Simulation of Slump in Plastic Pipe Extrusion

1992 ◽  
Vol 114 (1) ◽  
pp. 81-83 ◽  
Author(s):  
D. N. Githuku ◽  
A. J. Giacomin
Keyword(s):  
Numerical Scheme ◽  
Cold Water ◽  
Pipe Wall ◽  
Large Diameter ◽  
Three Dimensional ◽  
Pipe Wall Thickness ◽  
Plastic Pipe ◽  
Model Predictions ◽  
Long Time ◽  
Pipe Extrusion

Extruded plastic pipe leaving an annular die is solidified in a long cooling tank by spraying the outer surface with cold water. The inside surface can take a long time to solidify as the solidification progresses radially inward. This results in flow of molten polymer down the inside of the pipe. This gravity flow of molten extrudate is called slumping, and it can cause serious nonuniformity in pipe wall thickness particularly in large diameter, thick walled pipes. It can also lead to another phenomenon known as “knuckle” formation where melt accumulates at specific locations. A simple numerical scheme to model this flow has been developed. Three-dimensional graphical illustrations of the slumping phenomenon based on this simulation are presented in this paper. The model predictions have been compared with commerical pipe data and they are in qualitative agreement.

Effect of Including the Bauschinger Phenomenon in the Formula for Collapse Pressure of Thin-Walled Pipes

2020 ◽  
Author(s):  
Alastair Walker ◽  
Ruud Selker ◽  
Ping Liu ◽  
Erich Jurdik
Keyword(s):  
Hydrostatic Pressure ◽  
Wall Thickness ◽  
Bauschinger Effect ◽  
Pipe Wall ◽  
Large Diameter ◽  
Pipe Material ◽  
Pipe Wall Thickness ◽  
Collapse Pressure ◽  
Compressive Stresses ◽  
Thin Walled

Abstract The method presented by DNVGL in DNVGL-ST-F101 [1], “Submarine pipeline systems”, 2017, for calculating the collapse pressure of submerged pipelines is well-known for design of pipes intended to operate in very deep water. Such pipes are regarded as quite thick-walled with diameter to wall thickness ratio in the range of 15 to 30. There is now substantial experience in the practical manufacture, installation and operation of such pipes. Recently there has been a growing use of large diameter pipelines to transport high volumes of gas over great lengths at moderate water depths. The pipes are considered to be thin-walled with ratios of diameter to wall thickness in the range of 30 to 45. This paper assesses the validity of the DNVGL design method when applied to the design of such thin-walled pipes. A particular aspect of the buckling pressure of large diameter pipes is the effect of the Bauschinger phenomenon. The phenomenon occurs when pipes made using the UOE method are subjected to internal pressure, to provide expansion of the pipe during manufacture, thus reducing the out-of-roundness of the pipe wall, and subsequently subjected to external hydrostatic pressure during pipeline operation. To date the Bauschinger phenomenon has been recognised as resulting in a reduction of the circumferential compressive yield of the pipe material. This reduction is accommodated in the DNVGL design formula. Recent research into material properties has shown that the Bauschinger effect also has the effect of reducing the modulus of steel materials over a range of values of applied circumferential compressive stresses. The paper reviews the basis of the Bauschinger phenomenon and presents results from very detailed accurate testing of UOE pipe material. The tests determine the levels of modulus for pipes subject to circumferential compressive stresses. Although results for compressive stress-strain values have previously been available for pipes subject to high levels of hydrostatic pressure it has been considered that the Bauschinger effect is not generally significant for thick-walled pipes. The tests reported here consider the calculation of material modulus levels for low levels of stress that correspond to the buckling stress of thin-walled pipes. The calculated collapse pressure for such pipes is examined in this paper and compared to corresponding results from the DNVGL design formula to provide guidance on the effect of design levels of pipe wall thickness due to inclusion of the Bauschinger effect. The comparisons are for example pipe wall thickness and material conditions. Conclusions are drawn that including the Bauschinger effect in the calculated pipe wall thickness can have a beneficial effect with regard to pipe manufacturing and installation costs for pipe subjected to mild heat treatment.

