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Thomas G Chondros

UNIVERSITY OF PATRAS
School of Engineering
Mechanical Engineering
and Aeronautics Department
265 00 Patras, Greece.
Phone +302610997263
Cel. +306934966445
Fax. +302610997744
chondros@mech.upatras.gr
Thomas G. Chondros, born in Lamia, Greece, 1953. Mechanical Engineer, 1977. Ph.D. in Mechanical Engineering, 1982. Assistant Professor at the University of Patras, Greece, Mechanical Engineering and Aeronautics Department since 1990. Elected in the Associate Professor’s rank in 2010. Visiting Assistant Professor in Washington University in St. Louis during 1994 with a sabbatical leave from the University of Patras. National Member Committee Representative in the International Federation for the Theory of Machines and Mechanisms since 1999, and member of the Permanent Commission for the History of Mechanism and Machine Science since 2002. Research activities and teaching include dynamics of machines and mechanisms, mechanisms kinematics, vibration engineering, non destructive testing and analysis of structures, automotive dynamics and design, and history of technology. From 1977 to 1990 he was occupied in Industry in major Greek enterprises (B.P. of Greece Ltd, Piraiki-Patraiki Cotton Manufacturing Co S.A., FRIGOREX ABEE (a subsidiary of the Coca-Cola group), E.G.L. Western Greece Paper Mills S.A.). Last position was that of the Managing Director of EGL Western Greece Paper Mills S.A. from 1989 to 1990. He served in the Public Sector (Ministry of Transportation 1984-1988, last position technical director). Director General of the Association of Vehicles Importers and Representatives in Greece (1999-2000). Technical Director of the ADR Laboratory, Univ. of Patras (2001-today). He has more than 100 research papers published in scholarly journals, peer reviewed conference proceedings, and research reports.

