Numerical Study of a Panel with Big Grooves Subjected to In-Plane Tension

2010 ◽  
Vol 102-104 ◽  
pp. 297-300
Author(s):  
Ning Huang ◽  
Ming Hui Huang ◽  
Li Hua Zhan
Keyword(s):  
Stress Concentration ◽  
Numerical Study ◽  
Main Idea ◽  
Stress Relief ◽  
Structure Design ◽  
The Body ◽  
Transition Structure ◽  
Calculation Results ◽  
Relief Groove ◽  
Close Distance

The purpose of the present study is to propose a new technical method for improving the fatigue life of a panel with big grooves by setting rounded transition structure and stress relief slots in the vicinity of it. The main idea of the method is to reduce the stress concentration at the edges of rounded transition structure. To confirm the effectiveness of the method, analyses were performed by using software for two-dimensional elastic problems based on the body-force method. The calculation results show that the existence of stress relief slots effectively reduced the stress concentration at the edges of rounded transition structure. A close distance between the rounded transition structure and the stress relief groove resulted in a little influence of stress concentration at the edge of rounded transition structure. Also, a lower stress concentration was obtained by increasing the diameter and numbers of stress relief grooves. Results prove the effectiveness and certain engineering practicability of this method. The method is helpful for structure design.

Design of Flat Ends in Pressure Boilers with Circular and Elliptical Stress Relieve Grooves

2013 ◽  
Vol 477-478 ◽  
pp. 49-53 ◽  
Author(s):  
Bogdan Szybiński
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Circumferential Stress ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Optimal Choice ◽  
Circular Shape ◽  
Relief Groove ◽  
Two Parameters

Flat ends in cylindrical pressure vessels are a certain alternative for commonly used in boilers dished ends. These ends can have different form and one of the admitted proposals is the plate with the internally introduced circumferential stress relief groove. In codes [1, the grooves of circular shape are recommended. Three parameters describe the groove configuration, namely the groove radius, the minimum endplate thickness under the relief groove and the chamfer angle. The respective formulas for calculations of the first two parameters are expressed in the form of inequalities. This means that a certain range of their variation is possible. The existing codes do not give the clear suggestion about the optimal choice of values of the groove parameters, leading to the minimal value of the stress concentration in the groove area. This is usually done by numerical analysis. The significant reduction of stress concentration is observed when changing the shape of the groove from the circular to the elliptical one, which is also shown in the paper.

Numerical and Experimental Analysis of Stress and Strains in Flat Ends of High-Pressure Vessels

2011 ◽  
Vol 490 ◽  
pp. 226-236 ◽  
Author(s):  
Bogdan Szybiński ◽  
Paweł Romanowicz ◽  
Andrzej P. Zieliński
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Experimental Investigations ◽  
Engineering Practice ◽  
Junction Area ◽  
Definite Answer ◽  
Asme Code ◽  
Relief Groove

Application of flat welded ends with stress relief grooves in high-pressure vessels is a common alternative to use of dished vessel ends. It is well established and follows calculation rules given in codes: EN-12952-3 [1], EN-13445-3 [2], or in ASME code [3]. However the calculation rules do not give any definite answer what should be the choice of parameters defining a circular stress relief groove, for example, position of the groove and its radius. Usually the choice of them relies on engineering practice. The present paper clearly shows the influence of this choice on stress concentration in the cylinder-endplate junction area. The results of numerical study are verified in experimental investigations performed for a cylindrical high-pressure vessel.

scholarly journals Optimization of Flat Ends in Pressure Vessels

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4194 ◽  
Author(s):  
Bogdan Szybiński ◽  
Paweł J. Romanowicz
Keyword(s):  
Stress Concentration ◽  
Parametric Optimization ◽  
Stress Relief ◽  
Pressure Vessels ◽  
Optimal Choice ◽  
Operating Pressure ◽  
Plastic Properties ◽  
Optimal Values ◽  
Relief Groove ◽  
Minimum Stress

The application of flat ends in pressure boilers is inevitably associated with the presence of stress concentration, which is observed in the vicinity of the junction of the cylinder and the closing flat plate. The analyzed flat end plates with stress relief grooves fall into the group of solutions recognized by the respective Standards of Calculations of Pressure Vessels. Unfortunately, no clear evidence is given in the Standards on how to choose the best groove parameters. This opens up the problem of the optimal choice of the groove parameters providing a minimum stress level. Even for the optimal values defining the stress relief groove geometry, certain plastic deformations are observed in the groove area for materials which exhibit elastic-plastic properties. Such a situation is completely unacceptable during exploitation, and a suitable reduction of the operating pressure is necessary. This paper discusses the effectiveness of other designs for flat ends used in pressure vessels. The proposed modifications took the form of external ribs applied around the top of the endplate circumference. The dimensions of these ribs were set using parametric optimization. The results of the study encouraged the authors to perform a more general analysis with the use of topology optimization. The results of all performed studies proved that the reduction of stress concentration and the full elimination of plastic deformation are possible. All numerical calculations were made using the finite element code (FEM), Ansys.

scholarly journals A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4459
Author(s):  
José R. González ◽  
Charbel Damião ◽  
Maira Moran ◽  
Cristina A. Pantaleão ◽  
Rubens A. Cruz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thyroid Nodules ◽  
Numerical Study ◽  
Computational Study ◽  
Internal Heat ◽  
Heat Transfer Process ◽  
The Body ◽  
Physical Parameters ◽  
Infrared Sensors ◽  
Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

scholarly journals Designs of InGaN Micro-LED Structure for Improving Quantum Efficiency at Low Current Density

