A Review of Theoretical and Experimental Research on Various Autofrettage Processes

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Rajkumar Shufen ◽  
Uday S. Dixit
Keyword(s):  
Experimental Studies ◽  
Theoretical Models ◽  
Pressure Vessels ◽  
Future Research ◽  
Spherical Vessel ◽  
Considerable Research ◽  
Wide Range ◽  
Set Up ◽  
Compressive Residual Stresses ◽  
Spherical Pressure

Autofrettage is a metal forming technique widely incorporated for strengthening the thick-walled cylindrical and spherical pressure vessels. The technique is based on the principle of initially subjecting the cylindrical or spherical vessel to partial plastic deformation and then unloading it; as a result of which compressive residual stresses are set up. On the basis of the type of the forming load, autofrettage can be classified into hydraulic, swage, explosive, thermal, and rotational. Considerable research studies have been carried out on autofrettage with a variety of theoretical models and experimental methods. This paper presents an extensive review of various types of autofrettage processes. A wide range of theoretical models and experimental studies are described. Optimization of an autofrettage process is also discussed. Based on the review, some challenging issues and key areas for future research are identified.

Three-Dimensional Stress Intensity Factors for Ring Cracks and Arrays of Coplanar Cracks Emanating From the Inner Surface of a Spherical Pressure Vessel

2013 ◽  
Author(s):  
M. Perl ◽  
V. Berenshtein
Keyword(s):  
Crack Depth ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Intensity Factors ◽  
Spherical Vessel ◽  
Wide Range ◽  
Inner Surface ◽  
Ring Crack ◽  
Spherical Pressure ◽  
Coplanar Cracks

Certain spherical pressure vessels are composed of two hemispheres joined together by a girth weld. These vessels are susceptible to multiple cracking along the weld resulting in one or more cracks developing from the inner surface of the vessel and creating either a ring (circumferential) crack, or an array of coplanar cracks on the equatorial-weld plane. In order to assess the fracture endurance and the fatigue life of such vessels it is necessary to evaluate the Stress Intensity Factors (SIF) distribution along the fronts of these cracks. However, to date, only two solutions for the SIF for an internal ring crack as well as two 3-D solutions for a single internal semi-elliptical crack prevailing in various spherical pressure vessels are available. In the present analysis, mode I SIF distributions for a wide range of ring, lunular, and crescentic cracks are evaluated. The 3-D analysis is performed, via the FE method employing singular elements along the crack front. SIFs for numerous ring cracks of different depths prevailing in thin, moderately thick, and thick spherical vessels are evaluated first. Subsequently, Three-dimensional Mode I SIF distributions along the crack fronts of a variety of lunular and crescentic crack array configurations are calculated for three spherical vessel geometries, with outer to inner radii ratios of R0/Ri = 1.01, 1.1, and 1.7 representing thin, moderately thick, and thick spherical vessels. SIFs are evaluated for arrays of density δ = 0 to 0.99; for a wide range of crack-depth to wall-thickness ratios, a/t, from 0.025 to 0.95; and for various lunular and crescentic cracks with ellipticities, i.e., the ratio of crack-depth to semi-length, a/c, from 0.2 to 1.5. The obtained results clearly indicate that the SIFs are considerably affected by the three-dimensionality of the problem and by the following parameters: the crack density of the array – δ, the relative crack depth – a/t, crack ellipticity – a/c, and the geometry of the spherical vessel – η. Furthermore, it is shown that in some cases the commonly accepted approach that the SIF for a ring crack of any given depth is the upper bound to the maximum SIF occurring in an array of coplanar cracks, of the same depth, is not universal.

A review on recent advances and challenges of ionic wind produced by corona discharges with practical applications

2021 ◽  
Author(s):  
Jingguo Qu ◽  
Minjun Zeng ◽  
Dewei Zhang ◽  
Dakai Yang ◽  
Xiongwei Wu ◽  
...  
Keyword(s):  
Corona Discharge ◽  
Experimental Studies ◽  
Wind Generation ◽  
Future Research ◽  
Discharge Process ◽  
Ionic Wind ◽  
Practical Applications ◽  
Wind Generators ◽  
Wide Range ◽  
Gas Ionization

