Physics-Informed Data-Driven Models for Predicting Time- and Temperature-Dependent Viscoelastic Material Behaviors of Optical Glasses

2021 ◽  
Author(s):  
Anh Tuan Vu ◽  
Shrey Gulati ◽  
Paul-Alexander Vogel ◽  
Tim Grunwald ◽  
Thomas Bergs
Keyword(s):  
Viscoelastic Material ◽  
Data Driven ◽  
Temperature Dependent ◽  
Optical Glasses ◽  
Material Behaviors

Uniaxial Wave Propagation in a Viscoelastic Material Using Measured Material Properties

1968 ◽  
Vol 35 (3) ◽  
pp. 449-453 ◽  
Author(s):  
W. G. Knauss
Keyword(s):  
Wave Propagation ◽  
Viscoelastic Material ◽  
Material Properties ◽  
Material Characterization ◽  
Wave Speed ◽  
Initial Temperature ◽  
Initial Step ◽  
Shift Factor ◽  
Temperature Dependent ◽  
The Difference

The dynamic response of a long viscoelastic bar due to a step displacement at the end is considered. Neglecting geometric dispersion, the effect of realistic viscoelastic material properties is studied theoretically. The solution is obtained in the form of a Fourier sine integral, the convergence of which is studied numerically by piecewise integration to produce an alternating series. It is found that the initial step wave propagates with a high velocity corresponding to the glassy modulus of the material and its amplitude decays with time and distance along the rod. From a practical viewpoint the wave front may decay to immeasurable proportions and any measurable disturbance appears to travel thereafter, with a velocity which is smaller than the glassy wave speed. The effect of initial temperature is discussed. It is shown for thermorheologically simple materials that both the time and spatial variable are scaled by the same temperature dependent (shift) factor. As a consequence, the difference of wave propagation in hard and viscoelastic polymers is illustrated. It is also shown that limited material characterization is sufficient for certain dynamic problems. Comparison of the exact solution with two approximations is made.

Analysis of Two Surfaces under Viscoelastic Contact

2013 ◽  
Vol 818 ◽  
pp. 77-82
Author(s):  
M. Mongkolwongrojn ◽  
J. Panichakorn ◽  
S. Supawanich ◽  
S. Chutima
Keyword(s):  
Film Thickness ◽  
Viscoelastic Material ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Material Behaviors ◽  
Minimum Film Thickness ◽  
Heavy Loads ◽  
Element Technique ◽  
Cylindrical Roller ◽  
Viscoelastic Contact

This paper presents the analysis of the contact surfaces between a rigid cylinder and a soft plate for viscoelastic material. The contact pressure and deformation of the plate in contact region were determined using finite element technique. Moreover, the characteristics of two surfaces of cylindrical roller and plate under elastohydrodynamic lubrication with nonNewtonian fluid were examined using finite difference technique with full adaptive multigrid method . In this study the simulation of viscoelastic material in contact was under taken to determine the effects of material behaviors on the deformation of plate compared to the elastic materials. The results indicated that the deformation shapes were nonlinearly dependent with the applied loads. Furthermore, the deformation of elastic material would reach a certain value in a period of time whereas the deformation of viscoelastic material was increased inconsistently with time. The film pressure and film thickness profiles in the contact regime were investigated at various loads. The minimum film thickness occurs near the trailing edge of contact region and becomes very small under heavy loads.

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

Sign in / Sign up

Export Citation Format

Share Document