An Analysis on the Force Requirement of Combined Operations for Forward and Backward Tube Forming

2006 ◽  
pp. 943-948
Author(s):  
Beong Bok Hwang ◽  
G.M. Lee ◽  
Y.H. Lee ◽  
J.H. Ok ◽  
S.H. Kim
Keyword(s):  
Tube Forming ◽  
Force Requirement ◽  
Combined Operations

scholarly journals Cold Forging Effect on the Microstructure of Motorbike Shock Absorbers Fabricated by Tube Forming in a Closed Die

2021 ◽  
Vol 11 (5) ◽  
pp. 2142
Author(s):  
Trung-Kien Le ◽  
Tuan-Anh Bui
Keyword(s):  
Material Flow ◽  
Cold Forging ◽  
Technological Parameters ◽  
Forming Process ◽  
Tube Forming ◽  
Shock Absorbers ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Quality Of Products ◽  
Forming Defects

Motorbike shock absorbers made with a closed die employ a tube-forming process that is more sensitive than that of a solid billet, because the tube is usually too thin-walled to conserve material. During tube forming, defects such as folding and cracking occur due to unstable tube forming and abnormal material flow. It is therefore essential to understand the relationship between the appearance of defects and the number of forming steps to optimize technological parameters. Based on both finite element method (FEM) simulations and microstructural observations, we demonstrate the important role of the number and methodology of the forming steps on the material flow, defects, and metal fiber anisotropy of motorbike shock absorbers formed from a thin-walled tube. We find limits of the thickness and height ratios of the tube that must be held in order to avoid defects. Our study provides an important guide to workpiece and processing design that can improve the forming quality of products using tube forming.

Plastic Forming Processes Through Rotating Conical Dies1

2001 ◽  
Vol 68 (6) ◽  
pp. 894-902 ◽  
Author(s):  
D. Durban ◽  
G. Davidi ◽  
D. Lior
Keyword(s):  
Single Phase ◽  
Large Strain ◽  
Single Layer ◽  
Wall Friction ◽  
Nonlinear Ordinary Differential Equations ◽  
Tube Forming ◽  
Perfectly Plastic ◽  
Governing System ◽  
Plastic Forming ◽  
Exact Relations

Drawing and extrusion of single-phase and multilayered tubes through rotating conical dies is investigated within the framework of continuum plasticity. Large strain perfectly plastic J2 flow theory models constitutive behavior along with a radial-helical flow pattern. The governing system for a single-layer process is reduced to three coupled nonlinear ordinary differential equations. An approximate solution is developed for long and tapered working zones with low wall friction. That solution is used to simulate the field within each layer in composite tube forming. Exact relations are derived for the n-layered tube and it is shown that wall rotation can considerably reduce the required working loads. Dedicated to Professor Dietmar Gross on the occasion of his 60th birthday

William III and his two navies

1989 ◽  
Vol 43 (2) ◽  
pp. 117-132
Keyword(s):  
Turning Point ◽  
Short Interval ◽  
17Th Century ◽  
Dutch Republic ◽  
Glorious Revolution ◽  
Combined Operations ◽  
Common Enemy ◽  
The Common ◽  
William Iii ◽  
The Glorious Revolution

Soon after his accession to the English throne William’s two navies started combined operations against the common enemy France. The Nine Years War had broken out, and this was followed after a short interval by the War of the Spanish Succession. Combined naval operations by two allies were nothing uncommon in those days. Anglo- French fleets had fought the Dutch in no fewer than four fierce battles in 1672 and 1673. French and Dutch squadrons had cooperated against the English Navy in 1666, and much earlier in 1596 and 16252727 Anglo- Dutch fleets jointly attacked Spanish ports (1). In these examples cooperation never lasted long nor was it very close. Problems concerning the command structure were seldom satisfactorily solved. Allies regularly changed sides during the 17th century. The Glorious Revolution, however, can be treated as a turning point. England became involved in a generations-long struggle against France. The Dutch Republic under William III had already started to fight Louis XIV’s urge for expansion, more than 15 years earlier. Both countries almost became traditional allies. Right from the beginning in 1689 detailed arrangements were made for naval cooperation, long-standing ones as later developments showed.

