Measurement of Shear Stress and Temperature Using MEMS Fabricated Sensors

1999 ◽  
Author(s):  
Kenneth S. Breuer ◽  
Robert L. Bayt ◽  
Anju Nayaar
Keyword(s):  
Shear Stress ◽  
Silicon Nitride ◽  
Temperature Sensors ◽  
Test Results ◽  
Thin Membrane ◽  
Sensor Element ◽  
Successful Operation ◽  
Thermal Isolation ◽  
Varying Length ◽  
Vacuum Cavity

Abstract The design, fabrication and testing of microfabricated thermal shear stress and temperature sensors are sensors is discussed. The devices are fabricated on a silicon substrate with a platinum sensor element 5 microns wide, 1000-Å thick and of varying length. The electrical leads are comprised of 5000-Å of gold deposited above the platinum sensor metal. The sensing area is isolated from the substrate by a thin membrane of silicon nitride covering a vacuum cavity. Test results are presented confirming the good thermal isolation of the sensor element from the substrate as well as the successful operation of the device.

Thermal Modeling and Experimental Investigation for Laser Assisted Milling of Silicon Nitride Ceramics

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Xinwei Shen ◽  
Shuting Lei
Keyword(s):  
Silicon Nitride ◽  
Heat Generation ◽  
Feed Rate ◽  
Laser Power ◽  
Cutting Speed ◽  
Thermal Characteristics ◽  
Successful Operation ◽  
Element Analysis ◽  
Nitride Ceramics ◽  
Operating Temperatures

This study is motivated by the fact that temperature control is very important for the success of laser assisted milling. A transient three-dimensional thermal model is developed using finite element analysis for laser assisted milling (LAMill) of silicon nitride ceramics, and then validated through a series of experiments of laser assisted face milling. This study aims to explore the thermal characteristics in LAMill of silicon nitride ceramics and thus provide guidelines on parameter selection for future operations. In addition, heat generation associated with machining is considered, and the effects of laser power, feed, and cutting speed on temperature are investigated. Simulation results show that heat generation associated with machining can be neglected. Laser power is one critical parameter for successful operation of LAMill. Moreover, both feed and cutting speed can affect the operating temperatures by varying feed rate; however, once feed rate is fixed, they have a little impact on the operating temperatures.

Direct and Flexural Shear Strength of Composite Beam with Perforbond Rib

2018 ◽  
Vol 26 (1) ◽  
pp. 9-18
Author(s):  
Dooyong Cho ◽  
Jinwoong Choi ◽  
Hoseong Jeong
Keyword(s):  
Shear Stress ◽  
Shear Test ◽  
Shear Resistance ◽  
Shear Behavior ◽  
Flexural Behavior ◽  
Direct Shear ◽  
Test Results ◽  
Shear Connectors ◽  
The Difference ◽  
Push Out

When Perfobond Rib shear connectors are used as flexural materials in structures such as bridges, they show flexural shear behavior due to external force, rather than direct shear behavior. The aim of this study is thus to analyze the difference between both behaviors. First, we prepared a specimen to analyze direct shear behavior using Perfobond Rib shear connectors, analyzed the characteristics of behavior with a push-out test and proposed a formula of shear resistance assessment. Proposed formula shows a relatively good fit with less than 10% error. A flexural shear test was then conducted based on the result of the direct shear test. Based on the static flexural test it analyzed the flexural behavior and the flexural shear stress it calculated. Direct shear stress and EN 1994-1-1 to lead and be calculated, it compared the flexural shear stress and it analyzed in about the shear resistance stress which it follows in load direction. Finally, we compared both test results, and the comparison showed that the flexural shear stress is approximately 6% stronger than the direct shear stress.

Rheological Flow Study of Molten Weld Metal Using the Modified Casson Prediction Model

2011 ◽  
Vol 403-408 ◽  
pp. 491-495
Author(s):  
Joseph I Achebo
Keyword(s):  
Shear Stress ◽  
Weld Metal ◽  
Prediction Model ◽  
Mechanical Test ◽  
Mechanical Tests ◽  
Test Results ◽  
Upward Flow ◽  
Viscoplastic Flow ◽  
Flow Equations ◽  
Flow Study

