Fire resistance of stainless steel slender elliptical hollow section beam-columns

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Flávio Alexandre Matias Arrais ◽  
Nuno Lopes ◽  
Paulo Vila Real
Keyword(s):  
Stainless Steel ◽  
Design Methodology ◽  
Elevated Temperatures ◽  
Numerical Study ◽  
Bending Moment ◽  
Content Type ◽  
Hollow Section ◽  
Beam Columns ◽  
Finite Element Software ◽  
Aesthetic Appearance

PurposeStainless steel has different advantages when compared to conventional carbon steel. The corrosion resistance and aesthetic appearance are the most known; however, its better behaviour under elevated temperatures can also be important in buildings design. In spite of the initial cost, stainless-steel application as a structural material has been increasing. Elliptical hollow sections integrate the architectural attributes of the circular hollow sections and the structural advantages of the rectangular hollow sections (RHSs). Hence, the application of stainless-steel material combined with elliptical hollow profiles stands as an interesting design option. The purpose of the paper is to better understand the resistance of stainless-steel-beam columns in case of fireDesign/methodology/approachThe research presents a numerical study on the behaviour of stainless-steel members with slender elliptical hollow section (EHS) subjected to axial compression and bending about the strong axis at elevated temperatures. A parametric numerical study is presented here considering with and without out-of-plane buckling different stainless-steel grades, cross-section and member slenderness, bending moment diagrams and elevated temperatures.FindingsThe tested design methodologies proved to be inadequate for the EHS members being in some situations too conservative.Originality/valueThe safety and accuracy of Eurocode 3 (EC3) design methodology and of a recent design proposal developed for I-sections and cold-formed RHSs are analysed applying material and geometric non-linear analysis considering imperfections with the finite element software SAFIR.

Numerical study of fire resistance of stainless steel circular hollow section columns

2020 ◽  
Vol 38 (2) ◽  
pp. 156-172
Author(s):  
Flávio Arrais ◽  
Nuno Lopes ◽  
Paulo Vila Real
Keyword(s):  
Stainless Steel ◽  
Life Cycle Cost ◽  
Elevated Temperatures ◽  
Numerical Study ◽  
Steel Structures ◽  
Sustainable Construction ◽  
Hollow Section ◽  
Structural Applications ◽  
Eurocode 3 ◽  
Circular Hollow Section

Stainless steel has countless desirable characteristics for a structural material. Although initially more expensive than conventional carbon steel, stainless steel structures can be competitive due to their smaller need for fire protection material and lower life-cycle cost, thus contributing to a more sustainable construction. The most common stainless steel groups used in structural applications are the austenitic, ferritic and austenitic–ferritic (also known as Duplex grades). This work presents a numerical study on the behaviour of stainless steel circular hollow section members under axial compression at elevated temperatures, with different cross-section slenderness. The numerically obtained ultimate load-bearing capacities are compared with simplified calculation formulae from Eurocode 3 for columns under fire situation. A parametric study, considering different stainless steel grades from the aforementioned groups, cross-sectional classes and slendernesses, is here presented for different elevated temperatures. The numerical analyses were performed with the finite element programme SAFIR, with material and geometric non-linear analysis considering imperfections. Comparisons between the numerical results and the Eurocode 3 rules demonstrated that a specific design approach must be developed for stainless steel columns under fire situation.

Lubricant compatibility of FKM seals in synthetic oils

2019 ◽  
Vol 72 (5) ◽  
pp. 557-565
Author(s):  
Dilek Bulut ◽  
Tatjana Krups ◽  
Gerhard Poll ◽  
Ulrich Giese
Keyword(s):  
Polyethylene Glycol ◽  
Design Methodology ◽  
Elevated Temperatures ◽  
Failure Mechanisms ◽  
Standard Test ◽  
New Method ◽  
Static Tests ◽  
Content Type ◽  
Lip Seals ◽  
First Results

