A constitutive model for temperature dependent behavior of ferroelectric materials

2009 ◽  
Author(s):  
Keigo Yoshida ◽  
Tadashige Ikeda ◽  
Tetsuhiko Ueda
Keyword(s):  
Constitutive Model ◽  
Ferroelectric Materials ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Temperature Dependent Behavior

Nonlinear Thermohyperviscoelastic Constitutive Model for Soft Materials with Strain Rate and Temperature Dependency

2020 ◽  
Vol 12 (06) ◽  
pp. 2050059
Author(s):  
Zahra Matin Ghahfarokhi ◽  
Mehdi Salmani-Tehrani ◽  
Mahdi Moghimi Zand
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Soft Materials ◽  
Material Behavior ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Temperature Dependent Behavior

Soft materials, such as polymeric materials and biological tissues, often exhibit strain rate and temperature-dependent behavior when subjected to external loads. To characterize the thermomechanical behavior of isotropic soft material, a thermohyperviscoelastic constitutive model has been developed through an additive decomposition of strain energy function into elastic and viscous parts. A three-term generalized Rivlin strain energy function is utilized to formulate the hyperelastic part of the model, while a new viscous potential function is proposed to describe the effect of strain rate and temperature on material behavior. Toward this end, a new procedure has been proposed to determine the viscous mechanical properties as a function of strain-rate and temperature. Comparing with the previously published experimental data for linear low-density polyethylene reveals that the proposed model can sufficiently capture the nonlinearity, rate- and temperature-dependent behavior of the soft materials.

scholarly journals LCST polymers with UCST behavior

Soft Matter ◽  
2021 ◽  
Author(s):  
Marzieh Najafi ◽  
Mehdi Habibi ◽  
Remco Fokkink ◽  
Wim Hennink ◽  
Tina Vermonden
Keyword(s):  
Block Copolymers ◽  
Aqueous Solutions ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Temperature Dependent Behavior

In this study, temperature dependent behavior of dense dispersions of core crosslinked flower-like micelles is investigated. Micelles were prepared by mixing aqueous solutions of two ABA block copolymers with PEG...

scholarly journals Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Henning Tesmer ◽  
Rani Razzouk ◽  
Ersin Polat ◽  
Dongwei Wang ◽  
Rolf Jakoby ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Insertion Loss ◽  
Phase Shifter ◽  
Ground Plane ◽  
Temperature Dependent ◽  
Differential Phase ◽  
Dependent Behavior ◽  
The Impact ◽  
Temperature Dependent Behavior

In this paper we investigate the temperature dependent behavior of a liquid crystal (LC) loaded tunable dielectric image guide (DIG) phase shifter at millimeter-wave frequencies from 80 GHz to 110 GHz for future high data rate communications. The adhesive, necessary for precise fabrication, is analyzed before temperature dependent behavior of the component is shown, using the nematic LC-mixture GT7-29001. The temperature characterization is conducted by changing the temperature of the LC DIG’s ground plane between −10∘C and 80 ∘C. The orientation of the LC molecules, and therefore the effective macroscopic relative permittivity of the DIG, is changed by inserting the temperature setup in a fixture with rotatable magnets. Temperature independent matching can be observed, while the insertion loss gradually increases with temperature for both highest and lowest permittivity of the LC. At 80 ∘C the insertion loss is up to 1.3dB higher and at −10∘C it is 0.6dB lower than the insertion loss present at 20 ∘C. In addition, the achievable differential phase is reduced with increasing temperature. The impact of molecule alignment to this reduction is shown for the phase shifter and an estimated 85% of the anisotropy is still usable with an LC DIG phase shifter when increasing the temperature from 20 ∘C to 80 ∘C. Higher reduction of differential phase is present at higher frequencies as the electrical length of the phase shifter increases. A maximum difference in differential phase of 72∘ is present at 110 GHz, when increasing the temperature from 20 ∘C to 80 ∘C. Nevertheless, a well predictable, quasi-linear behavior can be observed at the covered temperature range, highlighting the potential of LC-based dielectric components at millimeter wave frequencies.

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