Superplastic Dome Forming of Machined Sheets

1999 ◽  
Vol 601 ◽  
Author(s):  
Nihat Akkus ◽  
Toshihiro Usugi ◽  
Masanori Kawahara ◽  
Ken-ichi Manabe ◽  
Hisashi Nishimura
Keyword(s):  
Constant Pressure ◽  
Thickness Distribution ◽  
Pressure Control ◽  
Control Mode ◽  
Constant Thickness ◽  
Al Alloy ◽  
Deformation Model ◽  
Final Thickness ◽  
Incremental Strain ◽  
Reverse Deformation

AbstractAn experimental work on the superplastic bulge forming of machined sheets is presented in this study. Unlike the previously employed incremental-iterative method, a reverse deformation model was used to estimate the initial thickness distribution of the machined sheets from which a constant final thickness can be obtained when the shape of the bulged sheet is hemisphere. The reverse deformation modci was obtained by modifying previously-known models, which were based on the axisymmetric membrane and the incremental strain theory.Bulge forming experiments were conducted on machined sheets of Al alloy, A5083, at about 530°C under constant pressure control mode. The result of this simulation to estimate the final constant thickness distribution agreed well with the experiment, and confirmed that the reverse deformation model can be successfully applied in optimizing the thickness distribution of the starting sheets in order to obtain the desired final thickness distribution of the free bulged hemispherical product.

scholarly journals Strain State in Metal Sheet Axisymmetric Stretching with Variable Initial Thickness: Numerical and Experimental Results

2021 ◽  
Vol 11 (17) ◽  
pp. 8265
Author(s):  
Gillo Giuliano ◽  
Wilma Polini
Keyword(s):  
Strain State ◽  
Thickness Distribution ◽  
Element Model ◽  
Alloy Sheet ◽  
Metal Sheet ◽  
Constant Thickness ◽  
Initial Thickness ◽  
Final Thickness ◽  
Stretching Process ◽  
Commercial Sheet

This work presents a finite element model to analyze the distribution of the strains due to an axisymmetric stretching of a metal sheet. The sheet is characterized by a variable initial thickness. The resulting strain state is compared with that of a sheet with a constant initial thickness. The results of the present study allow asserting that the distribution of strains in the sheet can be controlled by setting opportunely the trend of the sheet initial thickness. In this way, it is possible to see that, starting from a sheet with variable initial thickness, a lighter final product is obtained, whose final thickness distribution is more uniform than that of the product obtained from a classic stretching process that requires a sheet with constant initial thickness. Encouraging results from an experimental activity carried out on an AA6060 aluminum alloy sheet, whose trend of initial thicknesses was prepared by removing material from a commercial sheet with a constant thickness, allow us to note the good agreement with what was theoretically highlighted.

Fuzzy Control-Based Air-Compressor Constant Pressure Gas Intelligent Control

2011 ◽  
Vol 230-232 ◽  
pp. 187-191
Author(s):  
Gong Fa Li ◽  
Si Qiang Xu ◽  
Jin Hui Wang ◽  
Jin Tang Yang ◽  
Jian Yi Kong ◽  
...  
Keyword(s):  
Control System ◽  
Fuzzy Control ◽  
Constant Pressure ◽  
Pressure Control ◽  
Air Compressor ◽  
Time Varying Delay ◽  
Important Sense ◽  
Pressure Control System ◽  
Working Characteristic ◽  
Varying Delay

The air compressor system is a time-varying, delay and nonlinear complex system, it has a very important sense to ensure that the supply pressure is stable in the compressor control system. According to the working characteristic of air compressor system, the fuzzy control theory, as one of the modern control theories, was applied into the constant pressure control system to design a fuzzy pressure controller. The simulation results show that the controller was more convenient and effective; it has certain directive significance and reference for the other parameter’s control of air compressor system.

scholarly journals Maintenance of end-expiratory recruitment with increased respiratory rate after saline-lavage lung injury

