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.

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.

Strain-Rate Effect on the Tensile Behaviour of High Strength Alloys

2011 ◽  
Vol 82 ◽  
pp. 124-129 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Stefano Bianchi
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Cross Sectional ◽  
Split Hopkinson Tensile Bar ◽  
Wide Range ◽  
First Results

In this paper the first results of the mechanical characterization in tension of two high strength alloys in a wide range of strain rates are presented. Different experimental techniques were used for different strain rates: a universal machine, a Hydro-Pneumatic Machine and a JRC-Split Hopkinson Tensile Bar. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. An increase of the stress at a given strain increasing the strain-rate from 10-3 to 103 s-1, a moderate strain-rate sensitivity of the uniform and fracture strain, a poor reduction of the cross-sectional area at fracture with increasing the strain-rate were shown. Based on these experimental results the parameters required by the Johnson-Cook constitutive law were determined.

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.

scholarly journals Effects of loading rate on strength and deformation characteristics of gypsum mixed sand

2019 ◽  
Vol 92 ◽  
pp. 05008
Author(s):  
Zain Maqsood ◽  
Junichi Koseki ◽  
Hiroyuki Kyokawa
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Constitutive Modelling ◽  
Strain Rates ◽  
Deformation Characteristics ◽  
Wide Range ◽  
Strength And Deformation ◽  
Loading Tests ◽  
Rational Evaluation ◽  
Strain Responses

It has been unanimously acknowledged that the strength and deformation characteristics of bounded geomaterials, viz. cemented soils and natural rocks, are predominantly governed by the rate of loading/deformation. Rational evaluation of these time-dependent characteristics due to viscosity and ageing are vital for the reliable constitutive modelling. In order to study the effects of ageing and loading/strain rate (viscosity) on the behaviour of bounded geomaterials, a number of unconfined monotonic loading tests were performed on Gypsum Mixed Sand (GMS) specimens at a wide range of axial strain rates; ranging from 1.9E-05 to 5.3E+00 %/min (27,000 folds), and at different curing periods. The results indicate shifts in the viscous behaviour of GMS at critical strain rates of 2.0E-03 and 5.0E-01 %/min. In the light of this finding, the results are categorized into three discrete zones of strain rates, and the behaviour of GMS in each of these zones is discussed. A significant dependency of peak strength and stress-strain responses on strain rate was witnessed for specimens subjected to strain rates lesser than 2.0E-03 %/min, and the effects of viscosity/strain rate was found to be insignificant at strain rate higher than 5.0E-01%/min.

scholarly journals Dynamic Mechanical Characteristics and Constitutive Modeling of Rail Steel over a Wide Range of Temperatures and Strain Rates

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Peijie Liu ◽  
Yanming Quan ◽  
Guo Ding
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Split Hopkinson Pressure Bar ◽  
Rail Steel ◽  
Strain Rates ◽  
Dynamic Mechanical ◽  
Flow Response ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error ◽  
Wide Range

Rail steel plays an indispensable role in the safety and stability of the railway system. Therefore, a suitable constitutive model is quite significant to understand the mechanical behavior of this material. Here, the compressive mechanical behavior of heat-treated U71Mn rail steel over a wide range of strain rates (0.001 s−1–10000 s−1) and temperatures (20°C–800°C) was systematically investigated via uniaxial quasistatic and dynamic tests. The split Hopkinson pressure bar (SHPB) apparatus was utilized to perform dynamic mechanical tests. The effects of temperature, strain, and strain rate on the dynamic compressive characteristics of U71Mn were discussed, respectively. The results indicate that the flow response of U71Mn is both temperature-sensitive and strain rate-sensitive. However, the influence of temperature on the flow response is more remarkable than that of strain rate. On the basis of the experimental data, the original and modified Johnson-Cook (JC) models of the studied material were established, respectively. Using correlation coefficient and average absolute relative error parameters, it is revealed that better agreement between the experimental and predicted stress is reached by the modified JC model, which demonstrates that the modified one can characterize the mechanical behavior of the studied material preferably.

