Material Property Effects on Critical Buckling Strains in Energy Pipelines

2002 ◽  
Author(s):  
Alfred B. Dorey ◽  
David W. Murray ◽  
J. J. Roger Cheng
Keyword(s):  
Material Property ◽  
Parametric Study ◽  
Numerical Models ◽  
Local Buckling ◽  
Analytical Models ◽  
Basic Material ◽  
Line Pipe ◽  
Moment Capacity ◽  
Yield Plateau ◽  
Critical Buckling Strain

Investigations in the development of a predictive critical buckling strain equation have shown that the grade of the material is one of five fundamental non-dimensional parameters in determining the critical local buckling strain for line pipe under combined loads. Further to this, the shape of the material curve also plays a significant role in the resulting critical buckling strain. Over 50 full-scale test specimens have been tested at the University of Alberta and effective numerical finite element analytical models have been developed. A parametric study consisting of 170 analyses was performed using the numerical models and critical buckling strain equations were derived. One of the essential variables in the new equations is a function of the specimen’s material properties. The results indicate that the higher the grade of the material the lower the value of the critical buckling strain. Furthermore, the level of agreement between the new equations and the experimental data was found to be dependent on the shape of the material curve for the specimen. Experimentally, two basic material curve shapes were observed, namely: specimens with a “rounded” material curve through the yield strength and specimens with a material property that exhibited a distinct “yield plateau” or yield point. Comparison of the experimental and numeric data showed that the specimens that were fabricated from material with a distinct yield plateau had different critical buckling strains when compared to specimens tested with rounded material curves. A subsequent parametric study was undertaken to examine the effect that the different shaped material curves had on the local and global behaviour. The results of this subsidiary parametric study showed that the global moment capacity was essentially independent of the shape of the material curve (the ratio of the peak moment from the yield plateau material to the peak moment for the rounded material was 1.018). However, the local critical buckling strain was significantly lower for the specimens analyzed with the material that had the yield plateau (the ratio of the critical strains for the two different material curves was 0.710).

Parametric Study of Compound Cold-Formed Steel Sections as Flexural Members

2015 ◽  
Vol 74 (4) ◽  
Author(s):  
Ker Shin Mu ◽  
Poi Ngian Shek ◽  
Arizu Sulaiman ◽  
Boon Cheik Tan
Keyword(s):  
Parametric Study ◽  
Local Buckling ◽  
Bending Moment ◽  
Steel Plates ◽  
Pure Bending ◽  
Moment Capacity ◽  
Flexural Members ◽  
Bending Capacity ◽  
Steel Sections ◽  
Cold Formed Steel

This paper presents a parametric study on compound cold-formed steel sections as flexural members. The compound members are used to sustain higher load and solve the problems of local buckling and lateral torsional buckling. The aim of this study is to investigate the strength of compound cold-formed steel section subjected to pure bending. Moment capacity of the compound section is calculated in accordance to Eurocode 3. The compound cold-formed steel sections proposed in this study are made up of two cold-formed steel C-section and hot-rolled plates. Steel plates with thickness of 3 mm to 8 mm are added to the cold-formed double C-section with the purpose to increase the bending capacity. From the comparison, moment capacity of compound sections give higher value as compared to cold-formed steel C-section with the comparison ratios range between 1.15 and 3.30. Results from the study show that compound cold-formed steel sections able to enhance the strength in resisting pure bending by adding steel plate at the flanges and web of the section. On the other hand, finite element modeling using ANSYS is carried out on two of the selected compound cold-formed steel sections and the results show good agreement with analytical results.

scholarly journals Gaining a better understanding of the extrusion process in fused filament fabrication 3D printing: a review

