On Strain of Gear Meshing Thermo-Mechanical Coupling

Involute helical gears are widely used in high-speed and heavy-load transmission systems of automobiles, helicopters, etc. Poor working conditions lead to fatigue crack and other faults of gear key parts such as tooth face and tooth root. To identify the root causes of gear faults, strain monitoring methods are often used to monitor the stress changes of gear key parts so as to work out individualized improvement plans. However, stress of gears in the work process is typically the result of the coupling effect of thermal stress and mechanical stress. The existing strain monitoring methods cannot separate them effectively, and thus it is impractical to quickly find the corresponding improvement measures. To reveal the coupling relationship between thermal stress and mechanical stress during gear meshing and find out the source of gear faults, this paper uses the transient finite element-based analysis method to study the coupling relationship between thermal strain and mechanical strain of a pair of helical gears in the test direction and find the coupling rules of thermal strain and mechanical strain among the strains of gears in the strain test direction that may provide effective guidance for the fault diagnosis of gear meshing.

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Accuracy Analysis of Gear Root Strain Test under Different Rotational Speed

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1030-1032.1142 ◽

2014 ◽

Vol 1030-1032 ◽

pp. 1142-1146

Author(s):

Hao Zhu ◽

Yu Mei Hu ◽

Yi Min Shao

Keyword(s):

High Speed ◽

Dynamic Strain ◽

Test Accuracy ◽

Tooth Root ◽

Adhesive Failure ◽

Monitoring Methods ◽

Element Analysis ◽

Helical Gears ◽

Stress Changes ◽

The Impact

Involute helical gears, with advantages of large carrying capacity, smooth transmission and long life, etc., are widely used in automotive, mining, helicopters and other high-speed and heavy-load transmission system. Poor working conditions lead to fatigue crack and other faults of gear key parts such as tooth root and tooth face. To identify the root causes of gear faults, strain monitoring methods are often used to monitor the stress changes of gear key parts so as to work out individualized improvement plants. Good test results can be obtained using real-time wireless data collection technology when the gear is in low-speed and light loading condition, and we can get important data such as speed, torque and dynamic strain on tooth root, etc. However, involute helical gears tend to work in high-speed and heavy harsh conditions, especially when the gear speed reaches a large value (eg. 10000r/min above), gear strain measurement device will suffer big centrifugal force and the impact of shear force which may results partial bonded adhesive failure (cracks, erosion, etc.) and even whole peeling of strain gages, thus inaccurate and even error results will be obtained. Transient finite element analysis method is used in this paper to study the relationship between rotation velocity and test accuracy of strain gauge as well as the process of the bonded adhesive failure, which may provide effective guidance for the fault diagnoses of gear meshing.

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Thermo-Mechanical and Hygro-Mechanical Stress Analyses of an Organic Multilayer Sheet

ASME 2007 InterPACK Conference, Volume 2 ◽

10.1115/ipack2007-33212 ◽

2007 ◽

Author(s):

Toru Ikeda ◽

Tomonori Mizutani ◽

Noriyuki Miyazaki

Keyword(s):