Abstract Ionic wind, an induced phenomenon during corona discharge, possessing the features of silent operation and no moving parts, has a wide range of applications. Ionic wind generation is accompanied by complex physical processes, involving gas ionization, ion recombination, flow, and various chemical reactions, as well as mutual couplings between some of them. Therefore, understanding the corona discharge process and ionic wind generation is crucial for researchers and engineers to better utilize this phenomenon in practical applications. In this review, the principles of corona discharge and its induced ionic wind are presented. Subsequently, ionic wind generators (IWGs) are discussed according to their applications, and the corresponding advances based on experimental studies and numerical simulations are also reviewed. Moreover, the challenges of transitioning the ionic wind technology from laboratory studies to practical applications are discussed. These challenges include the excessively high onset voltage of the corona, ozone emission, and influence of environmental conditions. Furthermore, the mechanisms of these barriers and several effective approaches for mitigating them are provided. Finally, some future research prospects and the conclusions are presented.

3-D Stress Intensity Factors for Arrays of Inner Radial Lunular or Crescentic Cracks in Thin and Thick-Walled Spherical Pressure Vessels

2008 ◽  
Author(s):  
M. Perl ◽  
V. Bernstein
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Intensity Factors ◽  
Fe Method ◽  
Inner Radius ◽  
Wide Range ◽  
Spherical Pressure

Some spherical pressure vessels are manufactured by methods such as the Integrated Hydro-Bulge Forming (IHBF) method, where the sphere is composed of a series of double curved petals welded along their meridional lines. Such vessels are susceptible to multiple radial cracking along the welds. For fatigue life assessment and fracture endurance of such vessels one needs to evaluate the Stress Intensity Factors (SIF) distribution along the fronts of these cracks. However, to date, only one 3-D solution for the SIF for a circumferential crack in a thick sphere is available, as well as 2-D SIFs for one through the thickness crack in thin spherical shells. In the present paper, mode I SIF distributions for a wide range of lunular and crescentic cracks are evaluated. The 3-D analysis is performed, via the FE method employing singular elements along the crack front, for five geometries representing thin, moderately thick, and thick spherical pressure vessels with outer to inner radius ratios of η = Ro/Ri = 1.01, 1.05, 1.1, 1.7, and 2.0. SIFs are evaluated for arrays containing n = 1–20 cracks; for a wide range of crack depth to wall thickness ratio, a/t, from 0.025 to 0.95; and for various ellipticities of the crack, i.e., the ratio of crack depth to semi crack length, a/c, from 0.2 to 1.5. The obtained results clearly indicate that the SIFs are considerably affected by the three-dimensionality of the problem and by the following parameters: the geometry of the sphere-η, the number of cracks in the array-n, the depth of the cracks-a/t, and their ellipticity-a/c.

Biomechanics of Growth, Remodeling, and Morphogenesis

1995 ◽  
Vol 48 (8) ◽  
pp. 487-545 ◽  
Author(s):  
Larry A. Taber
Keyword(s):  
Shape Change ◽  
Experimental Studies ◽  
Cell Movement ◽  
Theoretical Models ◽  
Cellular Level ◽  
Experimental Results ◽  
Future Research ◽  
Cell Sheets ◽  
Biomechanical Models ◽  
Division Cell

This review deals with biomechanical aspects of growth (mass change), remodeling (property change), and morphogenesis (shape change) in living systems. The emphasis is on theoretical models, but relevant experimental results also are discussed. As an aid to the reader, the fundamental biological terms and concepts are defined for the general problem and for each specific topic. At the outset, the processes involved in growth, remodeling, and morphogenesis are described and placed within the context of the evolution of species. Next, some of the analytical methods used in biomechanical models for these processes are presented. Then, applications of these and other techniques to specific systems are discussed, beginning at the cellular level and proceeding upward to the tissue and organ levels. At the cellular level, modeling and experimental studies are reviewed for cell division, cell movement, and pattern formation, and then morphogenetic mechanisms for epithelia (cell sheets) are discussed. At the tissue and organ levels, the musculoskeletal and cardiovascular systems are considered. Several models are described for growth, remodeling, and morphogenesis of bone, and mainly experimental results are examined in the cases of skeletal muscle, the heart, and arteries. Specific topics for the cardiovascular system include hypertrophy, residual stress, atherosclerosis, and embryonic development. Finally, some future research directions are suggested.

scholarly journals Utility value interventions: Why and how instructors should use them in college psychology courses.