2021 ◽  
Author(s):  
Bahaa Shaqour ◽  
Mohammad Abuabiah ◽  
Salameh Abdel-Fattah ◽  
Adel Juaidi ◽  
Ramez Abdallah ◽  
...  
Keyword(s):  
3D Printing ◽  
Numerical Models ◽  
Extrusion Process ◽  
Analytical Models ◽  
Limiting Factor ◽  
Fused Filament Fabrication ◽  
Promising Tool ◽  
Relevant Work ◽  
3D Printing Technique ◽  
Required Quality

AbstractAdditive manufacturing is a promising tool that has proved its value in various applications. Among its technologies, the fused filament fabrication 3D printing technique stands out with its potential to serve a wide variety of applications, ranging from simple educational purposes to industrial and medical applications. However, as many materials and composites can be utilized for this technique, the processability of these materials can be a limiting factor for producing products with the required quality and properties. Over the past few years, many researchers have attempted to better understand the melt extrusion process during 3D printing. Moreover, other research groups have focused on optimizing the process by adjusting the process parameters. These attempts were conducted using different methods, including proposing analytical models, establishing numerical models, or experimental techniques. This review highlights the most relevant work from recent years on fused filament fabrication 3D printing and discusses the future perspectives of this 3D printing technology.

Modelling of interactions between dykes, inclined sheets and faults at Santorini volcano

2021 ◽  
Author(s):  
Kyriaki Drymoni ◽  
John Browning ◽  
Agust Gudmundsson
Keyword(s):  
Tensile Strength ◽  
Fault Zone ◽  
Numerical Models ◽  
Damage Zone ◽  
Sheet Thickness ◽  
Analytical Models ◽  
Energy Conditions ◽  
Dyke Swarm ◽  
Normal Faults ◽  
Santorini Volcano

<p>Dykes and inclined sheets are known occasionally to exploit faults as parts of their paths, but the conditions that allow this to happen are still not fully understood. Here we report field observations from a well-exposed dyke swarm of the Santorini volcano, Greece, that show dykes and inclined sheets deflected into faults and the results of analytical and numerical models to explain the conditions for deflection. The deflected dykes and sheets belong to a local swarm of 91 dyke/sheet segments that was emplaced in a highly heterogeneous and anisotropic host rock and partially cut by some regional faults and a series of historic caldera collapses, the caldera walls providing, excellent exposures of the structures. The numerical models focus on a normal-fault dipping 65° with a damage zone composed of parallel layers or zones of progressively more compliant rocks with increasing distance from the fault rupture plane. We model sheet-intrusions dipping from 0˚ to 90˚ and with overpressures of alternatively 1 MPa and 5 MPa, approaching the fault. We further tested the effects of changing (1) the sheet thickness, (2) the fault-zone thickness, (3) the fault-zone dip-dimension (height), and (4) the loading by, alternatively, regional extension and compression. We find that the stiffness of the fault core, where a compliant core characterises recently active fault zones, has pronounced effects on the orientation and magnitudes of the local stresses and, thereby, on the likelihood of dyke/sheet deflection into the fault zone. Similarly, the analytical models, focusing on the fault-zone tensile strength and energy conditions for dyke/sheet deflection, indicate that dykes/sheets are most likely to be deflected into and use steeply dipping recently active (zero tensile-strength) normal faults as parts of their paths.</p>

scholarly journals Modelling the high temperature oxidation of titanium alloys: review of analytical models and development of a new numerical tool PyTiOx

2020 ◽  
Vol 321 ◽  
pp. 06012
Author(s):  
C. Ciszak ◽  
D. Monceau ◽  
C. Desgranges
Keyword(s):  
Numerical Models ◽  
Ecological Impact ◽  
Operating Costs ◽  
Analytical Models ◽  
Temperature Oxidation ◽  
Ti Alloys ◽  
State Diffusion ◽  
First Results ◽  
Aeronautical Industry ◽  
Numerical Tool