Journal articles

2010
A S Papadogiannis, M C Tsakoumaki, T G Chondros (2010)  "Deus-Ex-Machina" Mechanism Reconstruction in the Theater of Phlius, Corinthia   JOURNAL OF MECHANICAL DESIGN 132: 38. - JAN  
Abstract: In some ancient Greek drama plays, the stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term deus-ex-machina, was used for the solution of an apparently insoluble crisis. A twin-facing stone base was found in the theater of Phlius in Corinthia, Greece, behind the stage building. The existence of similar foundations in other ancient theaters indicates their use for specific purposes connected with the needs of the play. An attempt to reconstruct the mechanism is presented based on archeological evidence and literary descriptions. The reconstructed mechanism was designed for path generation and comprised a single beam with ropes controlling its planar motion and a sidle twin lifting system.
Notes: Times Cited: 0
T G Chondros (2010)  Archimedes life works and machines   MECHANISM AND MACHINE THEORY 45: 71. 1766-1775 NOV  
Abstract: Archimedes (ca. 287-212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics probably at the Museum in Alexandria and made important contributions to the field of mathematics. Archimedes discovered fundamental theorems concerning the centre of gravity of plane geometric shapes and solids. He is the founder of statics and of hydrostatics. Archimedes was both a great engineer and a great inventor, his machines fascinated subsequent writers, and he earned the honorary title "father of experimental science". Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which mechanics and engineering could be developed as a science using mathematics and reason. (C) 2010 Elsevier Ltd. All rights reserved.
Notes: Times Cited: 0
T G Chondros (2010)  Mini-Cars Design, Styling and Form - A Case Study   International Journal of Terraspace Science and Engineering 2: 2. 1-14  
Abstract: In 2008 the China carmaker Shuanghuan Auto launched sales of the Noble SUV in Europe after Asia. The car generated large controversies with Daimler AG, the parent company of Mercedes-Benz and Smart, due to the Noble’s similarities in styling with Smart Fortwo. Mercedes-Benz persuaded the Greek court to prohibit the car from being sold in the market on the basis that infringes its design copyright for the Smart ForTwo model. An experts’ appraisement was asked from China Motors, the company which imports the Noble in Greece, to the automotive Lab in the University of Patras. Styling and the issues concerned with automotive design are presented here. The design and styling process of E-240-Rio a mini-car built in the University of Patras in 1992 is demonstrated here along with the design issues of Smart that launched the Greek market in 1998, and the Noble first appearing in 2008.
Notes:
T G Chondros (2010)  A road-accident of bus and road-tanker and the risks from the transportation of dangerous goods.   International Journal of Terraspace Science and Engineering 2: 2. 31-49  
Abstract: An accident of a road-tanker that collided at the back of a bus with four fatalities and 6 serious injuries in the island of Creta, Greece, is investigated and reconstructed in an attempt to provide a methodology for an expert’s judgment technique in accidents involving transportation of hazardous materials by road. Furthermore, the analysis provides data for the engineers and traffic planners to assess the criteria which could be adopted in order to judge risk acceptability and strategies for handling emergencies, and minimize the impact of similar accidents. The investigation starts with a reconstruction of the road-accident and the identification of the requirements set by the European Agreement concerning the international carriage of dangerous goods by road (ADR). A detailed and complete understanding of all the relevant contributing factors reveal that although human error is implicated as a direct cause of the incident, inherent poor safety management systems, poor safety culture, inadequate assessment of thresholds on societal risks, potential threats from the operation of aged heavy vehicles, and inappropriate emergency handling strategies were detected.
Notes:
2009
2008
2007
T G Chondros, G Michalos, P Michaelides, E Fainekos (2007)  An approximate method for the evaluation of the roll stiffness of road tankers   PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING 221: 14. 1499-1512 DEC  
Abstract: The rollover stability of tank vehicles depends on a number of factors that result in a lateral shift of the centre of gravity, which influences roll dynamics in cornering. The most important factors are the height of the centre of gravity, the track width, the axle roll stiffness, suspension and lyre compliance, and suspension roll stiffness. A tilt table test and, alternatively, a calculation method are suggested for implementation by United Nations Economic Commission for Europe (UNECE) Regulation 111. In Greece, no available approved testing rig is available to carry out the required tests for the conformity of those vehicles with Regulation I I I and, consequently, the calculation method is almost exclusively adopted. However, the calculation method for Regulation 111 still remains a theoretical way to check the vehicle behaviour owing to the large number of non-validated physical parameters involved. Thus, there is a lack of reliability between results obtained by the calculation method from different inspection bodies for similar vehicles. A combined experimental and calculation method that determines the overall torsion-angular displacement relation for a vehicle on an inclined level under its own weight is discussed, and results of the application of this method in a large series of various types of road tanker are presented in this paper.
