scholarly journals On the Suitability of Vibration Acceptance Criteria of Process Pipework

2022 ◽  
Vol 2022 ◽  
pp. 1-9
Author(s):  
Omar Tawfik Shady ◽  
Jamil Renno ◽  
M. Shadi Mohamed ◽  
Sadok Sassi ◽  
Asan G. A. Muthalif
Keyword(s):  
Finite Element ◽  
Confidence Level ◽  
Experimental Studies ◽  
Point Load ◽  
Life Assessment ◽  
Fluid Composition ◽  
Finite Element Models ◽  
Acceptance Criteria ◽  
Acceptance Criterion ◽  
Spectral Density Functions

The risk of vibration-induced fatigue in process pipework is usually assessed through vibration measurements. For small-bore pipework, integrity personnel would measure the vibration of the pipework and refer to widely used charts to quantify the risk of vibration-induced fatigue. If the vibration levels are classified as OK, no action is required on behalf of the operators. However, if it is a CONCERN or PROBLEM vibration level, strain measurements are required to adequately quantify the risk through a fatigue life assessment. In this paper, we examine the suitability of a widely used vibration acceptance criteria through finite element models. A total of 4,800 models are used to study the suitability of this vibration acceptance criteria by monitoring both the vibration and dynamic stress. The model comprises a small-bore pipe (2″ SCH 40) that is fitted on a mainline size 5″ SCH 40 using a weldolet; the length of the mainline takes three values resulting in three models. The mainline supporting conditions will be varied using translational and rotational springs. The finite element models will be excited using a point load resembling flow-induced forces (with varying flow velocity and fluid composition). These excitations are obtained from the literature and are based on experimental studies as power spectral density functions. The results show that the studied vibration acceptance criterion is suitable in 99.73% of all the studied models with 68.27% confidence level. For the models with a shorter mainline pipe, the criterial is suitable in 76.5% of the time with 68.27% confidence level.

scholarly journals Increasing Damping of Thin-Walled Structures Using Additively Manufactured Vibration Eliminators

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2125 ◽  
Author(s):  
Paweł Dunaj ◽  
Stefan Berczyński ◽  
Karol Miądlicki ◽  
Izabela Irska ◽  
Beata Niesterowicz
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Steel Beam ◽  
Finite Element Models ◽  
Fem Model ◽  
Thin Walled Structures ◽  
Resonance Frequencies ◽  
Thin Walled ◽  
Parametric Analyses

The paper presents a new way to conduct passive elimination of vibrations consisting of covering elements of structures with low dynamic stiffness with polylactide (PLA). The PLA cover was created in 3D printing technology. The PLA cover was connected with the structure by means of a press connection. Appropriate arrangement of the PLA cover allows us to significantly increase the dissipation properties of the structure. The paper presents parametric analyses of the influence of the thickness of the cover and its distribution on the increase of the dissipation properties of the structure. Both analyses were carried out using finite element models (FEM). The effectiveness of the proposed method of increasing damping and the accuracy of the developed FEM models was verified by experimental studies. As a result, it has been proven that the developed FEM model of a free-free steel beam covered with polylactide enables the mapping of resonance frequencies at a level not exceeding 0.6% of relative error. Therefore, on its basis, it is possible to determine the parameters of the PLA cover. Comparing a free-free steel beam without cover with its PLA-covered counterpart, a reduction in the amplitude levels of the receptance function was achieved by up to 90%. The solution was validated for a steel frame for which a 37% decrease in the amplitude of the receptance function was obtained.

An Authoritative Comparison of Remaining Life Assessments for Pipeline Dents

2018 ◽  
Author(s):  
Rhett Dotson ◽  
Chris Holliday ◽  
Luis Torres ◽  
Damien Hagan
Keyword(s):  
Finite Element ◽  
American Petroleum Institute ◽  
Assessment Methods ◽  
Ease Of Use ◽  
Life Assessment ◽  
Finite Element Models ◽  
Remaining Life ◽  
Calculated Stress ◽  
Stress Concentration Factors ◽  
Remaining Life Assessment

