NUMERICAL ANALYSIS OF HEAT TRANSFER AND CHEMICAL REACTION COUPLING IN THE RUBBER SEAL VULCANIZATION PROCESS

2021 ◽  
Author(s):  
Zhaoxiang Zhang ◽  
Xiaohong Jia ◽  
Fei Guo ◽  
Xing Huang ◽  
Yuming Wang
Keyword(s):  
Energy Savings ◽  
Structural Parameters ◽  
Element Model ◽  
Mold Temperature ◽  
Design Parameters ◽  
Cross Sectional ◽  
Rubber Seal ◽  
Reaction Coupling ◽  
And Control ◽  
Vulcanization Process

ABSTRACT Vulcanization parameters significantly affect the performance of rubber seals and the energy savings of the manufacturing process, which require a relationship between process parameters and vulcanization characteristics. Based on the vulcanization kinetics of rubber seal materials, a transient thermochemical-coupled finite-element model of the vulcanization process was established and solved. Changes in thermal conductivity and specific heat capacity during vulcanization were considered in detail. The effects of operational and structural parameters, such as mold temperature, heating duration, and rubber seal shape, cross-sectional dimensions on vulcanization characteristics were investigated. Finally, feasible suggestions for the vulcanization production of rubber seals are discussed. The study is expected to design parameters and control the vulcanization process of rubber seals accurately.

Sealing performance and fatigue life of the fracturing packer rubber of various materials

2019 ◽  
Vol 233 (17) ◽  
pp. 6157-6166 ◽  
Author(s):  
Fuying Zhang ◽  
Haoche Shui ◽  
Jun-Mei Yang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Contact Stress ◽  
Field Experiments ◽  
Structural Parameters ◽  
Element Model ◽  
Rubber Seal ◽  
Maximum Contact Stress ◽  
Different Temperatures ◽  
Maximum Contact

The finite element model of four packer rubber materials was established by using ABAQUS and FE-SAFE software. The initial sealing load (the load is the pressure) was 11.85 MPa, and the working load was 58.15 MPa. The sealing evaluation coefficient, maximum contact stress, and fatigue life value of four material packer rubbers were considered when considering temperature changes and fatigue unit nodes. The results show that when the working load and the structural parameters of the rubber are the same, the sealing evaluation coefficient of the four material rubber increases with the increase of temperature. When the working temperature reaches 125 ℃, the value of the rubber seal evaluation coefficient of the HNBR material is the largest, and the value of the rubber seal evaluation coefficient of the EPDM material is the smallest. Similarly, the maximum contact stress of the four material rubbers increases with increasing temperature. When the temperature reaches 125 ℃, the maximum contact stress of the HNBR material is the largest, and the maximum contact stress of the EPDM material is the smallest. The rubber of the four materials increase the fatigue life value with the increase in the temperature within the operating temperature range studied. When the temperature is lower than 120 ℃, the fatigue life value of the HNBR material rubber is the largest. When the temperature is higher than 120 ℃, the fatigue life value of the CR material rubber is the largest. Regardless of the temperature change, the fatigue life value of the EPDM is the smallest. By comparing the results of field experiments with the results of finite element models, the two are found to have good consistency, which verifies the validity and feasibility of the model. The research results have important guiding significance for the fatigue life prediction of various material packer rubbers under different temperatures.

scholarly journals The Effects of Structural Parameter Variation on Cable Force of Fast Cable-Net Structure

2014 ◽  
Vol 6 ◽  
pp. 912158
Author(s):  
Qiming Wang ◽  
Peng Jiang ◽  
Xu Kong
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Structural Parameters ◽  
Element Model ◽  
Design Parameters ◽  
Structural Parameter ◽  
Global Sensitivity ◽  
Fatigue Stress ◽  
Cutting Length ◽  
Cable Force

Five-hundred-meter aperture spherical radio telescope (FAST) is supported by a cable-net structure, which enables its surface to form a real-time paraboloid by active control. FAST project is currently in the construction and implementation stage. However, there are always a considerable amount of errors that existed in practice which may result in the deviation of the structure from its ideal model or design. Therefore, structural parameter sensitivity analysis was discussed, which is indispensable. However, such deformation operation would lead to about 500 MPa of fatigue stress variation amplitude in the cable-net structure. Optimized deformation strategy is proposed to release the fatigue stress of the cable-net structure, which would be of advantage to improve the reliability of the cable-net structure. In the paper, the variation ranges of structural parameters were rationally determined. Based on local sensitivity analysis and global sensitivity analysis method, finite element model was used to study the effect of different structural parameters on the static behavior. It can be concluded that the effect of several key design parameters such as the cutting length and the elastic modulus of cable on the cable force is significant. The global sensitivity analysis indicates that the cable force range of the cable-net is −19% to 27%.