Liquid Crystal ◽

Heat Conduction ◽

Thermal Stress ◽

Liquid Crystal Display ◽

Mechanical Strain ◽

Thermal Strain ◽

Transient Heat Conduction ◽

Fick’S Law ◽

Fick's Law ◽

Liquid Crystal Display Panel

A polarizing plate, which is an important part of a liquid crystal display panel, is made by sandwiching an organic polarizer between protecting films. An organic polarizer is both a hygroscopic and orthotropic material. The hygroscopic swelling and drying shrinkage of the organic polarizer can cause the polarizing plate to crack and the liquid crystal display panel to warp. The diffusion coefficient and Henry’s law coefficient were measured using a thermo-gravimetric analyzer (TGA) under controlled humidity, while the coefficient of moisture expansion (CME) was measured using a thermo-mechanical analyzer (TMA), also under controlled humidity. The thermo-mechanical and hygro-mechanical deformation of a polarizing plate was analyzed using the finite element method (FEM). This analysis was performed as follows. The distribution of the moisture concentration was analyzed according to Fick’s law. The equation of Fick’s law is similar to that of the transient heat conduction, and the FEM for the transient heat conduction was utilized for the transient diffusion analysis. The hygro-mechanical analysis was then carried out in a way similar to the thermal stress analysis. Thermal stress was analyzed separately using the FEM. Finally, the obtained hygro-mechanical strain and stress were added to the thermal strain and stress, respectively. The measured CME of a polarizing plate corresponds to the analyzed CME using the CMEs of a polarizer and protecting films. The warpage of a liquid crystal display panel sometimes causes light leakage along the frame of the display panel due to contact of the display panel with the bezel of the frame. The warpage was analyzed according to the thermo-mechanical strain and the hygro-mechanical strain. The contact between the display panel and the bezel, which causes the light leakage, was estimated.

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Identification of Sleeper Support Conditions Using Mechanical Model Supported Data-Driven Approach

Sensors ◽

10.3390/s21113609 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3609

Author(s):

Mykola Sysyn ◽

Michal Przybylowicz ◽

Olga Nabochenko ◽

Lei Kou

Keyword(s):

High Speed ◽

Experimental Studies ◽

Dynamic Interaction ◽

Theoretical Research ◽

Rolling Stock ◽

Monitoring Methods ◽

Beam Dynamic ◽

Track Geometry ◽

Data Driven Approach ◽

Support Conditions

The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement.

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Mechanical strain increases velocity and extent of shortening in cultured airway smooth muscle cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1999.277.2.l343 ◽

1999 ◽

Vol 277 (2) ◽

pp. L343-L348 ◽

Cited By ~ 14

Author(s):

Paul G. Smith ◽

Chaity Roy ◽

Jamie Dreger ◽

Frank Brozovich

Keyword(s):

Smooth Muscle ◽

Mechanical Stress ◽

Airway Smooth Muscle ◽

Light Chain ◽

Myosin Light Chain ◽

Mechanical Strain ◽

Airway Smooth Muscle Cells ◽

Maximal Velocity ◽

Cell Contractility ◽

Cell Shortening

Abnormal mechanical stress on lung tissue is associated with increased mass and contractility of airway smooth muscle (ASM). We have reported that cultured ASM cells subjected to cyclic strain exhibit increased myosin light chain kinase (MLCK) and stress filaments. Increased MLCK may increase contractile velocity, whereas increased stress filaments could impede cell shortening by increasing the cell’s internal load. To study strain-induced changes in cell contractility, the time course of shortening of individual cells exposed to 90 mM KCl was recorded. Length vs. time plots revealed significantly greater maximal velocity of shortening in strain cells than control (no strain). This correlated with an increase in MLCK and myosin light chain phosphorylation measured in strain cells in separate experiments. The extent of cell shortening tended to be greater in the strain cells so that increased impedance to shortening was not detected. Mechanical stress may therefore increase the contractility of ASM by increasing the content of MLCK.

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Optimum Design of Inductors Used for Wireless Power Transmission Micro-Module

Design Engineering ◽

10.1115/imece2004-59934 ◽

2004 ◽

Author(s):

Chao-Liang Chang ◽

Uei-Ming Jow ◽

Chao-Ta Huang ◽

Hsiang-Chi Liu ◽

Jr-Yuan Jeng ◽

...