Purpose Elastomer seals are used in many applications. They are exposed to lubricants and additives at elevated temperatures, as well as mechanical stresses. They can only provide good sealing function when they have resistance to those factors. There are many elastomer-lubricant compatibility tests based on DIN ISO 1817 in industry. However, they are insufficient and costly. Correlations between the tests and the applications are inadequate. The purpose of this study is investigating lubricant compatibility of fluoroelastomers (FKM) seals in polyethylene-glycol (PG)- and polyalphaolefin (PAO)- based synthetic oils and developing a methodology to predict seal service life. Design/methodology/approach A new compatibility test which is more sufficient in terms of time and cost was developed and compared with a standard test, currently used in industry. Compatibility of FKM radial lip seals with PG- and PAO-based synthetic oils with different additives was investigated chemically and dynamically. Failure mechanisms were examined. Findings The new method and the Freudenberg Flender Test FB 73 11 008 showed similar results concerning damages and similar tendencies regarding wear. The additive imidazole derivative was the most critical. Static tests give indications of possible chemically active additives, but alone they are insufficient to simulate the dynamic applications. Originality/value The paper describes a new method to investigate elastomer-lubricant compatibility and gives first results with a variety of lubricants.

The prediction of the cyclic mechanical behavior of stainless steel 304L at room temperature

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hala Messai ◽  
Salim Meziani ◽  
Athmane Fouathia
Keyword(s):  
Stainless Steel ◽  
Design Methodology ◽  
Room Temperature ◽  
Type Model ◽  
Good Prediction ◽  
304L Stainless Steel ◽  
Content Type ◽  
The Third ◽  
Chaboche Model

Purpose The purpose of this paper is to highlight the performance of the Chaboche model in relation to the database identification, tests with imposed deformations were conducted at room temperature on 304L stainless steel specimens. Design/methodology/approach The first two tests were performed in tension-compression between ±0.005 and ±0.01; in the third test, each cycle is composed of the combination of a compression tensile cycle between ±0.01 followed by a torsion cycle between ±0.01723 (non-proportional path), and the last, uniaxial ratcheting test with a mean stress between 250 MPa and −150 MPa. Several identifications of a Chaboche-type model were then performed by considering databases composed of one or more of the cited tests. On the basis of these identifications, the simulations of a large number of ratchet tests in particular were carried out. Findings The results present the effect of the optimized parameters on the prediction of the behavior of materials which is reported in the graphs, Optimizations 1 and 2 of first and second tests and Optimization 4 of the third test giving a good prediction of the increasing/decreasing pre-deformation amplitude. Originality/value The quality of the model's predictions strongly depends on the richness of the database used for the identification of the parameters.

Tribology of Ge thin films on stainless steel

2017 ◽  
Vol 69 (2) ◽  
pp. 182-189
Author(s):  
Lubomir Krabac ◽  
Vladimir Pejaković ◽  
Vladislav Drinek ◽  
Nicole Dörr ◽  
Ewald Badisch
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Stainless Steel ◽  
Design Methodology ◽  
Friction And Wear ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Chemical Vapor Deposition Method ◽  
Content Type ◽  
Sliding Distance

Purpose The purpose of this paper is to study the friction and wear behavior of germanium (Ge) thin films deposited by low-pressure chemical vapor deposition method on a chromium (Cr)-nickel (Ni) stainless steel substrate after being exposed to relatively mild sliding conditions (low loads and sliding distances). Design/methodology/approach Wear and friction experiments were conducted with a 100Cr6 steel ball sliding against flat Ge thin-film-coated stainless steel sheets (ball-on-flat microtribometer, no lubricant, normal loads of 50-100 mN, initial Hertzian contact pressures of 385-485 MPa, total sliding distance up to 200 mm and room temperature). Findings Scanning electron microscopy results revealed that prepared Ge thin films consisted of two different morphologies: curved nanowires and cone-shaped nano-/microdroplets. Regarding friction and wear characteristics of the investigated samples, the substrates coated with Ge thin films did not affect the coefficient of friction significantly by load. The wear of the base material (Cr-Ni stainless steel) was not observed under the mentioned experimental conditions (see the “Design/methodology/approach” section); however, with increased sliding distance and/or applied load, a rupture of the Ge film and an exposure of the stainless steel substrate to the 100Cr6 ball can be expected. Furthermore, the observations suggest that the smearing of Ge nano- and microstructures, plastically deformed during tribotesting, over the surface exposed to the sliding contact is the dominant tribological process. Originality/value For the first time, the tribological interaction between Ge thin film and steel surface was investigated under dry sliding conditions using a ball-on-flat microtribometer, and the obtained results provide a useful base for the further research on tribology of Ge-based thin films.

