Buckling Strength of Towers Having Partial Metal Loss on Shell Under Overturning Moment

2015 ◽  
Author(s):  
Masayuki Ozaki ◽  
Atsushi Yamaguchi ◽  
Takuyo Kaida ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Loss ◽  
Element Analysis ◽  
Buckling Strength ◽  
Buckling Stress ◽  
Critical Issues ◽  
Process Plants ◽  
Overturning Moment ◽  
Good Agreement

Reliability of Fitness-For-Service assessment has become more important especially for the aged pressure equipment such as towers in process plants put in service operation over decades. The effects of partial metal loss on buckling strength of the towers subject to overturning moment due to seismic or wind load are one of the critical issues to be clarified. The present paper simulates the buckling strength of towers under overturning moment by means of finite element analysis considering the condition that the shell has suffered from partial metal loss, and evaluates the validity of the buckling stress formulae of API 579-1/ASME FFS-1, NASA, and Donnell. It has been demonstrated that the buckling strength predicted by API formulae shows fairly good agreement with that simulated by finite element analysis. Finite element analysis results have shown that the axial length of metal loss does not affect the buckling stress very much while the buckling stress depends on the circumferential width of metal loss. It has been revealed that the API formulae underestimate the buckling stress when the width of metal loss is smaller than about 30 deg. The paper proposes the modification to the API formulae in this condition that gives more accurate buckling stress than the original formulae.

Burst Pressure of Pressurized Cylinders With Hillside Nozzle

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
H. F. Wang ◽  
Z. F. Sang ◽  
L. P. Xue ◽  
G. E. O. Widera
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Models ◽  
Burst Pressure ◽  
Element Analysis ◽  
Test Models ◽  
Scale Test ◽  
Failure Location ◽  
Dimensional Instability ◽  
Good Agreement

The burst pressure of cylinders with hillside nozzle is determined using both experimental and finite element analysis (FEA) approaches. Three full-scale test models with different angles of the hillside nozzle were designed and fabricated specifically for a hydrostatic test in which the cylinders were pressurized with water. 3D static nonlinear finite element simulations of the experimental models were performed to obtain the burst pressures. The burst pressure is defined as the internal pressure for which the structure approaches dimensional instability, i.e., unbounded strain for a small increment in pressure. Good agreement between the predicted and measured burst pressures shows that elastic-plastic finite element analysis is a viable option to estimate the burst pressure of the cylinders with hillside nozzles. The preliminary results also suggest that the failure location is near the longitudinal plane of the cylinder-nozzle intersection and that the burst pressure increases slightly with an increment in the angle of the hillside nozzle.

Using Finite Element Analysis to Prioritize ILI Calls for Combined Features: Dents in Bends

2018 ◽  
Author(s):  
David Kemp ◽  
Justin Gossard ◽  
Shane Finneran ◽  
Joseph Bratton
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Loss ◽  
Remaining Life ◽  
Case Scenario ◽  
Element Analysis ◽  
Pipe Bend ◽  
Worst Case ◽  
Worst Case Scenario ◽  
Combined Features

Pipeline in-line-inspections (ILI) are used to assess and track the integrity of pipelines, aiding in identifying a variety of features such as: metal loss, dents, out-of-roundness, cracks, etc. The presence of these features can negatively affect the operation, integrity, and remaining life of a pipeline. Proper interpretation of the impacts these features may have on a pipeline are crucial to maintaining the integrity of a pipeline. Several codes and publications exist to assess the severity of these features under known operating conditions, either through empirical formulations or more detailed analysis, in order to aid the operator in determining a corrective action plan. These empirical formulations are generally applicable to assess a singular defect but require a more detailed assessment to evaluate combined defects (i.e. dent in a bend). These detailed assessments typically require a higher level numerical simulation, such as Finite Element Analysis (FEA). This detailed FEA can be quite costly and time consuming to evaluate each set of combined features in a given ILI run. Thus, engineering judgement is critical in determining a worst-case scenario of a given feature set in order to prioritize assessment and corrective action. This study aims to assess dent features (many associated with metal loss) occurring in a pipe bend to determine a worst-case scenario for prioritization of a given feature listing. FEA was used to simulate a field bend of a given radius and angle in order to account for residual stresses in the pipe bend. A rigid indenter was used to form a dent of the approximate length, width, and depth from the ILI data. Separate models were evaluated considering the dent occurring in the intrados, extrados, and neutral axis of the pipe bend to evaluate the worst-case scenario for further assessment. The resulting stresses in the pipe bend-dent geometry, under proper loading were compared to the same dent scenario in a straight pipe segment to develop a stress concentration factor (SCF). This SCF was used in the API 579-1/ASME FFS-1 Fitness for Service (API 579) [1] methodology to determine the impact on the remaining life of the combined features.

