Deformation Behavior of Intrusion Bending for Steel Pipes

2003 ◽  
Author(s):  
Tetsuaki Sano ◽  
Hisashi Naoi
Keyword(s):  
Wall Thickness ◽  
Deformation Behavior ◽  
Diameter Ratio ◽  
Radius Ratio ◽  
Outer Diameter ◽  
Thickness Increase ◽  
Steel Pipes ◽  
Bending Radius ◽  
Outside Diameter ◽  
Wall Thickness Increase

We have investigated the intrusion bending for steel pipes for several years. The bending machine consists of three parts. They are called pusher, guide cylinder and gyro. The aim of this investigation is to reveal the effect of size and strength of materials, pushing forces and so on. That we study in this report are as follows: (1) The effect of bending radius ratio on ovality of outer diameter and eccentricity of wall thickness, and (2) the effect of ratio of wall thickness to outer diameter on ovality of outer diameter and eccentricity of wall thickness. The conclusions of this study are summarized as follows. (1) The ovality of outer diameter and the eccentricity of wall thickness increase as the bending radius ratio decreases. (2) The ovality of outer diameter decreases and the eccentricity of wall thickness increase as thickness outside diameter ratio increases.

Effects of Mandrel Shape and Dimension on Deformation Behavior for Hot Mandrel Bending

2006 ◽  
Author(s):  
Soon-Tae Jang ◽  
Hisashi Naoi ◽  
Takashi Kurita
Keyword(s):  
Wall Thickness ◽  
Deformation Behavior ◽  
Small Deviation ◽  
Axial Strain ◽  
Research Work ◽  
Expansion Ratio ◽  
Radius Ratio ◽  
Outer Diameter ◽  
Thickness Strain ◽  
Bending Radius

Elbows, which belong to butt-welded steel pipe joints, are used in piping of various plants. Elbows are mainly manufactured by hot mandrel bending. In hot mandrel bending, short straight pipes are inserted into an inner tool of mandrel and are bent at specified bending radius, while they are compressed by pusher from one end of pipes and their outer diameter are expanded. Elbows manufactured by this bending process have small deviation in wall thickness and also high accuracy in roundness, even when they are processed into short bending radius. Shape and dimension of mandrel are designed by trial and error through many experimental tests. However, there are a few research works on hot mandrel bending. We focus on expansion ratio and bending radius ratio of mandrel, which are main variables, and greatly affect deformation behavior of hot mandrel bending. And we conducted experiment and numerical analysis using mandrels which have several kinds of expansion ratio and bending radius ratio. Following items are clarified by this research work: At extrados, axial strain decreases slightly, when expansion ratio increases. As a results, neutral axis of bending moves from extrados toward intrados by increasing of expansion ratio. And at intrados, wall thickness strain at intrados decreases, when expansion ratio increases. Wall thickness strain at intrados decreases, when bending radius ratio increases. Forming load increases, when expansion ratio increases and with bending radius ratio decreases. When experimental conditions do not coincide with optimized expansion ratio and bending radius ratio, deviation of wall thickness occurs in elbow.

Analysis of Plain and Gouged Dents in Steel Pipes Subjected to Pressure and Moment Loading

2006 ◽  
Author(s):  
J. Blachut ◽  
I. B. Iflefel
Keyword(s):  
Mild Steel ◽  
Test Data ◽  
Wall Thickness ◽  
Experimental Test ◽  
Bending Moment ◽  
Diameter Ratio ◽  
Numerical Results ◽  
Steel Pipes ◽  
Outside Diameter ◽  
Good Agreement

Six laboratory scale, mild steel pipes with the outside diameter-to-wall-thickness ratio, Do/t ≅ 40, were dented to about 15%–20% of outside diameter Do, by a hemispherical indenter with its diameter to pipe’s outside diameter ratio, d/Do ≅ 0.41. Three pipes had surface gouges running axially in them, and the remaining three were gouge-free. Five of them were then collapsed by a bending moment followed by pressure burst tests. Experimental test data has been used to benchmark the FE results, details of which are given in the paper. Good agreement between experimental and numerical results was obtained.