Anatomically Complete Supraclavicular Reoperation for Recurrent Neurogenic Thoracic Outlet Syndrome: Clinical Characteristics, Operative Findings, and Long-term Outcomes

Hand ◽  
2021 ◽  
pp. 155894472098807
Author(s):  
Momodou L. Jammeh ◽  
J. Westley Ohman ◽  
Chandu Vemuri ◽  
Ahmmad A. Abuirqeba ◽  
Robert W. Thompson
Keyword(s):  
Thoracic Outlet Syndrome ◽  
Length Of Hospital Stay ◽  
Functional Improvement ◽  
Scalene Muscle ◽  
Neurogenic Thoracic Outlet Syndrome ◽  
First Rib ◽  
Previous Operation ◽  
Combined Operations ◽  
The Mean ◽  
Operative Findings

Background: The clinical outcomes of reoperations for recurrent neurogenic thoracic outlet syndrome (NTOS) remain undefined. Methods: From 2009 to 2019, 90 patients with recurrent NTOS underwent anatomically complete supraclavicular reoperation after previous operation(s) performed at other institutions using either supraclavicular (Prev-SC = 48), transaxillary (Prev-TA = 31), or multiple/combination (Prev-MC = 11) approaches. Prospectively maintained data were analyzed retrospectively. Results: The mean patient age was 39.9 ± 1.4 years, 72% were female, and the mean interval after previous operation was 4.1 ± 0.6 years. The mean Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score was 62 ± 2, reflecting substantial preoperative disability. Residual scalene muscle was present in 100% Prev-TA, 79% Prev-SC, and 55% Prev-MC ( P < .05). Retained/residual first rib was present in 90% Prev-TA, 75% Prev-SC, and 55% Prev-MC ( P < .05). There were no differences in operative time (overall 210 ± 5 minutes), length of hospital stay (4.7 ± 0.2 days), or 30-day readmissions (7%). During follow-up of 5.6 ± 0.3 years, the improvement in QuickDASH scores was 21 ± 2 (36% ± 3%) ( P < .01) and patient-rated outcomes were excellent in 10%, good in 36%, fair in 43%, and poor in 11%. Conclusions: Anatomically complete decompression for recurrent NTOS can be safely and effectively accomplished by supraclavicular reoperation, regardless of the type of previous operation. Residual scalene muscle and retained/residual first rib are more frequently encountered after transaxillary operations than after supraclavicular or multiple/combined operations. Supraclavicular reoperation can achieve significant symptom reduction and functional improvement for approximately 90% of patients with recurrent NTOS.

Study of Dynamic Impacts at Combined Operations of the Thin Turning and Boring

2020 ◽  
pp. 226-235 ◽  
Author(s):  
Gennadii Oborskyi ◽  
Alexandr Orgiyan ◽  
Volodymyr Tonkonogyi ◽  
Albakush Aymen ◽  
Anna Balaniuk
Keyword(s):  
Combined Operations ◽  
Dynamic Impacts

scholarly journals Viability of thin wall tube forming of ATF FeCrAl

2016 ◽  
Author(s):  
Stuart Andrew Maloy ◽  
Eda Aydogan ◽  
Osman Anderoglu ◽  
Curt Lavender ◽  
Yukinori Yamamoto
Keyword(s):  
Thin Wall ◽  
Tube Forming

scholarly journals Mutational networks of escape from transmitted HIV-1 infection

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243391
Author(s):  
Elma H. Akand ◽  
Stephen J. Maher ◽  
John M. Murray
Keyword(s):  
Immune Response ◽  
Effective Vaccine ◽  
Subtype C ◽  
Hub And Spoke ◽  
Binding Domains ◽  
Immune Pressure ◽  
Subtype B ◽  
Combined Operations ◽  
Founder Virus ◽  
Coreceptor Binding

Human immunodeficiency virus (HIV) is subject to immune selective pressure soon after it establishes infection at the founder stage. As an individual progresses from the founder to chronic stage of infection, immune pressure forces a history of mutations that are embedded in envelope sequences. Determining this pathway of coevolving mutations can assist in understanding what is different with the founder virus and the essential pathways it takes to maintain infection. We have combined operations research and bioinformatics methods to extract key networks of mutations that differentiate founder and chronic stages for 156 subtype B and 107 subtype C envelope (gp160) sequences. The chronic networks for both subtypes revealed strikingly different hub-and-spoke topologies compared to the less structured transmission networks. This suggests that the hub nodes are impacted by the immune response and the resulting loss of fitness is compensated by mutations at the spoke positions. The major hubs in the chronic C network occur at positions 12, 137 (within the N136 glycan), and 822, and at position 306 for subtype B. While both founder networks had a more heterogeneous connected network structure, interestingly founder B subnetworks around positions 640 and 837 preferentially contained CD4 and coreceptor binding domains. Finally, we observed a differential effect of glycosylation between founder and chronic subtype B where the latter had mutational pathways significantly driven by N-glycosylation. Our study provides insights into the mutational pathways HIV takes to evade the immune response, and presents features more likely to establish founder infection, valuable for effective vaccine design.

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