Effects of outside diameter, wall thickness and bend radius on ovality of nylon tube during bending operation

1992 ◽  
Vol 52 (1) ◽  
pp. 145-148 ◽  
Author(s):  
D.Z. Luo
Keyword(s):  
Wall Thickness ◽  
Bend Radius ◽  
Nylon Tube ◽  
Outside Diameter

Modelling the Effects of Head Diameter and Cup Wall Thickness on Contact Mechanics and Wear of Cross-Linked UHMWPE Cups

2005 ◽  
Author(s):  
Lu Kang ◽  
Alison L. Galvin ◽  
Zhongmin Jin ◽  
John Fisher
Keyword(s):  
Wall Thickness ◽  
Three Dimensional ◽  
Volumetric Wear ◽  
Wear Model ◽  
Wear Factor ◽  
Head Diameter ◽  
Maximum Contact ◽  
Ultra High Molecular Weight ◽  
Outside Diameter

A three-dimensional contact-coupled wear model was developed and used to predict the long-term wear in both conventional and cross-linked ultra high molecular weight polyethylene (UHMWPE) cups, particular to examine the effect of the head diameter and the UHMWPE cup wall thickness. The wear factors were determined from the simulator testing of 28 mm diameter cups. The maximum contact pressure was found to decrease with the increase of head diameter up to 48 mm, corresponding to the decrease in the cup wall thickness for a fixed outside diameter of the cup. Volumetric wear rate was predicted to increase as the head size increased for the conventional UHMWPE, as well as the cross-linked UHMWPE, although at a much lower rate for the latter due to the smaller wear factor.

Pressure Reversal of Pipe during Hydrostatic Testing

2009 ◽  
Vol 417-418 ◽  
pp. 177-180
Author(s):  
Qing Quan Duan ◽  
Hong Zhang ◽  
Ya Feng Ji
Keyword(s):  
Plastic Deformation ◽  
Wall Thickness ◽  
Full Scale ◽  
Pressure Reversal ◽  
Test Pressure ◽  
Outside Diameter

The purpose of this paper is to discuss the plastic deformation and pressure reversal of pipe during hydrostatic testing. The higher the test pressure, the smaller the number of defects that remain undetected. In order to study the effect of hydrostatic testing, full scale burst experiments were carried out with API 5L X65 SSAW pipes of 660mm outside diameter and 12.5 mm wall thickness. Nine spiral oriented deflects had been machined in the weld. Deformations of deflects were measured. The pressure reversal was computed. It can be concluded that if a hydrostatic test can be successfully accomplished without the failure of any defect, the likelihood of a pressure reversal will be extremely small.

scholarly journals Crack Propagation and Burst Pressure of Pipeline with Restrained and Unrestrained Concentric Dent-Crack Defects Using Extended Finite Element Method

2020 ◽  
Vol 10 (21) ◽  
pp. 7554
Author(s):  
Allan Okodi ◽  
Yong Li ◽  
Roger Cheng ◽  
Muntaseer Kainat ◽  
Nader Yoosef-Ghodsi ◽  
...  
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Crack Depth ◽  
Mechanical Damage ◽  
Burst Pressure ◽  
Operating Pressure ◽  
Extended Finite Element ◽  
Outside Diameter ◽  
Combined Defects ◽  
Dent Depth

Mechanical damage in form of dents, cracks, gouges, and scratches are common in pipelines. Sometimes, these damages form in proximity of each other and act as one defect in the pipe wall. The combined defects have been found to be more injurious than individual defects. One of the combined defects in pipeline comprises of a crack in a dent, also known as dent-crack defect. This paper discusses the development of finite element models using extended finite element criterion (XFEM) in Abaqus to predict burst pressure of specimens of API X70 pipeline with restrained and unrestrained concentric dent-crack defects. The models are calibrated and validated using results of full-scale burst tests. The effects of crack length, crack depth, dent depth, and denting pressure on burst pressure are investigated. The results show that restrained dent-crack defects with shallow cracks (depth less than 50% wall thickness) inside dents do not affect pipeline operations at maximum allowable operating pressure if crack lengths are less than 200 mm. Releasing restrained dent-cracks when the pressure is at maximum allowable operating pressure can cause propagation of deep cracks (depth of 50% wall thickness or more) longer than 60 mm. However, only very long cracks (200 mm and higher) propagate to burst the pipe. Cracks of depth less than 20% of wall thickness inside dents formed at zero pressure are not propagated by the maximum allowable operating pressure. Dent-crack defects having dents of depth less than 2% outside diameter of pipe behave as plain cracks if the dents are formed at zero denting pressure but are more injurious than plain cracks if the dents are formed in pressurized pipes.