2007 ◽  
Vol 102 (1) ◽  
pp. 331-339 ◽  
Author(s):  
Rebecca S. Syring ◽  
Cynthia M. Otto ◽  
Rebecca E. Spivack ◽  
Klaus Markstaller ◽  
James E. Baumgardner
Keyword(s):  
Cardiac Output ◽  
Lung Injury ◽  
Respiratory Rate ◽  
Pressure Control ◽  
Plateau Pressure ◽  
Control Mode ◽  
Intrinsic Peep ◽  
Mixed Venous Saturation ◽  
Mixed Venous ◽  
Saline Lavage

Cyclical recruitment of atelectasis with each breath is thought to contribute to ventilator-associated lung injury. Extrinsic positive end-expiratory pressure (PEEPe) can maintain alveolar recruitment at end exhalation, but PEEPe depresses cardiac output and increases overdistension. Short exhalation times can also maintain end-expiratory recruitment, but if the mechanism of this recruitment is generation of intrinsic PEEP (PEEPi), there would be little advantage compared with PEEPe. In seven New Zealand White rabbits, we compared recruitment from increased respiratory rate (RR) to recruitment from increased PEEPe after saline lavage. Rabbits were ventilated in pressure control mode with a fraction of inspired O2 (FiO2) of 1.0, inspiratory-to-expiratory ratio of 2:1, and plateau pressure of 28 cmH2O, and either 1) high RR ( 24 ) and low PEEPe (3.5) or 2) low RR ( 7 ) and high PEEPe ( 14 ). We assessed cyclical lung recruitment with a fast arterial Po2 probe, and we assessed average recruitment with blood gas data. We measured PEEPi, cardiac output, and mixed venous saturation at each ventilator setting. Recruitment achieved by increased RR and short exhalation time was nearly equivalent to recruitment achieved by increased PEEPe. The short exhalation time at increased RR, however, did not generate PEEPi. Cardiac output was increased on average 13% in the high RR group compared with the high PEEPe group ( P < 0.001), and mixed venous saturation was consistently greater in the high RR group ( P < 0.001). Prevention of end-expiratory derecruitment without increased end-expiratory pressure suggests that another mechanism, distinct from intrinsic PEEP, plays a role in the dynamic behavior of atelectasis.

Adult respiratory distress syndrome: outcome in a community hospital

1994 ◽  
Vol 3 (5) ◽  
pp. 337-341 ◽  
Author(s):  
D Willms ◽  
M Nield ◽  
I Gocka
Keyword(s):  
Survival Rate ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Adult Respiratory Distress Syndrome ◽  
Distress Syndrome ◽  
Community Hospital ◽  
Survival Rates ◽  
Pressure Control ◽  
Control Mode ◽  
Significant Difference

BACKGROUND: Published reports indicate that survival rates of patients with adult respiratory distress syndrome have not improved dramatically since the first report of the condition in 1967. However, changes in ventilator strategies and improved critical care management may result in better survival rates in patients with well-defined, severe adult respiratory distress syndrome. OBJECTIVES: To report the outcomes of patients with adult respiratory distress syndrome treated in a community hospital and compare these findings with those in previously published reports. METHODS: A retrospective study design was used. All patients diagnosed with adult respiratory distress syndrome (N = 47) over a 2-year period were studied. RESULTS: For the study patients, the survival rate was 64%; 29% died from respiratory failure alone. Analysis demonstrated that advanced age was not associated with mortality. Pressure-control ventilation was used for 31 patients and there was no significant difference in the presence of barotrauma in the pressure-control mode vs volume ventilation. CONCLUSION: This survival rate exceeds most recently reported rates and thus supports the idea that improvement in treatment of adult respiratory distress syndrome is occurring.

