Thermally Induced Seizure in Journal Bearings During Startup and Transient Flow Disturbance

2003 ◽  
Vol 125 (4) ◽  
pp. 833-841 ◽  
Author(s):  
Rajesh Krithivasan ◽  
M. M. Khonsari
Keyword(s):  
Finite Element ◽  
Transient Flow ◽  
Empirical Relationship ◽  
Element Model ◽  
Flow Disturbance ◽  
Thermally Induced ◽  
Modeling And Analysis ◽  
Start Up ◽  
Insight Into ◽  
Good Agreement

This paper presents a finite element model that describes the thermomechanical interactions of a journal bearing undergoing thermally induced seizure (TIS). Two Categories of TIS are studied; the first part deals with occurrence of seizure during the start-up period followed by an investigation of TIS due to a transient flow-disturbance. The paper outlines the finite element modeling and analysis procedure involved in simulating TIS. An extensive set of parametric simulations covering load, speed, shaft radius, operating clearance, bearing length, friction coefficient and thermal expansion coefficient are performed to gain insight into the phenomenon of TIS. A statistical procedure is applied to the simulated results and an empirical relationship is derived. Good agreement between the empirical and published results attests to the capability of the model and its potential for predicting thermally induced seizure during system start up and during flow disturbance.

Rigid-Plastic Impact of Single Angular Particles

2021 ◽  
Author(s):  
Sandeep Dhar
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Orientation Dependence ◽  
Particle Orientation ◽  
Rigid Plastic ◽  
Plastic Model ◽  
Model Predictions ◽  
Good Agreement ◽  
Angular Particles

The trajectory of an angular particle as it cuts a ductile target is, in general, complicated because of its dependence not only on particle shape, but also on particle orientation at the initial instant of impact. This orientation dependence has also made experimental measurement of impact parameters of single angular particles very difficult, resulting in a relatively small amount of available experimental data in the literature. The current work is focused on obtaining measurements of particle kinematics for comparison to rigid plastic model developed by Papini and Spelt. Fundamental mechanisms of material removal are identified, and measurements of rebound parameters and corresponding crater dimensions of single hardened steel particles launched against flat aluminium alloy targets are presented. Also a 2-D finite element model is developed and a dynamic analysis is performed to predict the erosion mechanism. Overall, a good agreement was found among the experimental results, rigid-plastic model predictions and finite element model predictions.

scholarly journals Electrothermal Modeling and Analysis of Gallium Oxide Power Switching Devices

2019 ◽  
Author(s):  
Ramchandra M. Kotecha ◽  
Andriy Zakutayev ◽  
Wyatt K. Metzger ◽  
Paul Paret ◽  
Gilberto Moreno ◽  
...  
Keyword(s):  
Finite Element ◽  
Power Electronics ◽  
Gallium Oxide ◽  
Short Circuit ◽  
Thermal Characteristics ◽  
Wide Band ◽  
Element Model ◽  
Oxide Semiconductor ◽  
Modeling And Analysis ◽  
Device Architecture

Abstract Gallium oxide is an emerging wide band-gap material that has the potential to penetrate the power electronics market in the near future. In this paper, a finite-element gallium oxide semiconductor model is presented that can predict the electrical and thermal characteristics of the device. The finite element model of the two-dimensional device architecture is developed inside the Sentaurus environment. A vertical FinFET device architecture is employed to assess the device’s behavior and its static and dynamic characteristics. Enhancement-mode device operation is realized with this type of device architecture without the need for any selective area doping. The dynamic thermal behavior of the device is characterized through its short-circuit behavior. Based on the device static and dynamic behavior, it is envisioned that reliable vertical transistors can be fabricated for the power electronics applications.

New Hammerstein Modeling and Analysis for Controlling Melt Pool Width in Powder Bed Fusion Additive Manufacturing

2021 ◽  
pp. 1-7
Author(s):  
Dan Wang ◽  
Xinyu Zhao ◽  
Xu Chen
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Process Variations ◽  
Element Model ◽  
Hammerstein Model ◽  
Powder Bed Fusion ◽  
Modeling And Analysis ◽  
Powder Bed ◽  
Melt Pool ◽  
Linearized Model

Abstract Despite the advantages and emerging applications, broader adoption of powder bed fusion (PBF) additive manufacturing is challenged by insufficient reliability and in-process variations. Finite element modeling and control-oriented modeling have been identified fundamental for predicting and engineering part qualities in PBF. This paper first builds a finite element model (FEM) of the thermal fields to look into the convoluted thermal interactions during the PBF process. Using the FEM data, we identify a novel surrogate system model from the laser power to the melt pool width. Linking a linearized model with a memoryless nonlinear submodel, we develop a physics-based Hammerstein model that captures the complex spatiotemporal thermomechanical dynamics. We verify the accuracy of the Hammerstein model using the FEM and prove that the linearized model is only a representation of the Hammerstein model around the equilibrium point. Along the way, we conduct the stability and robustness analyses and formalize the Hammerstein model to facilitate the subsequent control designs.

