Influence of Ball Material on Deformation in Non-Conforming Contact Ball Elements
Suresha Gowda M. V1, Vidyasagar H. N2, Ranganatha S3
1Suresha Gowda M. V, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, (Karnataka), India.
2Dr. Vidyasagar H. N, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, (Karnataka), India.
4Dr. Ranganatha S, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, (Karnataka), India.
Manuscript received on 20 January 2016 | Revised Manuscript received on 30 January 2016 | Manuscript published on 30 January 2016 | PP: 1-9 | Volume-4 Issue-6, January 2016 | Retrieval Number: F1511014616©BEIESP
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Abstract: The life of machine element is important in industry so that the equipment is more reliable and economical in operation. Machineries invariably used rolling elements. The performance of these rolling elements depends on stress state. The deformation which is complicated in such elements depends on the type of materials used to manufacture the elements and nature of loading. The loads are in general repetitive in nature and hence the deformation becomes much more complicated. Such complicated deformation is also called as rolling contact fatigue (RCF). The state of stress is evaluated using Hertz’s stress contact theory. Such estimated stress could be used to predict deformations. The repetitive loading accompanied by Hertz’s type of contact stresses leads to complication in design in such rolling elements. The literature study showed that not much of work carried out in understanding the complex deformation due to cyclic Hertz contact stresses. In the present study a four ball test rig (ASTM D 4172 standard) was used to simulate the field conditions of the bearing element. The studies were carried out both for static and dynamic conditions. High carbon high chromium steel balls are used for static study. High carbon high chromium steel, case hardened carbon steel and stainless steel balls are used for dynamic study. Lubricant SAE 20W40 was used in dynamic test. The dynamic test was carried at a 1000 rpm at varying load levels of 50N, 100N, 150N, 300N, 500N, 700N and 900N. The experiments were conducted for a period of 30 minutes. The contact radius in case of static test and co-efficient of friction in case of dynamic test was estimated. Scanning electron micrographic studies were carried on wear scar. The wear grooves which represent the non-uniform deformations were observed to be dependent on load level and type of material. At higher load level the deformation was found to be uniform with the absence of wear grooves for all materials. In general the co-efficient of friction was found to depend on the applied normal load. There was a correlation between co-efficient of friction and state of deformation.
Keywords: Rolling contact fatigue, Four ball tester, Hertz contact stress
Scope of the Article: Materials Engineering