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Determining and analysing support conditions at variable construction of crankshafts

Nozdrzykowski K., Grządziel Z., Harušinec J.

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

553--560

EN

The article presents study results of the influence of crankshaft construction changes on the choice of support conditions allowing to eliminate deflections and elastic deformations of crankshafts under their self-weight. For the purpose of this study we implemented a programme for strength calculations Nastran FX 2010 which enables modelling the research subject with a finite element method and counting the value if reaction forces ensuring zero value of deflections on main journals at a change in the crankshaft’s angle of rotation.

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Applying Harmonic Analysis in the Measurements of Geometrical Deviations of the Crankshafts – Selecting Support Conditions

Nozdrzykowski K.

Multidisciplinary Aspects of Production Engineering

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2018

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Vol. 1, Iss. 1

191--195

EN

The article presents principles of the most suitable support conditions which enable elimination of deflections and elastic deformations of crankshafts under their self-weight. On the basis of the formulated principles sample calculations of force values of support reactions were performed. This guarantees zero value of deflections on main journals depending on the angle of rotation of the shaft, applying available programme of strength calculations Nastran FX 2010. The obtained results have been approximated with a mathematical equation applying the calculating method based on the harmonic analysis theory. Then a comparative assessment of the force diagram (the forces were obtained via strength calculations and mathematical model including so called mutual inter-correlation coefficient) was made. The obtained results of comparative analysis showed high correspondence between the compared diagrams. Presented procedures of determining the required forces ensuring elimination of deflections and elastic deformations can be applied to measurements of crankshaft geometrical deviations realized on the basis of a measuring system with, so called, flexible support of a measured object.

3

Procedury wyznaczania i realizacji sił reakcji w układzie elastycznego podparcia wału korbowego

Nozdrzykowski K.

Mechanik

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2018

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R. 91, nr 12

1129--1131

PL

Przedstawiono podstawowe elementy nowatorskiego systemu do pomiarów odchyłek geometrycznych wałów korbowych, zaopatrzonego w układ tzw. elastycznego podparcia. Umożliwia on wyeliminowanie występowania ugięć i odkształceń sprężystych obiektu mierzonego pod wpływem ciężaru własnego. Przedstawiono zasady wyznaczania najkorzystniejszych warunków podparcia, gwarantujących eliminację ugięć i odkształceń sprężystych wałów korbowych. Na podstawie sformułowanych zasad wykonano przykładowe obliczenia sił reakcji podpór, gwarantujących zerowe wartości ugięć na czopach głównych, w zależności od kąta obrotu wału, z wykorzystaniem programu do obliczeń wytrzymałościowych Nastran FX 2010. Wyniki zaproksymowano równaniem matematycznym z zastosowaniem aparatu obliczeniowego opartego na teorii analizy harmonicznej, a następnie dokonano oceny porównawczej wykresu sił otrzymanych drogą obliczeń wytrzymałościowych oraz zapisu matematycznego, wyliczając tzw. współczynnik interkorelacji wzajemnej. Ocena porównawcza wykazała wysoki stopień zgodności porównywanych wykresów. Przedstawione procedury wyznaczania sił gwarantujących eliminację ugięć i odkształceń sprężystych znajdują zastosowanie przy pomiarach odchyłek geometrycznych wałów korbowych, realizowanych na bazie zaprezentowanego systemu pomiarowego.

EN

The basic elements of an innovative system designed to measure geometric deviations of crankshafts provided with a so-called elastic support system are presented. The support system enables elimination of deflections and elastic deformations of the object measured under the influence of its own weight. The principles of the most suitable support conditions which enable elimination of deflections and elastic deformations of crankshafts under their self-weight were also presented. On the basis of the formulated principles sample calculations of force values of support reactions were performed. This guarantees zero value of deflections on main journals depending on the angle of rotation of the shaft, applying approximated with a mathematical equation applying the calculating method based on the harmonic analysis theory. Then a comparative assessment of the force diagram (the forces were obtained via strength calculations and mathematical model including so called mutual inter-correlation coefficient) was made. The results of comparative analysis showed high correspondence between the compared diagrams. Presented procedures of determining the required forces ensuring elimination of deflections and elastic deformations can be applied to measurements of crankshaft geometrical deviations on the basis of a measuring system with flexible support of a measured object.

4

Buckling stability assessment of plates under uniaxial compression

Riahi Farhad, Zirakian Tadeh, Ghaderi Vahed Mam, Arya Souran

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 2

97--105

EN

Buckling of thin-walled and load-bearing elements of a structure can have devastating consequences. Hence, buckling checks are an integral part of strength analysis of structures. The buckling problem of thin rectangular plates subjected to in-plane compressive and/or shear loading is of great importance in building, bridge, aerospace, marine, and shipbuilding industries. When buckling occurs, thin plates undergo large out-of-plane deflections, which in turn results in the development of large bending stresses and eventually complete failure of the structure. This paper deals with the buckling stability assessment of uniaxially-compressed plates with different support conditions within the framework of classical plate theory. The main objective of this research is to explore some uncovered aspects of buckling stability of plates by considering the effects of support conditions, aspect ratio, and slenderness ratio, which will consequently result in efficient design of such thin-walled structures. To this end, in addition to validation of the numerical simulation, some case studies have been performed in order to gain a better understanding of different aspects of buckling stability of such thin-walled structures.

5

Analysis and Measurement of Deformation of Multipoint-Supported Crankshafts

Nozdrzykowski K.

Machine Dynamics Research

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2017

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Vol. 41, No. 1

65--76

EN

The article presents the results of analyses which showed that the currently used methods for measuring the geometrical condition of execution and bearing mounting of large-size crankshafts do not guarantee complete and appropriate assessment of the shafts’ position in the main bearings due to the occurring elastic deformations caused by the support conditions of the measured object.Additionally, the results of the analyses enabled to determine the most advantageous support conditions, from the point of view of elimination of the shaft’s elastic deformation. A new concept of testing crank web deformation has been presented. The proposed symmetrical method eliminates a number of inconveniences of the existing testing methods and facilitates correct assessment of crankshaft deformation.

6

Sensitivity analysis of sandwich beams and plates accounting for variable support conditions

Studziński R., Pozorski Z., Garstecki A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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Vol. 61, nr 1

201-210

EN

The paper addresses the problems of the sensitivity analysis and optimal design of multi-span sandwich panels with a soft core and flat thin steel facings. The response functional is formulated in a general form allowing wide practical applications. Sensitivity gradients of this functional with respect to dimensional, material and support parameters are derived using adjoint variable method. These operators account for the jump of the slope of a Timoshenko beam or a Reissner plate at the position of concentrated active load or reaction, thus extending the sensitivity operators known in literature. The jump of slope is the effect of shear deformation of the core. Special attention is focussed on sensitivity and optimisation allowing for variable support position and stiffness, because local phenomena observed in supporting area of sandwich plates often initiate failure mechanisms. Introducing optimally located elastic supports allows to reduce the unfavourable influence of temperature on the state of stress. Several examples illustrate the application of derived sensitivity operators and demonstrate their exactness.