Modeling the Effects of Initial Tube-Tubesheet Clearance, Wall Reduction and Material Strain Hardening on Rolled Joint Strength

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
A. Al-Aboodi ◽  
N. Merah ◽  
A. R. Shuaib ◽  
Y. Al-Nassar ◽  
S. S. Al-Anizi
Keyword(s):  
Finite Element ◽  
Strain Hardening ◽  
Contact Pressure ◽  
Joint Strength ◽  
Design Parameters ◽  
Radial Clearance ◽  
Residual Pressure ◽  
Tube Material ◽  
Noticeable Effect ◽  
Interfacial Pressure

The tube-to-tubesheet joint strength is measured in terms of residual contact pressure between the tube’s outer surface and tubesheet hole surfaces. The joint integrity is affected by several design parameters, including the type of tube and tubesheet materials, the level of expansion, and the initial radial clearance between the tube and tubesheet. In the present work, an axisymmetric finite element model based on the sleeve diameter and rigid roller concepts is developed. The model has been used to evaluate the combined effects of clearance, wall reduction level, and strain hardening of tube and tubesheet materials on the interfacial pressure between tube and tubesheet. The finite element results show that the initial clearance effect is dependent on the strain hardening capability of the tube material. For low strain hardening tube materials, the interfacial pressure remains almost constant well above the Tubular Exchanger Manufacturing Association maximum radial over tolerance of 0.0254mm(0.001in.). These results are validated by the experimental data developed during the research program. As expected, a drastic reduction in joint strength is observed at high values of radial clearances. The cutoff clearance (clearance at which the interfacial pressure starts to drop) is found to vary linearly with tube material hardening level. The residual pressure is found to increase slightly for moderate strain hardening tube materials but shows lower cutoff clearances. Wall reductions ranging from 1% to 12% were utilized in calculating the contact pressure as a function of radial clearance. The results show that for low strain hardening materials the optimum value of residual contact stress is obtained for the industry recommended value of 5%. Finally, because of the absence of plastic deformation in the ligament, the level of tubesheet material strain hardening does not have any noticeable effect on the joint strength.

FEA of the Effects of Initial Tube-Tubesheet Clearance, Wall Reduction and Material Strain Hardening on Rolled Joint Strength

2006 ◽  
Author(s):  
A. Al-Aboodi ◽  
N. Merah ◽  
A. R. Shuaib ◽  
Y. Al-Nassar ◽  
S. S. Al-Anizi
Keyword(s):  
Strain Hardening ◽  
Contact Pressure ◽  
Joint Strength ◽  
Element Model ◽  
Design Parameters ◽  
Radial Clearance ◽  
Residual Pressure ◽  
Tube Material ◽  
Noticeable Effect ◽  
Interfacial Pressure

The tube-to-tubesheet joint strength is measured in terms of residual contact pressure between the tube’s outer surface and tubesheet hole surfaces. The joint integrity is affected by several design parameters, including the type of tube and-tubesheet materials, level of expansion and the initial radial clearance between the tube and tubesheet. In the present work, an axisymmetric finite element model based on the sleeve diameter and rigid roller concepts is developed. The model has been used to evaluate the combined effects of clearance, wall reduction level and the-strain hardening of tube and tubesheet materials on the interfacial pressure between tube and tubesheet. The FE results show that the initial clearance effect is dependent on the strain hardening capability of the tube material. For low strain hardening tube material the interfacial pressure remains almost constant well above the TEMA (Tubular Exchanger Manufacturing Association) maximum radial over tolerance of 0.0254 mm. These results are validated by the experimental data developed during the research program. As expected, a drastic reduction in joint strength is observed at high values of radial clearances. The cut-off clearance (clearance at which the interfacial pressure starts to drop) is found to vary linearly with the level tube material hardening level. The residual pressure is found to increase slightly for moderate strain hardening tube materials but shows lower cut-off clearances. Wall reductions ranging from 1% to 10% were utilized in calculating the contact pressure as a function of radial clearance. The results show that for low strain hardening materials the optimum value of residual contact stress is obtained for the industry recommended value of 5%. Finally, because of the absence plastic deformation in the ligament, the level of tubesheet material strain hardening does not have any noticeable effect to the joint strength.

