Author
Stefanos A. Paipetis
Bio: Stefanos A. Paipetis is an academic researcher from University of Patras. The author has contributed to research in topics: Torsional vibration & Rotor (electric). The author has an hindex of 3, co-authored 11 publications receiving 424 citations.
Papers
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TL;DR: In this paper, the authors reconstructed the Trojan Horse from the references in the Iliad and vase paintings, archeological evidence concerning the Troy siege, and the Homeric shipbuilding, and incorporated analytical and numerical methods to analyze the most conceivable loading situations of crucial structural elements of the reconstructed horse.
7 citations
01 Jan 2013
TL;DR: In this paper, the problem of cracked rotor dynamics is discussed and an analytical formulation for crack local flexibility in relation to crack depth yields a supervisory instrument which can give an early crack warning.
Abstract: The problem of cracked rotor dynamics is discussed in Chap. 6. Analytical formulation for crack local flexibility in relation to crack depth yields a supervisory instrument which can give an early crack warning. Fracture mechanics methods provide stress intensity factors for the investigation of rotor’s dynamic performance for varying crack depth. Open cracks lead to linear systems, while closing cracks lead to non-linear ones. Analytical solutions are obtained, which can be used to monitor crack propagation or to identify cracks in service.
5 citations
01 Jan 2013
TL;DR: In this paper, a general stiffness matrix for cracked structural members is introduced, to model the respective dynamic system, and this stiffness matrix can be further utilized for static, dynamic or stability analysis of a structure with cracked members of rectangular or circular cross-section.
Abstract: The question of crack detection from dynamic measurements is further extended and discussed in Chap. 7. A general stiffness matrix for cracked structural members is introduced, to model the respective dynamic system. This stiffness matrix can be further utilized for static, dynamic or stability analysis of a structure with cracked members of rectangular or circular cross-section. Off-diagonal terms indicate vibration coupling. The change in dynamic response is analytically evaluated for simple systems and by means of approximate methods for more complicated ones. The outlined procedure can be used for engineering analysis in two ways: (a) as a design tool, to assist in structural optimization with the objective of achieving certain specific dynamic characteristics; and (b) as a maintenance and inspection tool, to identify structural flaws, such as cracks, by linking the variations in service of the structure's natural frequencies to structural changes due to the cracks.
2 citations
01 Jan 2013
TL;DR: In this article, the authors investigated the Newkirk effect on the packing rub effect, which is the unstable vibration induced by friction forces and generated heat on a rotor when it rubs on a clearance annulus.
Abstract: Packing rub effect is the unstable vibration induced by friction forces and generated heat on a rotor when it rubs on a clearance annulus. Its main controlling factors are friction characteristics at the sliding contact and the dynamic response of the rotor, bearings, supports and foundation system. In Chapter 5 rotor instabilities are investigated, resulting from friction heating, a phenomenon known as the 'Newkirk effect'. The interaction between vibration characteristics and heat generation leads to a non-linear feedback system exhibiting either stable or unstable behavior.
1 citations
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TL;DR: In this paper, a crack in a structural member introduces a local flexibility that affects its vibration response, and the crack will open and close in time depending on the rotation and vibration amplitude.
1,080 citations
TL;DR: In this article, the authors proposed a non-destructive testing method for crack identification, which requires amplitude measurements at two positions of the structure only and is applicable to all one-dimensional structures.
721 citations
TL;DR: In this article, the coupling of longitudinal and bending vibrations of a rotating shaft, due to an open transverse surface crack, is investigated and the effects of unbalance and gravity are examined.
380 citations
TL;DR: In this article, the fundamental vibration mode of a cracked cantilever beam is analyzed using continuous wavelet transform and both the location and size of the crack are estimated by the sudden change in the spatial variation of the transformed response.
286 citations
TL;DR: In this paper, a de Laval rotor with an open crack is investigated by way of application of the theory of shafts with dissimilar moments of inertia, and analytical solutions are obtained for the closing crack under the assumption of large static deflections, a situation common in turbomachinery.
268 citations