scholarly journals Piezoelectric Normally Open Microvalve with Multiple Valve Seat Trenches for Medical Applications

2021 ◽  
Vol 11 (19) ◽  
pp. 9252
Author(s):  
Claudia Patricia Durasiewicz ◽  
Sophia Thekla Güntner ◽  
Philipp Klaus Maier ◽  
Wolfgang Hölzl ◽  
Gabriele Schrag
Keyword(s):  
Fatigue Tests ◽  
Medical Applications ◽  
Valve Seat ◽  
Cfd Simulations ◽  
Closed State ◽  
Low Leakage ◽  
Path Control ◽  
Element Simulation ◽  
Sealing Performance ◽  
Valve Operation

Microfluidic systems for medical applications necessitate reliable, wide flow range, and low leakage microvalves for flow path control. High design complexity of microvalves increases the risk of possible malfunction. We present a normally open microvalve based on energy-efficient piezoelectric actuation for high closing forces and micromachined valve seat trenches for reliable valve operation. A comprehensive investigation of influencing parameters is performed by extensive fluidic 3D finite element simulation, derivation of an analytical closed state leakage rate model, as well as fabrication and test of the microvalve. Additional valve seat coating and a high force actuator are introduced for further leakage reduction. The microvalve has a wide-open flow range as well as good sealing abilities in closed state. Extensive fatigue tests of 1 × 106 actuation cycles show that additional coating of the valve seat or increased actuator strength promote sealing performance stability. Analytical calculations of leakage are suitable to estimate experimentally obtained leakage rates and, along with computational fluidic dynamic (CFD) simulations, enable future microvalve design optimization. In conclusion, we demonstrate that the presented normally open microvalve is suitable for the design of safe and reliable microfluidic devices for medical applications.

Optimization of the Specimen Geometry of Unidirectional Reinforced Composites with a Fibre Orientation of 90° for Tensile, Quasi-Static and Fatigue Tests

2019 ◽  
Vol 809 ◽  
pp. 594-597
Author(s):  
Christian Schneider ◽  
Matthias Drvoderic ◽  
Clara Schuecker ◽  
Gerald Pinter
Keyword(s):  
Test Specimen ◽  
Fibre Orientation ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Fiber Direction ◽  
Optimized Design ◽  
Test Field ◽  
Reinforced Composites ◽  
Element Simulation ◽  
Shoulder Geometry

When testing unidirectional reinforced composites with a fiber orientation of 90° in tensile tests with rectangular specimens, the influence of the clamping often causes a failure in their vicinity and therefore the test cannot be regarded as valid. In this paper, a test specimen design was determined which is well suited for testing the material properties transverse to the fiber direction by calculating the influence of geometric details of shoulder bar specimens with the help of finite element simulation. The particularly critical clamping and shoulder areas were examined more closely to ensure failure mainly in the test field. In the clamping area the design of the glued-on tabs was investigated and in the shoulder area an optimization of the shoulder geometry was done. Based on the two optimized design proposals, test specimens were produced and evaluated by monotonous tensile tests. Subsequently, Wöhler tests were carried out at different R-ratios and load levels and compared with results of rectangular specimens.

Design of Magnetic Fluid Sealing Device and Computer Simulation in Sintering Machine

2011 ◽  
Vol 328-330 ◽  
pp. 2270-2273
Author(s):  
Ming Hua Bai ◽  
Qing Rong Liu ◽  
Hong Liang Zhou
Keyword(s):  
Magnetic Fluid ◽  
Magnetic Coupling ◽  
Simulation Software ◽  
Sintering Machine ◽  
Element Simulation ◽  
Sealing Performance ◽  
New Type ◽  
Set Up ◽  
Edge Temperature ◽  
Sealing Device

This paper, based on magnetic fluid dynamics, combined with the air leakage of sintering machine, proposes a new type of magnetic fluid sealing device in sintering machine. According to the sealing mechanism of MHD as well as Bernoulli equation, the sealing theory--pressure difference equation in static sealing by magnetic fluid is deduced for the actual model of sintering machine. By using ansys finite element simulation software, the two-dimensional numerical simulation of thermal magnetic- coupling inside of sealing device is set up, the effects of different temperature on the magnetic properties are analyzed and the best sealing performance is found, that is when the edge temperature of the sealing device is controlled from 30°C to 80°C.