This paper principally examines the flow pattern that occurs when molten weld metal droplets are detached from globule formations at the tip of an electrode and are thereafter transported to the weldpool. This viscoplastic flow study was done using the modified Casson prediction model which is based on the Newtonian Homogenous Flow equations. Both chemical and mechanical tests were done. The inclusions (Slag) were found to possess an upward flow of 3 ms-1. The mechanical test results show that the shear stress of 483.2 MPa, which exceeded a yield stress of 230 MPa, was responsible for the continuous slipping movement of the molten metal towards the center of the weld pool at a velocity of 1.2ms-1. The results obtained by the application of this model were validated by both computational and experimental results obtained by other researchers.

scholarly journals Practical Guide to the Design, Fabrication, and Calibration of NIST Nanocalorimeters

2019 ◽  
Vol 124 ◽  
Author(s):  
Feng Yi ◽  
Michael D. Grapes ◽  
David A. LaVan
Keyword(s):  
Thermal Analysis ◽  
Silicon Nitride ◽  
Temperature Sensor ◽  
Small Scale ◽  
Thermal Isolation ◽  
Calibration Process ◽  
Practical Guide ◽  
Silicon Nitride Membrane

We report here on the design, fabrication, and calibration of nanocalorimeter sensors used in the National Institute of Standards and Technology (NIST) Nanocalorimetry Measurements Project. These small-scale thermal analysis instruments are produced using silicon microfabrication approaches. A single platinum line serves as both the heater and temperature sensor, and it is made from a 500 μm wide, 100 nm thick platinum trace, suspended on a 100 nm thick silicon nitride membrane for thermal isolation. Supplemental materials to this article (available online) include drawing files and LabVIEW code used in the fabrication and calibration process.

INFLUENCE OF FILLERS ON THE RHEOLOGICAL PROPERTIES OF THEIR COMPOSITIONS WITH LUBRICATING GREASES

Tribologia ◽  
2018 ◽  
Vol 273 (3) ◽  
pp. 47-55 ◽  
Author(s):  
Ryszard CZARNY
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Tribological Properties ◽  
Corrosion Inhibitors ◽  
Experimental Tests ◽  
Lubrication System ◽  
Test Results ◽  
Rate Test ◽  
Oxidation And Corrosion ◽  
System Knowledge

The paper presents the results of studies on the influence of fillers, introduced into lubricating greases, on the rheological properties of resultant grease compositions. These fillers were graphite and PTFE powders. They are added to greases in order to improve their tribological properties. They also affect their rheological properties, and they mainly change the value of the shear stress in grease during its flow in a lubrication system. Knowledge of this value is important in designing automated central lubrication systems in which these compositions may be used. Measurements during experimental tests were performed by means of a rotary rheometer Rheotest 2.1. Tests were performed on pure lithium and bentonite greases, with the addition of oxidation and corrosion inhibitors as well as compositions of these greases with different shares of the above mentioned fillers. These tests were performed by changing the gradient of shearing rate. Test results have shown that both the kind of grease and the kind of filler introduced into this grease affect the rheological properties of produced grease compositions.

Research on Mechanism of Chemical Mechanical Polishing Process for Silicon Nitride Balls with CeO2 Abrasive

2008 ◽  
Vol 53-54 ◽  
pp. 131-136 ◽  
Author(s):  
Cong Rong Zhu ◽  
Bing Hai Lv ◽  
Ju Long Yuan
Keyword(s):  
Silicon Nitride ◽  
Chemical Mechanical Polishing ◽  
Mechanical Action ◽  
Mechanical Polishing ◽  
Test Results ◽  
Free Energy Of Formation ◽  
Key Factor ◽  
Ball Surface ◽  
Chemical Mechanical Polishing Process ◽  
Gibb’S Free Energy

Studies on chemical mechanical polishing (CMP) for silicon nitride (Si3N4) balls with CeO2 abrasive carried to investigate the mechanism of chemo-mechanical action between silicon nitride and CeO2. It is found that CeO2 is more effective to obtain smooth Si3N4 balls than other abrasives, and extremely smooth Si3N4 balls with surface Ra 4nm were obtained after polishing. XRD test is used to detect the reaction resultants on the ball surface, and the results show that SiO2 is the main resultant of the chemical reaction between Si3N4 and CeO2, and the test results confirm the correctness of thermodynamic analysis based on Gibb’s free energy of formation. It is also found that water play as a key factor in CMP.

scholarly journals Evaluation of erosion characteristics of soils using the pinhole test

