The Rate (Time)–Dependent Mechanical Behavior of the PMR-15 Thermoset Polymer at Temperatures in the 274–316 °C Range: Experiments and Modeling

2011 ◽  
Author(s):  
C. E. C. Ryther ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Deformation Behavior ◽  
Inelastic Deformation ◽  
Monotonic Loading ◽  
Relaxation Behavior ◽  
Time Dependent ◽  
Experimental Program ◽  
Model Parameters ◽  
Thermoset Polymer

The inelastic deformation behavior of the PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at temperatures in the 274–316 °C range. The experimental program was designed to explore the influence of strain rate on monotonic loading at various temperatures. In addition, the effects of prior strain rate on relaxation response and on creep behavior following strain controlled loading were examined at temperatures in the range of interest. Positive, nonlinear strain rate sensitivity is observed in monotonic loading at all temperatures investigated. Both relaxation behavior and creep are profoundly influenced by prior strain rate at all temperatures. The time-dependent mechanical behavior of the PMR-15 polymer is also strongly affected by temperature. The elastic modulus decreases and the departure from quasi-linear behavior is accelerated with increasing temperature. Stress levels in the region of inelastic flow decrease as the temperature increases. The relaxation behavior as well as the creep response is strongly influenced by temperature. The viscoplasticity theory based on overstress (VBO) is augmented to model the effects of temperature on the inelastic deformation behavior of PMR-15. VBO is a unified state variable theory with growth laws for three state variables: the equilibrium stress, the kinematic stress and the isotropic stress. Based on experimental findings several VBO model parameters are developed as functions of temperature. The augmented model is employed to predict the response of the material under both strain- and stress-controlled loading histories at temperatures in the range of interest. Comparison with experimental data demonstrates that the augmented VBO successfully predicts the inelastic deformation behavior of PMR-15 polymer under various loading histories at temperatures between 274 and 316 °C.

The Rate (Time)-Dependent Mechanical Behavior of the PMR-15 Thermoset Polymer at Temperatures in the 274–316 °C Range: Experiments and Modeling

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
C. E. C. Ryther ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Deformation Behavior ◽  
Inelastic Deformation ◽  
Monotonic Loading ◽  
Relaxation Behavior ◽  
Time Dependent ◽  
Experimental Program ◽  
Model Parameters ◽  
Thermoset Polymer

The inelastic deformation behavior of the PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at temperatures in the 274–316 °C range. The experimental program was designed to explore the influence of strain rate on monotonic loading at various temperatures. In addition, the effects of prior strain rate on relaxation response and on creep behavior following strain-controlled loading were examined at temperatures in the range of interest. Positive, nonlinear strain rate sensitivity is observed in monotonic loading at all temperatures investigated. Both relaxation behavior and creep are profoundly influenced by prior strain rate at all temperatures. The time-dependent mechanical behavior of the PMR-15 polymer is also strongly affected by temperature. The elastic modulus decreases and the departure from quasi-linear behavior is accelerated with increasing temperature. Stress levels in the region of inelastic flow decrease as the temperature increases. The relaxation behavior as well as the creep response is strongly influenced by temperature. The viscoplasticity theory based on overstress for polymers (VBOP) is augmented to model the effects of temperature on the inelastic deformation behavior of PMR-15. VBOP is a unified state variable theory with growth laws for three state variables: the equilibrium stress, the kinematic stress, and the isotropic stress. Based on the experimental findings several VBOP model parameters are developed as functions of temperature. The augmented model is employed to predict the response of the material under both strain- and stress-controlled loading histories at temperatures in the range of interest. Comparison with experimental data demonstrates that the augmented VBOP successfully predicts the inelastic deformation behavior of PMR-15 polymer under various loading histories at temperatures between 274 and 316 °C.

The Rate (Time)-Dependent Mechanical Behavior of the PMR-15 Thermoset Polymer at 316°C: Experiments and Modeling

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. B. Ruggles-Wrenn ◽  
O. Ozmen
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Inelastic Deformation ◽  
Rate Sensitivity ◽  
Experimental Program ◽  
Strain Rates ◽  
Neat Resin ◽  
Strain Behavior ◽  
Thermoset Polymer

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 316°C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain-controlled loading were examined. Positive, nonlinear strain rate sensitivity is observed in monotonic loading. The material exhibits nonlinear, “curved” stress-strain behavior during unloading at all strain rates. The recovery of strain at zero stress is strongly influenced by the prior strain rate. The prior strain rate also has a profound effect on relaxation behavior. Likewise, creep response is significantly influenced by the prior strain rate. The experimental data are modeled with the viscoplasticity theory based on overstress (VBO). The comparison with experimental data demonstrates that the VBO successfully predicts the inelastic deformation behavior of the PMR-15 polymer under various test histories at 316°C.

