A formulation of the cooperative model for the yield stress of amorphous polymers for a wide range of strain rates and temperatures

Polymer ◽  
2005 ◽  
Vol 46 (16) ◽  
pp. 6035-6043 ◽  
Author(s):  
J. Richeton ◽  
S. Ahzi ◽  
L. Daridon ◽  
Y. Rémond
Keyword(s):  
Yield Stress ◽  
Amorphous Polymers ◽  
Strain Rates ◽  
Cooperative Model ◽  
Wide Range

INVESTIGATING THE INFLUENCE OF ENVIRONMENTAL CONDITIONING ON EPOXY RESINS AT QUASISTATIC AND HIGH STRAIN RATES FOR MATERIAL OPERATING LIMIT

2021 ◽  
Author(s):  
SAGAR M. DOSHI, SAGAR M. DOSHI, ◽  
NITHINKUMAR MANOHARAN ◽  
BAZLE Z. (GAMA) HAQUE, ◽  
JOSEPH DEITZEL ◽  
JOHN W. GILLESPIE, JR.
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Yield Stress ◽  
High Strain ◽  
Operating Conditions ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Wide Range ◽  
Environmental Aging

Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.

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 Strain rate-dependent large deformation inelastic behavior of an epoxy resin

2019 ◽  
Vol 54 (1) ◽  
pp. 71-87 ◽  
Author(s):  
Sandeep Tamrakar ◽  
Raja Ganesh ◽  
Subramani Sockalingam ◽  
Bazle Z (Gama) Haque ◽  
John W Gillespie
Keyword(s):  
Strain Rate ◽  
Epoxy Resin ◽  
Yield Stress ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Internal Heat ◽  
Characteristic Relaxation Time ◽  
Strain Rates ◽  
Temperature Dependent ◽  
Wide Range

The objective of this paper is to model high strain rate and temperature-dependent response of an epoxy resin (DER 353 and bis( p-aminocyclohexyl) methane (PACM-20)) undergoing large inelastic strains under uniaxial compression. The model is decomposed into two regimes defined by the rate and temperature-dependent yield stress. Prior to yield, the model accounts for viscoelastic behavior. Post yield inelastic response incorporates the effects of strain rate and temperature including thermal softening caused by internal heat generation. The yield stress is dependent on both temperature and strain rate and is described by the Ree–Erying equation. Key experiments over the strain rate range of 0.001–12,000/s are conducted using an Instron testing machine and a split Hopkinson pressure bar. The effects of temperature (25–120 ℃) on yield stress are studied at low strain rates (0.001–0.1/s). Stress-relaxation tests are also carried out under various applied strain rates and temperatures to obtain characteristic relaxation time and equilibrium stress. The model is in excellent agreement over a wide range of strain rates and temperatures including temperature in the range of the glass transition. Case studies for a wide range of monotonic and varying strain rates and large strains are included to illustrate the capabilities of the model.

Temperature and Rate-Dependent Constitutive Relationship for Vanadium Alloy V-5Cr-5Ti and Failure Modes

2010 ◽  
Vol 44-47 ◽  
pp. 2336-2340
Author(s):  
Xi Cheng Huang ◽  
Wen Jun Hu ◽  
Yi Xia Yan ◽  
Ruo Ze Xie ◽  
Fang Ju Zhang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Yield Stress ◽  
Failure Modes ◽  
Constitutive Relationship ◽  
Strain Rates ◽  
Vanadium Alloy ◽  
Rate Dependent ◽  
Brittle Ductile Transition ◽  
Wide Range

In this work the static and dynamic properties of vanadium alloy V-5Cr-5Ti over a wide range of temperature from 20 to 1000 degree at strain rates ranged from 10-4/s~103/s were studied experimentally under uniaxial quasi-static tension with MTS universal testing machine, uniaxial dynamic compression and tension with split Hopkinson bar system with temperature control. The stress-strain curves of V-5Cr-5Ti at various temperatures and various strain rates were obtained. Experimental data show that V-5Cr-5Ti behaves strain-rate sensitive and temperature dependent, for instance the material parameters yield stress, tensile strength and failure strain. And fracture mode of the material is also dependent on strain-rate and temperature. Based on experimental data the temperature-rate-dependent constitutive relations were established in the form of Johnson-Cook and Cowper-Symonds models which are widely used in numerical simulation of dynamic processes of structures under impact loading. The material microstructures and failure modes were analyzed using optical microscope, TEM etc, and results shows that the yield stress and strength are increased with strain rate. The brittle-ductile transition strain-rate is from 101/s to102/s.

Temperature, Strain Rate and Pressure Sensitivity of the Polyetheretherketone’s Yield Stress

2017 ◽  
Vol 09 (07) ◽  
pp. 1750099 ◽  
Author(s):  
Zakaria El-Qoubaa ◽  
Ramzi Othman
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Strain Rates ◽  
Polymer Yield ◽  
Yield Behavior ◽  
Tensile Yield Stress ◽  
Wide Range ◽  
Eyring Equation ◽  
Temperature Strain ◽  
Two Temperature

The polymer yield behavior is affected by temperature, strain rate and pressure. In this work, tensile yield stress of polyetheretherketone (PEEK) is characterized for temperature ranging between [Formula: see text] and [Formula: see text] ([Formula: see text]C and [Formula: see text]C). The tensile yield stress is decreasing in terms of temperature. Two temperature transitions are observed: [Formula: see text] ([Formula: see text]C) and the glass transition temperature. The temperature sensitivity is well captured by the modified-Eyring equation proposed by the authors. This paper completes three previous works where the PEEK’s yield behavior was described under compression on wide ranges of strain rate and temperature and under tension on a wide range of strain rates. Thus, the pressure effect is analyzed in terms of temperature and strain rate. Using either the experimental data or the modified-Eyring equation, the effect of the hydrostatic pressure is increasing with temperature and decreasing with strain rate.

Free volume based nonlinear viscoelastic model for polyurea over a wide range of strain rates and temperatures

2021 ◽  
Vol 152 ◽  
pp. 103650
Author(s):  
Chencheng Gong ◽  
Yan Chen ◽  
Ting Li ◽  
Zhanli Liu ◽  
Zhuo Zhuang ◽  
...  
Keyword(s):  
Free Volume ◽  
Viscoelastic Model ◽  
Strain Rates ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Nonlinear Viscoelastic Model
Sign in / Sign up

Export Citation Format

Share Document