Thermal Vibrations of Beams With Temperature-Dependent Material Properties

1995 ◽  
Author(s):  
Abulkhair M. Masoom
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Stainless Steel ◽  
Elastic Modulus ◽  
Temperature Dependence ◽  
Material Properties ◽  
Temperature Dependent ◽  
Thin Beams ◽  
Thermal Vibrations ◽  
Coupled Theory

Abstract Thin beams subjected to thermal loads are considered. The formulation includes the temperature dependence of thermal conductivity and elastic modulus as well as coupled theory. A comparison is made between beams made of stainless steel and silicon carbide. Results show that significant differences are possible for temperature and stress solutions when temperature-dependent elasticity and conductivity are used, as opposed to the constant properties evaluated at a reference temperature.

Dissimilar Materials Laser Welding Characteristics of Stainless Steel and Titanium Alloy

2013 ◽  
Vol 465-466 ◽  
pp. 1060-1064 ◽  
Author(s):  
Zazuli Mohid ◽  
M.A. Liman ◽  
M.R.A. Rahman ◽  
N.H. Rafai ◽  
Erween Abdul Rahim
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Titanium Alloy ◽  
Thermal Properties ◽  
Material Properties ◽  
Dissimilar Materials ◽  
Scanning Speed ◽  
Welding Parameters ◽  
Melting Region ◽  
Offset Distance

Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.

On Free Vibrations at Temperature-Dependent Material Properties and Transient Temperature Fields

1972 ◽  
Vol 39 (3) ◽  
pp. 723-726 ◽  
Author(s):  
U. Olsson
Keyword(s):  
Temperature Dependence ◽  
Analytical Solutions ◽  
Material Properties ◽  
Free Vibrations ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Material Damping ◽  
Temperature Dependent ◽  
Temperature Variations ◽  
Damping Parameter

The influence of the temperature-dependence of the material properties on the free vibrations of transiently heated structures is investigated. Analytical solutions are given for linear, exponential, and harmonic temperature variations when the material damping parameter, Poisson’s ratio, and Young’s modulus depend on the temperature.

scholarly journals Effect of Fiber Geometry and Representative Volume Element on Elastic and Thermal Properties of Unidirectional Fiber-Reinforced Composites

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Siva Bhaskara Rao Devireddy ◽  
Sandhyarani Biswas
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
Thermal Properties ◽  
Elastic Modulus ◽  
Cross Section ◽  
Representative Volume Element ◽  
Material Properties ◽  
Volume Element ◽  
Unidirectional Fiber ◽  
Representative Volume

The aim of present work is focused on the evaluation of elastic and thermal properties of unidirectional fiber-reinforced polymer composites with different volume fractions of fiber up to 0.7 using micromechanical approach. Two ways for calculating the material properties, that is, analytical and numerical approaches, were presented. In numerical approach, finite element analysis was used to evaluate the elastic modulus and thermal conductivity of composite from the constituent material properties. The finite element model based on three-dimensional micromechanical representative volume element (RVE) with a square and hexagonal packing geometry was implemented by using finite element code ANSYS. Circular cross section of fiber and square cross section of fiber were considered to develop RVE. The periodic boundary conditions are applied to the RVE to calculate elastic modulus of composite. The steady state heat transfer simulations were performed in thermal analysis to calculate thermal conductivity of composite. In analytical approach, the elastic modulus is calculated by rule of mixture, Halpin-Tsai model, and periodic microstructure. Thermal conductivity is calculated analytically by using rule of mixture, the Chawla model, and the Hashin model. The material properties obtained using finite element techniques were compared with different analytical methods and good agreement was achieved. The results are affected by a number of parameters such as volume fraction of the fibers, geometry of fiber, and RVE.

scholarly journals Temperature Dependence of the Dynamic Parameters of Contact Thermometers

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2299 ◽  
Author(s):  
Silke Augustin ◽  
Thomas Fröhlich
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Temperature Dependence ◽  
Dynamic Behavior ◽  
Material Properties ◽  
Convective Heat Transfer Coefficient ◽  
Heat Radiation ◽  
Dynamic Parameters ◽  
Temperature Dependent

Contact thermometers are used in a wide temperature range as well as under various media and environmental conditions. The temperature can range from −200 °C to about 1500 °C. In this case, the dynamic parameters (time percentage values tx and time constants τ) depend on temperature. Several effects are superimposed. Constructional and material properties of the thermometer and the installation location affect the dynamic behavior as well as the type and material properties of the object to be measured. Thermal conductivity λ, specific heat capacity c, and density ρ depend on temperature. This temperature dependence can be mutually compensated for (see Section 3). At the same time, the dynamic behavior is also influenced by the temperature-dependent parameters of the medium. When the thermometers are installed in air, for example, the heat transfer coefficient α decreases with increasing temperature, owing to the temperature-dependent material data of the air, at constant speed v. At the same time, heat radiation effects are so strong that the heat transfer improves despite the decreasing convective heat transfer coefficient. In this paper, a number of examples are used to establish a model for the temperature dependence of the dynamic parameters for various thermometer designs. Both numerically and experimentally determined results for the determination of the dynamic characteristic values are included in the consideration.

