Adhesion and Thermal Deformation of Ceramic/ Polymer Heterostructures

1995 ◽  
Vol 385 ◽  
Author(s):  
Cynthia Madras ◽  
Peter Y. Wong ◽  
Ioannis N. Miaoulis
Keyword(s):  
Thermal Deformation ◽  
Thermal Stresses ◽  
Operating Temperature ◽  
Thermomechanical Properties ◽  
Initial Stresses ◽  
Processing Conditions ◽  
Temperature Dependent ◽  
Optical Ceramic ◽  
Dependent Behavior ◽  
Mechanical Adhesion

ABSTRACTThe adhesion and thermal properties of optical ceramic structures bonded by a polymer interlayer are explored. The mechanical, adhesion and optical properties of the heterostructure are dependent on the thickness of the bond and on the residual thermal stresses developed during the bonding process. The thermomechanical properties of a bonded structure over a range of temperatures are investigated, focusing on the thermal expansion and operating temperature limits of the polymer bond. The temperature and stress histories during manufacturing are determined through both numerical modeling and experimental analysis. The effect of stress relaxation and initial stresses on the behavior of the bonding material are examined for different processing conditions. The bond material relaxation time constant, activation energy, viscosity, and shear modulus are approximated from observation of the temperature-dependent behavior of the structure.

Elasto-Plastic Analysis of Thermal Stress Development During VAR of Ingots

1999 ◽  
Author(s):  
M. K. Alam ◽  
K. K. Wong ◽  
S. L. Semiatin
Keyword(s):  
Thermal Stresses ◽  
Plastic Material ◽  
Material Model ◽  
Thermomechanical Properties ◽  
Vacuum Arc ◽  
Aerospace Materials ◽  
Temperature Dependent ◽  
Vacuum Arc Remelting ◽  
High Cooling Rates ◽  
Dc Arc

Abstract The vacuum arc remelting (VAR) process has been developed to melt and cast high quality aerospace materials such as titanium alloys. VAR comprises the continuous remelting of a consumable electrode by means of a dc arc under vacuum or a low partial pressure of argon. The molten metal solidifies in a water-cooled copper crucible leading to high cooling rates that often results in large thermal stresses. The development of temperature gradients and the resulting thermal stresses during the VAR processes was investigated using an elasto-plastic material model with temperature dependent thermomechanical properties. Detailed solutions were obtained by using the commercial finite element code ABAQUS.

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.

scholarly journals A new boundary element algorithm for modeling and simulation of nonlinear thermal stresses in micropolar FGA composites with temperature-dependent properties

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Modeling And Simulation ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Computation Time ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Time Step ◽  
Kirchhoff Transformation ◽  
Nonlinear Temperature ◽  
Temperature Dependent Properties

AbstractThe main aim of this article is to develop a new boundary element method (BEM) algorithm to model and simulate the nonlinear thermal stresses problems in micropolar functionally graded anisotropic (FGA) composites with temperature-dependent properties. Some inside points are chosen to treat the nonlinear terms and domain integrals. An integral formulation which is based on the use of Kirchhoff transformation is firstly used to simplify the transient heat conduction governing equation. Then, the residual nonlinear terms are carried out within the current formulation. The domain integrals can be effectively treated by applying the Cartesian transformation method (CTM). In the proposed BEM technique, the nonlinear temperature is computed on the boundary and some inside domain integral. Then, nonlinear displacement can be calculated at each time step. With the calculated temperature and displacement distributions, we can obtain the values of nonlinear thermal stresses. The efficiency of our proposed methodology has been improved by using the communication-avoiding versions of the Arnoldi (CA-Arnoldi) preconditioner for solving the resulting linear systems arising from the BEM to reduce the iterations number and computation time. The numerical outcomes establish the influence of temperature-dependent properties on the nonlinear temperature distribution, and investigate the effect of the functionally graded parameter on the nonlinear displacements and thermal stresses, through the micropolar FGA composites with temperature-dependent properties. These numerical outcomes also confirm the validity, precision and effectiveness of the proposed modeling and simulation methodology.

Effects of inductor patterns on temperature and deformation behavior of ship hull plate by induction heating

2018 ◽  
Vol 232 (23) ◽  
pp. 4371-4389
Author(s):  
Shuiming Zhang ◽  
Cungen Liu ◽  
Xuefeng Wang ◽  
Zhi Yang
Keyword(s):  
Induction Heating ◽  
Opposite Direction ◽  
Thermal Deformation ◽  
Transient Analysis ◽  
Ship Hull ◽  
Temperature Dependent ◽  
Thermal Forming ◽  
Ship Hull Plate ◽  
Heating Direction ◽  
Transverse Shrinkage

This paper mainly investigated the effects of different inductor patterns on thermal forming behavior of ship hull plate by moving induction heating. Alternately-coupled electromagnetic-thermal analysis procedure considering temperature-dependent material properties was firstly implemented at each moving step of inductor, followed with uncoupled thermal-mechanical transient analysis to obtain corresponding thermal deformation. Then temperature distribution, dimensions (breadth b and depth h) of heat-affected zone, and deformation obtained from codirectional current-carrying inductor with no gap and opposite-direction current-carrying inductor with gap were compared, respectively. And effects of heating directions and distance T2 of ODIG were also analyzed. It turns out that codirectional current-carrying inductor with no gap can generate much larger transverse shrinkage at 1.8–2.5 mm/s than opposite-direction current-carrying inductor with gap, otherwise smaller at 3.2–4.0 mm/s, likewise larger temperature gradient at 1.8–4.0 mm/s and thus larger bending angular deformation. Besides, heating direction “Out” can generate larger deformation than “In” and deformation for opposite-direction current-carrying inductor with gap can be effectively improved through adjusting distance T2 until 13 mm. These indicate that adopting appropriate inductor patterns, heating direction and distance T2 of opposite-direction current-carrying inductor with gap can significantly improve thermal forming behavior.

Effects of Thermal Exposure on Microstructure and Mechanical Properties of Ni Based Superalloy GTD111

2011 ◽  
Vol 275 ◽  
pp. 31-34 ◽  
Author(s):  
Han Sang Lee ◽  
Keun Bong Yoo ◽  
Doo Soo Kim ◽  
Jae Hoon Kim
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Operating Temperature ◽  
Rupture Strength ◽  
Mechanical Test ◽  
Thermal Exposure ◽  
Creep Rupture Strength ◽  
Material Degradation ◽  
Temperature Dependent ◽  
Hot Gas

The rotating components in the hot sections of land-based gas turbine are exposed to severe environment during several ten thousand hours at above 1100 oC operating temperature. The failure mechanism of the hot gas components would be accompanied by material degradation in the properties of high temperature and creep rupture strength. Many hot gas components in gas turbine are made of Ni-based superalloy because of their high temperature performance. In this work, we surveyed the time and temperature dependent degradation of Ni-based superalloy. We prepared the specimens from GTD111 that are exposed at 871 oC and 982 oC in 1,000 ~ 10,000 hours. We carried out the mechanical test and microstructural observation.

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