Storey stability of unbraced steel frames subjected to non-uniform elevated temperature distribution

2014 ◽  
Vol 62-63 ◽  
pp. 164-173 ◽  
Author(s):  
L. Xu ◽  
Y. Zhuang
Keyword(s):  
Elevated Temperature ◽  
Temperature Distribution ◽  
Steel Frames

scholarly journals Numerical modelling approach for the temperature dependent forming behaviour of Ti-6Al-4V

2018 ◽  
Vol 190 ◽  
pp. 12004
Author(s):  
Thomas Papke ◽  
Matthias Graser ◽  
Marion Merklein
Keyword(s):  
Elevated Temperature ◽  
Temperature Distribution ◽  
Numerical Modelling ◽  
Tensile Test ◽  
Numerical Simulations ◽  
Numerical Models ◽  
Uniaxial Tensile ◽  
Temperature Dependent ◽  
Inhomogeneous Temperature ◽  
Forming Behaviour

Titanium alloys offer several beneficial characteristics, such as high specific strength, metallurgical stability at elevated temperature, biocompatibility and corrosion resistance. With regard to these superior properties, Ti-6Al-4V is a commonly used titanium alloy for aerospace components and medical products. The production of parts made of Ti-6Al-4V can be done in various ways. One approach is forming at elevated temperature, which requires a focused design of parts, processes and numerical modelling of the forming process. Essential input parameters for the numerical models are temperature dependent material parameters. Since, the yield stress and Young's modulus of the material decrease significantly at elevated temperature, the forming limits are enhanced. For the characterization of the forming behaviour, uniaxial tensile tests at temperatures from 250 °C to 400 °C have been conducted. The samples are heated by conduction in a thermal-mechanical simulator for the tensile test. However, the resulting inhomogeneous temperature distribution along the longitudinal axis of the specimen is a challenge in order to measure proper material properties. Inhomogeneous temperature distribution leads to varying mechanical properties and temperature dependent forming behaviour. To overcome this issue, simple numerical models based on experimental data are necessary, which allow the estimation of the influence of the inhomogeneous temperature distribution. In this paper, therefore, the temperature distribution and the subsequent tensile test are investigated using electrical-thermal and mechanical numerical simulations of the tensile test at elevated temperature. With the combined approach of experimental tests and numerical simulations, the forming behaviour of Ti-6Al-4V can be modelled.

Inelastic Analysis of Dissimilar Material Flanges With Metal Ring Gaskets at Elevated Temperature

2005 ◽  
Author(s):  
Takuya Sato ◽  
Kenichiro Kado
Keyword(s):  
Stainless Steel ◽  
Thermal Expansion ◽  
Elevated Temperature ◽  
Temperature Distribution ◽  
Dissimilar Material ◽  
Metal Ring ◽  
Low Alloy Steel ◽  
Uniform Temperature ◽  
Austenite Stainless Steel ◽  
Uniform Temperature Distribution

The dissimilar material flange connections are often adopted to connect the austenite stainless steel pipes to the low alloy steel pressure vessels operated at an elevated temperature. The behavior of this flange connection is very complicated because of the non-uniform temperature distribution and the thermal expansion difference of dissimilar materials. The application of the metal ring gasket makes the behavior more complicated. An elastic plastic finite element analysis is one of the adequate ways to investigate the behavior of the following dissimilar material flanges with the metal ring gasket under the high pressure and elevated temperature operation. (1) Pipe flange: standard configuration, austenite stainless steel, (2) Nozzle flange: forged thick nozzle neck, low alloy steel covered with stainless steel overlay. The material of ring gasket is also an austenite stainless steel. This ring gasket contacts to and slips on the ring groove surfaces of flanges. The axi-symmetric analyses were made considering the sequence of initial bolting, internal pressure and non-uniform temperature distribution. The elastic plastic properties and temperature dependency of the materials were considered. From these analyses, the effects of the non-uniform temperature distribution and the thermal expansion difference of dissimilar material flanges on the contact pressure of the ring gaskets were made clear. The effect of flange size (14”–36”) was also investigated.

scholarly journals Pulsed rapid cooling method of the massive relating to heat bodies

2018 ◽  
pp. 61-65
Author(s):  
I. A. Pribytkov ◽  
A. Yu. Terekhova ◽  
S. I. Kondrashenko
Keyword(s):  
Elevated Temperature ◽  
Temperature Distribution ◽  
Main Part ◽  
Rapid Heating ◽  
Rapid Cooling ◽  
Radial Temperature ◽  
Radial Temperature Distribution ◽  
Cooling Method ◽  
Cooling Conditions

The data are presented on the pulsed rapid enhanced cooling of the massive related to heat bodies. The pulsed rapid heating consisting of the alternating enhanced heating and retardation during which the main part of the heat applied to the metal by convection, supposes the elevated temperature raise rate just when heating. These cooling conditions influence substantially on the radial temperature distribution inside the metal during the cooling.Ill.5. Ref. 8.

Temperature distribution in steel frames exposed to a fire environment

1987 ◽  
Vol 10 (6) ◽  
pp. 615-623 ◽  
Author(s):  
Jiann‐Quo Tarn ◽  
Jenn‐Chuan Lay ◽  
Yi‐Bin Wang
Keyword(s):  
Temperature Distribution ◽  
Steel Frames ◽  
Fire Environment

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

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