• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.174-181
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• 2000

A brief review of previous studies on the behaviour of concrete at extremely low temperature is presented in this paper. In addition, to describe temperature dependent behaviour of concrete, simple piecewise linear stress-strain relation is introduced. The proposed curve shows good agreement with experimental stress-strain curves at various temperature conditions. Moreover, numerical analyses for two PC beams are conducted to verify the influence of extremely low temperature to the structural behaviour.

• Transactions of Materials Processing
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• v.7 no.2
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• pp.107-113
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• 1998

The high temperature mechanical behaviour of duplex stainless steels was examined. The relation-ship between the dynamic recrystallization substructures and the flow behaviour was analyzed in detail, and the flow behaviour was analyzed in detail, and the mechanisms of dynamic recrystallization were also discussed. The formation of disloca-tion cells and subgrain structures is of great significance to the understanding of high temperature deformation.

• Computers and Concrete
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• v.23 no.5
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• pp.321-327
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• 2019

Experimental isotherm compressive tests show that concrete behaviour is dependent on temperature. The aim of such tests is to reproduce how concrete will behave under environmental changes within a moderate range of temperature. In this paper, a novel constitutive elastic damage behaviour law is proposed based on a free energy with an apparent damage depending on temperature. The proposed constitutive behaviour leads to classical theory of thermo-elasticity at small strains. Fixed elastic mechanical characteristics and fixed evolution law of damage independent of temperature and the material volume element size are considered. This approach is applied to compressive tests. The model predicts compressive strength and secant modulus of elasticity decrease as temperature increases. A power scaling law is assumed for specific entropy as function of the specimen size which leads to a volume size effect on the stress-strain compressive behaviour. The proposed model reproduces theoretical and experimental results from literature for tempertaures ranging between $20^{\circ}C$ and $70^{\circ}C$. The effect of the difference in the coefficient of thermal expansion between the mortar and coarse aggregates is also considered which gives a better agreement with FIB recommendations. It is shown that this effect is of a second order in the considered moderate range of temperature.

• Transactions of Materials Processing
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• v.5 no.4
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• pp.327-336
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• 1996

The effect of dynamic strain aging on high temperature deformation behaviour of the A-Mg alloy was investigated by strain rate change tests and stress relaxation tests between 20$0^{\circ}C$and 50$0^{\circ}C$. Yield point, short stress transient and periodic discontinuities on the stress-strain curve were considered as an evidence of the effect of dynamic strain aging. With this criterion two distinct strain rate-temperature regimes could be manifested. Dynamic strain aging was considered to be effective in the high temperature-low strain rate regime, whereas dynamic recovery was a dominant deformation mechanism in the low temperature-high strain rate regime. It was found that dynamic strain aging in the high temperature deformation was governed by the mechcanism of diffusion-controlled, viscous dislocation movement.

• Journal of Welding and Joining
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• v.2 no.1
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• pp.18-24
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• 1984

With the use of a new method the deformation mechanism of high-temperature-brazed joints can be obtained in a very short time. For that purpose a SEM(Scanning Electron Microscope) was equipped with a high temperature tensile testing machine. By means of SEM-investigation the damage behaviour of high-temperature-brazed joints is exa mined at elevated temperature. Based on these it is possible to make a qualification of the influence over single parts on the damage beginning and behaviour in dependence of temperature. This shall be shown exemplarily for the high temperature material NiCr20TiAl (Nimonic 80A).

• Steel and Composite Structures
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• v.5 no.6
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• pp.485-513
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• 2005

This paper presents a state-of-the-art on the behaviour of steel joints under fire loading and some recent developments in this field, currently being carried out by the authors. Firstly, a review of the experimental research work on steel joints is presented, subdivided into isolated member tests, sub-structure tests and tests on complete building structures. Special emphasis is placed on the seventh Cardington test, carried out by the authors within a collaborative research project led by the Czech Technical University in Prague. Secondly, a brief review of various temperature distributions within a joint is presented, followed by a discussion of the behaviour of isolated joints at elevated temperature, focussing on failure modes and analytical procedures for predicting the moment-rotation behaviour of joints at elevated temperature. Finally, a description of the coupled behaviour of joints as part of complete structures is presented, describing previous work and investigations on real fire (including heating and cooling phases) currently being carried out by the authors.

• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.93-100
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• 2014

Ethylene Tetrafluoroethylene (ETFE) has been widely used in long-span buildings because of its light weight and high transparency. This paper studies the short and long term creep behaviour of ETFE foil. A series of short-term creep and recovery tests were performed, in which the residual strain was observed. A long-term creep test of the ETFE foil was also performed over 110 days. A viscoelastic-plastic model was then established to describe the short-term creep and recovery behaviour. The model contains a traditional multi-Kelvin part and an added steady-flow component to represent the viscoelastic and viscoplastic behaviour, respectively. The model successfully fit the data for three stresses and six temperatures. Additionally, time-temperature equivalency was adopted to predict the long-term creep behaviour of ETFE foil. Horizontal shifting factors were determined from the process of shifting creep-curves at six temperatures. The long-term creep behaviours at three temperatures were predicted. Finally, the long-term creep test showed that the short-term creep test at identical temperatures insufficiently predicted additional creep behaviour, and the long-term test verified the horizontal shifting factors derived from the time-temperature equivalency.

• Korea-Australia Rheology Journal
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• v.15 no.3
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• pp.109-115
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• 2003

Rheometry testing and the DSC measurement of five thermotropic liquid crystalline polymers (TLCP) have been carried out. The dynamic viscosities of the five TLCPs show a typical shear-thinning behaviour obeying the power-law with the power indices from 0.2 to 0.3. When these TLCPs are heated above the melting temperatures determined by the DSC measurements, the dynamic viscosities first rapidly decrease by 2～3 orders of magnitude then level off, finally increase gradually with the further increasing of temperature. The steady shearing exhibited the same behaviour as the dynamic shearing, but serious edge fracture of material slippage out of the plates occurred. The abnormal temperature dependence of the viscosities can be explained by the nematic-isotropic transition. By using the concept of activation energy, we propose a simple model which can fit the shear-thinning behaviour quite well and predict qualitatively correct temperature effects.

• Geosystem Engineering
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• v.21 no.5
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• pp.282-290
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• 2018

The onset of extreme fire behaviour in a mine drift with longitudinal ventilation was analysed. A fire in a mine drift with continuous fuel load, involving several separate fires may lead to flames tilted horizontally and filling up the entire cross section. This will lead to earlier ignition, higher fire growth rate, higher fire spread rate and a severe fire behaviour. The focus has been on what changes take place at the onset and signs of the impending phenomenon. It was found that the fire gas temperature at the ceiling level provided a poor indicator. At the downstream far-field region of the fire, the sudden temperature increase at the lowest levels of the cross section and the sudden increase in flow velocities would provide signs of extreme fire behaviour. The corresponding full-scale heat release rates of the experiments at the onset of extreme fire behaviour were found to be very high for mining applications but not necessarily for tunnel fires. The heat release rate threshold for a mine drift with smaller cross-sectional dimensions would decrease considerably, increasing the likelihood of occurrence. The distance between the fuel items will play an important role during the initiation of horizontal flames.

• Journal of Animal Science and Technology
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• v.60 no.4
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• pp.7.1-7.5
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• 2018

Background: Mice are widely accepted research models of great clinical significance. Maintenance of laboratory mice breed is an essential aspect for performing research activities in various fields of science. Infanticide is one of the prominent causes of litter loss during maintenance of laboratory mice stock. The present study is an effort to monitor the effect of change in ambient temperature of female mice below the normal range on cannibalism and infanticide during early postparturition phase. Adult female Swiss albino mice have been divided into two groups of control and treatment. On the day of litter group one was maintained under controlled temperature conditions (minimum $20^{\circ}C$ to maximum $23^{\circ}C$) throughout, while female mice belong to group two have been exposed to variation of room temperature (maximum $15^{\circ}C$ to minimum $10^{\circ}C$ for two nights and one day) until 36 h postparturition. Results: The effects of temperature changes were observed on the infanticide behaviour of dams along with the survival of pups in early postparturition phase till 36 h after delivery. The significant statistical difference (P < 0.05) was reported in infanticide behaviour of dams when control and treatment group was compared. It is observed that decrement in surrounding temperature promotes decrement in the ambient body temperature of dams during early postparturition. It is proposed that alteration of hypothalamic homeostasis due to temperature change induces cannibalism and infanticide behaviour. Lack of thermoregulation during early postparturition creates the sense of insecurity, in-satiety, anxiety and stress. Conclusions: Authors strongly recommend the maintenance of body and surrounding temperature to prevent infanticidal behaviour and cannibalism within Swiss albino mice population. Further investigations are advisable to authenticate the active behavioural and biochemical pathway behind the phenomena.