Strain Rate Dependence and Short-Term Relaxation Behavior of a Thermoset Polymer at Elevated Temperature: Experiment and Modeling

2008 ◽  
Author(s):  
A. J. W. McClung ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Strain Rate ◽  
Strain Curve ◽  
Strain Recovery ◽  
Relaxation Behavior ◽  
Solid Polymer ◽  
Experimental Program ◽  
Model Parameters ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Thermoset Polymer

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 288°C. The experimental program was designed to explore the influence of strain rate changes in the 10−6 to 10−3 s−1 range on tensile loading, unloading, and strain recovery behavior, as well as on the relaxation response of the material. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading. Nonlinear, “curved” stress-strain behavior during unloading is observed at all strain rates. The strain recovery at zero stress is profoundly affected by prior strain rate. The prior strain rate is also found to have a strong influence on relaxation behavior. The rest stresses measured at the termination of relaxation tests form the relaxation boundary which resembles a nonlinear stress-strain curve. The results suggest that the inelastic behavior of the PMR-15 solid polymer at 288°C can be represented using a unified constitutive model with an overstress dependence of the inelastic rate of deformation. The experimental data are modeled with the viscoplasticity theory based on over-stress (VBO). A systematic procedure for determining model parameters is presented and the model is employed to predict the response of the material under various test histories.

Strain Rate Dependence and Short-Term Relaxation Behavior of a Thermoset Polymer at Elevated Temperature: Experiment and Modeling

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
A. J. W. McClung ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Strain Rate ◽  
Strain Curve ◽  
Strain Recovery ◽  
Relaxation Behavior ◽  
Solid Polymer ◽  
Experimental Program ◽  
Model Parameters ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Thermoset Polymer

The inelastic deformation behavior of polymerization of monomeric reactants-15 (PMR-15) neat resin, a high-temperature thermoset polymer, was investigated at 288°C. The experimental program was designed to explore the influence of strain rate changes in the 10−6–10−3 s−1 range on tensile loading, unloading, and strain recovery behavior, as well as on the relaxation response of the material. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading. Nonlinear, “curved” stress-strain behavior during unloading is observed at all strain rates. The strain recovery at zero stress is profoundly affected by prior strain rate. The prior strain rate is also found to have a strong influence on relaxation behavior. The rest stresses measured at the termination of relaxation tests form the relaxation boundary, which resembles a nonlinear stress-strain curve. The results suggest that the inelastic behavior of the PMR-15 solid polymer at 288°C can be represented using a unified constitutive model with an overstress dependence of the inelastic rate of deformation. The experimental data are modeled with the viscoplasticity theory based on overstress. A systematic procedure for determining model parameters is presented and the model is employed to predict the response of the material under various test histories.

Strain rate effects on the mechanical behavior of single-lap glass/carbon nanofiber/epoxy composite bolted joints

2020 ◽  
Vol 54 (30) ◽  
pp. 4807-4819 ◽  
Author(s):  
AR Shamaei-Kashani ◽  
MM Shokrieh
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Epoxy Composite ◽  
Bolted Joints ◽  
Dynamic Strain ◽  
Experimental Program ◽  
Strain Rates ◽  
Mechanical Parameters ◽  
Damage Initiation ◽  
Bearing Strength

In the present research, effects of applying strain rate on the mechanical behavior of single-lap glass/CNF/epoxy composite bolted joints including, damage initiation bearing stress, 2% offset bearing strength, ultimate bearing strength, bearing chord stiffness, ultimate bearing strain, and energy absorption were studied. To this end, a comprehensive experimental program was conducted. The protruding head bolt was used, the clearance was considered to be near fit and a finger-tight bolt condition was applied to all joints. The dimensions of joints were chosen to promote the bearing failure mode based on the ASTM standard. Four types of single-lap bolted joints (SLJs) with lay-ups of [–45/0/45/90]s and [90/–452/45]s with and without CNFs were tested at strain rates in the range of 0.0048 s−1 to 0.89 s−1. Unlike the available experimental results, the results obtained by the present experiments showed that the strain rate has a significant effect on all the above-mentioned mechanical parameters of SLJs. Also, it was shown that employing CNFs improved the mechanical parameters of SLJs under quasi-static and dynamic strain rates.

