Author
Farshid Sadeghi
Other affiliations: University of Mohaghegh Ardabili
Bio: Farshid Sadeghi is an academic researcher from Purdue University. The author has contributed to research in topics: Lubrication & Damage mechanics. The author has an hindex of 40, co-authored 220 publications receiving 5395 citations. Previous affiliations of Farshid Sadeghi include University of Mohaghegh Ardabili.
Papers published on a yearly basis
Papers
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TL;DR: In this article, some of the most widely used RCF models are reviewed and discussed, and their limitations are addressed, and the modeling approaches recently proposed by the authors to develop life models and better understanding of the RCF.
Abstract: Ball and rolling element bearings are perhaps the most widely used components in industrial machinery. They are used to support load and allow relative motion inherent in the mechanism to take place. Subsurface originated spalling has been recognized as one of the main modes of failure for rolling contact fatigue (RCF) of bearings. In the past few decades a significant number of investigators have attempted to determine the physical mechanisms involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives. In this paper, some of the most widely used RCF models are reviewed and discussed, and their limitations are addressed. The paper also presents the modeling approaches recently proposed by the authors to develop life models and better understanding of the RCF.
438 citations
TL;DR: In this article, an elastic-plastic Voronoi finite element (EPVFE) model for rolling contact fatigue of Hertzian line contact was developed and the results indicated that material flaws within the domain lead to a significant decrease in fatigue lives and increase in life scatter.
120 citations
TL;DR: In this paper, a six-degree-of-freedom model was developed and used to simulate the motion of all elements in a cylindrical roller bearing and three different roller profiles have been used to study their impact on cage dynamics.
Abstract: A six-degree-of-freedom model was developed and used to simulate the motion of all elements in a cylindrical roller bearing. Cage instability has been studied as a function of the roller-race and roller-cage pocket clearances for light-load and high-speed conditions. The effects of variation in inner race speed, misalignment, cage asymmetry, and varying size of one of the rollers have been investigated. In addition, three different roller profiles have been used to study their impact on cage dynamics. The results indicate that the cage exhibits stable motion for small values of roller-race and roller-cage pocket clearances. A rise in instability leads to discrete cage-race collisions with high force magnitudes. Race misalignment leads to a rise in instability for small roller-cage pocket clearances since skew control is provided by the sides of the cage pocket. One roller of larger size than the others causes inner race whirl and leads to stable cage motion for small roller-race clearances without any variation in roller-cage pocket clearance. Cage asymmetry and different roller profiles have a negligible impact on cage motion.
117 citations
TL;DR: In this paper, an explicit finite element model was developed to investigate crack initiation and spall formation in machine elements subject to rolling contact fatigue, which utilizes continuum damage mechanics to capture the initiation and propagation of fatigue damage that leads to the formation of surface spall.
109 citations
TL;DR: The significantly better tribological performance of the hybrid lubricant is attributed to the perfectly spherical shape and ultrasmooth surface of carbon sphere additive filling the gap between surfaces and acting as a nanoscale ball bearing.
Abstract: Ultrasmooth submicrometer carbon spheres are demonstrated as an efficient additive for improving the tribological performance of lubricating oils. Carbon spheres with ultrasmooth surfaces are fabricated by ultrasound assisted polymerization of resorcinol and formaldehyde followed by controlled heat treatment. The tribological behavior of the new lubricant mixture is investigated in the boundary and mixed lubrication regimes using a pin-on-disk apparatus and cylinder-on-disk tribometer, respectively. The new lubricant composition containing 3 wt % carbon spheres suspended in a reference SAE 5W30 engine oil exhibited a substantial reduction in friction and wear (10–25%) compared to the neat oil, without change in the viscosity. Microscopic and spectroscopic investigation of the carbon spheres after the tribological experiments illustrated their excellent mechanical and chemical stability. The significantly better tribological performance of the hybrid lubricant is attributed to the perfectly spherical shape...
106 citations
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31 Oct 2001
TL;DR: The American Society for Testing and Materials (ASTM) as mentioned in this paper is an independent organization devoted to the development of standards for testing and materials, and is a member of IEEE 802.11.
Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.
3,792 citations
TL;DR: This survey is the first to bring to the attention of the controls community the important contributions from the tribology, lubrication and physics literatures, and provides a set of models and tools for friction compensation which will be of value to both research and application engineers.
2,658 citations
01 Apr 2002
TL;DR: This report surveys a number of possible combination rules for Dempster-Shafer structures and provides examples of the implementation of these rules for discrete and interval-valued data.
Abstract: Dempster-Shafer theory offers an alternative to traditional probabilistic theory for the mathematical representation of uncertainty. The significant innovation of this framework is that it allows for the allocation of a probability mass to sets or intervals. Dempster-Shafer theory does not require an assumption regarding the probability of the individual constituents of the set or interval. This is a potentially valuable tool for the evaluation of risk and reliability in engineering applications when it is not possible to obtain a precise measurement from experiments, or when knowledge is obtained from expert elicitation. An important aspect of this theory is the combination of evidence obtained from multiple sources and the modeling of conflict between them. This report surveys a number of possible combination rules for Dempster-Shafer structures and provides examples of the implementation of these rules for discrete and interval-valued data.
1,033 citations
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TL;DR: In this paper, the structure and properties of bearing steels prior to the point of service are first assessed and described in the context of steelmaking, manufacturing and engineering requirements, followed by a thorough critique of the damage mechanisms that operate during service and in accelerated tests.
729 citations
TL;DR: A review of the commonly used models for rolling resistance and a more general model is presented in this article, where the robustness of these models in reproducing rolling resistance effects arising from different physical situations was assessed by using several benchmarking test cases.
680 citations