Sensitivity Analysis of Beam Cross-Section Stiffness Using Adjoint Method

2017 ◽  
Author(s):  
Alfonso Callejo ◽  
Olivier Bauchau ◽  
Boris Diskin ◽  
Li Wang
Keyword(s):  
Sensitivity Analysis ◽  
Objective Function ◽  
Cross Section ◽  
Structural Parameters ◽  
Flexible Multibody Dynamics ◽  
Numerical Differentiation ◽  
Adjoint Equations ◽  
Design Parameters ◽  
Adjoint Sensitivity ◽  
Cross Sectional

The design optimization of rotorcraft through multidisciplinary aeroelastic models with hundreds of thousands of degrees of freedom requires a computationally efficient sensitivity analysis to obtain the objective function gradient. A fundamental part of rotorcraft analysis is the flexible multibody dynamics solver, which in the current work relies on an accurate three-dimensional representation of the beams. This paper presents the theoretical adjoint sensitivity analysis of the first structural analysis step, namely the computation of cross-sectional properties of the beams in the form of six-dimensional stiffness matrices. The adjoint equations are carefully derived, as are the derivatives of the objective function with respect to the design parameters. The method is then validated by comparing certain design sensitivities of a three-ply, composite cross-section with those obtained through real-step and complex-step numerical differentiation. The presented analysis allows the user to quantify the effect of basic structural parameters on fundamental sectional properties that can later be used in the full dynamic simulation.

scholarly journals Optimization of the Auxiliary-Beam System in Railway Bridge Vibration Mitigation Using FEM Simulation and Genetic Algorithms

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1089
Author(s):  
Jacobo Baldonedo ◽  
José A. López-Campos ◽  
Marcos López ◽  
Enrique Casarejos ◽  
José R. Fernández
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Finite Element Model ◽  
Structural Parameters ◽  
Fem Simulation ◽  
Element Model ◽  
Design Parameters ◽  
Vibration Mitigation ◽  
Resonance Effects ◽  
Beam System

In this paper, we present the optimization of a vibration mitigation system for railway bridges. These structures are subjected to significant moving loads, whose dynamic characteristics may produce resonance effects, compromising the integrity of the bridge and the security of the passengers if the speed or the load of the train is not controlled. The study focuses on the Auxiliary Beam system. It consists of a beam located under the bridge and connected to the slab by viscous dampers. The symmetry of the problem allowed for the use of a 2D Finite Element model of the system. This model was used together with a genetic algorithm in order to evaluate the behaviour of different candidates and to optimize the design parameters: the inertia of the beam and the damper coefficient. The goal of the optimization process is to minimize the acceleration of the bridge while adding the lightest mitigation system possible. The combination of a Finite Element Model and Genetic Algorithm helps to address the complex problem and to find an optimized set of structural parameters. The system finally shows good behaviour for optimal parameters.

Parameter Sensitivity and Reliability Analysis for Construction Control of Cable-Net Structure Supporting the Reflector of FAST

2013 ◽  
Vol 671-674 ◽  
pp. 529-533
Author(s):  
Xu Kong ◽  
Qi Ming Wang ◽  
Chuan Jia Liu ◽  
Zhong Yi Zhu
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Structural Parameters ◽  
Element Model ◽  
Parameter Sensitivity ◽  
Tension Force ◽  
Design Parameters ◽  
Structural Parameter ◽  
Global Sensitivity ◽  
The Impact

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is supported by cable-net structure, which enables its surface to form a paraboloid in real time under active control. FAST is now entering project construction and implement stage, however there are always a considerable amount of errors existed in practice which would result in the deviation of the structure from its ideal model. Therefore, structural parameter sensitivity analysis was indispensable discussed. In the paper, the variation ranges of structural parameters were rationally determined. Base on local sensitivity analysis and global sensitivity analysis method, Using the finite element model investigated the influence of different structural parameters change on the static behavior, gets the conclusions that the impact of several key design parameters on the tension force of cable-net is large. The results indicate that of all types of the structural parameters, the error of the length of cable plays the most important role, and the global sensitivity analysis indicates that the tension force range of cable-net is -18% to 27%.