Correlation Between Dynamic Strain-Stress and Vibration Based on Field Data

2005 ◽  
Author(s):  
Roman W. Motriuk
Keyword(s):  
Pipe Wall ◽  
Large Diameter ◽  
Three Dimensional ◽  
Sine Wave ◽  
Rotating Machinery ◽  
Dynamic Strain ◽  
Design Parameters ◽  
Acoustic Oscillations ◽  
Simplified Approach ◽  
Strain Stress

High pressure stages of rotating machinery often produce high-frequency vibrations that cause failures in machinery components, pipes and their connections. Such failures happen even when the machinery operates well within design parameters. Predominant pressure patterns generated by rotating machinery are higher-order three-dimensional acoustic oscillations. In most cases, the piping/component failures result from high cycle events. In these events, a pipe shell is forced into unsteady sine wave deflections, producing deformation forces that initiate cracks, directly or indirectly, in the stress concentration areas. These are most dangerous in pipe welds, particularly in small bore attachment welds. For this reason, rapid detection and estimation of high cycle stresses associated with vibrations is highly desirable. For many years, researchers have studied and developed relationships for estimating maximum stress levels and predicting the service life of piping and machinery components. These studies have been carried out mainly in laboratory set-ups with components of limited size and, limited excitation strengths. In addition, the components were tested in a classical manner, i.e. their vibratory responses were related to their natural frequencies and non-resonant excitations were rarely considered. This work attempts to offer a simplified approach to correlate measured dynamic strain-stress with pipe wall vibrations for large diameter piping (NPS 36, wt = 19.7 mm) excited by a 27 MW centrifugal compressor. Diffused bending wave field and multimode excitation of the pipe shell constricted by factual boundary conditions are used. Particular attention is paid to the value distribution of the ratio (stress/strain to pipe wall velocity) in the straight pipe and in the areas of threadolet connections.

scholarly journals Iterative tomography of pipes during operation

2021 ◽  
Vol 66 (4) ◽  
pp. 505-512
Author(s):  
S. A. Zolotarev ◽  
V. L. Vengrinovich ◽  
S. I. Smagin
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Three Dimensional ◽  
Projection Data ◽  
Beam Hardening ◽  
Pipe Wall Thickness ◽  
X Ray ◽  
Angle Of View ◽  
Imaging Plates ◽  
Made In

The pipe wall thickness was estimated based on three-dimensional images of the pipe recovered from several X-ray projections, which were made in a limited angle of view. Since the effects of scattered radiation and beam hardening are up to 50 % of the main radiation, ignoring them leads to blur of the image and inaccuracy in determining dimensions. To restore pipe images from projections, a volume and/or shell representation of the pipe is used, as well as iterative Bayesian methods. Using these methods, the error in estimating the pipe wall thickness from the projection data can be equal to or less than 300 μm. It has been shown that standard X-ray projections on the film or imaging plates used to obtain data can be used to restore pipe wall thickness profiles in factory conditions.

FEM Analysis of Cold Flaring Process of SUS304 Pipe

2018 ◽  
Vol 382 ◽  
pp. 120-126
Author(s):  
Shinichi Nishida ◽  
Junshi Ichikawa ◽  
Yuta Kashitani ◽  
Kentaro Tsunoda ◽  
Yusuke Takeuchi ◽  
...  
Keyword(s):  
Pipe Wall ◽  
Large Diameter ◽  
Fem Analysis ◽  
The Other ◽  
Taper Angle ◽  
Cold Forming ◽  
Pipe Wall Thickness ◽  
Plant Environment ◽  
Flange Forming ◽  
Large Diameter Pipes

This paper describes a production process for experiment and finite element method (FEM) analysis of cold forming of SUS304 pipe. These large diameter pipes such as φ114.3 mm are used for a plant as a flow channel of gas and liquid. The connection of pipes are generally welded at the plant. However, the other connecting method are required from a viewpoint of making the plant environment worse by welding. Therefore, flaring process of large diameter pipes were proposed. This flaring process is one of a method of pipe flange forming. The formed pipes were connected used with loose flange. Flaring process was generally hot process, thus it has some problem such as becoming complex of forming machine and accuracy of dimension. In this study, cold flaring process of SUS304 pipe was proposed to satisfy these requisitions. Experiment and FEM analysis of cold flaring process were performed to clarify the optimum forming conditions for the flat length of connecting surface such as a diameter of punch, punch stroke and taper angle of dies. As a result, a gap between punch and die was needed to match the pipe wall thickness.

