ◽  
Yoshiharu Kariya
Keyword(s):  
Solid Solution ◽  
Strain Hardening ◽  
Creep Damage ◽  
Cyclic Strain ◽  
Damage Mechanism ◽  
Strain Hardening Exponent ◽  
Large Size ◽  
Grain Boundary Fracture ◽  
Boundary Fracture ◽  
Compound Particle

The influence of cyclic strain-hardening exponents on fatigue ductility exponents for Sn-Bi solid solution alloys and Sn-Ag-Cu microsolder joints was investigated. In Sn-Bi solid solution alloys, the fatigue ductility exponent in Coffin-Manson’s law was confirmed to increase with a decrease in the cyclic strain-hardening exponent. On the other hand, in the Sn-Ag-Cu miniature solder joint, the fatigue ductility exponent increases with a rise in temperature and strain holding. Thus, the fatigue ductility exponents are closely related to the cyclic strain-hardening exponent: the former increases due to the depression of the latter with a rise in temperature and increase in intermetallic compound particle size during strain holding. The results differ for the creep damage mechanism (grain boundary fracture), which is the main reason for the life depression in large-size specimens.

scholarly journals Numerical Study of Thermal Shock Damage Mechanism of Polycrystalline Ceramics

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhenyuan Gong ◽  
Kang Guan ◽  
Pinggen Rao ◽  
Qingfeng Zeng ◽  
Jiantao Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Critical Stress ◽  
Crack Nucleation ◽  
Damage Mechanism ◽  
Shock Resistance ◽  
Grain Boundary Fracture ◽  
Boundary Fracture

A dual-scale model is proposed to study the effect of microstructure parameters (grain size and grain boundary fracture energy) on the thermal shock damage mechanism on an example of alumina. At microscale, representative volume element (RVE) models generated by Voronoi tessellation are simulated to obtain the mechanical parameters for macro models. At macroscale, a coupled thermomechanical model based on the finite–discrete element method (FDEM) is applied to simulate the crack nucleation and propagation. Energy dissipation (ALLDMD) is introduced to investigate the thermal shock cracking mechanism by combining crack patterns and crack density, which indicates that decreasing grain size and increasing grain boundary fracture energy have a positive effect on thermal shock resistance. The proposed models not only predict the critical stress temperature which is well consistent to the theoretical thermal shock resistance factor, but also quantify the two previously unconsidered stages (crack nucleation and crack instability stage). Our models suggest the crack nucleation and instability will not occur immediately when the model reaches critical stress, but the models can sustain for higher temperature difference. The thermal shock damage mechanism and the influence of microstructural parameters on thermal shock resistance have also been discussed in detail.

Effect of T6 Treatment on Low-Cycle Fatigue Properties of Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc Alloy

2014 ◽  
Vol 664 ◽  
pp. 28-33
Author(s):  
Ying Lan ◽  
Li Jia Chen ◽  
Xin Che ◽  
Feng Li
Keyword(s):  
Strain Hardening ◽  
Low Cycle Fatigue ◽  
Aging Treatment ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cyclic Strength ◽  
Fatigue Properties ◽  
Strain Hardening Exponent ◽  
Cycle Fatigue ◽  
Linear Behavior

The low-cycle fatigue behaviors of as-extruded and T6 treated Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloys at room temperature have been investigated under those total-strain amplitudes ranged from 0.3% to 1.0%, and the influence of T6 treatment on the low-cycle fatigue properties of Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy was clarified. The experimental results show that during fatigue deformation, the significant cyclic strain hardening and stable cyclic stress response can be noted for both as-extruded and T6 treated Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloys. The fatigue life of as-extruded Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy at all strain amplitudes is longer than that of the alloy subjected to T6 aging treatment. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively. The T6 treatment can significantly increase the cyclic strain hardening exponent and cyclic strength coefficient of extruded Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy.

Estimation of Cyclic Strain Hardening Exponent and Cyclic Strength Coefficient of Steels by Artificial Neural Networks

2008 ◽  
Author(s):  
R. Ghajar ◽  
J. Alizadeh K. ◽  
N. Naserifar
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Strain Hardening ◽  
Cyclic Strain ◽  
Cyclic Strength ◽  
True Stress ◽  
Strain Hardening Exponent ◽  
Strength Coefficient ◽  
Cyclic Strength Coefficient ◽  
Artificial Neural

The objective of this paper is to demonstrate the applicability of artificial neural networks on estimation of the cyclic strain hardening exponent and cyclic strength coefficient of steels on the basis of monotonic tensile tests properties. In order to demonstrate this applicability, steels tensile data was extracted from the literatures and two separate neural networks was conducted. One set of data was used for training networks and remaining of data for testing them. The regression analysis was used to check the system accuracy for training and test data at the end of learning. Comparing results of neural networks with values obtained from direct fitting of experimental data was indicated that cyclic strain hardening exponent and cyclic strength coefficient, which characterize the stable curves of true stress amplitude versus true plastic strain amplitude, were predicted reasonable. It was concluded that predicted stable cyclic true stress-strain curve properties by trained neural network are more accurate compared to approximate relations based on low-cycle fatigue properties.

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