Stress Concentration Factors for a Drilling Riser Containing Corrosion Pits

2007 ◽  
Author(s):  
Adilson C. Benjamin ◽  
Divino J. S. Cunha ◽  
Rita C. C. Silva ◽  
Joa˜o N. C. Guerreiro ◽  
George C. Campello ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Wall Thickness ◽  
External Surface ◽  
Corrosion Defects ◽  
Concentration Factors ◽  
Residual Fatigue ◽  
Stress Concentration Factors ◽  
Corrosion Pits ◽  
Outside Diameter

The residual fatigue life of a corroded riser joint can be evaluated by means of a fatigue analysis based on S-N data. In this case nominal stresses are determined through a global riser analysis in which the drilling riser is modeled as a tensioned beam subjected to loads throughout its length and with boundary conditions at each end. The effect of the corrosion defects is taken into account multiplying the nominal stresses by stress concentration factors (SCFs) derived by local Finite Element (FE) analyses of the riser joints containing corrosion defects. In this paper stress concentration factors for a drilling riser containing corrosion pits are calculated using solid FE models. These pits are situated on the external surface of the riser joints. Three shapes of corrosion pits are considered: semi spherical, cylindrical wide and cylindrical narrow. Five depths of corrosion pits are considered: 12.6%, 20.1%, 30.2%, 40.3% and 50.3% of the riser wall thickness. The riser outside diameter and the riser wall thickness are 533.4 mm (21 in) and 15.9 mm (0.625 in), respectively.

Developing in Biodegradable Stents Technology

2014 ◽  
Vol 625 ◽  
pp. 483-488 ◽  
Author(s):  
Sheng Yao Lin ◽  
Cheng Shun Chen ◽  
Yih Sharng Chen ◽  
Sheau Fan Ma
Keyword(s):  
Surface Modification ◽  
Wall Thickness ◽  
Laser Cutting ◽  
Poly Lactic Acid ◽  
Ultrasonic Cleaning ◽  
Geometry Design ◽  
Biodegradable Stents ◽  
Material Sample ◽  
Outside Diameter ◽  
Machine Processing

Biodegradable stents have been used for the treatment of cardiovascular diseases and are often placed inside coronary arteries. The manufacture of Biodegradable stents is an challenging issue because of the features, like geometry design, machine processing way and the material select of stents. An improved manufacturing process of biodegradable stents is presented. The proposed processes consist of the following steps: tube drawing (is use tube sinking manufacture), laser cutting and surface modification (annealing and ultrasonic cleaning). The precision injection and drawing operation is used to obtain the required wall thickness for seamless tube. The laser cutting is performed to change the shape of the stent, and the finishing operations are selected to modify the surface features, like smoothness and texture of stents. The smoothness of surface finish is one of the properties that determine the performance of a stent. Therefore, the surface modification process (vacuum annealing and ultrasonic cleaning) is important in the production of stents and in clinical treatments involving stents. Annealing is the key technology that affects the material’s final crystal grain size. Ultrasonic clean was of the stents to remove the slag (oxides) and burrs formed in laser production. Poly Lactic Acid material sample with an outside-diameter of 1.5 mm, a wall thickness of 0.08 mm, and a length of 10 mm, had been manufactured and demonstrated the proposed manufacture technology. The surface roughness of a stent manufactured is the value of Ra 13.7 nm which basically meets the design requirement for further performance evaluation. It is hoped that the above finding can be used for future study of stents.

scholarly journals Acetabular Component Deformation under Rim Loading Using Digital Image Correlation and Finite Element Methods

2010 ◽  
Vol 24-25 ◽  
pp. 275-280 ◽  
Author(s):  
H. Everitt ◽  
S.L. Evans ◽  
C.A. Holt ◽  
Rob Bigsby ◽  
Imran Khan
Keyword(s):  
Finite Element ◽  
Digital Image Correlation ◽  
Wall Thickness ◽  
Digital Image ◽  
Image Correlation ◽  
Acetabular Cup ◽  
Simple Method ◽  
Press Fit ◽  
Outside Diameter ◽  
Cobalt Chrome

