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.

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.

scholarly journals Strain-Rate-Dependent Deformation Behavior and Mechanical Properties of a Multi-Phase Medium-Manganese Steel

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 344 ◽  
Author(s):  
Simon Sevsek ◽  
Christian Haase ◽  
Wolfgang Bleck
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Manganese Steel ◽  
Strain Rates ◽  
Rate Dependent ◽  
Medium Manganese Steel ◽  
Multi Phase

The strain-rate-dependent deformation behavior of an intercritically annealed X6MnAl12-3 medium-manganese steel was analyzed with respect to the mechanical properties, activation of deformation-induced martensitic phase transformation, and strain localization behavior. Intercritical annealing at 675 °C for 2 h led to an ultrafine-grained multi-phase microstructure with 45% of mostly equiaxed, recrystallized austenite and 55% ferrite or recovered, lamellar martensite. In-situ digital image correlation methods during tensile tests revealed strain localization behavior during the discontinuous elastic-plastic transition, which was due to the localization of strain in the softer austenite in the early stages of plastic deformation. The dependence of the macroscopic mechanical properties on the strain rate is due to the strain-rate sensitivity of the microscopic deformation behavior. On the one hand, the deformation-induced phase transformation of austenite to martensite showed a clear strain-rate dependency and was partially suppressed at very low and very high strain rates. On the other hand, the strain-rate-dependent relative strength of ferrite and martensite compared to austenite influenced the strain partitioning during plastic deformation, and subsequently, the work-hardening rate. As a result, the tested X6MnAl12-3 medium-manganese steel showed a negative strain-rate sensitivity at very low to medium strain rates and a positive strain-rate sensitivity at medium to high strain rates.

Investigation of the Hot Deformation Behavior of an Al-Mg-Sc-Zr Alloy under Plane Strain Condition

2014 ◽  
Vol 611-612 ◽  
pp. 76-83 ◽  
Author(s):  
Johannes Taendl ◽  
Martina Dikovits ◽  
Cecilia Poletti
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Hot Deformation Behavior ◽  
Flow Curves ◽  
Increasing Temperature ◽  
Zr Alloy

This study investigates the hot deformation behavior of a new Al-Mg-Sc-Zr alloy under plane strain conditions. Flow curves corrected for deformation heating were calculated for strain rates between 0.01 and 10s-1 in a temperature range of 200 to 400°C. To evaluate the deformation behavior, strain rate sensitivity as well as flow localization parameter maps were calculated for strains of 0.2, 0.4, and 0.6. In addition, microstructural investigations and hardness measurements were performed for selected samples. It was shown that the flow stress decreased with deacreasing strain rate and increasing temperature. The best formability was observed for high strain rates and low temperatures as well as for low strain rates and high temperatures. In these cases no flow instabilities were observed.

Effect of Heat Treatment on Compressive Properties of Open Cell Aluminum Foams

2007 ◽  
Vol 124-126 ◽  
pp. 1417-1420
Author(s):  
Chen Li ◽  
Zhi Hua Wang ◽  
Hong Wei Ma ◽  
Long Mao Zhao ◽  
Gui Tong Yang
Keyword(s):  
Heat Treatment ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Compressive Properties ◽  
Aluminum Foams ◽  
Open Cell ◽  
Subsequent Deformation ◽  
Similar Deformation

This paper presents a study of heat treatment on the quasi-static and dynamic compressive properties of the open cell aluminum alloy foams in as-fabricated (F), age-hardened (A) and T6-strengthened (T6) conditions. Although the strain rate and heat treatment of foams are different, all exhibit similar deformation behavior in the subsequent deformation. The yield stress of foams at different strain rates are improved by heat treatment, all exhibit some strain rate sensitivity. However, the densification strain of foams is not sensitive to heat treatment.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

scholarly journals Comparison in Deformation Behavior, Microstructure, and Failure Mechanism of Nickel Base Alloy 625 under Two Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2652
Author(s):  
Meng Liu ◽  
Quanyi Wang ◽  
Yifan Cai ◽  
Dong Lu ◽  
Tianjian Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Base Alloy ◽  
Inconel 625 ◽  
Tensile Fracture ◽  
Nickel Base Superalloy ◽  
Strain Rates ◽  
Tensile Fracture Surface ◽  
Nickel Base

Tensile deformation behavior and microstructure of nickel-base superalloy Inconel 625 are investigated under different strain rates of 5 × 10−4 s−1 and 5 × 10−5 s−1. According to the experimental results, yield strength and ultimate tensile strength of the alloy increase with the increase in strain rate in room temperature. Microstructure results indicate that the size of dimples is smaller in the tensile fracture surface at low strain rate than the high strain rate, and the number of dimples is also related to the strain rates and twins appear earlier in the specimens with higher strain rates. Apart from Hollomon and Ludwik functions, a new formula considering the variation trend of strength in different deformation stages is deduced and introduced, which fit closer to the tensile curves of the 625 alloy used in the present work at both strain rates. Furthermore, the Schmid factors of tensile samples under two strain rates are calculated and discussed. In the end, typical work hardening behavior resulting from the dislocations slip behavior under different strain rates is observed, and a shearing phenomenon of slip lines cross through the δ precipitates due to the movement of dislocations is also be note.

The effect of strain rates on tensile deformation of ultrafine-grained copper

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744014
Author(s):  
M. Li ◽  
Q. W. Jiang
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Strain Rates ◽  
Roll Bonding ◽  
Fracture Elongation ◽  
Tensile Deformation Behavior ◽  
Ultrafine Grained ◽  
Flow Stress Level

Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10[Formula: see text] s[Formula: see text] led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10[Formula: see text] s[Formula: see text], indicating a typical brittle fracture mode. When the strain rate is 10[Formula: see text] or 10[Formula: see text] s[Formula: see text], a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

Dynamic Deformation Behavior of As-Extruded Mg-Gd-Y Magnesium Alloy and the Microstructural Evolution

2011 ◽  
Vol 284-286 ◽  
pp. 1579-1583
Author(s):  
Ping Li Mao ◽  
Zheng Liu ◽  
Chang Yi Wang ◽  
Feng Wang
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Strain Rates ◽  
Compression Axis ◽  
Deformation Localization ◽  
Dynamic Deformation Behavior

The dynamic deformation behavior of an as-extruded Mg-Gd-Y magnesium alloy was studied by using Split Hopkinson Pressure Bar (SHPB) apparatus under high strain rates of 102 s-1 to 103s-1 in the present work, in the mean while the microstructure evolution after deformation were inspected by OM and SEM. The results demonstrated that the material is not sensitive to the strain rate and with increasing the strain rate the yield stress of as-extruded Mg-Gd-Y magnesium alloy has a tendency of increasing. The microstructure observation results shown that several deformation localization areas with the width of 10mm formed in the strain rates of 465s-1 and 2140s-1 along the compression axis respectively, and the grain boundaries within the deformation localization area are parallel with each other and are perpendicular to the compression axis. While increasing the strain rate to 3767s-1 the deformation seems become uniform and all the grains are compressed flat in somewhat. The deformation mechanism of as-extruded Mg-Gd-Y magnesium alloy under high strain rate at room temperature was also discussed.

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

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