2020 ◽  
Author(s):  
Raechel N. Soicher ◽  
Kathryn A. Becker-Blease
Keyword(s):  
Achievement Motivation ◽  
Large Body ◽  
Experimental Studies ◽  
Future Research ◽  
College Level ◽  
Utility Value ◽  
Expectancy Value ◽  
Course Content ◽  
Future Goals ◽  
Wide Range

According to expectancy-value models of achievement motivation, a core component of increasing student motivation is utility value. Utility value refers to the importance that a task has in one’s future goals. Utility value interventions provide an opportunity for students to make explicit connections between course content and their own lives. A large body of literature suggests that utility value interventions are effective for a wide range of students (e.g., both adolescent and adult learners) in a variety of courses (e.g., introductory psychology, introductory biology, and physics). This review provides (1) an overview of an expectancy value model of achievement motivation, (2) a comprehensive review of the experimental studies of utility value interventions in psychology, (3) concrete pedagogical recommendations based on the evidence from over thirty studies of the utility value intervention, and (4) suggestions for future research directions. After reading this review, college-level psychology instructors should be able to decide whether the utility value intervention is appropriate for their own course and, if so, implement the intervention effectively.

scholarly journals CRISPR-RT: A web service for designing CRISPR-C2c2 crRNA with improved target specificity

2017 ◽  
Author(s):  
Houxiang Zhu ◽  
Emily Richmond ◽  
Chun Liang
Keyword(s):  
Web Service ◽  
Genome Editing ◽  
Rna Editing ◽  
Model Organisms ◽  
Future Research ◽  
Target Specificity ◽  
Link Type ◽  
Wide Range ◽  
Set Up

AbstractCRISPR-Cas systems have been successfully applied in genome editing. Recently, the CRISPR-C2c2 system has been reported as a tool for RNA editing. Here we describe CRISPR-RT (CRISPR RNA-Targeting), the first web service to help biologists design the crRNA with improved target specificity for the CRISPR-C2c2 system. CRISPR-RT allows users to set up a wide range of parameters, making it highly flexible for current and future research in CRISPR-based RNA editing. CRISPR-RT covers major model organisms and can be easily extended to cover other species. CRISPR-RT will empower researchers in RNA editing. It is available at http://bioinfolab.miamioh.edu/CRISPR-RT.

scholarly journals A Review on Progressive Collapse of Building Structures

2014 ◽  
Vol 8 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Hao Wang ◽  
Anqi Zhang ◽  
Yi Li ◽  
Weiming Yan
Keyword(s):  
Design Method ◽  
Progressive Collapse ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Collapse Mechanism ◽  
Building Structures ◽  
Wide Range ◽  
Collapse Behavior ◽  
Element Method

Progressive collapse of building structures is generally triggered by a local failure due to accidental actions, followed by subsequent chain effect of the structures which may result in wide range failure or even collapse of the entire buildings. Since the “911” event, progressive collapse of building structures has been widely concerned by engineers and researchers. This paper assesses the current researches on this issue from experimental study, numerical simulation and theoretical analysis. Given the limitation of costs and difficulties of experimental tests, the experimental studies investigate the collapse mechanism, such as development of stress/strain and damage/failure of materials, mainly via the scaled down specimens of structural components and substructures. On the other hand, the collapse behavior of entire building structures is analyzed via the numerical methods, such as the finite element method and the discrete element method. Further, the collapse resistance demand and the robustness assessment for building structures are theoretically studied in depth in which the simplified theoretical models of the collapse-resisting demand and the collapse risk assessment are proposed respectively. At last, the design method to prevent progressive collapse for building structures is also discussed.

scholarly journals Distributed Manufacturing of Open Source Medical Hardware for Pandemics

2020 ◽  
Vol 4 (2) ◽  
pp. 49 ◽  
Author(s):  
Joshua M. Pearce
Keyword(s):  
Open Source ◽  
Future Research ◽  
Open Hardware ◽  
Medical Supplies ◽  
Considerable Research ◽  
Wide Range ◽  
Core Areas ◽  
The Government ◽  
Hardware Designs ◽  
Good Samaritan Laws