A significant amount of effort has been expended in the area of advancing pipeline dent remaining life assessment methods beginning in the late 1980s and extending to the current day. Initial research efforts were primarily empirical in nature while more recent research efforts have incorporated finite element modelling. Coupled with advancements in assessment techniques, the capabilities of advanced in-line inspection (ILI) tools have increased to a point where they can provide consistent, reliable information that is suitable for dent assessments. As a result of these advancements in assessment models and ILI tools, operators can now perform remaining life assessments using ILI data, and a multitude of remaining life assessment models are available, including solutions from the European Pipeline Research Group (EPRG), Pipeline Research Council International (PRCI), American Petroleum Institute (API), and finite-element based approaches. In addition to these remaining life assessments, many operators routinely perform strain-based assessments based on guidance from ASME B31.8. To date, there have been few studies comparing the various assessment methods on large numbers of dents, and as a result, significant questions persist as to the conservatism inherent in each method. In addition, the EPRG and PRCI methods are largely based on full-scale testing and finite-element models performed with idealized indenter shapes while actual pipeline dents typically exhibit complex shapes and interactions between multiple dents. Each model also has limitations and advantages that are discussed in this paper, such as ease of use and how pipeline geometry and weld association are considered. This paper provides a robust comparison of selected dent assessment methodologies on 220 actual dents from a 24-inch pipeline with depths ranging from 0.6–4.5% OD, and 32 dents from a 30-inch line with depths ranging from 1–2.5% OD. The assessment includes both top and bottom of line dents and investigates the influence of restraint on remaining life. The results presented in the paper are based on high-resolution ILI caliper data collected during two in-line inspections. Furthermore, the paper provides statistical comparisons between strain and remaining life methodologies and also between the various remaining life assessments. The paper also provides a comparison of the restraint parameter from the PRCI model with calculated stress concentration factors from finite-element models. The paper provides a first of its kind comparison of the various methods and discusses how the work may be extended to other pipe diameters and wall thicknesses.

scholarly journals Finite Element Analysis of Reinforced Concrete Slabs with Spherical Voids

2013 ◽  
Vol 6 (4) ◽  
pp. 15-37
Author(s):  
Amer M. Ibrahim ◽  
Nazar K. Ali ◽  
Wissam D. Salman
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Compressive Strain ◽  
Strain Curve ◽  
Point Load ◽  
Concrete Slabs ◽  
Finite Element Models ◽  
Element Analysis ◽  
Reinforced Concrete Slabs ◽  
Spherical Voids

This paper presents a numerical analysis using ANSYS finite element program to simulate the reinforced concrete slabs with spherical voids when subjected to five point load. Six slabs with length 1.0m, width 1.0m, height (0.1m and 0.125m) and simply supported were modeled. Nonlinear materials behavior, as it relates to steel reinforcing bars and plain concrete, and linear behavior for steel plate is simulated using appropriate constitutive models. The results showed that the general behavior of the finite element models represented by the load-deflection curves at mid-span, ultimate load, load-maximum concrete compressive strain curve, and crack patterns show good agreement with the test data from the experimental test. The finite element models represented by this work can be used to carry out parametric study for the BubbleDeck slab specimens

scholarly journals Calculation of tube concrete elements with strengthened cores by numerical method

2020 ◽  
Vol 166 ◽  
pp. 08002
Author(s):  
Oleksandr Palyvoda ◽  
Dmytro Yermolenko ◽  
Oksana Demchenko ◽  
Oleksandr Andriichuk ◽  
Oleksandr Nyzhnyk
Keyword(s):  
Finite Element ◽  
Experimental Studies ◽  
High Strength ◽  
Confined Concrete ◽  
Finite Element Models ◽  
Structural Elements ◽  
Cross Sectional ◽  
The Difference ◽  
Concrete Elements ◽  
Elastic Stage

The paper considers the features of formation of finite element models of tube confined concrete structural elements in the form of centrally compressed rod with strengthened cores. The prerequisites, which underlies the proposed approach to the formation of finite element models of tube confined concrete elements with strengthened cores, are given. Lengthwise the tube confined concrete elements have constant dimensions and a set of cross-sectional components. It is proved that the use of high-strength concrete allows performing calculations in the elastic stage of the work of materials. When modeling the work of rod reinforcement in tube confined concrete elements with strengthened cores, it can be represented as an imaginary cylinder with a cross-sectional area equal to the area of the rod reinforcement. The proposed prerequisites for the numerical simulation of the work of tube confined concrete elements with the strengthened cores of the studied types allowed to construct adequate finite element models. The difference in the value of the load-bearing capacity obtained from the results of physical and numerical experimental studies was 5,94…7,72 %.