Keyword(s):

Thermal Stress ◽

Electrical Properties ◽

Optimum Design ◽

Thermal Loading ◽

Power Transmission ◽

Thermal Strain ◽

Electrical Performance ◽

Wireless Power ◽

Wireless Power Transmission ◽

Analysis Software

The micro-inductor is a key component in wireless power transmission micro modules. In this paper, an optimum design for the micro-inductor was studied and related MEMS fabrication techniques were also developed. Commercial electromagnetic property analysis software, ANSOFT, was used to screen the main design factors of the micro-inductor. It was found that the high inductance and high quality factors of the micro-inductor implied high power transmission efficiency for the micro-module’s wireless power transmission. The electrical performance of the micro-inductor was affected by the thermal stress and thermal strain induced in the operational environment of the wireless power transmission micro-module. In order to investigate the reliability of the micro-inductor, commercial stress analysis software, ANSYS, was used to calculate thermal stress and thermal strain. The deformed model of the micro-inductor was then imported into ANSOFT in order to calculate its electrical properties. Glass substrate Pyrex 7740 was used to reduce the substrate loss of the magnetic flux of the micro-inductor. The surface micromachining technique, a kind of MEMS processing, was chosen to fabricate the micro-inductor; the coil of the micro-inductor was electroplated with copper to reduce the series resistance. The minimum line width and line space of the coil were 20 μm and 20 μm respectively. Polyimide (PI) was used for supporting the structure of micro-inductors. The maximum shear stress was 74.09MPa and the maximum warpage was 2.197 μm at a thermal loading of 125°C. For the simulated data, the most suitable areas for 31-turn and 48-turn coils were at an area ratio of 1.27 and 2, respectively. The electrical properties of the inductors changed slightly under thermal loading.

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Parameters Affecting Thermo-Meohanical Cracking in Coated Media Due to High-Speed Friction Load

Journal of Tribology ◽

10.1115/1.3261589 ◽

1988 ◽

Vol 110 (2) ◽

pp. 222-227 ◽

Cited By ~ 12

Author(s):

F. D. Ju ◽

J. C. Liu

Keyword(s):

Fourier Transform ◽

Temperature Field ◽

Thermal Stress ◽

High Speed ◽

Coating Layer ◽

Infinite Medium ◽

Thermal Stress State ◽

Heating Effect ◽

Coated Surface ◽

Heat Checking

This investigation considers the thermo-mechanical effects of an asperity traversing at a high speed over a semi-infinite medium with a thin, hard coated surface. The general analytical solution of the temperature field and the thermal stress state are obtained and expressed in Fourier transform space. The analysis emphasizes the heating effect of the friction force, which leads to the initiation of the thermo-mechanical cracking or “heat-checking,” in the coating layer, the substrate, or their interface. For hard coated layers, the initiation of a crack will occur either in the coating layer, the substrate or the interface depending on the relative properties of the coating and the substrate and their bonding strength.

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A rig for controlled cyclic strain and temperature testing

The Journal of Strain Analysis for Engineering Design ◽

10.1243/03093247v171045 ◽

1982 ◽

Vol 17 (1) ◽

pp. 45-52 ◽

Cited By ~ 7

Author(s):

D J Beauchamp ◽

E G Ellison

Keyword(s):

Mechanical Strain ◽

Thermal Strain ◽

Cyclic Strain ◽

Heating System ◽

Temperature Cycle ◽

Transient Temperature ◽

Microprocessor System ◽

Hydraulic Test ◽

Heating And Cooling ◽

Phase Temperature

A servo-hydraulic test rig capable of applying combined temperature and strain or load cycles has been developed and commissioned. The nature of the test has dictated the specimen form as a hollow, hour-glass type. The critical problem of a suitable extensometer for temperature and strain cycling has been solved. The device designed and produced shows negligible transient temperature effects, has a high resolution of better than 0.1 μm, and is mechanically very stable. The heating and cooling is controlled by an induction heating system with grip cooling; additional cooling is available using compressed air passing through the hollow specimen. The system is capable of following a temperature ramp to within 1°C linearity. The thermal strain associated with a temperature cycle is compensated for using a microprocessor system specially developed for the purpose, which also enables a mechanical strain-stress loop to be plotted during a test. Both ‘in-phase’ and ‘out-of-phase’ temperature/strain cycles have been carried out and development continues to include dwell periods.

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