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Shiqiang Lu ◽  
Jinchai Li ◽  
Kai Huang ◽  
Guozhen Liu ◽  
Yinghui Zhou ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Current Density ◽  
Carrier Transport ◽  
Defect Density ◽  
Numerical Study ◽  
Structure Design ◽  
Operating Conditions ◽  
Hole Injection ◽  
Electron Blocking Layer ◽  
Recombination Processes

AbstractHere we report a comprehensive numerical study for the operating behavior and physical mechanism of nitride micro-light-emitting-diode (micro-LED) at low current density. Analysis for the polarization effect shows that micro-LED suffers a severer quantum-confined Stark effect at low current density, which poses challenges for improving efficiency and realizing stable full-color emission. Carrier transport and matching are analyzed to determine the best operating conditions and optimize the structure design of micro-LED at low current density. It is shown that less quantum well number in the active region enhances carrier matching and radiative recombination rate, leading to higher quantum efficiency and output power. Effectiveness of the electron blocking layer (EBL) for micro-LED is discussed. By removing the EBL, the electron confinement and hole injection are found to be improved simultaneously, hence the emission of micro-LED is enhanced significantly at low current density. The recombination processes regarding Auger and Shockley–Read–Hall are investigated, and the sensitivity to defect is highlighted for micro-LED at low current density.Synopsis: The polarization-induced QCSE, the carrier transport and matching, and recombination processes of InGaN micro-LEDs operating at low current density are numerically investigated. Based on the understanding of these device behaviors and mechanisms, specifically designed epitaxial structures including two QWs, highly doped or without EBL and p-GaN with high hole concentration for the efficient micro-LED emissive display are proposed. The sensitivity to defect density is also highlighted for micro-LED.

Kinematics and Dynamics Simulation Research for Roller Coaster Multi-Body System

2011 ◽  
Vol 421 ◽  
pp. 276-280 ◽  
Author(s):  
Ge Ning Xu ◽  
Hu Jun Xin ◽  
Feng Yi Lu ◽  
Ming Liang Yang
Keyword(s):  
Structural Design ◽  
3D Model ◽  
Structure Design ◽  
Dynamics Simulation ◽  
Body System ◽  
Load Spectrum ◽  
Roller Coaster ◽  
Simulation Research ◽  
Calculation Results ◽  
Multi Body

To assess the roller coaster multi-body system security, it is need to extract the running process of kinematics, dynamics, load spectrum and other features, as basis dates of the roller coaster structural design. Based on Solidworks/motion software and in the 3D model, the calculation formula of the carrying car velocity and acceleration is derived, and the five risk points of the roller coaster track section are found by simulation in the running, and the simulation results of roller coaster axle mass center velocity are compared with theoretical calculation results, which error is less than 4.1%, indicating that the calculation and simulation have a good fit and providing the evidence for the roller coaster structure design analysis.

A Parametric Study of Low-Frequency Damping of Mooring System

2014 ◽  
Author(s):  
Minglu Chen ◽  
Shan Huang ◽  
Nigel Baltrop ◽  
Ji Chunyan ◽  
Liangbi Li
Keyword(s):  
Low Frequency ◽  
Structure Design ◽  
The Body ◽  
Body Motion ◽  
Mooring Line ◽  
Offshore Structure ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Line System ◽  
Irregular Wave

Mooring line damping plays an important role to the body motion of moored floating platforms. Meanwhile, it can also make contributions to optimize the mooring line system. Accurate assessment of mooring line damping is thus an essential issue for offshore structure design. However, it is difficult to determine the mooring line damping based on theoretical methods. This study considers the parameters which have impact on mooring-induced damping. In the paper, applying Morison formula to calculate the drag and initial force on the mooring line, its dynamic response is computed in the time domain. The energy dissipation of the mooring line due to the viscosity was used to calculate mooring-induced damping. A mooring line is performed with low-frequency oscillation only, the low-frequency oscillation superimposed with regular and irregular wave-frequency motions. In addition, the influences of current velocity, mooring line pretension and different water depths are taken into account.

A NUMERICAL STUDY ON THE HEMODYNAMIC AND SHEAR STRESS OF DOUBLE ANEURYSM THROUGH S-SHAPED VESSEL

2015 ◽  
Vol 27 (04) ◽  
pp. 1550033 ◽  
Author(s):  
Mahdi Halabian ◽  
Alireza Karimi ◽  
Borhan Beigzadeh ◽  
Mahdi Navidbakhsh
Keyword(s):  
Blood Flow ◽  
Mechanical Behavior ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
The Body ◽  
Sweep Angle ◽  
Abdominal Aortic ◽  
Hemodynamic Characteristics ◽  
Refined Meshes

Abdominal aortic aneurysm (AAA) is a degenerative disease defined as the abnormal ballooning of the abdominal aorta (AA) wall which is usually caused by atherosclerosis. The aneurysm grows larger and eventually ruptures if it is not diagnosed and treated. Aneurysms occur mostly in the aorta, the main artery of the chest and abdomen. The aorta carries blood flow from the heart to all parts of the body, including the vital organs, the legs, and feet. The objective of the present study is to investigate the combined effects of aneurysm and curvature on flow characteristics in S-shaped bends with sweep angle of 90° at Reynolds number of 900. The fluid mechanics of blood flow in a curved artery with abnormal aortic is studied through a mathematical analysis and employing Cosmos flow simulation. Blood is modeled as an incompressible non-Newtonian fluid and the flow is assumed to be steady and laminar. Hemodynamic characteristics are analyzed. Grid independence is tested on three successively refined meshes. It is observed that the abrupt expansion induced by AAA results in an immensely disturbed regime. The results may have implications not only for understanding the mechanical behavior of the blood flow inside an aneurysm artery but also for investigating the mechanical behavior of the blood flow in different arterial diseases, such as atherosclerosis.

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