Total hip replacement is a highly successful operation; restoring function and reducing pain in arthritis patients. In recent years, thinner resurfacing acetabular cups have been introduced in order to preserve bone stock and reduce the risk of dislocation. However concerns have been raised that deformation of these cups could adversely affect the lubrication regime of the bearing; leading to equatorial and edge contact, possibly causing the implants to jam. This study aims to assess the amount of deformation which occurs due to the tight peripheral fit experienced during press-fit by applying rim loading to three different designs of acetabular cup: a clinically successful cobalt chrome resurfacing cup, a prototype composite resurfacing cup and a clinically successful polyethylene monobloc cup. Digital Image Correlation (DIC) was used to measure the deformation and to validate Finite Element (FE) models. DIC provided a non-contacting method to measure displacement; meaning the load could be increased continuously rather than in steps as in previous studies. The physical testing showed that the cobalt chrome cups were significantly stiffer than the composite prototype and polyethylene cups. The FE models were in good agreement with the experimental results for all three cups and were able to predict the deformation to within 10%. FE models were also created to investigate the effect of cup outside diameter and wall thickness on stiffness under rim loading. Increasing outside diameter resulted in a linear reduction in stiffness for all three materials. Increasing the wall thickness resulted in an exponential increase in cup stiffness. Rim loading an acetabular shell does not accurately simulate the in vivo conditions; however it does provide a simple method for comparing cups made of different materials.

Plastic Loads for Internally Pressurized Toroidal Shells

2004 ◽  
Author(s):  
J. Blachut
Keyword(s):  
Wall Thickness ◽  
Volume Change ◽  
Laboratory Scale ◽  
Numerical Predictions ◽  
Scale Models ◽  
316L Steel ◽  
Outside Diameter ◽  
Toroidal Shells

Tests on two internally pressurized toroidal shells are described in the paper. These were laboratory scale models manufactured by welding 90°, 316L steel elbows. Outside diameter of toroids was about 310.0 mm, radius of the tube was about 41.0 mm and the wall thickness was about 3.0 mm. Comparison of experimental and numerical plastic loads, based on pressure versus volume change plots, is given. The magnitude of experimentally derived plastic loads was about 16.0 MPa which was close to numerical predictions. Both shells failed by developing cracks in welds, at nozzles, at pressure of about 33.0 MPa.

Optimization Technology and Developing of Vascular Stents

2013 ◽  
Vol 284-287 ◽  
pp. 390-397 ◽  
Author(s):  
Cheng Shun Chen ◽  
Sheng Yao Lin ◽  
Nai Kuan Chou
Keyword(s):  
Wall Thickness ◽  
Laser Cutting ◽  
Vacuum Annealing ◽  
Steel Sample ◽  
Surface Finishing ◽  
Metal Stents ◽  
Stainless Steel Sample ◽  
Design Requirement ◽  
Vascular Stents ◽  
Outside Diameter

Stents have been used for the treatment of cardiovascular diseases and are often placed inside coronary arteries. The manufacture of metal stents is a challenging issue because of the features, like geometry and the material of stents. An improved manufacturing process of stents is presented. The proposed processes consist of the following steps: boring and polishing, laser cutting, vacuum annealing and surface finishing (ultrasonic cleaning, acid pickling, and electrolytic polishing). The precision boring operation is used to obtain the required wall thickness from off-the-shelf seamless tube. The laser cutting is performed to change the shape of the stent, and the finishing operations is selected to modify the surface features, like smoothness and texture of stents. 316LVM stainless steel sample with an outside-diameter of 3 mm, a wall thickness of 0.1 mm, and a length of 25 mm, had been manufactured and demonstrated the proposed manufacture technology. The surface roughness of a stent manufactured is the value of Ra 14.3 nm which basically meets the design requirement for further performance evaluation. It is hoped that the above finding can be used for future study of stents.

Plastic Loads for Internally Pressurized Toroidal Shells

2005 ◽  
Vol 127 (2) ◽  
pp. 151-156 ◽  
Author(s):  
J. Błachut
Keyword(s):  
Wall Thickness ◽  
Volume Change ◽  
Laboratory Scale ◽  
Numerical Predictions ◽  
Scale Models ◽  
316L Steel ◽  
Outside Diameter ◽  
Toroidal Shells

Tests on two internally pressurized toroidal shells are described in this paper. These were laboratory scale models manufactured by welding 90°, 316L steel elbows. The outside diameter of the toroids was about 310.0 mm, radius of the tube was about 41.0 mm, and the wall thickness was about 3.0 mm. Comparison of experimental and numerical plastic loads, based on pressure versus volume change plots, is given. The magnitude of experimentally derived plastic loads was about 16.0 MPa which was close to the numerical predictions. Both shells failed by developing cracks in welds, at nozzles, at pressure of about 33.0 MPa.

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