Elastic viscoplastic modelling of the time-dependent stress-strain behaviour of soils

1999 ◽  
Vol 36 (4) ◽  
pp. 736-745 ◽  
Author(s):  
Jian-Hua Yin ◽  
James Graham
Keyword(s):  
Strain Rate ◽  
Creep Test ◽  
Triaxial Compression ◽  
Constant Strain Rate ◽  
Time Dependent ◽  
Model Parameters ◽  
Stress Strain ◽  
Equivalent Time ◽  
Strain Behaviour ◽  
Modified Cam Clay

This paper presents a new framework for elastic viscoplastic (EVP) constitutive modelling. In developing the model, a general one-dimensional elastic viscoplastic (1D EVP) relationship is first derived for isotropic stressing conditions using an "equivalent-time" concept. This 1D EVP model is then generalized into a three-dimensional EVP model based on Modified Cam-Clay and viscoplasticity. Fitting functions are proposed for fitting data when model parameters are being determined. Using these functions, a specific EVP model is developed which describes the time-dependent stress-strain behaviour of soils under triaxial stress states. This model has been calibrated using data from a densely compacted sand-bentonite mixture. The calibrated model is used to compute time-dependent (or strain rate dependent) stress-strain curves from a multistage shear creep test and a step-changed, constant strain rate undrained triaxial compression test. Predictions from the EVP model are in general agreement with measured values. It is demonstrated that the model can simulate accelerating creep when deviator stresses are close to the shear strength envelope in a q creep test. It can also model the behaviour in unloading-reloading and relaxation. Limitations and possible improvements are also indicated.Key words: equivalent time, stress-strain, time dependent, elastic, viscoplastic, triaxial.

The Strain Rate- and Temperature-Dependent Mechanical Behavior of Veriflex-E in Tension

2010 ◽  
Author(s):  
A. J. W. McClung ◽  
G. P. Tandon ◽  
J. W. Baur
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Monotonic Loading ◽  
Poisson's Ratio ◽  
Strain Magnitude

In this study, the inelastic deformation behavior of Veriflex-E, a thermally-triggered shape memory polymer resin, was investigated. The experimental program was designed to explore the influence of strain rate on monotonic loading at various temperatures. In addition, the creep behavior of specimens at various temperatures was evaluated. The time-dependent mechanical behavior of the Veriflex-E resin is strongly influenced by the temperature as well as the deformation rate. Thermally-actuated shape memory polymers can be thought of as having two phases separated by the glass transition temperature (Tg). At temperatures well below the Tg (room temperature), the Veriflex-E exhibits a high elastic modulus and positive, nonlinear strain rate sensitivity in monotonic loading. Likewise, the room temperature creep response is significantly influenced by the prior strain rate. The Poisson’s ratio at room temperature is independent of the strain rate, but dependent upon the strain magnitude. As the temperature is increased, the strain rate sensitivity in monotonic loading decreases. Well above the Tg, the elastic modulus drops by several orders of magnitude, and strong strain rate sensitivity is no longer observed in the path of the stress-strain curve. In this high temperature region, the material achieves strain levels well above 100% and the Poisson’s ratio is constant at 0.5 regardless of strain rate or strain magnitude. The creep strain, on the other hand, is significantly influenced by the prior strain rate at the elevated temperature. A slight hysteresis is observed during unloading, while recovery following unloading shows a permanent strain.

Constitutive Modeling on Time-Dependent Deformation Behavior of 96.5Sn-3.5Ag Solder Alloy Under Cyclic Multiaxial Straining

2006 ◽  
Vol 129 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Xianjie Yang ◽  
Yan Luo ◽  
Qing Gao
Keyword(s):  
Solder Alloy ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Back Stress ◽  
Time Dependent ◽  
Model Parameters ◽  
Stress Evolution ◽  
Deformation Properties ◽  
Strain Paths ◽  
Cyclic Straining

Based on the time dependent multiaxial deformation behavior of 96.5Sn-3.5Ag solder alloy, a constitutive model is proposed which considers the nonproportional multiaxial cyclic deformation properties. In the back stress evolution equations of this model, the nonproportionality which affects the back stress evolution rate is introduced. The approach for the determination of model parameters is proposed. The model is used to describe the time-dependent cyclic deformation behavior of 96.5Sn-3.5Ag solder alloy under cross, rectangular, rhombic, and double-triangular tensile–torsion multiaxial strain paths at different strain rates with different dwell time. The comparison between the predicted and experimental results demonstrates that the model can satisfactorily describe the time-dependent multiaxial cyclic deformation behavior under complicated nonproportional cyclic straining.

Sign in / Sign up

Export Citation Format

Share Document