Failure Diagnosis in Rotory Dynamic Systems Based on Finite Element Prediction Model

Author(s):  
Amir Shirkhodaie ◽  
Julian Blair ◽  
Kemba Heard

Machinery such as steam turbines, compressors, and generators are rotating machines. Over the years these machines have become very complex, due to the increased need for higher speed rotating machinery. Overtime these machines develop excessive dynamic stresses if they are ran at speeds near to their natural frequencies or under abnormal operating conditions. Many technological advances in the aerospace and automotive industries can be held accountable for these faster speeds. Currently, machinery diagnostics is being used to monitor rotating machinery and determine their condition while in operation. To determine how a system will behave under certain operation conditions, a physics-based model of the system can be modeled and analyzed using finite element analysis. These results will provide stress, deformation, flexibility, stiffness, and vibration characteristics of the system. These results can show where the critical points are on the system and how the system’s load is distributed. By using finite element techniques engineers can simulate the behavior of the system under different loading conditions, which can justify the selection of a particular design alternative, and ultimately save time and money. This paper discusses our technical approach used to develop a physics-based model of a rotor dynamic system and discusses results of this research effort.

2013 ◽  
Vol 823 ◽  
pp. 247-250
Author(s):  
Jie Dong ◽  
Wen Ming Cheng ◽  
Yang Zhi Ren ◽  
Yu Pu Wang

Because of the huge lifting weight and complex structure of large-tonnage gantry crane and in order to effectively design and review it, this paper aims to carry out a research on its structural performance based on the method of theoretical calculation and finite element analysis. During the early period of design, the method of theoretical calculations is adopted, and after specific design it comes the finite element analysis, so as to get the results of analysis under a variety of operating conditions, which illustrates that the structural design and review of large-tonnage gantry crane based on theoretical calculations and finite element are feasible, and also verifies that the method of finite element is an effective way to find a real dangerous cross-section, thus providing the basis for the design and manufacture of the crane structure.


Author(s):  
Scott D. Ironside ◽  
L. Blair Carroll

Enbridge Pipelines Inc. operates the world’s longest and most complex liquids pipeline network. As part of Enbridge’s Integrity Management Program In-Line Inspections have been and will continue to be conducted on more than 15,000 km of pipeline. The Inspection Programs have included using the most technologically advanced geometry tools in the world to detect geometrical discontinuities such as ovality, dents, and buckles. During the past number of years, Enbridge Pipelines Inc. has been involved in developing a method of evaluating the suitability of dents in pipelines for continued service. The majority of the work involved the development of a method of modeling the stresses within a dent using Finite Element Analysis (FEA). The development and validation of this model was completed by Fleet Technology Limited (FTL) through several projects sponsored by Enbridge, which included field trials and comparisons to previously published data. This model combined with proven fracture mechanics theory provides a method of determining a predicted life of a dent based on either the past or future operating conditions of the pipeline. CSA Standard Z662 – Oil and Gas Pipeline Systems provides criteria for the acceptability of dents for continued service. There have been occurrences, however, where dents that meet the CSA acceptability criteria have experienced failure. The dent model is being used to help define shape characteristics in addition to dent depth, the only shape factor considered by CSA, which contribute to dent failure. The dent model has also been utilized to validate the accuracy of current In-Line Inspection techniques. Typically a dent will lose some of its shape as the overburden is lifted from the pipeline and after the indentor is removed. Often there can be a dramatic “re-rounding” that will occur. The work included comparing the re-rounded dent shapes from a Finite Element model simulating the removal of the constraint on the pipe to the measured dent profile from a mold of the dent taken in the field after it has been excavated. This provided a measure of the accuracy of the tool. This paper will provide an overview of Enbridge’s dent management program, a description of the dent selection process for the excavation program, and a detailed review of the ILI validation work.


2006 ◽  
Vol 129 (1) ◽  
pp. 58-65 ◽  
Author(s):  
B. Scott Kessler ◽  
A. Sherif El-Gizawy ◽  
Douglas E. Smith

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. To this end, a robust ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is developed and linked with finite element code. Comparisons of this novel method with conventional means are carried out to demonstrate the advantages of this approach.


Author(s):  
Vladimir Panchenko ◽  
Sergey Chirskiy ◽  
Valeriy Vladimirovich Kharchenko

The chapter discusses the simulation of thermal operating conditions and the optimization of the design of solar photovoltaic thermal modules. As a realization of the developed method, two photovoltaic thermal modules with one-sided solar cells with one-sided heat removal and two-sided solar cells with two-sided heat removal are presented. The components of the developed models of solar modules must be optimized on the basis of the required indicators of the thermal mode of operation of the modules. For this task, a method has been developed for visualizing thermal processes using the Ansys system of finite element analysis, which has been used to research thermal modes of operation and to optimize the design of the modules created. With the help of the developed method, the temperature fields of the module components, coolant velocity and its flow lines in the developed models of a planar photovoltaic thermal roofing panel and a concentrator photovoltaic thermal two-sided module are visualized.