Stability check of tapered steel beams in fire

2019 ◽  
Vol 10 (4) ◽  
pp. 373-398 ◽  
Author(s):  
Carlos Couto ◽  
Élio Maia ◽  
Paulo Vila Real ◽  
Nuno Lopes
Keyword(s):  
Design Methodology ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Numerical Models ◽  
Design Methods ◽  
Steel Beams ◽  
Content Type ◽  
Design Methodologies ◽  
Accurate Design ◽  
Improved Design

Purpose The purpose of this paper is to assess whether the adaptation to fire of current proposals/design methodologies at normal temperature is capable of producing accurate predictions of resistance for the out-of-plane stability of tapered beams. Design/methodology/approach The adaptation of these methodologies to fire has been done by accounting for the reduction in steel material properties with the temperature. Results were then compared to FEM calculations by performing GMNIA analyses to determine the ultimate strength of the numerical models and to ascertain the validity and accuracy of the adapted methodologies. Findings Although all methodologies produce safe results at normal temperatures, only the general method is recommended for the safety verification at elevated temperatures, although the data points were overly conservative. This investigation demonstrates the need of proper and accurate design methods for tapered beams at elevated temperatures, which should be the subject of future developments. Research limitations/implications The research in this paper is limited to the adaptation of existing room temperature design methods to fire. Therefore, possible assumptions made during the conception of the initial formulae, which may be valid exclusively for 20ºC, may have been disregarded. Originality/value For the time being, design methodologies for the safety check of tapered beams for the case of fire are inexistent. This paper investigates the adaptation of existing room temperature design to the fire situation by providing insights on their accuracy level, as well as on how to proceed. Finally, a safe design methodology for tapered beams in case of fire is provided until improved design methods are developed.

Three-dimensional analysis of anchored wall with concrete bearing pads

2020 ◽  
Vol 18 (6) ◽  
pp. 1469-1486
Author(s):  
Hamed Arefizadeh ◽  
Hadi Shahir
Keyword(s):  
Design Methodology ◽  
Three Dimensional ◽  
Bending Moments ◽  
Dimensional Model ◽  
Discrete Elements ◽  
Three Dimensional Model ◽  
Content Type ◽  
Finite Element Software ◽  
Internal Forces ◽  
Soldier Pile

Purpose Anchorage with concrete bearing pad is commonly used in Iran for stabilization of excavations because of the ease of construction, less costs and less time consumption than the soldier pile method. In this method, a wall facing which includes the concrete bearing pads at the location of the anchors and a shotcrete layer between the bearing pads is constructed parallel to the excavation operation similar to the nailing method. Design/methodology/approach In this paper, using the finite element software Abaqus, a three-dimensional model of the above-mentioned type of wall is constructed, and the effect of spacing and size of bearing pads on the wall behavior is discussed. Findings According to the obtained results, the size of the concrete bearing pads has little effect on wall deformations, but the internal forces and bending moments developed in the shotcrete layer between the bearing pads are greatly influenced by the bearing pads dimensions and spacing. Originality/value Owing to the discrete elements of the wall facing, the behavior of this system is completely three-dimensional.

Frictional characteristics of thin-walled tubes in liquid impact forming

2019 ◽  
Vol 72 (5) ◽  
pp. 637-643
Author(s):  
Jianping Ma ◽  
Lianfa Yang ◽  
Yulin He ◽  
Jian Guo
Keyword(s):  
Stainless Steel ◽  
Peer Review ◽  
Deformation Process ◽  
Design Methodology ◽  
Steel Tubes ◽  
Content Type ◽  
Liquid Impact ◽  
The Coefficient Of Friction ◽  
Thin Walled ◽  
Short Time

Purpose This paper aims to study frictional characteristics of thin-walled tubes in the liquid impact forming (LIF) process. Design/methodology/approach LIF experiments under various impacting velocities were performed on SUS304 stainless steel tubes with various guiding lengths on a custom-designed measurement system to investigate the effects of impacting velocity and guiding length on the coefficient of friction (COF) in the guiding zone. Findings The results indicate that the COF changes dynamically in the guiding zone and decreases with the deformation process. The reduction range of the COF is wider in LIF than in both the conventional and pulsating hydroforming (THF), which may be contributed to the impacting velocities in a short time. Moreover, the COF decreases faster in the first half of the LIF process than in the second half. Under different impacting velocities and guiding lengths, the decreasing rate of the COF in the first half is more sensitive and obvious than that in the second half. Originality/value A method for determining the COF in the guiding zone in LIF is proposed and the frictional characteristics in LIF are studied. Comparing the COF of tubes in conventional THF, pulsating THF and the LIF process is valuable for improving and predicting the tubular formability in various hydraulic environments for industrial production. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0269