Thermal-Electric Finite Element Analysis of Electrosurgical Cautery Process

2007 ◽  
Author(s):  
Robert E. Dodde ◽  
Scott F. Miller ◽  
Albert J. Shih ◽  
James D. Geiger
Keyword(s):  
Heat Transfer ◽  
Electrical Conductivity ◽  
Finite Element ◽  
Biological Tissue ◽  
Tissue Temperature ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Temperature Dependent Thermal Conductivity ◽  
Insight Into ◽  
Good Agreement

Cautery is a process to coagulate tissues and seal blood vessels using the heat. In this study, finite element modeling (FEM) was performed to analyze temperature distribution in biological tissue subject to cautery electrosurgical technique. FEM can provide detailed insight into the heat transfer in biological tissue to reduce the collateral thermal damage and improve the safety of cautery surgical procedure. A coupled thermal-electric FEM module was applied with temperature-dependent electrical and thermal properties for the tissue. Tissue temperature was measured at different locations during the electrosurgical experiments and compared to FEM results with good agreement. The temperature-dependent electrical conductivity has demonstrated to be critical. In comparison, the temperature-dependent thermal conductivity does not impact heat transfer as much as the electrical conductivity. FEM results show that the thermal effects can be varied with the electrode geometry that focuses the current density at the midline of the instrument profile.

Automotive Glass Exciter Technology for Acoustic Application

2014 ◽  
Author(s):  
Babak Ebrahimi ◽  
Amir Khajepour ◽  
Todd Deaville
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Fe Model ◽  
Component Level ◽  
Modeling And Analysis ◽  
Electric Actuator ◽  
Conventional Systems ◽  
Fine Tune

This paper discusses the modeling and analysis of a novel audio subwoofer system for automotive applications using the automobile windshield glass. The use of a piezo-electric actuator coupled with a mechanical amplifier linked to a large glass panel provides a highly efficient method of producing sound. The proposed subwoofer system has the advantage over existing conventional systems of not only reducing the weight of the automobile, but also a significant power savings resulting in an increase of expected fuel economy. Among various design challenges, the glass-sealing design is of huge importance, as it affects the system dynamic response and so the output sound characteristics. The main goal in this manuscript is to evaluate different glass-sealing design configurations by providing a comprehensive Finite Element model of the system. To do so, a comprehensive, yet simplified FE model is developed, and experimental studies are performed in the component level to fine-tune and verify the model. Harmonic response of the system for each sealing configuration design is obtained in the frequency range of 0–200 Hz, and the results are compared and discussed. The finite element model is also beneficial in preliminary design of other components as well as the exciter placement, and predicting the performance of the overall system.

Failure Prediction of Flip Chip Packages Using Finite Element Technique

2002 ◽  
Author(s):  
Abm Hasan ◽  
H. Mahfuz ◽  
M. Saha ◽  
S. Jeelani
Keyword(s):  
Finite Element ◽  
Flip Chip ◽  
Thermal Loading ◽  
Failure Modes ◽  
Element Model ◽  
Thermally Induced ◽  
Operational Life ◽  
Flip Chip Assembly ◽  
The Individual ◽  
Element Technique

Flip-chip electronic package undergoes thermal loading during its curing process and operational life. Due to the thermal expansion coefficient (CTE) mismatch of various components, the flip-chip assembly experiences various types of thermally induced stresses and strains. Experimental measurement of these stresses and strains is extremely tedious and rigorous due to the physical limitations in the dimensions of the flip-chip assembly. While experiments provide accurate assessment of stresses and strains at certain locations, a parallel finite element (FE) analysis and analytical study can complementarily determine the displacement, strain and stress fields over the entire region of the flip-chip assembly. Such combination of experimental, finite element and analytical studies are ideal to yield a successful stress analysis of the flip-chip assembly under the various loading conditions. In this study, a two-dimensional finite element model of the flip-chip consisting of the silicon chip, underfill, solder ball, copper pad, solder mask and substrate has been developed. Various stress components under thermal loading condition ranging from −40°C to 150°C have been determined using both the finite element and analytical methods. Stresses such as (σ11, σ12, ε12 etc. are extracted and analyzed for the individual components as well as the entire assembly, and the weakest positions of the flip-chip have been discovered. Detailed description of FE modeling is presented and the different failure modes of chip assembly are discussed.