Development of a mathematical model of the influence of wall thickness on the strain rate when profiling pipes by drawing

2020 ◽  
pp. 49-52
Author(s):  
R.A. Okulov ◽  
N.V. Semenova
Keyword(s):  
Mathematical Model ◽  
Strain Rate ◽  
Wall Thickness ◽  
Pipe Wall ◽  
Strain Intensity ◽  
Thickness Strain ◽  
Pipe Wall Thickness

The change in the intensity of the deformation of the pipe wall during profiling by drawing was studied. The dependence of the strain intensity on the wall thickness of the workpiece is obtained to predict the processing results in the production of shaped pipes with desired properties. Keywords drawing, profile pipe, wall thickness, strain rate. [email protected]

Effects of Velvet Antler Polypeptide-Collagen/Chitosan Materials on Proliferation of Osteoblast

2013 ◽  
Vol 380-384 ◽  
pp. 4295-4298
Author(s):  
Wen He Zhu ◽  
Jun Jie Xu ◽  
Wei Zhang ◽  
Yan Li ◽  
Xiao Jing Lu ◽  
...  
Keyword(s):  
Drug Treatment ◽  
Bone Defect ◽  
Three Dimensional ◽  
Chitosan Scaffold ◽  
Release Drug ◽  
Dimensional Network ◽  
Velvet Antler ◽  
Result Show ◽  
Long Time ◽  
Velvet Antler Polypeptide

A highly osteogenic hybrid bioabsorbable scaffold was developed for bone reconstruction. Though the use of a bioabsorbable collagen and chitosan scaffold for loading velvet antler polypeptide to repair bone defect and drug treatment. Velvet antler polypeptide and collagen were extracted for developing the compounded material. The SEM results show that the collagen and chitosan scaffold maintain the natural three dimensional network structures. The cell proliferation experiment result show that the can promote the osteoblast proliferation for a long time . These results indicated that this compound scaffold can sustainable to release drug and is a good material in bone defect and drug treatment.

Research on cargo-loading optimization based on genetic and fuzzy integration

2021 ◽  
Vol 40 (4) ◽  
pp. 8493-8500
Author(s):  
Yanwei Du ◽  
Feng Chen ◽  
Xiaoyi Fan ◽  
Lei Zhang ◽  
Henggang Liang
Keyword(s):  
Genetic Algorithm ◽  
Mathematical Model ◽  
Three Dimensional ◽  
Distribution Center ◽  
Long Time ◽  
Low Efficiency ◽  
Decision Making Model ◽  
The Mathematical Model ◽  
Loading Scheme

With the increase of the number of loaded goods, the number of optional loading schemes will increase exponentially. It is a long time and low efficiency to determine the loading scheme with experience. Genetic algorithm is a search heuristic algorithm used to solve optimization in the field of computer science artificial intelligence. Genetic algorithm can effectively select the optimal loading scheme but unable to utilize weight and volume capacity of cargo and truck. In this paper, we propose hybrid Genetic and fuzzy logic based cargo-loading decision making model that focus on achieving maximum profit with maximum utilization of weight and volume capacity of cargo and truck. In this paper, first of all, the components of the problem of goods stowage in the distribution center are analyzed systematically, which lays the foundation for the reasonable classification of the problem of goods stowage and the establishment of the mathematical model of the problem of goods stowage. Secondly, the paper abstracts and defines the problem of goods loading in distribution center, establishes the mathematical model for the optimization of single car three-dimensional goods loading, and designs the genetic algorithm for solving the model. Finally, Matlab is used to solve the optimization model of cargo loading, and the good performance of the algorithm is verified by an example. From the performance evaluation analysis, proposed the hybrid system achieve better outcomes than the standard SA model, GA method, and TS strategy.

A Research on the Morphology and Composition of Flocs (Part 1: Floc Breaage Disregarded)

2013 ◽  
Vol 726-731 ◽  
pp. 1566-1572 ◽  
Author(s):  
Shi Qiang Ding ◽  
Qing Na Li ◽  
Xin Rong Pang ◽  
Ji Run Xu
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
New Classification ◽  
Suspension Viscosity ◽  
Primary Particles ◽  
Long Time ◽  
Relationship Of ◽  
The Relationship ◽  
Three Dimensional Space ◽  
Floc Breakage

The characteristics of flocs aggregated in flocculation have been paid more and more attention for a long time. In this paper, a new classification and analyses method dealing with the flocs is developed. The flocs formed after flocculation is divided into four kinds, including the left primary particles, linear flocs with all component particles in a line, planar flocs with all component particles on a plane and volumetric flocs with all component particles in a three-dimensional space. By analyzing the formation approaches of different kind of flocs regardless of the floc breakage, the number of every kind of floc is analyzed to be related with the suspension concentration mathematically. After comparing the different items in the models describing the relationship of floc number and concentration, a series of simplified expressions are presented. Lastly, a mathematical equation relating the measurable suspension viscosity with the numbers of different flocs is obtained.

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