Combined Effects of Tube Projection, Initial Tube-Tubesheet Clearance, and Tube Material Strain Hardening on Rolled Joint Strength

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
N. Merah ◽  
A. Al-Aboodi ◽  
A. N. Shuaib ◽  
Y. Al-Nassar ◽  
S. S. Al-Anizi
Keyword(s):  
Finite Element ◽  
Strain Hardening ◽  
Contact Pressure ◽  
Joint Strength ◽  
Element Model ◽  
Design Parameters ◽  
Radial Clearance ◽  
Tube Material ◽  
Element Analysis ◽  
Interfacial Pressure

The tube-to-tubesheet joint strength is measured in terms of interfacial pressure between the tube’s outer surface and tubesheet bore. The strength of a rolled joint is influenced by several design parameters, including the type of tube and tubesheet materials, initial tube projection, and the initial radial clearance between the tube and tubesheet, among other factors. This paper uses finite element analysis (FEA) to evaluate the effect of several parameters on the strength of rolled joints having large overtolerances, a situation that applies to used equipment. An axisymmetric finite element model based on the sleeve diameter and rigid tube expanding roller concepts was used to analyze the effects of tube projection, initial tube-tubesheet clearance, and tube material strain-hardening property on the deformation behavior of the rolled tube and on the strength of the tube-tubesheet joint. The FEA results show that for zero tube projection (flush) the initial clearance effect is dependent on the strain-hardening capability of the tube material. For low strain-hardening tube material the interfacial pressure remains constant well above the Tubular Exchanger Manufacturer’s Association maximum overtolerance. A drastic reduction in joint strength is observed at high values of radial clearances. The cut-off clearance (clearance at which the interfacial pressure starts to drop) is found to vary linearly with the tube material hardening level, and the contact stress increases slightly for moderate strain-hardening tube materials but shows lower cut-off clearance levels. Furthermore, with flush tubes the maximum contact pressure occurs close to the secondary face (at the end of rolling) while for joints with initial tube projection the contact pressure shows two maxima occurring near the primary and the secondary faces. This is attributed to the presence of two elbows in tube deformation near the primary and secondary faces. The average interfacial pressure increased with increasing projection length for all clearances. Tube material strain hardening enhances the interfacial pressure in a similar fashion for all initial tube projection lengths considered in the analysis.

Influence of Acetabular Liner Design on Periprosthetic Pressures during Daily Activities

2014 ◽  
Vol 601 ◽  
pp. 159-162
Author(s):  
Mircea Krepelka ◽  
Mirela Toth-Taşcău
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Pressure ◽  
Design Parameters ◽  
Acetabular Liner ◽  
Hip Prostheses ◽  
Small Influence ◽  
The Difference ◽  
Contact Pressures ◽  
Element Method

In this study, periacetabular pressures produced by different acetabular liner geometries were analyzed using Finite Element Method. The cup models consist of hemispherical metal shells fitted with normal and different chamfered polyethylene liner geometries, with the same degree of femoral head coverage. The aim of this study was to understand the influence of the design parameters of the chamfered liners, which are primarily designed to increase the range of motion (ROM) of the hip joint and reduce the risk of impingement, on the acetabular contact pressures. The cup models were loaded to simulate periacetabular pressures during routine activities. The proposed models have been analyzed considering a cup position of 40olateral abduction and 15oanteversion. The results show that the difference in contact pressure between the normal and chamfer models was not substantial in the given orientation of the cup. Also, the increase of the chamfer angle has a small influence on the maximum contact pressures, although that could be also dependent on the reduction of the polyethylene thickness. Pre-clinical testing of total hip prostheses using Finite Element Method enables the evaluation of contact pressures and stress distribution, and proves to be a valuable tool to analyze the parameters reducing the contact pressure.

Finite Element Numerical Simulation of Tubing Premium Connection

2012 ◽  
Vol 217-219 ◽  
pp. 1622-1627
Author(s):  
Fu Xiang Zhang ◽  
Bing Yin Ji ◽  
Xiang Tong Yang ◽  
Yong Han ◽  
Ze Liang Chang
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Contact Pressure ◽  
Joint Strength ◽  
Compression Loading ◽  
Threaded Connection ◽  
Sealing Performance ◽  
Metal Seal ◽  
Tension Loading ◽  
Contact Pressures

The environment and load condition of tubing is severe in high pressure wells. The sealability and joint strength of tubing string plays an important role in production operation. In this study, the makeup, sealability and joint strength was analyzed from conditions of make-up loading, tension loading, compression loading and internal pressure loading by finite element method. The makeup torque, the contact pressure distributions of metal seal along the axis and the stress distributions of threaded connection are given. The results show that under tension loading, compression loading and internal pressure, the overall stress level of threaded connection is lower than of pipe. The anti-compression performance and joint strength of threaded connection is greater than of pipe. The contact pressures of metal seal maintain relatively high level of contact pressures under tension loading, compression loading and internal pressure. Tension loading and compression loading reduces the sealing performance and the internal pressure increases the sealing performance from the integral of the contact pressure.

