Cyclic Stress-Strain Response and Dislocation Configuration of a Beta Phase Containing TiAl Alloy during Isothermal Fatigue Tests under Different Strain Rate

2013 ◽  
Vol 683 ◽  
pp. 314-317
Author(s):  
Hong Fu Xiang ◽  
Jing Hai Tao ◽  
Ji Heng Wang ◽  
Hui Li ◽  
An Lun Dai
Keyword(s):  
Strain Rate ◽  
Tial Alloy ◽  
Beta Phase ◽  
Cyclic Stress ◽  
Strain Rates ◽  
Strain Response ◽  
Stress Strain ◽  
Aluminum Compound ◽  
Dislocation Configuration ◽  
Isothermal Fatigue

A beta phase containing titanium aluminum compound was prepared. Isothermal Fatigue(IF) were subjected at 650 °C at three strain rates, such as 6.67×10-3s-1, 6.67×10-4s-1, 6.67×10-5s-1to determine the effect of strain rate on cyclic stress-strain response (CSSR) of TiAl alloy during IF tests. The curves of cyclic stress-strain response were discussed and dislocations configuration were also observed by TEM. The results show that strain rates have an apparent effect on CSSR of TiAl alloy during IF tests and CSSR was identified that it had a close relationship with dislocation configuration and deformation twin.

Mechanical Response of Human Muscle at Intermediate Strain Rates

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Xuedong Zhai ◽  
Eric A. Nauman ◽  
Yizhou Nie ◽  
Hangjie Liao ◽  
Roy J. Lycke ◽  
...  
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Mechanical Response ◽  
Human Muscle ◽  
Fiber Direction ◽  
Strain Rates ◽  
Strain Response ◽  
Stress Strain ◽  
Intermediate Strain Rates

We experimentally determined the tensile stress–strain response of human muscle along fiber direction and compressive stress–strain response transverse to fiber direction at intermediate strain rates (100–102/s). A hydraulically driven material testing system with a dynamic testing mode was used to perform the tensile and compressive experiments on human muscle tissue. Experiments at quasi-static strain rates (below 100/s) were also conducted to investigate the strain-rate effects over a wider range. The experimental results show that, at intermediate strain rates, both the human muscle's tensile and compressive stress–strain responses are nonlinear and strain-rate sensitive. Human muscle also exhibits a stiffer and stronger tensile mechanical behavior along fiber direction than its compressive mechanical behavior along the direction transverse to fiber direction. An Ogden model with two material constants was adopted to describe the nonlinear tensile and compressive behaviors of human muscle.

The effects of gage length and strain rate on tensile behavior of Kevlar® 29 single filament and yarn

2016 ◽  
Vol 51 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Yunfu Ou ◽  
Deju Zhu ◽  
Mengying Huang ◽  
Hang Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Strain Rate ◽  
Gage Length ◽  
Strain Rates ◽  
Strain Response ◽  
Stress Strain ◽  
Single Filament ◽  
Weibull Parameters ◽  
Structural Scale

The mechanical properties of Kevlar® 29 single filaments and yarns with different gage lengths were investigated by utilizing an MTI miniature tester and an MTS load frame. Single yarns of 25 mm were also tested over four different strain rates using a drop-weight impact system. The experimental results showed that the mechanical properties of Kevlar® 29 are sensitive to gage length, structural size scale, and strain rate. The tensile strength decreased with increasing gage length and the structural scale from fiber to yarn, and increased with increasing strain rate. Weibull analysis was conducted to quantify the degree of variability in tensile strength. The obtained Weibull parameters were then used in an analytical model to simulate the stress–strain response of single yarn. Finally, Weibull parameters of single filaments with other gage lengths and strain rates were also obtained by fitting the stress–strain curves of single yarns with corresponding testing conditions.