Dimensional Changes in Tube Swaging

1966 ◽  
Vol 88 (2) ◽  
pp. 147-150 ◽  
Author(s):  
Serope Kalpakjian
Keyword(s):  
Wall Thickness ◽  
Appreciable Effect ◽  
Process Variables ◽  
Workpiece Material ◽  
Thickness Increase ◽  
Dimensional Changes ◽  
Independent Variables ◽  
Rotary Swaging ◽  
Diameter Reduction ◽  
Wall Thickness Increase

The purpose of this study was to investigate changes in the wall thickness of tubes sunk by the rotary swaging process. The independent variables were: Workpiece material, original wall thickness of tube, die angle, die overgrind, and diameter reduction. The results indicated that of these five variables only the diameter reduction was a factor in wall-thickness increase. Material and other process variables did not appear to have appreciable effect within the range studied.

Theoretical, Numerical and Experimental Investigation of the Effects of Manufacturing Process Parameters on Thin-Walled Tube Bending Defects

2009 ◽  
Vol 83-86 ◽  
pp. 1107-1112
Author(s):  
J. Taheri Kahnamouei ◽  
Mohammad Sedighi
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Tube Bending ◽  
Effective Parameters ◽  
Bending Process ◽  
Thin Walled Tube ◽  
Bending Radius ◽  
Thin Walled

The aim of this paper is to survey thin-walled tube bending process (without use of mandrel and booster). In tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, and centerline bending radius-to-outer diameter ratio. Any mismatch in selecting these parameters would cause defects like wrinkling, variation in wall thickness, and cross section distortion. Firstly, the effects of these parameters on the initiation of the wrinkle, depth of wrinkling, change in wall thickness, and cross section distortion are studied. For this purpose, an FE commercial code has been used to simulate the process. Then, a series of experimental tests have been carried out to verify the results simulation. A comparison between analytical and experimental results shows a reasonable agreement with each other. Based on this comparison, it has been observed that there is a critical bending radius for any tube with a certain radius and thickness, in which the wrinkling begins to occur. For a certain bending angle and radius, it have been observed that the depth of wrinkling, change in wall thickness, and cross section distortion increase with reduction in wall thickness and outer diameter-to-wall thickness ratio

Experimental Study on Residual Cross-Sectional Flattening of Thin-Walled Pipes Under Pure Plastic Bending

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ziqian Zhang
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Residual Deformation ◽  
Outer Diameter ◽  
Cross Sectional ◽  
Plastic Bending ◽  
Thin Walled Pipe ◽  
Bending Radius ◽  
Thin Walled ◽  
The Cross

Abstract Cross-sectional ovalization (ovalization) usually occurs when thin-walled pipe is subjected to large plastic bending. This paper is concerned with residual deformation of thin-walled pipe's cross section in a radial direction when external bending moment is removed. In order to clarify the fundamental ovalization characteristics, find out what factors influence the residual flattening (value of ovalization), the ovalization behavior is investigated experimentally. The experiments are carried out on 21 stainless steel specimens with different geometric parameters under different bending radii by means of a four-point pure bending device. The residual cross-sectional flattenings are monitored continuously by scanning the cross section periodically along the circumferential direction. From the experimental results, it is observed that the cross-sectional shape of the thin-walled pipe is not perfect standard ellipse, and the appearance of the maximum residual flattening is usually found in the direction normal to the neutral surface. It is also revealed the relationships between the residual flattening and the bending radius, the wall thickness, and the pipe outer diameter, i.e., the residual flattening increases as the bending radius and the wall thickness reduce, but it increases as the outer diameter increases. These results are expected to find their potential application in thin-walled pipe bending operation.

scholarly journals Evaluation of Fecal Calprotectin, D-Lactic Acid and Bedside Gastrointestinal Ultrasound Image Data for the Prediction of Acute Gastrointestinal Injury in Sepsis Patients