In order to limit the ecological impact of air traffic and its operating costs, the aeronautical industry is looking for improving engines efficiencies and substitutes to high density Ni-based superalloys. Thus, a wider use of Ti-alloys operating at higher temperatures is one of the developed solutions. Being able to predict as accurately as possible the oxidation behavior of Ti-based components at high temperatures appears therefore crucial to improve their sizing and durability. Analytical models based on the solid-state diffusion laws can be found in the litterature. They are fairly accurate in most cases, but they reveal some intrinsic limitations in specific cases such as temperature transients or thin components. Numerical models were later developed to break down these limitations. First results from a new numerical tool called “PyTiOx” (still under development are presented here. They confirm the intrinsic limitations of analytical models. In the case of thin samples, the numerical model predicts an increase of scaling kinetic when metal becomes O-saturated, whereas analytical models do not.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

2020 ◽  
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need for re-examining the assumption of pre-determined frictional breakdown energy common in dynamic rupture modeling and for better understanding of the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

scholarly journals Nonlinear processes in the bunched electron beams of high-power klystrons and the limits of analytical and one-dimensional numerical models applicability for their analysis.

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
V.Y. Rodyakin ◽  
◽  
V.M. Pikunov ◽  
V.N. Aksenov ◽  
◽  
...  
Keyword(s):  
Electron Beam ◽  
High Power ◽  
Numerical Models ◽  
Nonlinear Effects ◽  
Analytical Models ◽  
Modulation Amplitude ◽  
Two Dimensional ◽  
One Dimensional ◽  
Charge Parameter ◽  
Program Data

We present the results of a comparative theoretical analysis of the electron beam bunching in a single-stage klystron amplifier using analytical models, a one-dimensional disk program, and a two-dimensional program. Data on the influence of various one-dimensional and two-dimensional nonlinear effects on the efficiency of electron beam bunching at different values of the space charge parameter and the modulation amplitude are presented. The limits of applicability of analytical and one-dimensional numerical models for electron beam bunching analysis in high-power klystron amplifiers are found.

Closed-form expressions for the steady-state response of damped transmission line conductors considering their bending stiffness

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1319-1329
Author(s):  
Marcelo A Ceballos ◽  
José E Stuardi
Keyword(s):  
Steady State ◽  
Transmission Line ◽  
Numerical Models ◽  
Mechanical Impedance ◽  
Steady State Solution ◽  
Bending Stiffness ◽  
Analytical Models ◽  
Dispersive Media ◽  
Overhead Transmission Line ◽  
Damper Design

This paper begins with a brief compilation of analytical models typically used to calculate the dynamic response of a conductor span belonging to an overhead transmission line, with a Stockbridge-type damper located near one of its ends. In most of analyses found in the literature, the calculation of the response is done through the superposition of waves that propagate in both longitudinal directions impinging and reflecting at the span ends and at the damper attachment points. The approach proposed in this paper allows obtaining the response as the steady-state solution of the governing differential equations providing suitable analytical expressions for conductors with bending stiffness, which are dispersive media for propagating waves. Using these analytical solutions, the influence of bending stiffness on the efficiency and on the optimal mechanical impedance of the damper, which are of great importance in damper design, can be described explicitly. At the same time, the proposed methodology avoids the need of numerical models or approximate formulas to calculate the bending strains in critical points of the conductor with a single damper.

Offshore Installation of Welded Pipe: Local Buckling Evaluation

2010 ◽  
Author(s):  
Luciano Mantovano ◽  
Richard E. Bravo ◽  
Sebastian Cravero ◽  
Hugo A. Ernst
Keyword(s):  
Numerical Models ◽  
Local Buckling ◽  
Good Control ◽  
Plastic Instability ◽  
Lead Times ◽  
Geometrical Parameters ◽  
Seamless Pipe ◽  
Project Costs ◽  
Girth Welds ◽  
Welded Pipe

Up to the present, most of the pipes used in offshore applications installed with methods introducing plastic deformation have been seamless pipes; however, welded pipes can also be used. Welded pipes offers benefits over seamless pipe in terms of improved lead times, lower project costs, tighter dimensional tolerance and good control of mechanical properties and chemistry resulting in excellent weldability. During installation of welded pipes, failure by fracture, plastic collapse and local buckling may occur. In this work, the occurrence of the local buckling phenomenon, produced during the installation method, was evaluated. Numerical models were developed to study the effect of materials and geometrical parameters on the local bucking of pipes subjected to bending. Specifically, the loads and strains at which the plastic instability occurs were determined for each particular condition. In addition, the influence of longitudinal and girth welds on the local bucking occurrence was assessed.

