Modeling and Simulation of Transverse Cracks for Rotor-Bearing Systems

1996 ◽  
Author(s):  
Tachung Yang ◽  
Shi-An Chen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Strain Energy ◽  
Catastrophic Failure ◽  
Transverse Cracks ◽  
Finite Element Approach ◽  
Rotor Bearing ◽  
Element Approach ◽  
Rotating Shafts ◽  
Bearing System

Undetected cracking of rotating shafts can lead to catastrophic failure of turbomachinery. This paper investigated the dynamic response of rotor-bearing systems containing transverse cracks with a finite element approach. The breathing effect of cracks was analyzed based on the whirling conditions of the rotor, and different crack models were posed for different rotating speeds. The strain energy released due to the cracks was calculated. Then, the finite element for the shaft portion containing cracks was formulated and incorporated into the system matrices of the rotor-bearing system.

A Finite Element Approach to Pad Flexibility Effects in Tilt Pad Journal Bearings: Part II—Assembled Bearing and System Analysis

1990 ◽  
Vol 112 (2) ◽  
pp. 178-182 ◽  
Author(s):  
L. L. Earles ◽  
A. B. Palazzolo ◽  
R. W. Armentrout
Keyword(s):  
Finite Element ◽  
System Analysis ◽  
Journal Bearings ◽  
Complex Eigenvalue ◽  
Finite Element Approach ◽  
Rotor Bearing ◽  
Element Approach ◽  
Bearing System

Pad flexibility effects are studied in an actual bearing. This flexibility is shown to decrease the predicted instability onset speed of the rotor bearing system. The use of complex eigenvalue dependent bearing coefficients as compared with using synchronously reduced coefficients is seen to produce a more significant decrease in the instability onset speed. Further reductions in the instability onset speed are obtained by including pivot stiffness in the complex eigenvalue dependent bearing coefficients.

Potential Failure Sites in a Flip-Chip Package With and Without Underfill

1998 ◽  
Vol 120 (4) ◽  
pp. 336-341 ◽  
Author(s):  
E. Madenci ◽  
S. Shkarayev ◽  
R. Mahajan
Keyword(s):  
Finite Element ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Flip Chip ◽  
Singular Behavior ◽  
Stress Concentrations ◽  
Finite Element Approach ◽  
Element Approach ◽  
Potential Failure ◽  
Material Discontinuities

In this study, the effect of underfill on the level of stress concentrations is investigated and possible failure sites are identified by using a global/local finite element approach. The global elements capture the exact singular behavior of the stresses near the geometric and material discontinuities. Application of the strain energy density criterion indicates the possible failure sites and how they shift due to the presence of underfill.

Finite Element Modelling of a Generic Rotor-Bearing System and Experimental Validation

2015 ◽  
Author(s):  
A. Rehman ◽  
K. S. Ahmed ◽  
F. A. Umrani ◽  
B. Munir ◽  
A. Mehboob ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Element Model ◽  
Mode Shapes ◽  
Efficient Operation ◽  
Critical Speeds ◽  
Rotor Bearing ◽  
The Impact ◽  
Bearing System

The design and development of the rotating machinery require a precise identification of its dynamic response for efficient operation and failure prevention. Determination of critical speeds and mode shapes is crucial in this regard. In this paper, a finite element model (FEM) based on the Euler beam theory is developed for investigating the dynamic behavior of flexible rotors. In-house code in Scilab environment, an open source platform, is developed to solve the matrix equation of motion of the rotor-bearing system. The finite element model is validated by the impact hammer test and the dynamic testing performed on the rotors supported on a purpose-built experimental setup. Bearing stiffness is approximated by using the Hertzian contact theory. Obtaining the critical speeds and mode shapes further improves the understanding of dynamic response of rotors. This study paves way towards advanced research in rotordynamics in Faculty of Mechanical Engineering, GIK Institute.

A Finite Element Approach by Contact Transformation for the Prediction of Structural Wear

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
James Shih-Shyn Wu ◽  
Yi-Tsung Lin ◽  
Yuan-Lung Lai ◽  
P.-Y. Ben Jar
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Fe Simulation ◽  
Current Method ◽  
Solution Procedure ◽  
Computational Time ◽  
Contact Transformation ◽  
Qualitative Comparison ◽  
Finite Element Approach ◽  
Element Approach

Understanding of the wear behaviors between mechanical components is a significant task in engineering design. Finite element (FE) simulation may offer valuable wear information. However, longer computational time, poor data precision, and possible divergence of results are unavoidable in repetitive procedures, especially for large FE structures. To address these issues, the current method proposes a hypothesis that the strain energy is completely transferred through the contact regions of components; further that only variables on the contact surface are involved in the solution procedure. Our qualitative comparison demonstrates that the formulations in the current study are valid, offering significant implications for further application.

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