Life Assessment of Turbine Components Through Experimental and Numerical Investigations

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Guicang Hou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Life Assessment ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Creep Fatigue ◽  
Turbine Component ◽  
Good Agreement

A new lifetime criterion for withdrawal of turbine components from service is developed in this paper based on finite element (FE) analysis and experimental results. Finite element analysis is used to determine stresses in the turbine component during the imposed cyclic loads and analytically predict a fatigue life. Based on the finite element analysis, the critical section is then subjected to a creep-fatigue test, using three groups of full scale turbine components, attached to an actual turbine disc conducted at 750 °C. The experimental data and life prediction results were in good agreement. The creep-fatigue life of this type of turbine component at a 99.87% survival rate is 30 h.

A study on finite element analysis for simplification of curvature extrusion method

2018 ◽  
Vol 32 (19) ◽  
pp. 1840043
Author(s):  
J. O. Yu ◽  
Y. H. Kim ◽  
Nagamachi Takuo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Extrusion Process ◽  
Experimental Results ◽  
Element Analysis ◽  
Extrusion Method ◽  
Good Agreement

To eliminate the complexity of curvature extrusion process, a new extrusion method was proposed. In this study, a finite element analysis for curvature extrusion was studied to commercialize this extrusion method that creates curvature in a tilting method. When simulating an extrusion process, it is important to fix the appropriate friction coefficient and fillet value to avoid peel-out problems such that the finite element disappears. Therefore, the actual extrusion results and the simulated results were compared to find conditions that the element would not disappear. There was a good agreement between the simulation and experimental results when the coefficient friction was 0.4 and the fillet was 0.4 mm.

The Effect of the Die Temperature on the Solidification Behaviour of the Al/SiCp Metal Matrix Composite: A Comparative Study of Experimental and Finite Element Analysis

2014 ◽  
Vol 893 ◽  
pp. 314-319
Author(s):  
P. Gurusamy ◽  
S. Balasivanandha Prabu ◽  
R. Paskaramoorthy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Time History ◽  
Cooling Curves ◽  
Element Analysis ◽  
Solidification Behaviour ◽  
The Finite Element Analysis ◽  
Die Temperature ◽  
Temperature Time ◽  
Good Agreement

This paper discusses the influence of die temperature on the solidification behaviour of A356/SiCp composites fabricated by squeeze casting method. Information on the solidification studies of squeeze cast composites is somewhat scarce. Experiments were carried out by varying the die temperatures for cylindrical shaped composite castings K-type thermocouples were interfaced to the die and the temperature-time history was recorded to construct the cooling curves. The cooling curves are also predicted from the finite element analysis (FEA) software ANSYS 13. The experimental and predicted cooling curves are not in good agreement. In addition to, the experimental and theoretical solidification times are studied. It was understood that the increase in the die temperature decreases the cooling rate.

Using Isochronous Method to Calculate Creep Damage in Pressure Vessel Components: Part 2

2017 ◽  
Author(s):  
Chithranjan Nadarajah ◽  
Benjamin F. Hantz ◽  
Sujay Krishnamurthy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Closed Form Solution ◽  
Creep Damage ◽  
Form Solution ◽  
Creep Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Good Agreement

This paper is Part 2 of two papers illustrating how isochronous stress strain curves can be used to calculate creep stresses and damage for pressure vessel components. Part 1 [1], illustrated the use of isochronous stress strain curves to obtain creep stresses and damages on two simple example problems which were solved using closed form solution. In Part 2, the isochronous method is implemented in finite element analysis to determine creep stresses and damages on pressure vessel components. Various different pressure vessel components are studied using this method and the results obtained using this method is compared time explicit Omega creep model. The results obtained from the isochronous method is found to be in good agreement with the time explicit Omega creep model.

