scholarly journals The rate (time)-dependent mechanical behavior of the PMR-15 thermoset polymer at elevated temperature

2008 ◽  
Vol 27 (7) ◽  
pp. 908-914 ◽  
Author(s):  
A.J.W. McClung ◽  
M.B. Ruggles-Wrenn
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Time Dependent ◽  
Thermoset Polymer

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.

Microstructure, excess solid solubility, and elevated-temperature mechanical behavior of spray-atomized and codeposited Al-Ti-SiCP

1992 ◽  
Vol 23 (6) ◽  
pp. 719-736 ◽  
Author(s):  
M. Gupta ◽  
J. Juarez-Islas ◽  
W. E. Frazier ◽  
F. A. Mohamed ◽  
E. J. Lavernia
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Solid Solubility

scholarly journals Time-dependent mechanical behavior of lime-mortar masonry

2010 ◽  
Vol 44 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Els Verstrynge ◽  
Luc Schueremans ◽  
Dionys Van Gemert
Keyword(s):  
Mechanical Behavior ◽  
Time Dependent ◽  
Lime Mortar

scholarly journals Time-dependent alterations in the deformability of human neutrophils in response to chemotactic activation

Blood ◽  
1990 ◽  
Vol 76 (12) ◽  
pp. 2606-2612 ◽  
Author(s):  
RS Frank
Keyword(s):  
Mechanical Behavior ◽  
Control Level ◽  
Colchicine Treatment ◽  
Time Dependent ◽  
Cell Stiffness ◽  
Human Neutrophils ◽  
Partial Recovery ◽  
Cell Deformability ◽  
Two Phase ◽  
Transit Times

Abstract Transit times of individual human neutrophils through single capillary- sized pores were measured to determine the time-dependent changes in the mechanical behavior of the cells during activation by the chemotactic agent formyl-methionyl-leucyl-phenylalanine (FMLP) and in response to cytochalasin B (CTB) and colchicine. FMLP elicited a two- phase response consisting of a rapid increase in cell stiffness, which peaked between 2 and 3 minutes, followed by a partial recovery of deformability to a level significantly above that of control after 5 minutes. The mechanical changes closely followed changes in F-actin content, although the peak in cell stiffness appeared to lag the F- actin response. Treatment with 3 mumols/L CTB produced a transient decrease in cell rigidity followed by a return to control level in 10 minutes, whereas treatment with 30 mumols/L CTB resulted in a sustained decrease in cell transit times to a level 60% of control. Addition of 3 mumols/L CTB to cells prestimulated with FMLP produced a rapid (1 to 2 minutes) cessation of changes in cellular deformability produced by the FMLP. Colchicine treatment did not decrease cell rigidity, but produced a delayed increase in F-actin content accompanied by increased stiffness of the cells. These results implicate actin as the major determinant of the mechanical behavior of the neutrophil, as measured by whole cell deformability tests. The significant changes in cell deformability that occur in response to fractional changes in F-actin content suggest that changes in the structure of the actin network occur during these processes.

The Effect of Low-Angle and High-Angle Grain Boundaries on Elevated Temperature Strength

1994 ◽  
Vol 362 ◽  
Author(s):  
M. E. Kassner
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Large Angle ◽  
High Angle ◽  
Elevated Temperature Strength ◽  
Ambient Temperatures ◽  
The Past ◽  
Creep Regime ◽  
New Evidence ◽  
General Opinion

AbstractThe influence of small (subgrain) misorientation interfaces on the mechanical behavior of metals and alloys deforming within the creep regime has been intensively studied over the past several decades. Controversies have existed, but some new experiments suggest, contrary to the general opinion, that low-angle boundaries are not associated with the rate controlling process for plasticity and do not affect strength. The new evidence will be discussed in terms of other established experimental trends. Large-angle boundaries may have a smaller effect on elevated temperature strength than at ambient temperatures and do not appear to dramatically affect elevated temperature strength. Superplastic effects are not addressed.

Sign in / Sign up

Export Citation Format

Share Document