Towards a Failure Criterion for Microtubules Based on Matching Strength Analysis in Finite Element Models to AFM Loads

2011 ◽  
Author(s):  
William Taylor ◽  
W. Steve Shepard ◽  
Candace L. Floyd
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Brain Injury ◽  
Failure Criterion ◽  
Point Load ◽  
Strength Analysis ◽  
Finite Element Models ◽  
Loading Conditions ◽  
Starting Point ◽  
The Impact

In previous research studies, the geometric and elastic properties for a critical component of axon health, the microtubule (MT), have been determined using lateral indentation with the tip of an atomic force microscope (AFM). Although the response due to the indentations caused by the AFM was observed to be linear for most of the tests, forces greater than 300pN would result in a permanent irreversible collapse of the MT’s structure. While the intent of those researchers was not to evaluate microtubule strength properties, that load can be used as a starting point to evaluate internal stress failure criterion for such structures. To that end, the current research is investigating MT strength by replicating the loading and boundary conditions in a finite element model. This work is an extension of previous work aimed at using this 300 pN point load to develop failure criteria for MTs under more realistic loading conditions. In the present work, modeling has been used to correlate the AFM point load response with the more realistic distributed loading conditions that would result during a brain injury event. Furthermore, the impact of nearby MTs on the stresses that occur under similar loading conditions is also examined. These results are being used to analytically determine a stress threshold related to MT structural failure. Correspondingly, models that include dynamic wave propagation through the microtubule will be studied. The failure criterion determined in both cases would aid in evaluating brain injury studies that involve pressure wave propagation in whole-head finite element models, even when such models represent the white matter using homogeneous properties.

scholarly journals Image-based finite element modeling of alveolar epithelial cell injury during airway reopening

2009 ◽  
Vol 106 (1) ◽  
pp. 221-232 ◽  
Author(s):  
H. L. Dailey ◽  
L. M. Ricles ◽  
H. C. Yalcin ◽  
S. N. Ghadiali
Keyword(s):  
Finite Element ◽  
Cell Morphology ◽  
Mechanical Response ◽  
Cell Injury ◽  
Alveolar Epithelial Cell ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Finite Element Models ◽  
Airway Reopening ◽  
Hydrodynamic Stresses

The acute respiratory distress syndrome (ARDS) is characterized by fluid accumulation in small pulmonary airways. The reopening of these fluid-filled airways involves the propagation of an air-liquid interface that exerts injurious hydrodynamic stresses on the epithelial cells (EpC) lining the airway walls. Previous experimental studies have demonstrated that these hydrodynamic stresses may cause rupture of the plasma membrane (i.e., cell necrosis) and have postulated that cell morphology plays a role in cell death. However, direct experimental measurement of stress and strain within the cell is intractable, and limited data are available on the mechanical response (i.e., deformation) of the epithelium during airway reopening. The goal of this study is to use image-based finite element models of cell deformation during airway reopening to investigate how cell morphology and mechanics influence the risk of cell injury/necrosis. Confocal microscopy images of EpC in subconfluent and confluent monolayers were used to generate morphologically accurate three-dimensional finite element models. Hydrodynamic stresses on the cells were calculated from boundary element solutions of bubble propagation in a fluid-filled parallel-plate flow channel. Results indicate that for equivalent cell mechanical properties and hydrodynamic load conditions, subconfluent cells develop higher membrane strains than confluent cells. Strain magnitudes were also found to decrease with increasing stiffness of the cell and membrane/cortex region but were most sensitive to changes in the cell's interior stiffness. These models may be useful in identifying pharmacological treatments that mitigate cell injury during airway reopening by altering specific biomechanical properties of the EpC.

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

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