Finite Element Stress Analysis for Leak Tests of Pipe Flange Connections Subject to Internal Pressure and Bending Moment

2011 ◽  
Author(s):  
Satoshi Nagata ◽  
Toshiyuki Sawa ◽  
Takashi Kobayashi ◽  
Hirokazu Tsuji
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Bending Moment ◽  
Strain Gages ◽  
Element Analysis ◽  
Element Simulation ◽  
Sealing Performance ◽  
Gas Leak ◽  
Helium Gas

This paper reports the results of finite element analysis representing the sealing performance tests on the slip-on type pipe flange connections for 8 inch and 16 inch. The flange connections are subjected to internal pressure and bending moment. Internal pressure is applied by helium gas and the bending moment is loaded through 4 points bending equipment. Gas leak rates are measured by pressure decay method. During the test, the variations in the axial bolt force are monitored for all the bolts by strain gages. The pipe stress at the junction of pipe and flange is also measured. Finite element analysis simulates the tests and the simulated results are compared with the measured data. Then the behaviors of the slip-on type flange connections under internal pressure and bending moment as well as the sealing performance are clarified by the experiment and the finite element simulation.

On the Development of a Pressure Actuated Leaf Seal for Turbomachinery Applications

2019 ◽  
Author(s):  
Ernesto Pedraza-Valle ◽  
Georgios Papageorgiou ◽  
Aaron Bowsher ◽  
Peter F. Crudgington ◽  
Carl M. Sangan ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Applied Pressure ◽  
Stable Operation ◽  
Pressure Drops ◽  
Low Leakage ◽  
Turbine Efficiency ◽  
Sealing Performance ◽  
Improved Performance ◽  
Shaft Seals ◽  
Opening And Closing

Abstract In gas turbines, seals that reduce the leakage between high and low pressure regions are critical for improved performance. Damaging rubs between the rotating and non-rotating parts of turbomachinery shaft seals occur due to thermal and assembly misalignments, and rotordynamic vibration during engine start-up and shut-down transients. These rubs lead to increased seal leakage and hence to reduced overall turbine efficiency and life span. The Film Riding Pressure Actuated Leaf Seal (FRPALS) is a non-contacting compliant seal under development to adapt to varying clearances without rubbing, while maintaining low leakage. This paper presents the measurements of the FRPALS in a test rig specifically designed to test novel shaft seals for turbomachinery. The rig features a 254 mm diameter rotor with a maximum surface speed of 200 m/s. Pressure drops of up to 3.5 bar can be achieved. The results of initial testing at zero rotational speed are presented for the FRPALS in a reverse orientation. The opening and closing translations of the leaves have been measured using eddy current displacement probes targeting the movable parts of the seal. The seal clearance has been shown to remain constant for a range of applied pressure drops, which indicates the stable operation of the seal, though resulting in contact with the rotor at 1.5 bar. Mass flow leakage measurements have also demonstrated the sealing performance of the FRPALS. They show the potential of the seal to film ride subject to design modifications to maintain a more uniform film thickness. The steady-state Reynolds equation for lubrication has been used to predict the pressure along the seal clearance. The predictions have been compared with pressure measurements from a transducer located in the clearance fluid thin film.

Design Improvement of the Jellyfish Valve for Long-term Use in Artificial Hearts

2001 ◽  
Vol 24 (7) ◽  
pp. 463-469 ◽  
Author(s):  
K. Iwasaki ◽  
M. Umezu ◽  
K. Imachi ◽  
K. Iijima ◽  
T. Fujimoto
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Tests ◽  
Engineering Analysis ◽  
Valve Seat ◽  
Concentric Ring ◽  
Element Analysis ◽  
Design Improvement ◽  
Artificial Hearts

In a previous communication, we reported a leaflet fracture in a Jellyfish valve that was incorporated into a blood pump, after a 312-day animal implant duration. Subsequent finite element analysis revealed that the fracture location was consistent with an area of maximum strain concentration. Therefore, the aim of this study was to improve the durability in the light of these findings. Based on the engineering analysis results, a new valve seat having a concentric ring of 0.5mm width, located at a radius of 7.0 mm, was designed and fabricated. Accelerated fatigue tests, conducted under the conditions recommended by ISO 5840, demonstrated that the durability of this new prototype was extended by a factor of 10, as compared to the original valve. Moreover, further finite element analysis indicated that the maximum equivalent elastic strain of the proposed new valve was reduced by 52.3% as compared to the original valve. Accordingly, it has been confirmed that the modified Jellyfish valve is suitable for use in long-term artificial hearts.

