Reconfiguration and Static Joint Force Variation of a 3rRPS Metamorphic Parallel Mechanism with 3R and 1T2R Motion

Riser Tensioner Force Variations

Society of Petroleum Engineers Journal ◽

10.2118/6309-pa ◽

1978 ◽

Vol 18 (06) ◽

pp. 399-408

Author(s):

T.J. Kozik ◽

J. Noerager

Keyword(s):

Support System ◽

Strong Dependence ◽

Technical Conference ◽

Ball Joint ◽

Joint Force ◽

Support Mechanism ◽

Original Manuscript ◽

Drilling Operations ◽

Force Variation ◽

Tank Pressure

Original manuscript received in Society of Petroleum Engineers office Feb. 24, 1976. Paper accepted for publication June 14, 1977. Revised manuscript received Aug. 21, 1978. Paper (SPE 6309, OTC 2648) first presented at the Eighth Annual Offshore Technical Conference, held in presented at the Eighth Annual Offshore Technical Conference, held in Houston, May 3-6, 1976. Abstract Excessive riser-force variation on the upper joint in a riser string can lead to buckling and excessive fatigue. This variation is caused by two components of the riser support system - the riser tensioning system and the telescopic, or slip, joint. Using specific examples, two conclusions are reached. First, the force variation at the top of the riser string may be much greater than that indicated by monitoring the tensioner system's air-tank pressure. Second, a major contribution to this pressure. Second, a major contribution to this variation can be pressure drop in the air valves. Introduction The riser tensioners and slip joint (Fig. 1) form the support system for the riser string used in floating drilling operations. Although tensioners are the primary support mechanism, their forces are transmitted through the slip joint to the upper joint in the riser string. In many deep-water drilling operations, the riser string is isolated in bending by an upper ball joint from the more massive telescopic joint. This upper ball joint interacts directly with the riser string; therefore, the forces seen at that joint become riser-string forces because of the tensioner support system. Ideally, the tensioner support-system forces at the upper ball joint should provide a net axial load on the riser string and should be constant in magnitude as well as direction. However, the nonideal behavior of the riser tensioners - as well as the inertia and geometrical effects associated with vessel, slip joint, and riser-string motions - result in load variations. Generally, the upper ball-joint force vector depends on time. No limits as yet have been determined for allowable variations of the riser-string forces resulting from the riser support mechanism. Nevertheless, measuring these variations analytically and qualitatively is important when assessing the effectiveness of the support mechanism or when providing important information about the boundary providing important information about the boundary conditions necessary to analyze the riser string. Our paper has two purposes. First, to emphasize by numerical examples the strong dependence of riser-tensioner force variations on the character of the assumed losses (pressure chop) in the tensioner-system air valves. Second, to present an analytical expression and numerical results for the tensioner-system force variations at the upper ball joint, thereby emphasizing the strong effects of vessel motion on riser-string force. TENSIONER ANALYSIS The typical drilling riser tensioner is a hydropneumatic mechanical system (Fig. 2) that provides tension in the cable attached to and supporting the outer barrel of the slip joint. Kozik studied the cable tensioner variation (r) resulting from cable motion. A convenient form for his equation is .....................(1) SPEJ P. 399

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Joint force decomposition and variation in unified inverse dynamics analysis of a metamorphic parallel mechanism

Meccanica ◽

10.1007/s11012-015-0216-y ◽

2015 ◽

Vol 51 (7) ◽

pp. 1583-1593 ◽

Cited By ~ 10

Author(s):

Dongming Gan ◽

Jian S. Dai ◽

Jorge Dias ◽

Lakmal Seneviratne

Keyword(s):

Parallel Mechanism ◽

Inverse Dynamics ◽

Dynamics Analysis ◽

Joint Force ◽

Inverse Dynamics Analysis ◽

Force Decomposition

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NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

Public administration and local government ◽

10.33287/101910 ◽

2019 ◽

pp. 73-81

Author(s):

Oleh Poshedin

Keyword(s):

North Atlantic ◽

Task Force ◽

Response Force ◽

Cyber Attack ◽

Adaptation Measures ◽

Joint Force ◽

Security Environment ◽

The North ◽

The North Atlantic ◽

Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

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Finite Element Analysis of Nonuniformity of Tires with Imperfections5

Tire Science and Technology ◽

10.2346/1.2768607 ◽

2007 ◽

Vol 35 (3) ◽

pp. 226-238 ◽

Cited By ~ 1

Author(s):

K. M. Jeong ◽

K. W. Kim ◽

H. G. Beom ◽

J. U. Park

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Three Dimensional ◽

Element Model ◽

Radial Force ◽

Element Analysis ◽

The Finite Element Analysis ◽

Dimensional Finite Element ◽

Force Variation ◽

Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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Influence of Rim Run-Out on the Nonuniformity of Tire-Wheel Assemblies

Tire Science and Technology ◽

10.2346/1.2139538 ◽

1994 ◽

Vol 22 (2) ◽

pp. 99-120 ◽

Cited By ~ 1

Author(s):

T. B. Rhyne ◽

R. Gall ◽

L. Y. Chang

Keyword(s):

Finite Element ◽

Radial Force ◽

Membrane Model ◽

Model Experiments ◽

Force Variation ◽

One To One ◽

The One

Abstract An analytical membrane model is used to study how wheel imperfections are converted into radial force variation of the tire-wheel assembly. This model indicates that the radial run-out of the rim generates run-out of the tire-wheel assembly at slightly less than the one to one ratio that was expected. Lateral run-out of the rim is found to generate radial run-out of the tire-wheel assembly at a ratio that is dependent on the tire design and the wheel width. Finite element studies of a production tire validate and quantify the results of the membrane model. Experiments using a specially constructed precision wheel demonstrate the behavior predicted by the models. Finally, a population of production tires and wheels show that the lateral run-out of the rims contribute a significant portion to the assembly radial force variation. These findings might be used to improve match-mounting results by taking lateral rim run-out into account.

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