High Performance MEMS Thermal Gyroscope

To Come ◽

This paper reports modeling a new design of Thermal MEMS gyroscope through the use of the Comsol Multiphysics software package. Being very small and having no movable parts have made thermal MEMS gyroscope very practical. Previously designed Thermal MEMS gyroscope shows some limitation such as being vulnerable to gravity force. Finding a technique to increase the range of thermal MEMS gyroscope reliability motivated us to come up with a new design that we will refer to as the ‘Forced Convection MEMS gyroscope’. A two-dimensional finite-element model of the device has been developed to investigate its performance. An external force has been introduced to the system to create a higher-velocity hot gas stream that will be deviated more in response to rotation. The external force should be great enough that convection currents resulting from gravity or acceleration will have minimal impact on the gyroscope sensitivity. A heating element can still be used, but its primary purpose is now to warm the flowing gas so that it can be detected by the sensors. In this paper we will also show that, in order to completely eliminate the impact of gravity and increase the sensitivity of the gyroscope, it is possible to eliminate the heaters entirely and instead use heated sensors to detect gas currents. In other words, the sensors are working as hot-wire anemometers. Our simulations suggest that this design variant results in higher sensitivity. We have also carried out optimization studies to identify the best location for the heaters and sensors. A prototype of this device has been fabricated based on MEMS techniques, and an external pump is used to produce an oscillating gas flow within the device.

Focality of the Induced E-Field Is a Contributing Factor in the Choice of TMS Parameters: Evidence from a 3D Computational Model of the Human Brain

Brain Sciences ◽

10.3390/brainsci10121010 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1010

Author(s):

Deepika Konakanchi ◽

Amy L. de Jongh Curry ◽

Robert S. Waters ◽

Shalini Narayana

Keyword(s):

Spatial Distribution ◽

Three Dimensional ◽

Fem Simulation ◽

Element Model ◽

Brain Areas ◽

Invasive Approach ◽

Non Invasive ◽

Transcranial magnetic stimulation (TMS) is a promising, non-invasive approach in the diagnosis and treatment of several neurological conditions. However, the specific results in the cortex of the magnitude and spatial distribution of the secondary electrical field (E-field) resulting from TMS at different stimulation sites/orientations and varied TMS parameters are not clearly understood. The objective of this study is to identify the impact of TMS stimulation site and coil orientation on the induced E-field, including spatial distribution and the volume of activation in the cortex across brain areas, and hence demonstrate the need for customized optimization, using a three-dimensional finite element model (FEM). A considerable difference was noted in E-field values and distribution at different brain areas. We observed that the volume of activated cortex varied from 3000 to 7000 mm3 between the selected nine clinically relevant coil locations. Coil orientation also changed the induced E-field by a maximum of 10%, and we noted the least optimal values at the standard coil orientation pointing to the nose. The volume of gray matter activated varied by 10% on average between stimulation sites in homologous brain areas in the two hemispheres of the brain. This FEM simulation model clearly demonstrates the importance of TMS parameters for optimal results in clinically relevant brain areas. The results show that TMS parameters cannot be interchangeably used between individuals, hemispheres, and brain areas. The focality of the TMS induced E-field along with its optimal magnitude should be considered as critical TMS parameters that should be individually optimized.

Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

Shock and Vibration ◽

10.1155/2019/3237960 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Jie Hong ◽

Tianrang Li ◽

Zhichao Liang ◽

Dayi Zhang ◽

Yanhong Ma

Keyword(s):

High Speed ◽

High Performance ◽

Element Model ◽

Physical Parameters ◽

Test Rig ◽

Calculation Results ◽

Rotor Support ◽

Blade Tip ◽

Set Up ◽

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

Optimization of the Engine Hood to Reduce the Head Injury during the Vehicle-Human Collision

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.192.29 ◽

2012 ◽

Vol 192 ◽

pp. 29-36

Author(s):

Yu Xin Wang ◽

Qing Chun Wang ◽

Jian Rong Fu ◽

Hong Hai Qiao

Keyword(s):

Finite Element ◽

Head Injury ◽

Optimization Design ◽

Three Dimensional ◽

Element Model ◽

Head Model ◽

Modeling Software ◽

Effect of hard point of the engine hood on the head injury during the vehicle-human collision was studied to improve the design of engine hood. Firstly, the current common model of the engine hood was established with three-dimensional finite element modeling software, and 20 areas were divided, also a standard head finite element model was imported, secondly, each area of the engine hood was clashed by the standard head model, then the impact on the head injure was analyzed and the hard point of the hood area was achieved, thirdly, the optimization of the inside and outside panel materials and the plate structure were carried out to reduce the head damage. The simulation results show that the engine hood after optimization gave less damage to the head, which means the research carried out here is of a good reference to the engine hood optimization design for human protection