Notes: Times Cited: 0
T G Chondros, G N Labeas (2007)  Torsional vibration of a cracked rod by variational formulation and numerical analysis   JOURNAL OF SOUND AND VIBRATION 301: 32. 994-1006 APR 3  
Abstract: The torsional vibration of a circumferentially cracked cylindrical shaft is studied through an "exact" analytical solution and a numerical finite element (FE) analysis. The Hu-Washizu-Barr variational formulation is used to develop the differential equation and the boundary conditions of the cracked rod. The equations of motion for a uniform cracked rod in torsional vibration are derived and solved, and the Rayleigh quotient is used to further approximate the natural frequencies of the cracked rod. Results for the problem of the torsional vibration of a cylindrical shaft with a peripheral crack are provided through an analytical solution based on variational formulation to derive the equation of motion and a numerical analysis utilizing a parametric three-dimensional (3D) solid FE model of the cracked rod. The crack is modelled as a continuous flexibility based on fracture mechanics principles. The variational formulation results are compared with the FE alternative. The sensitivity of the FE discretization with respect to the analytical results is assessed. (c) 2006 Elsevier Ltd. All rights reserved.
Notes: Times Cited: 3
2006
2005
T G Chondros (2005)  Variational formulation of a rod under torsional vibration for crack identification   THEORETICAL AND APPLIED FRACTURE MECHANICS 44: 36. 95-104 SEP  
Abstract: A variational formulation is developed for the torsional vibration of a cylindrical shaft with a circumferential crack. The work is compared with existing methods. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked rod. The general variational principle and the independent assumptions about the displacement, the momentum, the strain and the stress fields of the cracked rod, and the equations of motion for a uniform rod in torsional vibration, are derived. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack, found with fracture mechanics methods. Rayleigh quotient was used to approximate the natural frequencies of the cracked rod. Independent evaluations of crack identification methods in rotating shafts are reported and compared with methods using the continuous crack flexibility theory. (c) 2005 Elsevier Ltd. All rights reserved.
Notes: Times Cited: 8
2001
T G Chondros, A D Dimarogonas, J Yao (2001)  Vibration of a beam with a breathing crack   JOURNAL OF SOUND AND VIBRATION 239: 21. 57-67 JAN 4  
Abstract: A continuous cracked beam vibration theory is used for the prediction of changes in transverse vibration of a simply supported beam with a breathing crack. The equation of motion and the boundary conditions of the cracked beam considered as a one-dimensional continuum were used. The eigenfrequency changes due to a breathing edge-crack are shown to depend on the bi-linear character of the system. The associated linear problems are solved over their respective domains of definition and the solutions are matched through the initial conditions. The changes in vibration frequencies for a fatigue-breathing crack are smaller than the ones caused by open cracks. The method has been tested for the evaluation of the lowest natural frequency of lateral Vibration for beams with a single-edge breathing crack. Experimental results from aluminium beams with fatigue cracks are used for comparison with the analytical results. (C) 2001 Academic Press.
Notes: Times Cited: 56
T G Chondros (2001)  In memoriam A.D. Dimarogonas (1938-2000)   JOURNAL OF SOUND AND VIBRATION 244: 1. 21-33 JUN 28  
Abstract: This memorial tribute to the late Professor Andrew D. Dimarogonas is in two parts. The first part is a brief account of his life and his professional career and achievements. The second part is a bibliography of his publications. (C) 2001 Academic Press.
Notes: Times Cited: 0
S D Panteliou, T G Chondros, V C Argyrakis, A D Dimarogonas (2001)  Damping factor as an indicator of crack severity   JOURNAL OF SOUND AND VIBRATION 241: 45. 235-245 MAR 22  
Abstract: When a material is subjected to an alternating stress field there are temperature fluctuations throughout its volume due to thermoelastic effect. The resulting irreversible heat conduction leads to entropy production, which in turn is the cause for thermodynamic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of shape and magnitude of existing crack in the structure. A homogeneous, isotropic, elastic bar of orthogonal shape is considered with a single-edge crack under alternating uniform axial stress. The analytical determination of the dynamic characteristics of the cracked structure yielded the damping factor of the bar, the material damping factor and a good correlation of depth of crack with the damping factor. Experimental results on cracked bars are in good correlation with the analysis. (C) 2001 Academic Press.
Notes: Times Cited: 22
T G Chondros (2001)  The continuous crack flexibility model for crack identification   FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES 24: 12. 643-650 OCT  