scholarly journals Increase the Efficiency of an Induction Motor Feed from Inverter for Low Frequencies by Combining Design and Control Improvements

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 530
Author(s):  
Maria Dems ◽  
Krzysztof Komeza ◽  
Jacek Szulakowski ◽  
Witold Kubiak
Keyword(s):  
Energy Savings ◽  
High Efficiency ◽  
Open Loop ◽  
Design Parameters ◽  
Optimal Size ◽  
Low Frequencies ◽  
Field Weakening ◽  
Speed Regulation ◽  
Wide Range ◽  
And Control

Speed-controlled induction motors have the most significant potential for energy savings. The greatest problems with obtaining high efficiency occur in motors with a wide range of rotational speed regulation, as in the motors for driving industrial washing machines under consideration. While for the highest speeds, the dominant phenomenon is at field weakening. The problem is obtaining the optimal size of the magnetic flux for low rotation speed to prevent excessive saturation increasing current, and reduction of efficiency. This problem is usually solved by selecting the appropriate control for an already built machine. The authors propose a combination of activities when designing the motor structure with the selection of proper control, which allows for high efficiency. Since the drive does not require precise speed control or obtaining the required dynamics, it was possible to use an inexpensive control in an open loop, avoiding the cost of transmitters. Furthermore, the number of design parameters that are subject to change is significantly limited by technological factors and the available space in the washing machine. Proper parameter selection was made using a peripheral method assisted by field-circuit simulations. The proposed approach can be used in designing structures and selecting motors controls for other applications.

Concurrent Design Optimization of Mechanical Structure and Control for High Speed Robots

1994 ◽  
Vol 116 (3) ◽  
pp. 344-356 ◽  
Author(s):  
Jahng-Hyon Park ◽  
Haruhiko Asada
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Structural Parameters ◽  
Integrated Design ◽  
Settling Time ◽  
Design Parameters ◽  
Concurrent Design ◽  
Programming Technique ◽  
Mechanical Structure ◽  
And Control

A concurrent design method of mechanical structure and control is developed for two-link high speed robots. An integrated design approach to achieve high speed positioning is explored, in which comprehensive design parameters describing arm link geometry, actuator locations, and feedback gains are optimized with respect to the settling time of the system. First, a two-link, nonrigid arm is analyzed and a simple dynamic model representing rapid positioning processes is obtained. Optimal feedback gains minimizing the settling time are obtained as functions of structural parameters involved in the dynamic model. The structural parameters are then optimized using a nonlinear programming technique in order to obtain an overall optimal performance. Based on the optimal design, a prototype high speed robot is built and tested. The resultant arm design shows an outstanding performance, which is otherwise unattainable if the structure and control are designed separately.

X-Ray Replication of Submicrometer Linewidth Patterns

1977 ◽  
Vol 35 ◽  
pp. 136-137
Author(s):  
Henry I. Smith ◽  
D.C. Flanders
Keyword(s):  
Electron Beam Lithography ◽  
Cross Sectional ◽  
X Ray ◽  
Electron Backscattering ◽  
Spatial Frequencies ◽  
Cross Sectional Profile ◽  
Carbon Foils ◽  
Sectional Profile ◽  
And Control ◽  
Soft Radiation

Scanning electron beam lithography has been used for a number of years to write submicrometer linewidth patterns in radiation sensitive films (resist films) on substrates. On semi-infinite substrates, electron backscattering severely limits the exposure latitude and control of cross-sectional profile for patterns having fundamental spatial frequencies below about 4000 Å(l),Recently, STEM'S have been used to write patterns with linewidths below 100 Å. To avoid the detrimental effects of electron backscattering however, the substrates had to be carbon foils about 100 Å thick (2,3). X-ray lithography using the very soft radiation in the range 10 - 50 Å avoids the problem of backscattering and thus permits one to replicate on semi-infinite substrates patterns with linewidths of the order of 1000 Å and less, and in addition provides means for controlling cross-sectional profiles. X-radiation in the range 4-10 Å on the other hand is appropriate for replicating patterns in the linewidth range above about 3000 Å, and thus is most appropriate for microelectronic applications (4 - 6).