Finite Element Simulation of Sealing Performance in Bolted Flange Joints of Longitudinal Baffle Type Heat Exchanger

2011 ◽  
Author(s):  
Hiroshi Yamanaka
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Finite Element Analyses ◽  
Oil Refineries ◽  
Element Simulation ◽  
Start Up ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Bolted Flange

Bolted flange joints are used in heat exchangers and piping of oil refineries, chemical refineries and various other industries. Above all, it is reported that bolted flange joints of longitudinal baffle type heat exchanger are easy to leak as compared with other type heat exchangers in start up of units. In this study, outside influence on operating and structure of longitudinal baffle type heat exchanger which affect sealing performance were analyzed using finite element analyses to prevent leakage accidents. As a result, it is understood that the sealing performance in bolted flange joints decreases remarkably when the shell of heat exchanger transforms like a bow with a rise in temperature. In addition, it is clarified that retightening, increases in bolt preload and thickness of gasket keep sealing performance well in bolted flange joints of longitudinal baffle type heat exchanger.

Computer Simulation and Modelling of Passive Humidification Device Cavity for Intensive Care Patient Medical Applications

2014 ◽  
Author(s):  
Mahmoud Shafik ◽  
Anne Lechevretel
Keyword(s):  
Heat Transfer ◽  
Intensive Care Patient ◽  
Care Patient ◽  
Medical Applications ◽  
Cfd Simulations ◽  
Moisture Exchange ◽  
Flow And Heat Transfer ◽  
Computational Fluid Dynamics Cfd ◽  
Heat And Moisture ◽  
Exchange Properties

This paper presents the research that has been undertaken into the passive humidification device cavity airflow structures and patterns. This was aiming to improve the device airflow, Heat and Moisture Exchange (HME) materials performance, for a greater patient care. However the objectives were to assist in understanding the optimal cavity structural geometries, generating improved airflow patterns over target HME material structures and consequently leading to improved heat and moisture exchange properties. Airflow studies of the device have been undertaken using the Computational Fluid Dynamics (CFD) interface of the ANSYS. The CFD package enables analysis of fluid flow and heat transfer. This paper presents the results of the CFD simulations carried out on different passive humidification device cavity designs and materials arrangements. An optimised design leading to enhanced airflow structures and patterns, heat and moisture properties of the device is also presented in this paper.

Creep Analysis of Combined Bolted Flange Joints under High Temperature

2014 ◽  
Vol 624 ◽  
pp. 187-192
Author(s):  
He Hui Wang ◽  
Yan Zhang
Keyword(s):  
High Temperature ◽  
Loading Condition ◽  
Film Stress ◽  
Load Relaxation ◽  
Tightening Force ◽  
Element Simulation ◽  
Sealing Performance ◽  
Creep Analysis ◽  
Sealing Pressure ◽  
Bolted Flange

The tightness of bolted flange joints will weaken due to the loss of bolt load as a result of creep under high temperature. There exists no mature calculation procedure that can accounts for creep. Based on the finite element simulation of a combined flanged joint under four various conditions, the strength integrity and sealing performance of it are evaluated according to the code JB4732-2005. The results show that the integrity and tightness of the combined flanged joint under pre-loading condition, pressure condition and operating condition (except local film stress) meet requirements. However, more than 50% of the bolt load relaxation is found due to creep, part of the gasket residual stress is lower than the required minimum sealing pressure. It can lead to leakage. Bigger bolt pre-tightening force, materials with good creep relaxation resistance and hot-tighting method are recommended to reduce the influence of creep.

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