Modeling a Three-Axis Thermal MEMS Gyroscope

Volume 9: Micro- and Nano-Systems Engineering and Packaging, Parts A and B ◽

10.1115/imece2012-89451 ◽

2012 ◽

Author(s):

Nilgoon Zarei ◽

Albert M. Leung ◽

John D. Jones

Keyword(s):

Three Dimensional ◽

Element Model ◽

Micro Electro Mechanical System ◽

Comsol Multiphysics ◽

Mems Gyroscope ◽

Mems Gyroscopes ◽

Axis Rotation ◽

Single Axis Rotation

This paper reports modeling of a three-axis thermal Micro-Electro-Mechanical System, MEMS, gyroscope through the use of the COMSOL Multiphysics software package. Being very small and having no movable parts makes the thermal MEMS gyroscope very reliable. Previously designed Thermal MEMS gyroscopes have the capability of detecting single-axis rotation. A three-dimensional finite-element model of the device has been developed to investigate three-axis rotation detection possibilities. The effect of gravity has been also investigated and we show techniques for suppressing this interference.

Optimization of Pass Design of Bidirectional Thermal-Insulation Bricks

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1008-1009.1348 ◽

2014 ◽

Vol 1008-1009 ◽

pp. 1348-1351

Author(s):

Sha Sha Dong ◽

Xiao Ping Feng

Keyword(s):

Thermal Conductivity ◽

Thermal Resistance ◽

Thermal Insulation ◽

Thermal Performance ◽

Element Model ◽

Two Dimensional ◽

Pass Design ◽

The Impact ◽

Better Than

The thermal performance of perforated brick is affected by various factors, thermal conductivity, the holes rates, the pass design and etc. included. In order to analyze the impact of the pass design on the thermal performance of bidirectional thermal insulation bricks, the two-dimensional finite element model was developed using ANSYS. The simulated result shows that existence of vertical holes can enhance the thermal resistance in the longer dimension of the perforated brick. Under the condition of the same holes rates, narrowing the width of the vertical holes helps to improve the thermal resistance in the shorter dimension of the perforated brick. The function of these blocks are extremely influenced by the distribution of the vertical holes, the concentrated better than the both-sided when it comes to advancing the whole function.

Impact of Self-Assembly Process Errors on Thermoelectric Performance

Journal of Electronic Packaging ◽

10.1115/1.4006709 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 1

Author(s):

Nathan B. Crane ◽

Patrick McKnight

Keyword(s):

Self Assembly ◽

High Performance ◽

Three Dimensional ◽

Assembly Process ◽

Thermoelectric Devices ◽

One Dimensional ◽

Assembly Accuracy ◽

Thermoelectric devices have many scaling benefits that motivate miniaturization, but assembly of small components is a significant challenge. Self-assembly provides a promising method for integrating very small elements. However, it introduces the possibility of stochastic errors with significant performance impacts. This work presents a method to estimate the impact of these errors on system performance. Equivalent thermoelectric properties are developed that adjust for the effect of missing elements in one-dimensional thermoelectric models. The models show that the thermoelectric devices can accommodate significant self-assembly errors by incorporation of redundant electrical paths. The model shows nearly linear decline in effective power factor with declining assembly accuracy, but the effective figure of merit (ZT) is relatively insensitive to assembly errors. Predictions from the modified one-dimensional model agree well with three-dimensional finite element simulations. This work identifies two basic strategies for how devices such as thermoelectric could be designed for self-assembly and demonstrates that it is possible to achieve high performance despite self-assembly process errors.

Simulation and Test for the Lightning Damage of the Glass Fiber Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1003.78 ◽

2014 ◽

Vol 1003 ◽

pp. 78-84

Author(s):

Xiao Ning Chen ◽

Jin Long Zhao ◽

Yun Sheng Zhang ◽

Bin Zhang

Keyword(s):

Finite Element ◽

Three Dimensional ◽

Element Model ◽

Damage Mechanism ◽

Glass Fiber Composites ◽

Aircraft Composites ◽

The Impact ◽

Composites Panel

Theoretical deducing, simulated lightning test and finite element simulation are used to research the mechanism and state of lightning damage of the aircraft composites sandwich panels. It provides the basis for the design of the aircraft lightning protection. The three-dimensional finite element model of the composites panel is constructed through the thermal electrical-mechanical multi-Physics coupling field. According to the structure and the role process, the lightning effect of the aircraft composites is analysed to study the damage mechanism and the possible state of the composites panel that is struck by lightning. The impact current generator is used to carry out the simulated lightning test to observe the lightning effect of the composites panel. By comparing the results of the test and the simulation, the effectiveness and the correctness of the simulation are verified.