Abstract: The presence of a crack in a structural member introduces a local flexibility that affects its dynamic response. Moreover, the crack will open and close in time depending on the loading conditions and vibration amplitude. The changes in dynamic characteristics can be measured and lead to an identification of the structural changes which eventually might lead to the detection of a structural flaw. The results of various independent evaluations of changes in the natural frequency of vibrations of cracked structural elements are reported. A crack model of a continuous flexibility, found with fracture mechanics methods using the displacement field in the vicinity of the crack developed recently is used here. The analytical results for the cracked elements behaviour based on the continuous crack flexibility vibration theory were correlated with numerical solutions, the lumped-crack beam vibration analysis and experimental results obtained on aluminium and steel beams with open cracks.
Notes: Times Cited: 24
2000
1999
1998
T G Chondros, A D Dimarogonas, J Yao (1998)  Longitudinal vibration of a continuous cracked bar   ENGINEERING FRACTURE MECHANICS 61: 21. 593-606 NOV  
Abstract: A continuous cracked bar vibration theory is developed for longitudinal vibration of rods with an edge crack. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked bar as a one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of longitudinal vibrations of a bar with a single edge crack are presented: the continuous cracked bar vibration theory, the lumped crack bar vibration analysis, and experimental results obtained on aluminum bars with fatigue cracks. Experimental results fall between the values predicted by the two analytical methods. Moreover, the continuous bar theory agrees better with the experimental results than the lumped crack flexibility theory for small cracks. For larger cracks, a/h > 0.4, experimentation was difficult due to the coexistence of several coupled modes and no reliable results could be obtained. (C) 1998 Elsevier Science Ltd. All rights reserved.
Notes: Times Cited: 11
T G Chondros, A D Dimarogonas, J Yao (1998)  A continuous cracked beam vibration theory   JOURNAL OF SOUND AND VIBRATION 215: 38. 17-34 AUG 6  
Abstract: A continuous cracked beam vibration theory is developed for the lateral vibration of cracked Euler-Bernoulli beams with single-edge or double-edge open cracks. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked beam as a one-dimensional continuum. The displacement field about the crack was used to modify the stress and displacement field throughout the bar. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack, found with fracture mechanics methods. The results of two independent evaluations of the lowest natural frequency of lateral vibrations for beams with a single-edge crack are presented: the continuous cracked beam vibration theory developed here, and a lumped cracked beam vibration analysis. Experimental results from aluminum beams with fatigue cracks are very close to the values predicted. A steel beam with a double-edge crack was also investigated with the above mentioned methods, and results compared well with existing experimental data. (C) 1998 Academic Press.
Notes: Times Cited: 96
T G Chondros, A D Dimarogonas (1998)  Vibration of a cracked cantilever beam   JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 120: 17. 742-746 JUL  
Abstract: A continuous cracked bar vibration model is developed for the lateral vibration of a cracked Euler-Bernoulli cantilevered beam with an edge crack. The Hu-Washizu-Barr variational formulation was Ic sed to develop the differential equation and the boundary conditions for the cracked beam as an one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of lateral vibrations of an aluminum cantilever beam with a single-edge crack are presented: the continuous cracked beam vibration model, the lumped crack model vibration analysis, and experimental results. Experimental results fall very close to the values predicted by the continuous crack formulation. Moreover, the continuous cracked beam theory agrees better with the experimental results than the lumped crack flexibility theory.
Notes: Times Cited: 21
1997
T G Chondros, A D Dimarogonas, J Yao (1997)  A consistent cracked bar vibration theory   JOURNAL OF SOUND AND VIBRATION 200: 16. 303-313 FEB 27  
Abstract: A consistent continuous cracked bar vibration theory is developed. The stress and displacement held about the crack was used to modify the stress and displacement held throughout the bar, and reduction to one spatial dimension was achieved by integrating the stress and displacement fields throughout the bar cross-sections so that the total displacement would be exact. The resulting linear differential equation with variable coefficients has the modified displacement field due to the crack imbedded in it. Any number of cracks can be introduced into the differential equation as modifications of the displacement field. A numerical solution and a first order perturbation solution are presented for the prediction of changes in longitudinal vibration natural frequencies of a fixed-free bar with a single open-edge transverse crack. To assess the validity of the assumptions made experiments on aluminum bars with fatigue cracks were performed. The analytical results correlate very closely with experimental results with better correlation than the local flexibility solution. (C) 1997 Academic Press Limited.
Notes: Times Cited: 4
1994
1990
1989
1980

Book chapters

2010
2007
1992
1987
1983

PhD theses

1982

Masters theses

1977
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