A Numerical Model for the Identification of the Structural Damages in Rolling Contact Bearings Using Matrix Method of Dimensional Analysis

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
I. M. Jamadar ◽  
D. P. Vakharia

The damages to the structural elements, viz., inner race, outer race, rollers, cage, etc., of rolling contact bearings if not detected in time can cause tragic failures of the machineries supported by these bearings. The operating parameters like variations in the machinery speed, unbalance, operating load, etc., can cause a bearing to vibrate at higher energy levels and consequently will accelerate its wear. An attempt is made in this study, and a generalized model is developed using matrix method of dimensional analysis (MMDA) that predicted the response and correlated the dependent parameter, i.e., response with the significant independent parameters. Combined use of response surface methodology (RSM) is made to explore the dependence of various factors such as size of the defect, unbalance, speed, and their interactions on the vibration characteristics of the bearings. It is observed from the study that the model developed based on the MMDA has provided an efficient approach in recognizing the damaged bearing state, which can be easily implemented in the condition-based preventive maintenance strategies. Also, the effectiveness of MMDA as compared to the conventional Buckingham's pi theorem in the dimensional analysis (DA) practice, especially in the problems involving multiple variables, is shown in this study.

Author(s):  
Luiz R. Sobenko ◽  
José A. Frizzone ◽  
Antonio P. de Camargo ◽  
Ezequiel Saretta ◽  
Hermes S. da Rocha

ABSTRACT Venturi injectors are commonly employed for fertigation purposes in agriculture, in which they draw fertilizer from a tank into the irrigation pipeline. The knowledge of the amount of liquid injected by this device is used to ensure an adequate fertigation operation and management. The objectives of this research were (1) to carry out functional tests of Venturi injectors following requirements stated by ISO 15873; and (2) to model the injection rate using dimensional analysis by the Buckingham Pi theorem. Four models of Venturi injectors were submitted to functional tests using clean water as motive and injected fluid. A general model for predicting injection flow rate was proposed and validated. In this model, the injection flow rate depends on the fluid properties, operating hydraulic conditions and geometrical characteristics of the Venturi injector. Another model for estimating motive flow rate as a function of inlet pressure and differential pressure was adjusted and validated for each size of Venturi injector. Finally, an example of an application was presented. The Venturi injector size was selected to fulfill the requirements of the application and the operating conditions were estimated using the proposed models.


2010 ◽  
Vol 148-149 ◽  
pp. 702-706
Author(s):  
Liang Han ◽  
Rong Du

The paper analyzes the application of traditional Boston matrix method and three dimensional analysis chart method on product portfolio of metallurgical enterprise, and raises a four dimensional analysis method by inheriting their advantages and improve disadvantages. It is more effectively and practically to establish optimum product portfolio of domestic metallurgical enterprise by the four dimensional analysis method and the four elements are market share, sales growth rate, profitability and sales efficiency. When metallurgical enterprises analyze the optimum product portfolio using four dimensional analysis method, they should take sales efficiency fully into account, adjust product portfolio timely and at last realize the optimum product portfolio.


1968 ◽  
Vol 90 (1) ◽  
pp. 106-112 ◽  
Author(s):  
R. J. Parker ◽  
E. N. Bamberger ◽  
E. V. Zaretsky

Several lubricants that are considered candidates for ball bearing applications in the temperature range of 500 to 700 deg F were investigated in full-scale ball bearings and in a rolling-contact fatigue rig. Bearing endurance tests indicate that a synthetic paraffinic oil with an antiwear additive can perform beyond catalog rating at temperatures up to 600 deg F in a low oxygen environment. In a rolling-contact fatigue tester, this synthetic paraffinic oil exhibited at least twice the fatigue life at the 10 percent level of a fluorocarbon and a polyphenyl ether. Based on bearing race groove appearance, elasto-hydrodynamic lubrication was apparent at outer-race temperatures up to 700 deg F.


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