THERMOMECHANICAL RESPONSE OF THE ROTARY FORGED WHA OVER A WIDE RANGE OF STRAIN RATES AND TEMPERATURES

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5431-5437 ◽  
Author(s):  
W. G. GUO ◽  
C. QU ◽  
F. L. LIU
Keyword(s):  
Strain Rate ◽  
Dislocation Motion ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Thermomechanical Response ◽  
Tension Tests ◽  
Wide Range ◽  
Physically Based ◽  
Split Hopkinson ◽  
Modeling Prediction

This paper is to understand and model the thermomechanical response of the rotary forged WHA, uniaxial compression and tension tests are performed on cylindrical samples, using a material testing machines and the split Hopkinson bar technique. True strains exceeding 40% are achieved in these tests over the range of strain rates from 0.001/s to about 7,000/s, and at initial temperatures from 77K to 1,073K. The results show: 1) the WHA displays a pronounced changing orientation due to mechanical processing, that is, the material is inhomogeneous along the section; 2) the dynamic strain aging occurs at temperatures over 700K and in a strain rate of 10-3 1/s; 3) failure strains decrease with increasing strain rate under uniaxial tension, it is about 1.2% at a strain rate of 1,000 1/s; and 4) flow stress of WHA strongly depends on temperatures and strain rates. Finally, based on the mechanism of dislocation motion, the parameters of a physically-based model are estimated by the experimental results. A good agreement between the modeling prediction and experiments was obtained.

High Strain-Rate Compressive Behavior and Constitutive Modeling of Selected Polymers Using Modified Ramberg-Osgood Equation

2014 ◽  
Vol 566 ◽  
pp. 80-85
Author(s):  
Kenji Nakai ◽  
Takashi Yokoyama
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Compressive Stress ◽  
Constitutive Modeling ◽  
High Strain ◽  
Strain Rates ◽  
Stress Strain ◽  
Strain Behavior ◽  
Least Squares Fit ◽  
Wide Range

The present paper is concerned with constitutive modeling of the compressive stress-strain behavior of selected polymers at strain rates from 10-3 to 103/s using a modified Ramberg-Osgood equation. High strain-rate compressive stress-strain curves up to strains of nearly 0.08 for four different commercially available extruded polymers were determined on the standard split Hopkinson pressure bar (SHPB). The low and intermediate strain-rate compressive stress-strain relations were measured in an Instron testing machine. Six parameters in the modified Ramberg-Osgood equation were determined by fitting to the experimental stress-strain data using a least-squares fit. It was shown that the monotonic compressive stress-strain behavior over a wide range of strain rates can successfully be described by the modified Ramberg-Osgood constitutive model. The limitations of the model were discussed.

Effect of Si Content on Fracture Behaviour Change by Strain Rate in Si Steels

2010 ◽  
Vol 654-656 ◽  
pp. 1303-1306 ◽  
Author(s):  
Takashi Mizuguchi ◽  
Ryota Oouchi ◽  
Rintaro Ueji ◽  
Yasuhiro Tanaka ◽  
Kazunari Shinagawa
Keyword(s):  
Strain Rate ◽  
Fracture Behaviour ◽  
Tensile Tests ◽  
Strain Rates ◽  
Wide Range ◽  
Work Hardening Rate ◽  
Brittle Fractures ◽  
Mechanism Transition ◽  
Si Content ◽  
Si Addition

Fracture behaviour transitions due to change in the strain rate in steels with various Si content ranging from 2% to 5 wt% were studied. Room-temperature tensile tests were conducted over wide range of strain rates ranging from 10-3 s-1 to 103 s-1. Concerning of the steels with low Si content (no more than 3%), the nominal stress - nominal strain curves represented both uniform and local elongations at all strain rates. On the other hand, in 4% Si steel at a strain rate higher than 101 s-1, the tensile sample broke down without local elongation (necking). The stress at breaking was found to be nearly equal to its work hardening rate. The strain rate at which fracture behaviour transition took place in 5% Si steel (10-1s-1) was lower than that in 4% Si steel. TEM observations clarified the existence of deformation twins in the sample that fractured without necking. These results indicated that Si addition is subject to the brittle fractures and that the fracture mechanism transition is closely related with the deformation twinning behaviour.

Sign in / Sign up

Export Citation Format

Share Document