Influence of vessel dimensions on particles homogenization and heat removing in TMF stirrer

2020 ◽  
Vol 39 (1) ◽  
pp. 125-132
Author(s):  
Shvidkiy Evgeny ◽  
Igor Sokolov ◽  
Kirill Bolotin ◽  
Valery Zakharov
Keyword(s):  
Design Methodology ◽  
Heat Removal ◽  
Side Surface ◽  
Transient Simulation ◽  
Particle Tracing ◽  
Content Type ◽  
Exothermic Reactions ◽  
Finite Element Software ◽  
Traveling Magnetic Field ◽  
Practical Implications

Purpose The purpose of this paper is to determine how the shape of the container affects the efficiency of a traveling magnetic field (TMF) stirring. Design/methodology/approach The modeling approach is based on finite element software Comsol which includes harmonic electromagnetic (EM), transient CFD and particle tracing modules. For evaluating efficiency of stirring the particle, homogenization parameter is used. Findings It has been determined that the use of an elliptical cylinder-shaped vessel allows better heat removal from the side surface and, at the same time, the stirring efficiency does not drop significantly. Practical implications The results of the work can be used in the design of EM stirring installations in which exothermic reactions occur. Originality/value The transient simulation of particle transport in a TMF-driven melt flow gives the opportunity to estimate the efficiency of stirring process in different vessel shapes.

Numerical study of external explosion characteristics induced by indoor natural gas vented explosion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lei Pang ◽  
Qianran Hu ◽  
Kai Yang
Keyword(s):  
Natural Gas ◽  
Design Methodology ◽  
Large Scale ◽  
Numerical Study ◽  
Outdoor Environment ◽  
Gas Explosion ◽  
Content Type ◽  
Gas Explosions ◽  
Explosion Overpressure ◽  
Vented Explosion

Purpose The purpose of this paper is to ascertain the harm to personnel and equipment caused by an external explosion during natural gas explosion venting. The external explosion characteristics induced by the indoor natural gas explosion are the focal points of the investigation. Design/methodology/approach Computational fluid dynamics technology was used to investigate the large-scale explosion venting process of natural gas in a 6 × 3 × 2.5 m room, and the characteristics of external explosion under different scaled vent size (Kv = Av/V2/3, 0.05, 0.08, 0.13, 0.18) were numerically analyzed. Findings When Kv = 0.08, the length and duration of the explosion fireball are 13.39 and 450 ms, respectively, which significantly expands the degree and range of high-temperature hazards. The suitable flow-field structure causes the external explosion overpressure to be more than twice that indoors, i.e. the natural gas explosion venting overpressure may be considerably more hazardous in an outdoor environment than inside a room. A specific range for the Kv can promote the superposition of outdoor rupture waves and explosion shock waves, thereby creating a new overpressure hazard. Originality/value Little attention has been devoted to investigating systematically the external explosion hazards. Based on the numerical simulation and the analysis, the external explosion characteristics induced by the indoor large-scale gas explosion were obtained. The research results are theoretically significant for mitigating the effects of external gas explosions on personnel and equipment.

The electric energy stored in PEDOT:PSS capacitors integrated on textile substrate

2018 ◽  
Vol 30 (6) ◽  
pp. 808-816 ◽  
Author(s):  
Sheilla Atieno Odhiambo ◽  
Piotr Fiszer ◽  
Gilbert De Mey ◽  
Carla Hertleer ◽  
Ida Nuramdhani ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Design Methodology ◽  
Dielectric Material ◽  
Electric Energy ◽  
Content Type ◽  
Fully Integrated ◽  
Smart Clothing ◽  
Further Development ◽  
Textile Fabric ◽  
Important Significance

Purpose The purpose of this paper is to develop a capacitor fully integrated into a wearable textile fabric for the application on smart clothing. Design/methodology/approach A small capacitor with stainless steel yarns as the electrodes and poly-(3,4–ethylenedioxythiophene): polystryrene sulphonate (PEDOT:PSS) as the dielectric material has been made, integrated into a textile fabric. The electric performance of the capacitor was analyzed and compared with other kinds of electric capacitors. Findings The fabricated small, PEDOT:PSS capacitor could finally power a calculator for 37 s with the energy stored in it. Originality/value This finding is of an important significance for a further development on the capacitor with a better performance.

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