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.

High Strain-Rate Compressive Behavior and Constitutive Modeling of Selected Polymers Using Modified Ramberg-Osgood Equation

2014 ◽  
Vol 566 ◽  
pp. 80-85
Author(s):  
Kenji Nakai ◽  
Takashi Yokoyama
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Compressive Stress ◽  
Constitutive Modeling ◽  
High Strain ◽  
Strain Rates ◽  
Stress Strain ◽  
Strain Behavior ◽  
Least Squares Fit ◽  
Wide Range

The present paper is concerned with constitutive modeling of the compressive stress-strain behavior of selected polymers at strain rates from 10-3 to 103/s using a modified Ramberg-Osgood equation. High strain-rate compressive stress-strain curves up to strains of nearly 0.08 for four different commercially available extruded polymers were determined on the standard split Hopkinson pressure bar (SHPB). The low and intermediate strain-rate compressive stress-strain relations were measured in an Instron testing machine. Six parameters in the modified Ramberg-Osgood equation were determined by fitting to the experimental stress-strain data using a least-squares fit. It was shown that the monotonic compressive stress-strain behavior over a wide range of strain rates can successfully be described by the modified Ramberg-Osgood constitutive model. The limitations of the model were discussed.

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.

scholarly journals Determination of High Strain-Rate Compressive Stress-Strain Loops of Selected Polymers

2010 ◽  
Vol 24-25 ◽  
pp. 349-355 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
Strain Rate ◽  
Compressive Stress ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Viscoelastic Behavior ◽  
Strain Range ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dissipation Energy

Compressive stress-strain loops of selected polymers at strain rates up to nearly 800/s are determined in a strain range of nearly 8% on the standard split Hopkinson pressure bar. Four different commercially available extruded polymers are tested at room temperature. The compressive stress-strain loops at low and intermediate strain rates are measured on an Instron testing machine. The effects of strain rate on the Young's modulus, flow stress and dissipation energy are discussed. It is shown that the area included within the stress-strain loop increases with increasing strain rate as well as a given strain, that is, all four extruded polymers tested exhibit intrinsic strain-rate dependent viscoelastic behavior and a high elastic aftereffect following complete unloading.

scholarly journals Mechanical properties and constitutive model of Sn-58Bi alloy

2021 ◽  
Author(s):  
Kebin Zhang ◽  
Wenbin Li ◽  
Ping Song ◽  
Changfang Zhao ◽  
Kewin Zhang
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Constitutive Model ◽  
Strain Rate ◽  
Compressive Stress ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Strain Rates ◽  
Stress Strain ◽  
Static Conditions

Abstract Sn-58Bi alloy is a strain-rate-sensitive material. To study the mechanical properties of Sn-58Bi alloy, an MTS universal testing machine and split-Hopkinson pressure bar were used to conduct quasi-static and dynamic testing on Sn-58Bi alloy, obtaining the stress-strain curve of Sn-58Bi alloy at the strain rate of 0.001–6316 s−1. By comparing the tensile and compressive stress–strain curves of Sn-58Bi alloy under quasi-static conditions, it is found that Sn-58Bi alloy is brittle, with its tensile yield strength lower than its compressive yield strength. By comparing the compressive stress–strain curves of Sn-58Bi alloy at different strain rates, it is found that the yield strength of Sn-58Bi alloy increases with increasing strain rate, and a strain-hardening phenomenon is manifested at high strain rate. By revising the Johnson–Cook constitutive model, the constitutive model of Sn-58Bi alloy at different strain rates was established, with the calculated results of the model in good agreement with the experimental results.

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.

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.

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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