Distributed digital manufacturing offers a solution to medical supply and technology shortages during pandemics. To prepare for the next pandemic, this study reviews the state-of-the-art of open hardware designs needed in a COVID-19-like pandemic. It evaluates the readiness of the top twenty technologies requested by the Government of India. The results show that the majority of the actual medical products have some open source development, however, only 15% of the supporting technologies required to produce them are freely available. The results show there is still considerable research needed to provide open source paths for the development of all the medical hardware needed during pandemics. Five core areas of future research are discussed, which include (i) technical development of a wide-range of open source solutions for all medical supplies and devices, (ii) policies that protect the productivity of laboratories, makerspaces, and fabrication facilities during a pandemic, as well as (iii) streamlining the regulatory process, (iv) developing Good-Samaritan laws to protect makers and designers of open medical hardware, as well as to compel those with knowledge that will save lives to share it, and (v) requiring all citizen-funded research to be released with free and open source licenses.

scholarly journals The role of memory in posttraumatic stress disorder: implications for clinical practice

2016 ◽  
Vol 38 (3) ◽  
pp. 119-127 ◽  
Author(s):  
Marcelo Montagner Rigoli ◽  
Gustavo Ramos Silva ◽  
Fernando Rainho de Oliveira ◽  
Giovanni Kuckartz Pergher ◽  
Christian Haag Kristensen
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Clinical Practice ◽  
Posttraumatic Stress ◽  
Stress Disorder ◽  
Traumatic Event ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Social Consequences ◽  
Future Research

Abstract Introduction: Posttraumatic stress disorder (PTSD) is a highly prevalent disorder with important social consequences. Several models have been developed with the aim of understanding the mechanisms underlying its symptoms. Intrusions are idiosyncratic symptoms that commonly take the form of involuntary recollection of images or flashbacks about the traumatic event. Objective: To review how memory is conceptualized in each of these models and the implications for clinical practice. Methods: A narrative review of the literature was conducted through analysis of the perspectives of memory in theoretical models of PTSD. Results: Two main perspectives were identified: 1) models in which specific mechanisms of memory for processing traumatic events are proposed, especially those based on clinical studies, and 2) models in which common mnemonic mechanisms are utilized to explain the phenomenon, primarily based on basic experimental research studies investigating memory. The different theories based on these approaches have led to distinct psychotherapy interventions. Conclusion: In order to clarify these discrepancies, future research should aim for the methodological rigor of experimental studies, while maintaining the ecological applicability of findings. Cognitive experimental psychopathology is therefore an area on which research funding should be focused. Such studies could elucidate the role of mnemonic aspects in PTSD and how they impact psychological treatments.

Three-Dimensional Stress Intensity Factors for Arrays of Radial Cracks Emanating From the Inner Surface of a Thick-Walled Spherical Pressure Vessel

2008 ◽  
Author(s):  
M. Perl ◽  
V. Bernstein
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Geometrical Parameters ◽  
Intensity Factors ◽  
Fe Method ◽  
Wide Range ◽  
Spherical Pressure

Some spherical pressure vessels are manufactured by methods such as the Integrated Hydro-Bulge Forming (IHBF) method, where the sphere is composed of a series of double curved petals welded along their meridional lines. Such vessels are susceptible to multiple radial cracking along the welds. For fatigue life assessment and fracture endurance of such vessels one needs to evaluate the Stress Intensity Factors SIF distribution along the fronts of these cracks. However, to date, only two-dimensional SIFs for one through the thickness crack in a thin spherical shells is available. In the present paper, mode I SIF distributions for a wide range of lunular and crescentic cracks are evaluated. The 3-D analysis is performed, via the FE method employing singular elements along the crack front, for three sphere geometries with outer to inner radius ratios of η = Ro/Ri = 1.1, 1.7, and 2.0. SIFs are evaluated for arrays containing n = 1–20 cracks,; for a wide range of crack depth to wall thickness ratio, a/t, from 0.025 to 0.8; and for various ellipticities of the crack, i.e., the ratio of crack depth to semi crack length, a/c, from 0.2 to 1.5. The obtained results clearly indicate that the SIFs are considerably affected by the three-dimensionality of the problem and by the geometrical parameters: the geometry of the sphere – η, the number of cracks in the array – n, the depth of the crack – a/t, and its ellipticity – a/c.

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