UV disinfection of water: the need for UV reactor validation

2003 ◽  
Vol 3 (4) ◽  
pp. 293-300 ◽  
Author(s):  
Y.A. Lawryshyn ◽  
B. Cairns
Keyword(s):  
Legionella Pneumophila ◽  
Uv Light ◽  
Numerical Models ◽  
Operating Conditions ◽  
Analytical Models ◽  
Human Consumption ◽  
Average Dose ◽  
Reactor Performance ◽  
Uv Reactor ◽  
Bioassay Data

Disinfection by ultraviolet light (UV) has received wide endorsement as an important contribution to the multiple barrier approach for protection of public health. UV can be used both to disinfect wastewater discharged to the environment, and to disinfect that water when it is picked up again for human consumption. UV readily blocks infectivity by such chlorine-resistant pathogens as Cryptosporidium parvum, Giardia lamblia and Legionella pneumophila. Multiple disinfectant use is now being discussed to broaden the spectrum of pathogens that can be inactivated by using disinfectants in their most strategically advantageous dose and function. Optimizing multiple barrier strategies requires attention to validation of the concepts and technologies involved. UV technology validation ensures that the equipment can deliver the target UV design dose, and that the monitoring/control technology modulates the dose appropriately with changes in water quality or operating conditions. The bioassay approach for UV reactor validation is recommended over analytical and numerical models. Analytical models, which provide an average dose estimate, have been shown to be inadequate. Numerical models, which utilize Computational Fluid Dynamics (CFD) and UV light intensity models to predict reactor performance, can be accurate when used by skilled professionals but require significant validation and/or calibration against bioassay data.

Analytical and Numerical Prediction of Springback of SS/Al-Alloy Cladded Sheet in V-Bending

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Pankaj Kumar Sharma ◽  
Vijay Gautam ◽  
Atul Kumar Agrawal
Keyword(s):  
Analytical Model ◽  
Outer Layer ◽  
Numerical Models ◽  
Yield Criterion ◽  
Bending Moment ◽  
Analytical Models ◽  
Bend Angle ◽  
Radius Of Curvature ◽  
Al Alloy ◽  
First Case

Abstract The present work deals with the development of an analytical model incorporating the effects of anisotropy and strain hardening to predict the springback in V-bending of two-ply sheet metal using a punch profile radius of 15 mm and included a bend angle of 90 deg. In the analytical model, the total bending moment is determined from resulting bending stresses for two different layers arranged in parallel planes one above the other and a new radius of curvature after springback is determined by applying a negative bending moment. The two-ply sheet composed of layers of AA1050 and SS430 is characterized for its tensile properties to be used in analytical and numerical models for prediction of springback. To study the effect of each layer during bending operation, two possible cases of sheet placements during bending and springback are studied; i.e., in the first case, the inner layer is of AA1050 while the SS430 layer is the outer layer whereas in the second case it is opposite. In all the cases of springback experiments when the outer layer is of SS430, the springback values are higher than the values obtained with the specimens when the inner layer is of SS430. This could be attributed to the higher tensile strength of the stainless steel layer and the higher bending radius experienced by it. The springback behaviors are also analyzed by simulations using Hill's anisotropic yield criterion in abaqus software. The springback results obtained by simulations and analytical models are in good agreement in general; however, in some cases, discrepancy of more than 15% is observed in the analytical results when compared with the experimental results.

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