2014 ◽  
Vol 945-949 ◽  
pp. 1143-1149
Author(s):  
Hai Xia Sun ◽  
Hua Kai Wei ◽  
Xiao Fang Zhao ◽  
Jia Rui Qi

The finite element model of the concrete mixing truck’s frame is builded by using shell as basic element, and the process of building the finite element model of the balance suspension is introduced in detail. Based on this, frame’s stress on five types of typical operating conditions are calculated by using the finite element analysis software, NASTRAN, and results can show the dangerous position and the maximum stress position on the frame. The analysis result on structural strength can provide the basis for further improving the frame structure.


2013 ◽  
Vol 871 ◽  
pp. 347-351
Author(s):  
Dun Cai Lei ◽  
Jin Yuan Tang

A lecture on the method to compute the the stress of V-tooth coupling under the actual operating conditions. the finite element analysis model of V-tooth coupling under the preload, axial load and torsion was established by used of the software ABAQUS,and the distribution of the bending stress at the root was obtained. The analytical method to compute the bending stress of V-tooth disk is deduced based on the basic principle of material mechanics, and the relative error within 10% compared with the results of finite element analysis.The paper work provide the reference for the precision design of V-tooth coupling.


Author(s):  
B. Scott Kessler ◽  
A. Sherif El-Gizawy

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. In the present work, a previously developed ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is incorporated with finite element code. Utilizing this linked approach, a preliminary model for forging an aluminum wheel is developed. This novel method, along with a conventional approach, is then measured against the forging process as it is currently performed in actual production.


Author(s):  
Jean Paul Kabche ◽  
Mauri´cio Rangel Pacheco ◽  
Ivan Thesi ◽  
Luiz Carlos Largura

Bolted connections are largely employed in various types of engineering structures to transfer loads from one member to another. In particular, the off-shore industry has made extensive use of these connections, predominantly at the sub-sea level. In spite of their advantages, bolted joints are critical regions and may become sources of structural weakness due to large stress concentrations. Under severe operating conditions, micro-cracks can develop in the bolt, creating regions of elevated stress which may significantly reduce the integrity of the connection and ultimately lead to failure. This paper presents the three-dimensional finite element analysis of a steel locked bolt assembly aimed to assess the effect of micro-cracks on the structural integrity of the assembly using the commercial finite element package ANSYS. Non-linear contact between the bolt and nut threads is considered, where frictional sliding between components is allowed. A bi-linear isotropic hardening model is used to account for non-linear material behavior. The assembly is loaded by applying a pre-load of fifty percent of the yield stress of the material, according to the API-6A Norm. Two geometric models are investigated: a healthy locked bolt assembly with no initial cracks; and a damaged model, where a circular crack is introduced at the root of the bolt threads. The effect of the crack size is studied by modeling the crack with three different radius sizes. The J-Integral fracture mechanics methodology was used to study the stress concentrations in the damaged model.


2015 ◽  
Vol 789-790 ◽  
pp. 236-240
Author(s):  
Jiao Zhang ◽  
Xi Li ◽  
Hao Xie

EMU gearbox is a key component of high-speed train, the reliability of the gearbox will directly affect the operational safety of EMU. The box of EMU gearbox is with light alloy materials, bearing structure, so the box is subjected to greater loads and shock and vibration. Designers most take into account the static strength and stiffness of the box, ignore the fatigue failure. Fatigue failure is the leading cause of mechanical structural failure, while the peak load cycle fatigue failure is often far less than estimated in accordance with the static fracture analysis "safe" load, so the EMU gearbox box’s fatigue analysis is needed. Combining high-speed EMU gearbox actual operating conditions, using finite element method to do fatigue analysis of the gearbox box while the analysis result is evaluated and amended by the Smith schematic analysis method.


2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Shexia Dong ◽  
Dongsheng Zhuang ◽  
Gongming Ji ◽  
Chunming Zhu ◽  
Ting Sun

Pilot test of complex thermal fluid recovery technology was conducted in NB35-2 heavy oil field. Wellhead uplift was detected among some oil wells, and development of offshore thermal recovery technology could be restricted by the serious safety problems behind. This paper is based on the specific operating conditions of one oil well in the trial block, and the simulation calculation of casing elongation and wellhead uplift are conducted by using finite element analysis. The total casing elongation calculated is 4.2 cm, which is consistent with the field test results. According to the research, we concluded that the wellhead uplift is caused by upper casing elongation. 88% of the total elongation happens in the air and seawater sections. Elongation is lesser in strata and the casing string below 360 m can be considered as anchored.


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