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 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.

FEM-Based Simulation of Temperature in Speed Stroke Grinding with 3D Transient Moving Heat Sources

2011 ◽  
Vol 223 ◽  
pp. 733-742 ◽  
Author(s):  
Barbara Linke ◽  
Michael Duscha ◽  
Anh Tuan Vu ◽  
Fritz Klocke
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Material Removal ◽  
Structural Changes ◽  
Numerical Technique ◽  
Temperature Fields ◽  
Fe Model ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Removal Rates

The grinding process is one of the most important finishing processes to obtain high surface quality. Nowadays, grinding is also considered as a high performance process with high material removal rates. Nevertheless, to avoid thermally-induced structural changes poses a major challenge for this manufacturing technology. Until now, the Finite Element Method (FEM) has been widely applied as a proper numerical technique to predict workpiece properties in machining processes. However, actual models in grinding are limited to conventional grinding processes with simple workpiece profiles and low table speeds. In this paper, finite element simulations are expanded to 3-dimensional (3D) models with temperature-dependent material properties and heat source profiles derived from experimental results, i.e. tangential forces. Both temperature simulation and measurement were conducted for deep grinding, pendulum grinding and speed stroke grinding in the table speed range of vw= 12 m/min to 180 m/min and specific material removal rates of Q’w= 40 mm³/mms. Overall, the simulation results show a good agreement with the measured temperature and surface integrity after grinding. This research indicates that a 3D FE model with temperature dependent material properties can predict realistic temperature fields in speed stroke grinding. Therefore, the experiment and measurement costs and time can be reduced by FEM simulation.

Prediction of thermally induced postbuckling of clutch disks using the finite element method

2020 ◽  
pp. 135065012090197
Author(s):  
Zhuo Chen ◽  
Yun-Bo Yi ◽  
Ke Bao
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Temperature Fields ◽  
Frictional Heat ◽  
Temperature Dependent ◽  
Displacement Fields ◽  
Element Analysis ◽  
Nonlinear Buckling ◽  
Thermally Induced ◽  
Linear Buckling

Buckling and postbuckling of automotive clutch disks can be excited by the temperature fields caused by frictional heat generation during engagement of clutch systems. Linear and nonlinear buckling finite element analyses are performed to evaluate the thermal postbuckling of clutch metal disks. The dominant buckling modes are first obtained through performing linear buckling finite element analysis (FEA) analyses. The scaled displacement fields obtained from the linear buckling FEA analyses are added to the original geometries to generate the perturbed meshes. The postbuckling is then investigated by performing nonlinear buckling FEA analyses. The commercial FEA software ABAQUS is used in the current study. The effects of the temperature-dependent material properties are studied. It is concluded that the temperature dependence of material properties affects the postbuckling behaviors significantly.

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.

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.

A Method of Analysis of Transient Thermal Stresses in Thermorheologically Simple Viscoelastic Solids

1964 ◽  
Vol 31 (1) ◽  
pp. 47-53 ◽  
Author(s):  
K. C. Valanis ◽  
George Lianis
Keyword(s):  
Thermal Stresses ◽  
Perturbation Technique ◽  
Sufficient Conditions ◽  
Solid Sphere ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Viscoelastic Solids ◽  
Temperature Dependent Properties ◽  
Transient Thermal

This paper is concerned with a perturbation technique suitable for the stress analysis of viscoelastic solids with temperature-dependent properties in the presence of nonuniform transient temperature fields. The problems of the infinite slab, solid sphere, and infinitely long viscoelastic cylinder are given solutions in the form of infinite series. Sufficient conditions for the convergence of the series are established.

Coupled Thermo-Mechanical Modelling of Friction Stir Welding

2007 ◽  
Author(s):  
Hongjun Li ◽  
Donald Mackenzie
Keyword(s):  
Friction Stir Welding ◽  
Material Properties ◽  
Numerical Models ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Significant Development ◽  
Friction Stir ◽  
Welding Technology ◽  
Ale Formulation

The significant development in welding technology for the last decade is the emergence of Friction Stir Welding (FSW). This paper investigates the thermo-mechanical phenomena involved in the FSW welded plates by Finite Element Analysis. The numerical models are fully thermo-mechanically coupled in that heat generated by material plastic deformation and temperature dependent mechanical material properties are taken into account. The whole FSW process is divided into three distinct stages: plunge, dwell and transverse. The transient temperature, stress and velocity of material particles around the tool are reported from the numerical models. It is found that temperature plays an important role in obtaining a sound weld, and only when a proper temperature field is established can the FSW process proceed to next stage. It is also found that it is not possible to fully simulate the FSW process using the ALE formulation without full remeshing during the travel stage of the process due to excessive element distortion.

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