Experimental Research and Finite Element Analysis of BFRP Flexural Strengthening Efficiencies of Pre-Damaged Concrete Beams

2013 ◽  
Vol 834-836 ◽  
pp. 720-725 ◽  
Author(s):  
Hai Liang Wang ◽  
Wei Chang ◽  
Xin Lei Yang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Element Analysis ◽  
Flexural Strengthening ◽  
Flexural Resistance ◽  
Good Agreement

Six reinforced concrete beams, including 4 beams strengthened with BFRP sheets at different layer of BFRP sheets and 2 control beams, are tested to investigate the effect of layer of BFRP sheets on the ultimate flexural resistance and load-deflection response of the pre-damaged concrete beams strengthened with BFRP sheets. Results show that the flexural resistance of pre-damaged concrete beams increases along with the BFRP sheets layer increasing,but the flexural resistance enhances the degree not to assume the linear relations to the enforcement layer.Numerical simulation of the pre-damaged concrete beams strengthened with BFRP sheets is conducted by ANSYS, and the results of numerical simulation are compared with those of the test results. It turns out that the results of numerical simulation are in good agreement with the test results.

scholarly journals Study on the characteristics of pipe buckling strength under pure bending and external stress using nonlinear finite element analysis

2021 ◽  
Vol 12 (2) ◽  
pp. 110-116
Author(s):  
Hartono Yudo ◽  
Wilma Amiruddin ◽  
Ari Wibawa Budi Santosa ◽  
Ocid Mursid ◽  
Tri Admono
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Nonlinear Finite Element Analysis ◽  
External Pressure ◽  
Diameter Ratio ◽  
Nonlinear Finite Element ◽  
Pure Bending ◽  
Element Analysis ◽  
Buckling Strength

Buckling and collapse are important failure modes for laying and operating conditions in a subsea position. The pipe will be subjected to various kinds of loads, i.e., bending moment, external pressure, and tension. Nonlinear finite element analysis was used to analyze the buckling strength of the pipe under pure bending and external pressure. The buckling of elastic and elasto-plastic materials was also studied in this work. The buckling strength due to external pressure had decreased and become constant on the long pipe when the length-to-diameter ratio (L/D) was increased. The non-dimensional parameter (β), which is proportionate to (D/t) (σy/E), is used to study the yielding influence on the buckling strength of pipe under combined bending and external pressure loading. The interaction curves of the buckling strength of pipe were obtained, with various the diameter-to-thickness ratio (D/t) under combination loads of external pressure and bending moment. For straight pipes L/D = 2.5 to 40, D = 1000 to 4000 mm, and D/t = 50 to 200 were set. The curved pipes D/t = 200, L/D =2.5 to 30 have been investigated by changing the radius of curvature-to-diameter ratio (R/D) from 50 to ∞, for each one. With decreasing R/D, the buckling strength under external pressure decreases slightly. This is in contrast to the bending of a curved pipe. When the value of R/D was decreased, the flexibility of the pipe was increased. However, the buckling strength of the pipe during bending was decreased due to the oval deformation at the cross-section.

scholarly journals Mechanics of Tubes Composed of Interlocking Building Blocks

2022 ◽  
Author(s):  
Kyle Mahoney ◽  
Thomas Siegmund
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Transfer ◽  
Building Blocks ◽  
Maximum Load ◽  
Finite Element Models ◽  
Element Analysis ◽  
Internal Load ◽  
Deformation Response ◽  
Good Agreement

Topologically interlocking material (TIM) systems are composed of convex polyhedral units placed such that building blocks restrict each other's movement. Here, TIM tubes are considered as rolled monolayers of such assemblies. The deformation response of these assembled tubes under diametrical loading is considered. This investigation employs experiments on additivelymanufactured physical realizations and finite element analysis with contact interactions. The internal load transfer in topologically interlocking tubes is rationalized through inspection of the distribution of minimum principalstress. A thrust-line (TL) model for the deformation of topologically interlocking tubes is established. The model approximates the deformation response of the assembled tubes as the response of a collection of Misestrusses aligned with paths of maximum load transfer in the system. The predictions obtained with the TL-model are in good agreement with results of finite element models. Accounting for sliding between building blocks in theTL-model yields a predicted response more similar to experimental results with additively manufactured tubes.

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