2021 ◽  
Vol 3 ◽  
Author(s):  
Junlu Li ◽  
Yanbo Ren ◽  
Chang Gao ◽  
Kaili Zhang ◽  
Fuwen Zheng ◽  
...  
Keyword(s):  
Small Intestine ◽  
Lactic Acid ◽  
Wall Thickness ◽  
Diameter Ratio ◽  
Cross Sectional Area ◽  
Gastric Antrum ◽  
Control Group ◽  
Outer Diameter ◽  
Sectional Area ◽  
Cross Sectional

Objective: To investigate the early warning and prognostic evaluation of fecal calprotectin (FC), D-lactic acid, and bedside gastrointestinal ultrasound (B-GIUS) data for acute gastrointestinal injury (AGI) in sepsis patients.Main Method: Sepsis patients were grouped based on the presence or absence of AGI into AGI and non-AGI groups. Healthy volunteers of the same period were selected as the control group. FC, B-GIUS data, D-lactic acid, etc. were collected on the 1st, 3rd and 7th days of admission. Twenty-eight-day mortality was recorded.Main Results: FC, D-lactic acid levels, gastric antrum cross-sectional area, and small intestine wall thickness were significantly increased in group A and B (P < 0.05); furthermore, inner-to-outer diameter ratio and cross-sectional area of small intestine were lower than those in the control group (P < 0.05). FC, D-lactic acid, gastric antrum cross-sectional area and small intestine wall thickness in AGI group were higher than those in non-AGI group (P < 0.05). Inner-to-outer diameter ratio and cross-sectional area of small intestine in AGI group were smaller than those in non-AGI group (P < 0.05). There was no difference in the thickness, inner-to-outer diameter ratio nor the cross-sectional area ratio of colon between AGI and non-AGI groups (P > 0.05). AUC for D-lactic acid was 0.881, which was higher than FC's (0.74). When the D-lactic acid cutoff value was 22.16 μmol/L, the sensitivity was 77.9% and the specificity was 92% for the prediction of AGI in sepsis. AUC for the cross-sectional area of the gastrointestinal antrum was 0.657, which was higher than the small intestine thickness's (0.629). When the gastric antrum cross-sectional area was larger than 4.20 cm2, the sensitivity was 64% and the specificity was 65.3%.Conclusion: D-Lactic acid and FC were early diagnostic indicators for sepsis with AGI, and D-lactic acid was the superior indicator. The gastric antrum cross-sectional area and the small intestine wall thickness had an early warning effect, and the prediction of the gastric antrum cross-sectional area was superior to that of the latter. Because it is non-invasive and convenient, B-GIUS can help in the diagnosis of sepsis with AGI.

Modeling and Experimental Validation of the Effect of Sand Filling on Avoiding Wrinkling Phenomenon in Thin-Walled Tube Bending Process

2010 ◽  
Author(s):  
Jalal Taheri Kahnamouei ◽  
Bashir Behjat
Keyword(s):  
Wall Thickness ◽  
Experimental Tests ◽  
Element Model ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Tube Bending ◽  
Effective Parameters ◽  
Bending Process ◽  
Bending Radius ◽  
Thin Walled

This paper investigates a method to avoid the wrinkling in thin-walled tubes in bending process. In the tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, centerline bending radius-to-outer diameter ratio. Any mismatch in the selection of the process parameters would cause defects like wrinkling, serve changes in wall thickness, and cross section distortion. For example, the depth of wrinkling increases with reduction in wall thickness and outer diameter-to-wall thickness ratio for a certain bending angle and radius. In this research, to avoid wrinkle initiation, tube is filled by sand and then bended. This sandy core is supported the tube from inner, and tube is prepared to bending. After bending process, sand is removed. In this work, to study the process numerically, a 3D finite element model of the horizontal bending process is built using ANSYS software. Then, experimental tests have been carried out to verify the simulation results and are developed to provide additional insight. A comparison between numerical and experimental results shows a reasonable agreement. It shows that wrinkle initiation can be avoided with filler material like sand.

