Crack Position and Depth Identification in Rotating Shafts: Part 1— Theoretical Model

2005 ◽  
Author(s):  
Nicolo` Bachschmid ◽  
Paolo Pennacchi ◽  
Andrea Vania
Keyword(s):  
Finite Element ◽  
Transverse Crack ◽  
Crack Identification ◽  
Finite Element Models ◽  
Equivalent System ◽  
Identification Method ◽  
Rotating Shafts ◽  
Breathing Mechanism ◽  
Crack Position ◽  
Relative Theory

This paper presents a model based transverse crack identification method in rotating shafts suitable for industrial machines. The identification method and the relative theory is fully discussed, by presenting the breathing mechanism of the crack, the equivalent system of forces, which excites the vibrations of rotating shafts, the way to localize the crack position along the shaft and finally to identify the depth of the crack. This is obtained by using standard finite element models of the machine and the vibration measured in the bearings only, as usual in industrial machines. The proposed method will be validated by means of experimental results which are described in detail in the second part of the paper.

Crack Position and Depth Identification in Rotating Shafts: Part 2 — Experimental Results

2005 ◽  
Author(s):  
Nicolo` Bachschmid ◽  
Paolo Pennacchi ◽  
Ezio Tanzi
Keyword(s):  
Dynamical Behavior ◽  
Industrial Applications ◽  
Experimental Results ◽  
Crack Identification ◽  
Identification Method ◽  
Different Types ◽  
Rotating Shafts ◽  
Short Time ◽  
Crack Position ◽  
Deep Crack

This paper presents the experimental validation of a model based transverse crack identification method suitable for industrial machines, described in part 1. The method is validated by experimental results obtained on two test rigs, which were expressly designed for investigating the dynamical behavior of cracked horizontal rotors. On the first test rig, only one crack type is considered, while on the second one three different types of crack have been analyzed: the first is a slot, therefore not actually a crack since it has not the typical breathing behavior, the second a small crack (14% of the diameter) and the third a deep crack (47% of the diameter). The excellent accuracy obtained in identifying position and depth of different cracks proves the effectiveness and reliability of the proposed method. Moreover, the implementation of identification method operates on a PC and takes short time to run, therefore is suitable for industrial applications.

Deflection of a beam with a transverse crack under dead load

2020 ◽  
Vol 65 (1) ◽  
pp. 145-152
Author(s):  
Marius-Vasile Pop
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cantilever Beam ◽  
Transverse Crack ◽  
Direct Relation ◽  
The Finite Element Method ◽  
Dead Load ◽  
Analytic Relation ◽  
Mathematical Relation ◽  
Crack Position

This paper proposes an analytic relation for the deflection of a cantilever beam with a transverse crack subjected to dead load. The mathematical relation is deduced involving the decreased capacity of the beam to store energy, which is in direct relation with the crack position and depth. Eventually, the validity of the relation is proved by means of the finite element method.

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

Estimation of the severity of damage produced by a transverse crack

2020 ◽  
Vol 65 (1) ◽  
pp. 137-144
Author(s):  
Marius-Vasile Pop
Keyword(s):  
Transverse Crack ◽  
Bending Moment ◽  
Cantilever Beams ◽  
Trend Line ◽  
The Real ◽  
Symmetrical Deformation ◽  
Frequency Drop ◽  
Equidistant Points ◽  
Fixed End ◽  
Crack Position

This paper presents a method to find the severity of a crack for cantilever beams that can be used to estimate the frequency drop due to the crack. The severity is found for the crack located at the location where the biggest curvature (or bending moment) is achieved. Because the fixing condition does not permit a symmetrical deformation around the crack, the apparent severity is smaller as the real one. The latter is found by the estimated value of the trend-line at the fixed end, it being constructed on points that consider the crack position (equidistant points in the proximity of the fixed end) and the resulted deflections.

Affordable structural optimization for large-size dynamic finite element models

1997 ◽  
Author(s):  
Francois Hemez ◽  
Emmanuel Pagnacco ◽  
Francois Hemez ◽  
Emmanuel Pagnacco
Keyword(s):  
Finite Element ◽  
Structural Optimization ◽  
Finite Element Models ◽  
Dynamic Finite Element ◽  
Large Size
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