Estimation of Master Curves of Relaxation Modulus and Tensile Properties for Solid Propellant

2013 ◽  
Vol 871 ◽  
pp. 247-252 ◽  
Author(s):  
Boh Wi Seo ◽  
Jae Hoon Kim
Keyword(s):  
Stress Relaxation ◽  
Tensile Properties ◽  
Solid Propellant ◽  
Master Curve ◽  
Classical Method ◽  
Viscoelastic Behavior ◽  
Temperature Shift ◽  
Relaxation Modulus ◽  
Tensile Tests ◽  
Shift Factor

The stress relaxation modulus E(t) is one of the most important properties of viscoelastic materials such as solid propellant, and it is used to define the viscoelastic behavior based on the influence of time and temperature. In this paper, stress relaxation tests are conducted under constant strain 2% for 600 seconds in the range of temperature 60°C to-60°C and tensile tests are performed for solid propellants under constant cross head rate 5 mm/min in the same temperatures as stress relaxation tests. Based on the results, time-temperature shift factors are obtainedby shifting the relaxation modulus curves horizontally and the master curve of relaxation modulus is generated. The master curve of relaxation modulus according to classical method and Williams-Landel-Ferry (WLF) method are discussed. Also, the master curve of tensile properties are drawn using predetermined shift factor and the results are discussed.

On the Relation between Stress Relaxation and Constant Strain Rate Tensile Behavior for Linear Viscoelastic Materials; An Engineering Approach

2012 ◽  
Vol 729 ◽  
pp. 314-319 ◽  
Author(s):  
Gábor Bódai ◽  
Tibor Goda
Keyword(s):  
Stress Relaxation ◽  
Master Curve ◽  
Superposition Principle ◽  
Constant Strain Rate ◽  
Relaxation Modulus ◽  
Tensile Tests ◽  
Time Frequency ◽  
Construction Methods ◽  
Linear Viscoelastic ◽  
Time Temperature Superposition Principle

The present paper, as a first step summarizes briefly the master curve construction methods applying the stress relaxation and DMTA based approach. Then, authors make recommendation to increase the covered time (frequency) domain of relaxation modulus master curve coming from standard tensile tests-performed at wide temperature range-by utilizing the time-temperature superposition principle. The proposed approach is used for natural rubber, whose tensile tests, for the sake of simplicity, are replaced by calculated engineering stress-strain curves. All in all, the proposed method gives fast and reliable way for engineers to identify the parameters of spring-dashpot models.

scholarly journals Study on Main curvature of Stress Relaxation Modulus of a Double-base solid propellant

2021 ◽  
Vol 1965 (1) ◽  
pp. 012023
Author(s):  
Zhang Jian-bin ◽  
Guo Lei ◽  
Li Guang-hua ◽  
Lu Bing-ju ◽  
Cheng Dong
Keyword(s):  
Stress Relaxation ◽  
Solid Propellant ◽  
Relaxation Modulus ◽  
Double Base

Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition

1997 ◽  
Vol 1570 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Sun Woo Park ◽  
Y. Richard Kim
Keyword(s):  
Linear Viscoelasticity ◽  
Superposition Principle ◽  
Asphalt Mixture ◽  
Temperature Shift ◽  
Relaxation Modulus ◽  
Analytical Description ◽  
Shift Factor ◽  
Temperature Correction ◽  
Temperature Superposition ◽  
Time Temperature Superposition

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.

Comparison of a Novel Nonlinear Viscoelastic Finite Ramp Time Correction Method to a Heaviside Step Assumption

2011 ◽  
Author(s):  
Kevin L. Troyer ◽  
Christian M. Puttlitz
Keyword(s):  
Stress Relaxation ◽  
Soft Tissues ◽  
Viscoelastic Behavior ◽  
Relaxation Modulus ◽  
Correction Method ◽  
Nonlinear Viscoelastic ◽  
Instantaneous Strain ◽  
Relaxation Experiments ◽  
Time Correction

Connective soft tissues exhibit time-dependent, or viscoelastic, behavior. In order to characterize this behavior, stress relaxation experiments can be performed to determine the tissue’s relaxation modulus. Theoretically, the relaxation modulus describes the stress relaxation behavior of the tissue in response to an instantaneous (step) application of strain. However, a step increase in strain is experimentally impossible and a pure ramp load is intractable due to the inertial limitations of the testing device. Even small deviations from an instantaneous strain application may cause significant errors in the determination of the tissue’s relaxation modulus.