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ba Huu Dinh ◽  
Anh-Dan Nguyen ◽  
Seo-Yong Jang ◽  
Young-Sang Kim
Keyword(s):  
Particle Size ◽  
Shear Stress ◽  
Erosion Rate ◽  
Critical Shear Stress ◽  
Soil Samples ◽  
Test Results ◽  
Coefficient Of Uniformity ◽  
Identification Parameter ◽  
Pinhole Test ◽  
Significant Factors

AbstractThis paper investigates the erosion characteristics of soils using the pinhole test. The tests were conducted with two undisturbed clay samples and five disturbed sandy soil samples. Based on the pinhole test results, a process to analyze the critical shear stress and erosion rate was proposed. The result indicates that the particle size distribution and coefficient of uniformity of soils are significant factors that affect the erosion characteristics of the soil. Samples with a grain size ranging from 0.2 to 0.6 mm is most susceptible to soil erosion. The erosion coefficients can be used to distinguish between the low erodible soils (ND3 and ND4) and high erodible ones (D1 and D2). Furthermore, it is interesting to note that the critical shear stress might be used as an identification parameter for erosion characteristics of the soil: τc > 3.5 Pa (ND3), 3.0 Pa < τc < 3.5 Pa (D2), and τc < 3.0 Pa (D1).

Pressure Sensitivity of a Thermal Shear Stress Sensor

2003 ◽  
Author(s):  
Jason Clendenin ◽  
Matt Gordon ◽  
Steve Tung
Keyword(s):  
Shear Stress ◽  
Numerical Study ◽  
Pressure Sensitivity ◽  
Sensitivity Testing ◽  
Stress Sensor ◽  
Mems Sensor ◽  
Stress Sensors ◽  
Shear Stress Sensors ◽  
Shear Stress Sensor ◽  
Vacuum Cavity

This paper reports on the pressure sensitivity testing of MEMS thermal shear stress sensors. The MEMS sensor is a micromachined, vacuum-cavity insulated, thermal shear stress sensor for underwater applications. This paper is focused on the combined experimental and numerical study carried out to examine the effects of changing environmental pressure on the MEMS-based shear stress sensors. Four different sensors were tested experimentally and numerically. The silicon nitride diaphragms for each sensor are 4-μm thick. The length of each diaphragm is 210-μm while the widths are 210-μm, 150-μm, 100-μm, and 75-μm respectively. It is found that reducing the surface area size and increasing the thickness of the sensor diaphragms are effective in minimizing the pressure sensitivity.

Stabilization of Railroad Ballast Using Polyurethane Under Various Coal Fouling Conditions

2021 ◽  
Author(s):  
Dinesh Gundavaram ◽  
Syed Khaja Karimullah Hussaini
Keyword(s):  
Shear Stress ◽  
Comparative Study ◽  
Efficiency Factor ◽  
Particle Sizes ◽  
Test Results ◽  
Contamination Index ◽  
Fouled Ballast ◽  
Study Test ◽  
Stabilization Technique ◽  
Coal Fines

Abstract This paper presents a comparative study on the shear behavior of coal fouled polyurethane-stabilized and polyurethane-stabilized coal fouled ballast. Fresh ballast and coal fines of mean particle sizes (D50) of 42 mm and 545 microns, and Elastan polyurethane polymer with a density of 1100 kg/m3 were used in the current study. Tests were conducted at normal stress (σn) varying from 60–120 kPa and at rate of shearing (Sr) 3 mm/min. To mimic the effect of coal fouling, a predetermined amount of coal was added that signifies a fouling level, of 30% void contamination index (VCI), in the present study. Test results highlighted that polyurethane stabilization technique enhanced shear stress of ballast. However, the coal fouling reduced the shear stress of polyurethane-stabilized and unstabilized ballast. The friction (φ) and dilation (ψ) angles of polyurethane-stabilized and unstabilized ballast were found to reduce non-linearly with an increase in σn. Furthermore, the values of φ and ψ of unstabilized ballast reduced from 65° to 60° and 21° to 16°, respectively due to coal fouling. The stabilization efficiency factor (Sef), stated as the ratio of the shear stress of stabilized ballast to the unstabilized ballast, differs from 1.70 to 1.75 for polyurethane-stabilized ballast as σn varies from 60 to 120 kPa. Moreover, it is observed in coal fouling conditions that the coal fouled polyurethane-stabilized ballast (FPSB) shown better performance when compared to polyurethane-stabilized coal fouled ballast (PSFB).

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