Determination of the Expansion Parameters for the Combined Welding and Expanding Connection of Tube-to-Tubesheet

2010 ◽  
Vol 118-120 ◽  
pp. 186-190
Author(s):  
Hui Fang Li ◽  
Cai Fu Qian ◽  
Lan Wang
Keyword(s):  
Numerical Simulation ◽  
Contact Pressure ◽  
Contact Surface ◽  
Driving Force ◽  
Expansion Pressure

In this paper, numerical simulation for hydraulic expanding connection of tube to tubesheet was performed. Residual contact preesure on the contact surface between tube and tubesheet as well as residual expansion stress in the tubesheet were investigated. It is seen the distribution of residual contact pressure is not uniform. Instead, near the two tubesheet surfaces, there are two tightness bands on which the residual contact pressure is high. Based on the fact that residual expansion stress could be a driving force for the tubesheet cracking, it is suggested that the expansion pressure should not be too large but enough to completely form the tightness bands on the contact surface. With this criterion, expansion pressures for typical tube materals and size are given.

Determination of Expanding Pressure of Hydraulically Expanded Tube-to-Tubesheet Joint

2010 ◽  
Vol 97-101 ◽  
pp. 2898-2902 ◽  
Author(s):  
Xie Tian ◽  
Xiao Ping Huang ◽  
Zhi Yong Fu
Keyword(s):  
Strain Hardening ◽  
Contact Pressure ◽  
Material Model ◽  
Linear Strain ◽  
Element Analysis ◽  
Hardening Material ◽  
Expansion Pressure ◽  
General Strain ◽  
Special Case

It is very important to determine the expansion pressure or residual contact pressure of tube-to-tubesheet joint. The expansion pressure and the residual contact pressure are affected by the geometry, material mechanical properties of the tube and tubesheet. In the basic theory of calculating the residual contact pressure of tube-to-tubesheet joints, the elastic-perfectly material is assumed. Because of the strain-hardening of the materials, linear strain-hardening or power strain-hardening were adopted in some analyzing models of the hydraulically expanded tube-to-tubesheet joint. In this paper, a general strain-hardening material model is adopted and an analytical model is proposed and validated by finite element analysis results. The elastic-perfectly model, linear strain-hardening model or power strain-hardening can be the special case of the present model.

scholarly journals Optimal design of the solar tracking system of parabolic trough concentrating collectors

2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Tracking System ◽  
Low Cost ◽  
Parabolic Trough ◽  
The North ◽  
Tracking Mode ◽  
Solar Tracking ◽  
East West

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking > north-south Earth’s axis tracking > north-south tilt tracking (β = 15°) > north-south tilt tracking (β = 45) > north-south horizontal tracking > east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

Multi-Tier Tensile Strain Models for Strain-Based Design: Part 2 — Development and Formulation of Tensile Strain Capacity Models

2012 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang ◽  
Yaxin Song ◽  
David Horsley ◽  
Steve Nanney
Keyword(s):  
Driving Force ◽  
Tensile Strain ◽  
Weld Strength ◽  
Experiment Data ◽  
Pipe Wall Thickness ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Welding Processes ◽  
Tensile Strain Capacity

This is the second paper in a three-paper series related to the development of tensile strain models. The fundamental basis of the models [1] and evaluation of the models against experiment data [2] are presented in two companion papers. This paper presents the structure and formulation of the models. The philosophy and development of the multi-tier tensile strain models are described. The tensile strain models are applicable for linepipe grades from X65 to X100 and two welding processes, i.e., mechanized GMAW and FCAW/SMAW. The tensile strain capacity (TSC) is given as a function of key material properties and weld and flaw geometric parameters, including pipe wall thickness, girth weld high-low misalignment, pipe strain hardening (Y/T ratio), weld strength mismatch, girth weld flaw size, toughness, and internal pressure. Two essential parts of the tensile strain models are the crack driving force and material’s toughness. This paper covers principally the crack driving force. The significance and determination of material’s toughness are covered in the companion papers [1,2].

Numerical Simulation of Contact Pressure Evolution in Fretting

1994 ◽  
Vol 116 (2) ◽  
pp. 247-254 ◽  
Author(s):  
L. Johansson
Keyword(s):  
Numerical Simulation ◽  
Contact Pressure ◽  
Stability Criterion ◽  
Frictional Contact ◽  
Elastic Bodies ◽  
Numerical Instabilities ◽  
Archard’S Law Of Wear ◽  
Pressure Evolution

In the present paper an algorithm for frictional contact between two elastic bodies is presented. The algorithm is applied to the calculation of the evolution of contact pressure between two elastic bodies when material is being removed by fretting. To this end Archard’s law of wear is implemented into the algorithm. It is noticed that the calculated pressures after a period of fretting differ considerably from the initial Hertz type pressures. Further, it is noted that numerical instabilities can occur in explicit type wear calculations, and a stability criterion is suggested.

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