Multilayer Plug Assisted Thermoforming-Concept and Practical Usefulness

2006 ◽  
Vol 514-516 ◽  
pp. 1467-1471
Author(s):  
Fernando M. Duarte ◽  
José A. Covas
Keyword(s):  
Mechanical Performance ◽  
Thickness Distribution ◽  
Relative Displacement ◽  
Simultaneous Increase ◽  
Final Thickness ◽  
Practical Usefulness

This work presents a methodology to improve the final thickness distribution of thermoformed parts. The conventional plug is replaced by a new version containing concentric layers with independent displacements. The results show that thickness gradients can be significantly reduced, with a simultaneous increase of the minimum values. Varying the relative displacement of the inner layers can bring about significant differences in the final thickness distribution, thus enabling the production of parts with prescribed thickness profiles that maximise their mechanical performance.

Performances analysis of a novel load-sensing hydraulic system with overriding differential pressure control

2016 ◽  
Vol 231 (23) ◽  
pp. 4331-4343 ◽  
Author(s):  
Hu Quanyi ◽  
Zhang Hong ◽  
Tian Shujun ◽  
Qin Xuxin
Keyword(s):  
Hydraulic System ◽  
Graph Model ◽  
Pressure Control ◽  
Bond Graph ◽  
Differential Pressure ◽  
Operating Conditions ◽  
Control Mode ◽  
Variable Pressure ◽  
Load Sensing ◽  
Sensing System

The traditional load-sensing hydraulic system is an energy-saving fluid power transmission, which supply “on-demand” flow at a prescribed pressure margin greater than the highest load pressure of the system. In this paper, a novel load-sensing system that has a variable pressure margin through overriding differential pressure control via integrating an electro-proportional three-way type pressure reducing valve into the hydro-mechanical load-sensing valve is proposed. Also, a bond graph model taking into account the dynamic characteristics of load-sensing valve and load-sensing path is constructed, and three group experiments are performed to verify the validation of the model. Based on the bond graph model, a series of theoretical simulations are carried out to prove that the proposed Load-Sensing system enables a satisfactory balance between energy efficiency and rapid dynamic response over a wide range of operating conditions. In addition, due to overriding differential pressure control, mode selection and power limit regulation can also be achieved.

Permanent-Pressure Control Tactic of Rudder Based on Fuzzy-Control Theorem

2012 ◽  
Vol 192 ◽  
pp. 360-364
Author(s):  
Xi Guang He ◽  
Ji Feng Xing ◽  
Jia Chen
Keyword(s):  
Fuzzy Control ◽  
Life Span ◽  
Hydraulic System ◽  
Constant Pressure ◽  
Pressure Control ◽  
Hydraulic Systems ◽  
Oil Pump ◽  
Controlling System ◽  
Save Energy ◽  
The Relationship

In order to guarantee that the rudder hydraulic systems work normally, the rudder hydraulic system must supply constant-pressure fluid to it. In this article, the author had analyzed the relationship between the power of the hydraulic oil pump and its motor revs, and done researches on its controlling tactics. Next, the author deigned its controller and controlling system based on fuzzy-control theorem. This system could extend the life-span of the pump motor and save energy, and it can also be utilized in other engineering fields.

Frequency Constant Pressure Control System Based on PLC

2013 ◽  
Vol 579-580 ◽  
pp. 798-803
Author(s):  
Qi Zhu ◽  
Zhi Wen Feng
Keyword(s):  
Wastewater Treatment ◽  
Control System ◽  
Constant Pressure ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Pressure Control ◽  
Pipe Network ◽  
Pumping Station ◽  
Pressure Control System

Sewage pumping station is pumping station import at the sewage treatment plant. Its role is to collect the wastewater from the sewage pipe network to subsequent wastewater treatment process facilities. The water level is usually low in sewage collection pipe network. And many wastewater treatment facilities is based on elevation settings. So it is necessary to use lift pump to improve lift of the collected sewage, using high gravity sewage errands subsequent process in order to reduce energy consumption. The traditional way of pumping generally has the shortcomings: the waste of power resources, low efficiency, poor reliability, low degree of automation, which seriously affects the urban sewage treatment capacity. This paper, views pump station control system at the sewage treatment plant as the background, researches frequency control constant pressure control system based on PLC, realizes the energy efficient, automated and reliable direction of development of the sewage pumping station.

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