P189 Use of transabdominal ultrasonography for the evaluation of Crohn’s disease activity

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S233-S233
Author(s):  
E Yorulmaz ◽  
B Yigit ◽  
M S Erturk ◽  
U Erdem ◽  
U Yanc ◽  
...  
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Disease Activity ◽  
Flow Velocity ◽  
Wall Thickness ◽  
Transabdominal Ultrasonography ◽  
Thickness Increase ◽  
Sensitivity Level ◽  
Crohn’S Disease Activity ◽  
Wall Thickness Increase

Abstract Background Ileocolonoscopy is accepted as the gold standard method for the diagnosis of Crohn’s disease (CD). However, there are cases where it is inadequate due to being invasive, failure to allow endoscopic exploration of the small intestine, and failure to show the extraintestinal pathologies. In the present study, it is aimed to compare clinical, endoscopic scores and computerised tomography enterography (CTE) findings with transabdominal ultrasonography (TAUS) findings in order to evaluate the activity of CD. Methods The study included 79 patients diagnosed with CD. Crohn’s Disease Activity Index (CDAI) and Harvey Bradshaw Index (HBI) were used for the evaluation of the clinical activities of the patients. The patients with CDAI equal to 150 and more and HBI equal to 5 points and more were assessed as clinically active. Colonoscopic disease activity was assessed by The Simple Endoscopic Score for Crohn’ disease (SES-CD), SES-CD score of 3 and higher was defined as endoscopically active. In the evaluation of CTE and TAUS, the measurement of the thickness of the intestinal wall above 3 mm was accepted as pathological. Abscess, mass, fistula and ileus were evaluated as complications. Superior mesenteric artery (SMA) flow velocity was assessed by Color Doppler US. Limberg score was graded from Grades 0 to 4 for Doppler TAUS. Results Of the patients, 57 (72.1%) were male and 22 (27.8%) were female. Age average of the patients was 37.5 years (17–64) and the mean duration of disease was 48.6 months (0–240 months). Increase in the wall thickness in CTE and TAUS, detection of inflammation and complication in mesenteric fatty planes were found to be highly significant (p ˂ 0.0001). Wall thickness increase sensitivity level of TAUS according to CTE was 82%, specificity level was 97%, sensitivity level of the inflammation finding in mesenteric fatty planes was measured as 80%, and specificity level as 95%. A significant correlation was found between the wall thickness increase in CTE and TAUS and inflammation in mesenteric fatty planes via CDAI, HBI and SES-CD scoring (p ˂ 0.05). In addition, there was a significant relationship between the presence of lymphadenopathy in CTE in active patients according to HBI (p ˂ 0.05). According to the CDAI and SES-CD scores, Doppler flow velocity of SMA was significantly higher in the active group than the inactive group (p ˂ 0.05). CDAI, HBI and SES-CD results were found highly significant via the Limberg Scoring results (p < 0.0001). Conclusion In the current study, it is shown that TAUS is a diagnostic tool as effective as CTE in the evaluation of CD activity. In addition, it is an important finding that the flow velocity of SMA increases as correlated with inflammation via the Doppler feature of TAUS.

scholarly journals Experimental and Numerical Investigation of Plain and Gouged Dents in Steel Pipes Subjected to Pressure and Moment Loading

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
J. Błachut ◽  
I. B. Iflefel
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Numerical Investigation ◽  
Test Data ◽  
Experimental Test ◽  
Bending Moment ◽  
Diameter Ratio ◽  
Steel Pipes ◽  
Outside Diameter ◽  
Good Agreement

Six laboratory scale, mild steel pipes with the outside diameter-to-wall-thickness ratio, Do∕t≅40, were dented to about 15–20% of outside diameter Do, by a hemispherical indenter with its diameter to pipe’s outside diameter ratio, 2a∕Do≅0.41. Three pipes had surface gouges running axially in them, and the remaining three were gouge free. Five of them were then collapsed by a bending moment followed by pressure burst tests. Experimental test data has been used to benchmark the finite element results, details of which are given in this paper. Good agreement between experimental and numerical results was obtained in the modeling of denting, but not so well in the modeling of bending—indicating the need for further work in order to address the discrepancies.

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