Effect of Temperature on Cyclic Behavior of AZ31 Mg Alloy Sheet

2014 ◽  
Vol 939 ◽  
pp. 47-52
Author(s):  
Takashi Katahira ◽  
Syohei Hosokawa ◽  
Tetsuo Naka ◽  
Masahide Kohzu ◽  
Hiroki Adachi ◽  
...  
Keyword(s):  
Strain Rate ◽  
Deformation Mechanism ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Cyclic Stress ◽  
Tension Test ◽  
Cyclic Plasticity ◽  
Strain Rates ◽  
Stress Strain ◽  
Az31 Sheet

Magnesium alloy sheets have a potential to be widely used in many fields of industry due to their excellent lightweight property. Although magnesium alloys have low ductility at the room temperature due to their hexagonal close-packed structure, their formability can be improved at elevated temperatures. Therefore, warm press-forming of magnesium alloy sheets is an attractive technology. The objective of the present work is to investigate the cyclic plasticity behavior of an AZ31 sheet at elevated temperatures by performing cyclic tension-compression experiments. The cyclic deformation mechanism is examined by measuring the crystallographic orientation distributions by means of X-ray diffraction method at each stage of the cyclic deformation. The present findings are summarized as follows: (1) Stress-strain responses of an AZ31 sheet were investigated at various temperatures (R.T, 100, 150 and 200°C) at strain rates of 0.001, 0.01 and 0.05 s-1. The flow stresses were insensitive to the strain rate at the room temperature, however the strain rate dependency of the flow stress becomes dominant at elevated temperatures of over 100 °C.(2) Cyclic plasticity behavior of the sheet at various elevated temperatures (R.T, 100, 150 and 200 °C) at strain rates of 0.001, 0.01 and 0.05 s-1 were investigated by performing warm in-plane cyclic compression-tension test. Similarly to the uniaxial tension test, apparent temperature and strain rate dependencies of the flow stress were observed at temperatures of over 100 °C. (3) At the room temperature an unusual cyclic stress-strain curve, which is very different from that of bcc and fcc metals, was observed. From the texture measurement it was found that such a specific stress-strain characteristic is due to its twinning and detwinning deformation mechanism.(4) In contrast, at an elevated temperature of 200 °C, the usual cyclic stress-strain response, which is similar to one appearing in most of metallic materials, was observed. This is because the major deformation mechanism at an elevated temperature is the slip, rather than twinning/detwinning, since the CRSS decreases drastically with increasing temperature.

Cyclic stress-strain response of porous aluminum

1990 ◽  
Vol 6 (2) ◽  
pp. 207-230 ◽  
Author(s):  
Han C. Wu ◽  
Paul T. Wang ◽  
W.F. Pan ◽  
Z.Y. Xu
Keyword(s):  
Cyclic Stress ◽  
Strain Response ◽  
Stress Strain ◽  
Porous Aluminum

Understanding Dynamic Recrystallization Behavior through a Delay Differential Equation Approach

2007 ◽  
Vol 558-559 ◽  
pp. 441-448 ◽  
Author(s):  
Jong K. Lee
Keyword(s):  
Differential Equation ◽  
Strain Rate ◽  
Critical Strain ◽  
Strain Curve ◽  
Single Peak ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Behavior ◽  
Delay Differential

During hot working, deformation of metals such as copper or austenitic steels involves features of both diffusional flow and dislocation motion. As such, the true stress-true strain relationship depends on the strain rate. At low strain rates (or high temperatures), the stress-strain curve displays an oscillatory behavior with multiple peaks. As the strain rate increases (or as the temperature is reduced), the number of peaks on the stress-strain curve decreases, and at high strain rates, the stress rises to a single peak before settling at a steady-state value. It is understood that dynamic recovery is responsible for the stress-strain behavior with zero or a single peak, whereas dynamic recrystallization causes the oscillatory nature. In the past, most predictive models are based on either modified Johnson-Mehl-Avrami kinetic equations or probabilistic approaches. In this work, a delay differential equation is utilized for modeling such a stress-strain behavior. The approach takes into account for a delay time due to diffusion, which is expressed as the critical strain for nucleation for recrystallization. The solution shows that the oscillatory nature depends on the ratio of the critical strain for nucleation to the critical strain for completion for recrystallization. As the strain ratio increases, the stress-strain curve changes from a monotonic rise to a single peak, then to a multiple peak behavior. The model also predicts transient flow curves resulting from strain rate changes.

Effect of loading history on cyclic stress–strain response

2001 ◽  
Vol 314 (1-2) ◽  
pp. 1-6 ◽  
Author(s):  
L Kunz ◽  
P Lukáš ◽  
B Weiss ◽  
D Melisova
Keyword(s):  
Cyclic Stress ◽  
Strain Response ◽  
Loading History ◽  
Stress Strain

scholarly journals A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Bin Xu ◽  
Xiaoyan Lei ◽  
P. Wang ◽  
Hui Song
Keyword(s):  
Strain Rate ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Experimental Results ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

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