ROLE OF PHARMACIST INTERVENTION ON COPD PATIENTS OF SELECTED AREAS IN CHITRADURGA: A KAP STUDY

2019 ◽  
Vol 8 (2) ◽  
Author(s):  
Melvin K Mathews ◽  
Abubaker Siddiq ◽  
Bharathi D R
Keyword(s):  
Illness Perceptions ◽  
Pharmacist Intervention ◽  
Cross Sectional Study ◽  
Chronic Obstructive ◽  
Cross Sectional ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients ◽  
Post Test ◽  
Knowledge Practice ◽  
And Control

Background: Chronic obstructive pulmonary disease (COPD) is preventable and treatable disease state characterized by air flow limitation that is not fully reversible. Severity of the symptoms is increased during exacerbations. Objectives: The purpose of the study is to assess and improve the knowledge regarding COPD among study subjects. Materials and Methods: A Cross-sectional interventional study was carried out among the peoples in selected areas of the Chitradurga city for a period of six months. Result: A total 207 subjects enrolled in the study in that 155 male and 52 females. In our study mean score of post test was more (5.87±1.68) when compare to pre-test (2.63±1.46) which show significant increase in their knowledge after educating them (p=0.000). A total of 207 subjects were enrolled into the study. SPSS Software was used to calculate the statistical estimation. Paired t-test was used to detect the association status of different variables. Conclusion: The relatively good level of COPD awareness needs to be maintained to facilitate future prevention and control of the disease. This study had identified that negative illness perceptions should be targeted, so that they will not avoid patients from seeking for COPD treatment and adhere to it. Key words: Cross sectional study, Knowledge, practice, COPD.

Cut off value of plasma 25-hydroxyvitamin D concentration for predicting metabolic syndrome

2019 ◽  
pp. 68-73
Author(s):  
Trong Nghia Nguyen ◽  
Thi Nhan Nguyen ◽  
Thi Dua Dao
Keyword(s):  
Metabolic Syndrome ◽  
Medical Center ◽  
Cross Sectional Study ◽  
Control Group ◽  
Cross Sectional ◽  
Hydroxyvitamin D ◽  
The Metabolic Syndrome ◽  
25 Hydroxyvitamin D ◽  
Key Words Metabolic Syndrome ◽  
And Control

Background: The metabolic syndrome is a constellation of cardiometabolic risk factors that tend to cluster together in affected individuals more often than predicted by chance. The presence of the metabolic syndrome substantially increases the risk of developing type 2 diabetes and cardiovascular disease, and is associated with a range of adverse clinical outcomes, many of which are closely associated with aging. Current estimates suggest that approximately 20 - 25% of the world’s population is affected by the metabolic syndrome. The prevalence of the metabolic syndrome rises with age and more than 45% of people aged over 60 years have the metabolic syndrome. Recent studies show that low vitamin D status is very common in the world and this is a risk factor of metabolic syndrome. Objective: (1) Plasma 25-hydroxyvitamin D concentration in subjects with metabolic syndrome. (2) Cut off value of plasma 25-hydroxyvitamin D concentration for predicting metabolic syndrome. Material and method: A cross-sectional study with control group on 318 adult subjects for health examinations at International Medical Center at Hue Central Hospital, including 139 subjects with metabolic syndrome and control group of 179 healthy subjects. Metabolic syndrome was defined according to the IDF, NHLBI, AHA, WHF, IAS, IASO (2009). Plasma hydroxyvitamin D concentration was measured using chemiluminescent microparticle immunoassay. Reciever operating characteristic (ROC) curve were generated to assess sensitivity and specificity for different cut off value of 25-hydroxyvitamin D concentration for predicting metabolic syndrome. Results: Plasma 25-hydroxyvitamin D concentration in subjects with metabolic syndrome was 26.4 ng/ml, incidence of plasma 25-hydroxyvitamin D deficiency (59.7%) was significantly higher than in control group (23.5%) (p < 0.001). The optimal cut off point for 25-OH-D concentration for predictor of metabolic syndrome as 26.4 ng/ml (AUC=0.657, sensitivity=53.4%, specificity=71.6%). Conclusion: In 139 subjects with metabolic syndrome, the plasma 25-hydroxyvitamin D concentration was 26.4 ng/ml and the incidence of 25-hydroxyvitamin D deficiency in the metabolic syndrome group was 59.7%. The optimal cut off point for plasma 25-hydroxyvitamin D concentration for predictor of metabolic syndrome as 26.4 ng/ml. Key words: Metabolic syndrome, 25-hydroxyvitamin D

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