Mechanical Behavior After Stress Relaxation in PVDF

2018 ◽  
Author(s):  
Rafael Luis Menezes Freitas ◽  
Celio Costa ◽  
Erica Gervasoni Chaves ◽  
Sylvia Teixeira
Keyword(s):  
Stress Relaxation ◽  
Tensile Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Yield Strain ◽  
Cooling Temperature ◽  
Cooling Conditions ◽  
C 23 ◽  
Processing Stress

This study presents the mechanical properties evaluation of two commercial grades of PVDFs, which were extruded with the same parameters but with different cooling temperatures. After processing, stress relaxation with 7% strain was imposed and tensile properties were measured. The cooling temperature after extrusion were 4°C, 23°C and 80°C. Then, the PVDFs were submitted to stress relaxation at 23°C and 7% strain. The as processed and after relaxation samples were characterized by FTIR, XRD, DSC and tensile tests at 23°C. The stress relaxation at 23 °C resulted in no change in volume fraction of crystallinity for PVDF A and B. The XRD and FTIR, for both PVDFs, showed that the crystalline phases were the same, for all cooling conditions and did not change after the stress relaxation. The tensile properties at room temperature showed that the yield stress was a little affect by the cooling temperature, while Young’s Modulus and yield strain were insensible to the cooling temperature. After the stress relaxation, these three tensile properties were slightly affected for both grades.

Viscoelastic Characterization of an Epoxy-Based Molding Compound

1995 ◽  
Vol 390 ◽  
Author(s):  
V. H. Kenner ◽  
M. R. Julian ◽  
C. H. Popelar ◽  
M. K. Chengalva
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Viscoelastic Behavior ◽  
Tensile Tests ◽  
Prony Series ◽  
Master Curves ◽  
Molding Compound ◽  
Relaxation Curves

ABSTRACTThis paper describes the viscoelastic characterization of a highly filled epoxy molding compound commonly used in electronic packaging applications. Both stress relaxation tests and constant strain rate tensile tests were conducted. The material was found to be nonlinear in its viscoelastic behavior and to be amenable to horizontal shifting to form master curves. A representation of the master stress relaxation curves in terms of a Prony series is given, and the use of this representation illustrated in the context of both linear and nonlinear representations of the viscoelastic behavior to predict the results of the constant strain rate experiments.

Stress Relaxation Behavior of Ethylene Propylene-Hexadiene Terpolymers

1971 ◽  
Vol 44 (4) ◽  
pp. 1057-1064
Author(s):  
C. K. Shih
Keyword(s):  
Stress Relaxation ◽  
Abrupt Change ◽  
Temperature Shift ◽  
Shift Factor ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Ethylene Propylene ◽  
Wlf Equation ◽  
Ethylene Content ◽  
Higher Temperature

Abstract 1. The stress relaxation behavior of E/P/hexadiene polymer over wide temperature [Tg to (Tg+140°C)] and composition (molar E/P = 1.7 to 4.4) ranges is described. 2. Although Tg of the polymers is essentially constant (− 60° C), the onset temperature for rubbery flow characterized by an abrupt change in the rate of stress relaxation is highly dependent upon composition. It increases to a higher temperature as the ethylene content is increased. It is also affected by the catalysts used for polymer synthesis. 3. The time-temperature shift factor for one sample was found to follow the WLF equation over the temperature range from − 50° C to 0° C.

The Stress-Relaxation Behavior of Rice as a Function of Time, Moisture and Temperature

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Pan Wang ◽  
Li-jun Wang ◽  
Dong Li ◽  
Zhi-gang Huang ◽  
Benu Adhikari ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Moisture Content ◽  
Master Curve ◽  
Superposition Principle ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Linear Viscoelastic ◽  
Single Rice

Abstract: Stress-relaxation behavior of single rice kernel was studied using a dynamic mechanical analyzer (DMA) in compression mode. The relaxation modulus was measured in a moisture content range of 12–30 % on dry basis (d.b.) and a temperature range of 25–80°C. A constant stain value of 1 % (within the linear viscoelastic range) was selected during the stress-relaxation tests. The relaxation modulus was found to decrease as the temperature and moisture increased. A master curve of relaxation modulus as a function of temperature and moisture content was generated using the time–moisture–temperature superposition principle. Results showed that the generalized Maxwell model satisfactorily fitted the experimental data of the stress-relaxation behavior and the master curve of relaxation modulus (R2> 0.997). By shifting the temperature curves horizontally, the activation energy of the stress relaxation was obtained which significantly decreased with increase in the moisture content.

Characterization of Viscoelasticity of Molding Compounds in Time Domain

2009 ◽  
Author(s):  
Seung-Hyun Chae ◽  
Jie-Hua Zhao ◽  
Darvin R. Edwards ◽  
Paul S. Ho
Keyword(s):  
Time Domain ◽  
Viscoelastic Properties ◽  
Viscoelastic Behavior ◽  
Relaxation Modulus ◽  
Polymeric Materials ◽  
Shift Factor ◽  
Microelectronics Packaging ◽  
Molding Compound ◽  
Relaxation Experiments ◽  
The Time Domain

Although polymer-based materials are widely used in microelectronics packaging and viscoelasticity is an intrinsic characteristic of polymers, viscoelastic properties of polymeric materials are often ignored in package stress analyses due to the difficulty of measuring this property. However, it is necessary to consider the viscoelastic behavior when an accurate stress model is required. Viscoelastic properties of materials can be characterized either in the time domain or frequency domain. In this study, stress relaxation experiments were performed on a molding compound in the time domain. Prony series expansion was used to express the material’s relaxation behavior. Thermo-rheologically simple model was assumed to deduce the master curve of relaxation modulus using the time-temperature equivalence assumption. Two methods were compared to determine the Prony pairs and shift factor.

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