Analysis of contact mechanics in ceramic-on-ceramic hip joint replacements

2002 ◽  
Vol 216 (4) ◽  
pp. 231-236 ◽  
Author(s):  
M M Mak ◽  
Z M Jin
Keyword(s):  
Femoral Head ◽  
Contact Mechanics ◽  
Contact Pressure ◽  
Contact Area ◽  
Design Parameters ◽  
Radial Clearance ◽  
Hip Implants ◽  
Acetabular Cup ◽  
Ceramic Insert ◽  
Ceramic On Ceramic

The contact mechanics in ceramic-on-ceramic hip implants has been analysed in this study using the finite element method. Only the ideal conditions where the contact occurs within the acetabular cup were considered. It has been shown that the contact pressure distribution and the contact area at the main articulating bearing surfaces depend largely on design parameters such as the radial clearance between the femoral head and the acetabular cup, as well as the thickness of the ceramic insert. For the ceramic-on-ceramic hip implants used in clinics today, with a minimum 5-mm-thick ceramic insert, it has been shown that the radius of the contact area between the femoral head and the acetabular cup is relatively small compared with that of the femoral head and the ceramic insert thickness. Consequently, Hertz contact theory can be used to estimate the contact parameters such as the maximum contact pressure and the contact area.

Modeling Hydraulically Expanded Tube-to-Tubesheet Joint Based on General Stress-Strain Curves of Tube and Tubesheet Materials

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Xiaoping Huang ◽  
Tian Xie
Keyword(s):  
Strain Hardening ◽  
Contact Pressure ◽  
Present Model ◽  
Design Parameters ◽  
Linear Strain ◽  
Stress Strain ◽  
Hardening Model ◽  
Expansion Pressure ◽  
Special Cases ◽  
Analytic Expressions

The strength of tube-to-tubesheet joints is crucial for the joint integrity and reliability of the tubular heat exchangers. The joint strength measured by residual contact pressure is affected by several design parameters, such as the yield strength and strain hardening of the tube and tubesheet materials, initial radial clearance between the tube and tubesheet hole, and the magnitude of the expansion. It is very important to determine the expansion pressure and the residual contact pressure in designing and manufacturing tube-to-tubesheet joints by the hydraulic expansion process. In this paper, a general strain-hardening material model and analytic expressions for calculating the expansion pressure and the residual contact pressure, considering the effect of the initial clearance and the material strain hardening, have been derived. The results predicted by the present model have been compared with the results predicted by elastic perfectly plastic model, linear strain-hardening model, and the nonlinear finite element analysis results. The comparison results show that the present analytic expressions can model the effects of strain-hardening of the materials and the clearance well. The models, such as elastic-perfect model, linear strain-hardening model, and power strain-hardening model, are the special cases of the present model. The parameters needed in the present model are determined by curve fitting of the actual tensile stress-strain data of tube and tubesheet materials, respectively.

Elastic-Plastic Finite Element Analysis of Repeated Indentation of a Half-Space by a Rigid Sphere

1993 ◽  
Vol 60 (4) ◽  
pp. 829-841 ◽  
Author(s):  
E. R. Kral ◽  
K. Komvopoulos ◽  
D. B. Bogy
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Half Space ◽  
Contact Pressure ◽  
Peak Load ◽  
Rigid Sphere ◽  
Load Range ◽  
Elastic Plastic ◽  
Residual Displacements

The elastic-plastic contact problem of a rigid sphere indenting a homogeneous halfspace is analyzed with the finite element method. Emphasis is placed on the load range between elastic and fully plastic deformation, which has not yet been fully investigated. The rigid sphere is modeled by contact elements, thus eliminating the need to assume a particular pressure profile. Different elastic properties, with both elastic-perfectly plastic and isotropic strain hardening behaviors, are considered. Up to four complete frictionless load-unload cycles are applied to a peak load of 300 times the load necessary for the initiation of yielding. Results for the contact pressure, surf ace and subsurface stresses, initiation and growth of the plastic zone, and yielding of the half-space during unloading are presented. The effect of residual displacements on the contact pressure during subsequent load cycles is examined. The influence of strain hardening on the loading and residual stresses is analyzed and the consequences for crack initiation are discussed in light of these results. The accumulation of plastic strain in the yielding regions is tracked through the subsequent load cycles as the material approaches a steady-state elastic cycle, and the significance of the loading and residual stresses on the deformation characteristics is interpreted in the context of finite element results.

Finite Element Simulation of Tire-Rim Interface

1989 ◽  
Vol 17 (4) ◽  
pp. 305-325 ◽  
Author(s):  
N. T. Tseng ◽  
R. G. Pelle ◽  
J. P. Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Simulation ◽  
Contact Pressure ◽  
Element Model ◽  
Experimental Measurements ◽  
Inflation Pressure ◽  
Interference Fit ◽  
Element Simulation ◽  
Rubber Composite

Abstract A finite element model was developed to simulate the tire-rim interface. Elastomers were modeled by nonlinear incompressible elements, whereas plies were simulated by cord-rubber composite elements. Gap elements were used to simulate the opening between tire and rim at zero inflation pressure. This opening closed when the inflation pressure was increased gradually. The predicted distribution of contact pressure at the tire-rim interface agreed very well with the available experimental measurements. Several variations of the tire-rim interference fit were analyzed.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

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