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8 articles for “T. Costopoulos”
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Research ArticleOpen accessIn the author namesTHE ADVERSE EFFECT OF STEEL PARTICLE CONTAMINANTS ON FATIGUE LIFE OF GREASE LUBRICATED BALL BEARINGSA. Stathis, Th. Costopoulos, D. Koulocheris, K. RaptisThe rating life of ball bearings is reduced when hard particle contaminants are present in the lubricant. Usually, this life reduction is taken into account in the calculation of modified rating life by using the contamination factor through a general characterization of the lubrication conditions. However, the impact of contaminant’s variables such as size, hardness and concentration level has to … …American Journal of Applied Sciences, Vol. 11, Issue 9 · 14 Jul 2014 · 6,991 accessesView PDFCite
Research ArticleOpen accessIn the author namesOperational Fault Diagnosis in Industrial Hydraulic Systems Through Modeling The Internal Leakage of its ComponentsP. Athanasatos, D. Koulocheris, T. Costopoulos, K. RaptisIn this study, a model of a high pressure hydraulic system was developed using the bond graph method to investigate the effect of the internal leakage of its main components (pump, cylinder and 4/2 way valve) on the operational characteristics of the system under various loads. All the main aspects of the hydraulic circuit (like the internal leakages, the compressibility … …American Journal of Applied Sciences, Vol. 10, Issue 12 · 7 Nov 2013 · 7,247 accessesView PDFCite
Research ArticleOpen accessIn the author namesComparison Between Niemann’s and Finite Element Method for the Estimation of Maximum Allowable Stress of Meshing Spur Gear Teeth at Highest Point of Single Tooth ContactKonstandinos G. Raptis, Theodore N. Costopoulos, Andonios D. TsolakisPurpose of this study is the consideration of loading and contact problems encountered at rotating machine elements and especially at toothed gears. The later are some of the most commonly used mechanical components for rotary motion and power transmission. This fact proves the necessity for improved reliability and enhanced service life, which require precise and clear knowledge of the stress … …American Journal of Engineering and Applied Sciences, Vol. 5, Issue 2 · 27 Aug 2012 · 7,759 accessesView PDFCite
Research ArticleOpen accessIn the author namesExperimental Study of Load Sharing in Roller-Bearing Contact by Caustics and PhotoelasticityKonstandinos G. Raptis, George A. Papadopoulos, Theodore N. Costopoulos, Andonios D. TsolakisProblem statement: In this study a comprehensive methodology for calculating load sharing in Roller-bearing contact was presented based on the experimental stress-optical method of caustics and Photoelasticity. Approach: The theoretical equations describing the geometry of transmitted caustic in relation to the length of the contact zone were derived and a simple mathematical set of equations correlating the maximum diameter of … …American Journal of Engineering and Applied Sciences, Vol. 4, Issue 2 · 13 Jul 2011 · 8,397 accessesView PDFCite
Research ArticleOpen accessIn the author namesRating of Spur Gear Strength Using Photoelasticity and the Finite Element MethodKonstandinos G. Raptis, Theodore N. Costopoulos, Georgios A. Papadopoulos, Αndonios D. TsolakisProblem statement: Toothed gears are some of the most used machine elements for motion and power transmission between rotating shafts. This fact induces the need for improved reliability and higher endurance, which require precise and clear knowledge of the gear tooth stress field during meshing. Approach: This study considered the calculation of maximum stress at gear tooth root when the … …American Journal of Engineering and Applied Sciences, Vol. 3, Issue 1 · 31 Mar 2010 · 7,879 accessesView PDFCite
Research ArticleOpen accessIn the author namesOn the Use of Rolling Element Bearings' Models in Precision MaintenanceIoannis S. Zotos, Theodore N. CostopoulosProblem statement: Rolling element bearings form a very important part of machinery. The increasing demands on their continuous reliable operation under diverse environments make maintenance a very important step towards the efficient use of them. To this end, precision maintenance is a very useful practice, since it deals not only with finding a possible fault of a machine, but also … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 2 · 30 Jun 2009 · 7,413 accessesView PDFCite
Research ArticleOpen accessIn the author namesA Study on the Increase of Numerical Stability and Accuracy of the Transfer Matrix MethodIoannis S. Zotos, Theodore N. CostopoulosProblem Statement: The transfer matrix method is a very useful tool for the static and dynamic analysis of structures. There are a number of issues though that worsens the numerical stability and the accuracy of this method. Approach: This study proposed a simple technique that can be used to handle these numerical difficulties and overcome the problems they give. Its … …Journal of Mathematics and Statistics, Vol. 4, Issue 4 · 31 Dec 2008 · 7,030 accessesView PDFCite
Research ArticleOpen accessIn the author namesIncreasing the Strength of Standard Involute Gear Teeth with Novel Circular Root Fillet DesignV. Spitas, Th. Costopoulos, C. SpitasIn this study the idea of spur gear teeth with circular instead of the standard trochoidal root fillet is introduced and investigated numerically using BEM. The strength of these new teeth is studied in comparison with the standard design by discretizing the tooth boundary using isoparametric Boundary Elements. In order to facilitate the analysis the teeth are treated as non-dimensional … …American Journal of Applied Sciences, Vol. 2, Issue 6 · 30 Jun 2005 · 7,586 accessesView PDFCite