A unified model for stiffness modulus of amorphous polymers across transition temperatures and strain rates

Polymer ◽  
2005 ◽  
Vol 46 (19) ◽  
pp. 8194-8201 ◽  
Author(s):  
J. Richeton ◽  
G. Schlatter ◽  
K.S. Vecchio ◽  
Y. Rémond ◽  
S. Ahzi
Keyword(s):  
Amorphous Polymers ◽  
Unified Model ◽  
Strain Rates ◽  
Transition Temperatures ◽  
Stiffness Modulus

Dynamic Mechanical Properties of PMMA/Organoclay Nanocomposite: Experiments and Modeling

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Rodrigue Matadi Boumbimba ◽  
Said Ahzi ◽  
Nadia Bahlouli ◽  
David Ruch ◽  
José Gracio
Keyword(s):  
Mechanical Properties ◽  
Amorphous Polymers ◽  
Dynamic Mechanical Properties ◽  
Unified Model ◽  
Strain Rates ◽  
Transition Temperatures ◽  
Two Phase ◽  
Stiffness Modulus ◽  
Dynamic Mechanical ◽  
Wide Range

Similarly to unfilled polymers, the dynamic mechanical properties of polymer/organoclay nanocomposites are sensitive to frequency and temperature, as well as to clay concentration. Richeton et al. (2005, “A Unified Model for Stiffness Modulus of Amorphous Polymers Across Transition Temperatures and Strain Rates,” Polymer, 46, pp. 8194–8201) has recently proposed a statistical model to describe the storage modulus variation of glassy polymers over a wide range of temperature and frequency. In the present work, we propose to extend this approach for the prediction of the stiffness of polymer composites by using two-phase composite homogenization methods. The phenomenological law developed by Takayanagi et al., 1966, J. Polym. Sci., 15, pp. 263–281 and the classical bounds proposed by Voigt, 1928, Wied. Ann., 33, pp. 573–587 and Reuss and Angew, 1929, Math. Mech., 29, pp. 9–49 models are used to compute the effective instantaneous moduli, which is then implemented in the Richeton model (Richeton et al., 2005, “A Unified Model for Stiffness Modulus of Amorphous Polymers Across Transition Temperatures and Strain Rates,” Polymer, 46, pp. 8194–8201). This adapted formulation has been successfully validated for PMMA/cloisites 20A and 30B nanocomposites. Indeed, good agreement has been obtained between the dynamic mechanical analysis data and the model predictions of poly(methyl-methacrylate)/organoclay nanocomposites.

scholarly journals Longitudinal Compressive Property of Three-Dimensional Four-Step Braided Composites after Cyclic Hygrothermal Aging under High Strain Rates

2020 ◽  
Vol 10 (6) ◽  
pp. 2061 ◽  
Author(s):  
Kailong Xu ◽  
Wei Chen ◽  
Lulu Liu ◽  
Gang Luo ◽  
Zhenhua Zhao
Keyword(s):  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Peak Stress ◽  
Strain Rates ◽  
Braided Composites ◽  
High Strain Rates ◽  
Stiffness Modulus ◽  
Hygrothermal Aging

The longitudinal compressive behavior of the three-dimensional four-step braided composites after cyclic hygrothermal aging was investigated using a split Hopkinson pressure bar (SHPB) apparatus under high strain rates (1100~1250 s−1, 1400~1600 s−1, 1700~1850 s−1, respectively). The SEM micrographs were examined to the damage evolution of the composites after cyclic hygrothermal aging. A high-speed camera was employed to capture the progressive damage process for the composites. The results indicate that the saturated moisture absorption of the composites was not reached during the whole 210 cyclic hygrothermal aging days. The composites mainly underwent epoxy hydrolysis and interfaces debonding during continuous cyclic hygrothermal aging time. The peak stress of the composites still behaved as a strain rate effect after different cyclic hygrothermal aging days, but the dynamic stiffness modulus clearly had no specific regularity. In addition, the peak stress and the dynamic stiffness modulus of the composites after 210 cyclic hygrothermal aging days almost decreased by half when subjected to longitudinal compression.

scholarly journals A Unified Model for De Novo Design of Elastin-like Polypeptides with Tunable Inverse Transition Temperatures

2013 ◽  
Vol 14 (8) ◽  
pp. 2866-2872 ◽  
Author(s):  
Jonathan R. McDaniel ◽  
D. Christopher Radford ◽  
Ashutosh Chilkoti
Keyword(s):  
De Novo ◽  
De Novo Design ◽  
Unified Model ◽  
Transition Temperatures ◽  
Inverse Transition

scholarly journals Curvilinear Squeeze Film Bearing Lubricated with a Dehaven Fluid or with Similar Fluids

2017 ◽  
Vol 22 (3) ◽  
pp. 697-715
Author(s):  
A. Walicka ◽  
P. Jurczak ◽  
J. Falicki
Keyword(s):  
Reynolds Equation ◽  
Equations Of Motion ◽  
Unified Model ◽  
Squeeze Film ◽  
Successive Approximations ◽  
Method Of Successive Approximations ◽  
Shear Stresses ◽  
Strain Rates ◽  
Load Carrying Capacity ◽  
Load Carrying

AbstractIn the paper, the model of a DeHaven fluid and some other models of non-Newtonian fluids, in which the shear strain rates are known functions of the powers of shear stresses, are considered. It was demonstrated that these models for small values of material constants can be presented in a form similar to the form of a DeHaven fluid. This common form, called a unified model of the DeHaven fluid, was used to consider a curvilinear squeeze film bearing. The equations of motion of the unified model, given in a specific coordinate system are used to derive the Reynolds equation. The solution to the Reynolds equation is obtained by a method of successive approximations. As a result one obtains formulae expressing the pressure distribution and load-carrying capacity. The numerical examples of flows of the unified DeHaven fluid in gaps of two simple squeeze film bearings are presented.

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