524 Effect of Density on Contact Fatigue Behavior and Damage Mechanism of Sintered Alloys

2001 ◽  
Vol 2001.9 (0) ◽  
pp. 409-410
Author(s):  
Makoto HORIKOSHI ◽  
Yukio MIYASHITA ◽  
Rajapa Gnanamoorthy ◽  
Jin-Quan XU ◽  
Yoshiharu MUTOH ◽  
...  
2001 ◽  
Vol I.01.1 (0) ◽  
pp. 309-310
Author(s):  
Makoto HORIKOSHI ◽  
Yukio MIYASHITA ◽  
Jin-Quan XU ◽  
Yoshiharu MUTOH ◽  
Hitoshi FUKUHARA

Author(s):  
Peitang Wei ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Haifeng He

Contact fatigue failures of gears, especially those used in heavy duty conditions such as wind turbine gears, become important issues in mechanical transmission industry. In the present work, a continuous damage mechanism and Voronoi-based finite element model is developed to investigate the contact fatigue of a wind turbine gear. Plane strain assumption is adopted to simplify the gear contact model. Voronoi tessellations are utilized to represent the microstructure topology of the gear material, and continuous damage mechanism is implemented to reflect the material degradation within critical substrate area. With the developed framework, the contact pressure distribution, intergranular mechanical response and the progressive fatigue damage at the grain boundaries during repeated gear meshing are evaluated and discussed in detail. The depths of the maximum shear stress reversal and the crack initiation agree well with previously reported findings. The influence of microstructure on the gear contact fatigue behavior is also investigated.


2019 ◽  
Vol 743 ◽  
pp. 314-321 ◽  
Author(s):  
Y.M. Liu ◽  
L. Wang ◽  
G. Chen ◽  
B.B. Li ◽  
X.H. Wang

Author(s):  
Guillermo E Morales-Espejel ◽  
Antonio Gabelli

The effects of kinematic sliding on rolling contact fatigue life have been discussed in many occasions, often with some disregard of the fundamental principles of tribology. In this paper, the authors’ intention is to discuss this issue with a perspective as objective as possible and performing a study on factual and known scientific knowledge, applying tribology modelling and methods. The effects of kinematic sliding of Hertzian contacts are studied from three different standpoints: (1) by analysing the combination of sliding speed and contact pressure giving rise to seizure, that is high instantaneous contact temperatures leading to film collapse, (2) by assessing the possible effects of sliding to surface traction and fatigue, (3) by discussing other possible effects of sliding in heavily loaded lubricated contacts as the concurrent damage mechanism caused by wear and rolling contact fatigue. Throughout the paper, different numerical models are presented and discussed alongside with some experimental data. This approach provides a comprehensive assessment of the various phenomena related to the kinematic sliding of rolling bearings. The different mechanisms involved and the interaction of sliding with the elastohydrodynamic lubricant film, frictional stress, wear and fatigue are discussed, and their significance to the performance of the bearing is qualified.


Author(s):  
S. Aksoy

A series of experiments were conducted to investigate the thermomechanical fatigue behavior of SiC(SCS-6)/Ti-6-4 composite. Three types of tests were conducted. In the first, specimens were subjected to load-controlled mechanical cycling under isothermal conditions. The other two types of test involved simultaneous cycling of load and temperature: in-phase and out-of-phase cycles. The effect of temperature cyclic ranges of 250°C to 528°C were evaluated for the out-of-phase (low temperature-high stress) conditions. A single temperature range of 250°C was employed for the in-phase (high temperature-high stress) condition. Fatigue-life diagrams were developed to evaluate the fatigue performance of the composite based on certain damage mechanism maps. In addition, micromechanical stresses in the fiber and matrix were computed using a generalized plane strain finite element analysis. The intention of this analytical effort was to provide the understanding of the fundamental mechanisms governing material behavior for guiding the development of life prediction methodology.


Author(s):  
Sung-Choong Woo ◽  
Nam Seo Goo

The aim of this study is to investigate fully reversed electric fatigue behavior of a piezoelectric composite actuator (PCA). For that purpose, fatigue tests with different loading conditions have been conducted and the performance degradation has been monitored. During a preset number of loading cycles, non-destructive acoustic emission (AE) tests were used for monitoring the damage evolution in real time. The displacement-cycle curves were obtained in fully reversed cyclic bending loading. The microstructures and fracture surfaces of PCA were examined to reveal their fatigue damage mechanism. The results indicated that the AE technique was applicable to fatigue damage assessment in the piezoelectric composite actuator. It was shown that the initial damage mechanism of PCAs under fully reversed electric cyclic loading originated from the transgranular fracture in the PZT ceramic layer; with increasing cycles, local intergranular cracking initiated and the either developed onto the surface of the PZT ceramic layer or propagated into the internal layer, which were some different depending on the drive frequencies and the lay-up sequence of the PCA.


2019 ◽  
Vol 366 ◽  
pp. 321-330 ◽  
Author(s):  
Ya-Long Zhang ◽  
Fu-Qiang Lai ◽  
Sheng-Guan Qu ◽  
Hai-Peng Liu ◽  
Dong-Sheng Jia ◽  
...  

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