Hall Effect Measurements on New Thermoelectric Materials

2003 ◽  
Vol 793 ◽  
Author(s):  
Jarrod Short ◽  
Sim Loo ◽  
Sangeeta Lal ◽  
Kuei Fang Hsu ◽  
Eric Quarez ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Measurement System ◽  
Material Properties ◽  
Figure Of Merit ◽  
New Materials ◽  
Temperature Dependent ◽  
Additional Insight ◽  
Hall Effect Measurements

ABSTRACTIn the field of thermoelectrics, the figure of merit of new materials is based on the electrical conductivity, thermoelectric power, and thermal conductivity of the sample, however additional insight is gained through knowledge of the carrier concentrations and mobility in the materials. The figure of merit is commonly related to the material properties through the B factor which is directly dependent on the mobility of the carriers as well as the effective mass.To gain additional insight on the new materials of interest for thermoelectric applications, a Hall Effect system has been developed for measuring the temperature dependent carrier concentrations and mobilities. In this paper, the measurement system will be described, and recent results for several new materials will be presented.

Anomalous temperature dependent thermal conductivity of two-dimensional silicon carbide

2019 ◽  
Vol 30 (44) ◽  
pp. 445707 ◽  
Author(s):  
A S M Jannatul Islam ◽  
Md Sherajul Islam ◽  
Naim Ferdous ◽  
Jeongwon Park ◽  
A G Bhuiyan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Anomalous Temperature ◽  
Temperature Dependent Thermal Conductivity

Low thermal conductivity of monolayer ZnO and its anomalous temperature dependence

2017 ◽  
Vol 19 (20) ◽  
pp. 12882-12889 ◽  
Author(s):  
Huimin Wang ◽  
Guangzhao Qin ◽  
Guojian Li ◽  
Qiang Wang ◽  
Ming Hu
Keyword(s):  
Thermal Conductivity ◽  
Zinc Oxide ◽  
Temperature Dependence ◽  
Anomalous Temperature Dependence ◽  
Temperature Dependent ◽  
Anomalous Temperature ◽  
Low Thermal Conductivity ◽  
Temperature Dependent Thermal Conductivity

The temperature dependent thermal conductivity of monolayer Zinc Oxide (ZnO) is found largely deviating from the traditional 1/T law.

Effects of thermal material properties on precision of transient temperatures in pulsed laser welding of Ti6Al4V alloy

2018 ◽  
Vol 233 (9) ◽  
pp. 3170-3181
Author(s):  
Massab Junaid ◽  
Taqi Ahmad Cheema ◽  
Hani Haleem ◽  
Saad-ul-Fatah ◽  
Khalid Rahman ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Temperature Profile ◽  
Material Properties ◽  
Pulsed Laser ◽  
Ti6al4v Alloy ◽  
Transient Temperature ◽  
Constant Density ◽  
Temperature Dependent ◽  
Temperature Distributions

This study investigates the effect of temperature-dependent material properties on the precision of a simulation in pulsed laser beam welding of Ti6Al4V alloy. Ti6Al4V is one of the most extensively used titanium alloys. The precision in transient temperature distributions developed in the thermal modeling part of a sequentially coupled thermo-mechanical simulation is crucial to the end results of structural mechanics. The temperature profile obtained by a finite element model at two distinct locations is validated by experimental results using temperature-dependent material properties. Then, the effect of assuming constant room temperature values for thermal conductivity, specific heat, and density on the temperature distribution is studied at different welding speeds. Temperature distributions are unaffected by the constant density assumption. The constant thermal conductivity assumption underestimates the peak temperatures far from the weld region, whereas the constant specific heat assumption overestimates these temperatures. This effect becomes prominent at low welding speeds. The temperature profile when conductivity and specific heat are assumed to be constant is nearly similar to that in the case of constant conductivity when conductivity and specific heat are assumed constant. Therefore, conductivity is the dominant variable. The constant conductivity assumption also restricts the heat flow from the weld to the edge region, thus increasing the size of the weld pool. This effect also becomes increasingly prominent at low welding speeds.

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