Simplified finite element method analysis of ultra-high-performance fibre-reinforced concrete columns under blast loads

Advances in Structural Engineering ◽

10.1177/1369433216646012 ◽

2016 ◽

Vol 20 (1) ◽

pp. 139-151

Author(s):

Juechun Xu ◽

Chengqing Wu ◽

Jun Li ◽

Jintao Cui

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Finite Element Model ◽

High Performance ◽

Concrete Columns ◽

Element Model ◽

Fibre Reinforced Concrete ◽

Reinforced Concrete Columns ◽

High Performance Fibre

Ultra-high-performance fibre-reinforced concrete has exceptional mechanical properties including high compressive and tensile strength as well as high fracture energy. It has been proved to be much higher blast resistant than normal concrete. In this article, flexural behaviours of ultra-high-performance fibre-reinforced concrete columns were investigated through full-scale tests. Two 200 mm × 200 mm × 2500 mm columns with and without axial loading were investigated under three-point bending tests, and their load–displacement relationships were recorded and the moment curvatures were derived. The derived moment curvature relationships of ultra-high-performance fibre-reinforced concrete columns were then incorporated into a computationally efficient one-dimensional finite element model, which utilized Timoshenko beam theory, to determine flexural response of ultra-high-performance fibre-reinforced concrete columns under blast loading. After that, the one-dimensional finite element model was validated with the real blast testing data. The results show good correlation between the advanced finite element model and experimental results. The feasibility of utilizing the one-dimensional finite element model for simulating both high-strength reinforced concrete and ultra-high-performance fibre-reinforced concrete columns against blast loading conditions is confirmed.

Dynamic Response Analysis of Xi'an Bell Tower Timber Structure under the Metro-Vibration Loading of Line 2 and 6

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.1732 ◽

2013 ◽

Vol 353-356 ◽

pp. 1732-1738

Author(s):

Zhao Bo Meng ◽

Teng Fei Zhao ◽

Jie Jin ◽

Xi Feng Li

Keyword(s):

Technical Specification ◽

Interaction Model ◽

Time History ◽

Element Model ◽

Response Analysis ◽

Winkler Foundation ◽

Analysis Model ◽

Bell Tower ◽

The effects of metro line 2 and line 6 on Xi'an Bell Tower was studied by numerical analysis in this paper. At first, according to the theory of Euler-Bernoulli beam in Winkler foundation, the analysis model of train-track-foundation system was established, and then, time-history curve of metro-induced loading acts on tunnel structure is obtained by using Matlab produce platform. Secondly, two-dimensional finite element model of the structure-soil-tunnel interaction model was established using ANSYS. Finally, the impact of metro line 2 and 6 and ground transportation on Xi’an Bell Tower was evaluated according to the Technical specification for protection of historic buildings against man-made vibration. The construction of Metro Line 2 and Line 6 will affect the safety of Xi'an Bell Tower.

Gas-solid Erosion Wear Characteristics of Two-phase Flow Tee Pipe

Mechanika ◽

10.5755/j02.mech.27478 ◽

2021 ◽

Vol 27 (3) ◽

pp. 193-200

Author(s):

Jin HU ◽

Hao ZHANG ◽

Jie ZHANG ◽

Shiwei NIU ◽

Wenbo CAI

Keyword(s):

Gas Flow ◽

Two Phase Flow ◽

Flow Direction ◽

Element Model ◽

Phase Flow ◽

Erosion Wear ◽

Two Phase ◽

Wear Characteristics ◽

Volume Method ◽

Particles erosion wear always consist in the intersection of tee pipe, which is an inevitable problem. In order to obtain the erosion wear characteristics of two-phase flow tee pipe, several cases of different inlet diameters are investigated numerically in this paper. Euler-Lagrange method is adopted to describe the gas-solid two-phase flow and the finite volume method is adopted to solve the erosion results. Meshing O-type grids to obtain the reasonable boundary layer in ICEM CFD. By verifying and comparing the turbulence intensity and velocity of the six meshes, a reasonable finite element model is selected. Intersection, the severest erosion region, is the location where the gas flow direction changes. The inlet diameter determines the region of the impact particles directly hitting the wall. When the inlet diameter is smaller, the erosion of the intersection is severer. As the inlet velocity increases, both the erosion of the intersection and the outlet pipe become severer. However, there are only the erosion scars at the intersection are affected, with the increase of particle mass flow.