Examination of the Transferability of CTOA From Small-Scale DWTT to Full-Scale Pipe Geometries Using a Cohesive Zone Model

2020 ◽  
Author(s):  
Chris Bassindale ◽  
Xin Wang ◽  
William R. Tyson ◽  
Su Xu
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Full Scale ◽  
Opening Angle ◽  
Small Scale ◽  
Zone Model ◽  
Pipe Model ◽  
Good Agreement

Abstract In this work, the cohesive zone model (CZM) was used to examine the transferability of the crack tip opening angle (CTOA) from small-scale to full-scale geometries. The pipe steel STPG370 was modeled. A drop-weight tear test (DWTT) model and pipe model were studied using the finite element code ABAQUS 2017x. The cohesive zone model was used to simulate crack propagation in 3D. The CZM parameters were calibrated based on matching the surface CTOA measured from a DWTT finite element model to the surface CTOA measured from the experimental DWTT specimen. The mid-thickness CTOA of the DWTT model was in good agreement with the experimental value determined from E3039 and the University of Tokyo group’s load-displacement data. The CZM parameters were then applied to the pipe model. The internal pressure distribution and decay during the pipe fracture process was modeled using the experimental data and implemented through a user-subroutine (VDLOAD). The mid-thickness CTOA from the DWTT model was similar to the mid-thickness CTOA from the pipe model. The average surface CTOA of the pipe model was in good agreement with the average experimental value. The results give confidence in the transferability of the CTOA between small-scale specimens and full-scale pipe.

scholarly journals Evaluation of Strains at the Bottom of the Asphalt Base Layer of a Semi-Rigid Pavement Under a Class 6 Vehicle

2019 ◽  
Vol 271 ◽  
pp. 08008
Author(s):  
Mohsen Talebsafa ◽  
Stefan A. Romanoschi ◽  
Athanassios T. Papagiannakis ◽  
Constantin Popescu
Keyword(s):  
Finite Element ◽  
Longitudinal Direction ◽  
Element Model ◽  
Base Layer ◽  
Rigid Pavement ◽  
Finite Element Program ◽  
Element Program ◽  
Transverse Strains ◽  
Longitudinal Strains ◽  
Good Agreement

A newly constructed pavement on US-287 near Mansfield, TX was instrumented with gauges installed at the bottom of the asphalt concrete base layer to measure the longitudinal and transverse strains developed under a test vehicle. The finite element program Abaqus was used to compute the strains at the location of the gauges; they were found in good agreement with the measured strains. The research showed that the strains under the steering axle were of similar magnitude as the strains under the rear tandem axle. The measured transverse strains were in general slightly bigger than the corresponding longitudinal strains, while the finite element model computed higher strains in the longitudinal direction. These findings suggest the need to account for the strain responses from the steering axle of trucks and to account for both the longitudinal and the transverse strains when computing the fatigue damage induced by trucks.

An assessment of the Sachs method for measuring residual stresses in cold worked fastener holes

1998 ◽  
Vol 33 (4) ◽  
pp. 263-274 ◽  
Author(s):  
D J Smith ◽  
C G C Poussard ◽  
M J Pavier
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Cold Working ◽  
Element Model ◽  
Fe Model ◽  
Working Process ◽  
Element Analysis ◽  
Near Surface ◽  
Cold Worked ◽  
Good Agreement

Measurements of residual stresses in 6 mm thick aluminium alloy 2024 plates containing 4 per cent cold worked fastener are made using the Sachs method. The measurements are made on discs extracted from the plates. The measured tangential residual stress distribution adjacent to the hole edge are found to be affected by the disc diameter. The measured residual stresses are also in good agreement with averaged through-thickness predictions of residual stresses from an axisymmetric finite element (FE) model of the cold working process. A finite element analysis is also conducted to simulate disc extraction and then the Sachs method. The measured FE residual stresses from the Sachs simulation are found to be in good agreement with the averaged through-thickness predicted residual stresses. The Sachs simulation was not able to reproduce the detailed near-surface residual stresses found from the finite element model of the cold working process.

Dynamic Modeling and Analysis of Guideway Joint of Engraving Machine

2011 ◽  
Vol 121-126 ◽  
pp. 3248-3252 ◽  
Author(s):  
Xiao Li Jin ◽  
Bao Ji Ma ◽  
Tao Feng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Performance Prediction ◽  
Element Model ◽  
Contact Element ◽  
Modeling And Analysis ◽  
Fundamental Parameters ◽  
Joint Characteristics ◽  
Actual Force ◽  
Theory Research

Combined the theory research with the actual force and deformation of the guideway joint, the isoparametric eight-node contact element is proposed, the element reflects the joint characteristics of guideway of engraving machine. A finite element model of guidway joint is build. The fundamental parameters of the contact element are deduced by finite element method, which can apply with the performance prediction of the whole engraving machine in the process of design.

Sign in / Sign up

Export Citation Format

Share Document