scholarly journals DYNAMIC MECHANICAL PROPERTIES OF PASSIVE SINGLE CARDIAC FIBERS FROM THE CRAB CANCER MAGISTER

1993 ◽  
Vol 185 (1) ◽  
pp. 207-249 ◽  
Author(s):  
E. Meyhofer
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Energy Dissipation ◽  
Strain Rate ◽  
Sarcomere Length ◽  
Viscoelastic Behavior ◽  
Dynamic Mechanical Properties ◽  
Cancer Magister ◽  
Dynamic Mechanical ◽  
Cardiac Fibers

I determined the dynamic mechanical properties of single relaxed cardiac fibers from the Dungeness crab Cancer magister. Single fibers were mechanically isolated, chemically skinned and subjected to small-amplitude sinusoidal length perturbations over a wide range of strain rates and sarcomere lengths to characterize their viscoelastic behavior. The observed mechanical properties, together with transcardiac pressure recordings and ultrastructural measurements, were related to the overall function of the heart. Single fibers, often longer than 1 mm, could be mechanically dissected from the heart of Cancer magister. They typically ranged from 20 to 100 micrometre in diameter and were surrounded by a 100- 400 nm thick extracellular matrix. In situ, under normal physiological loads, the heart of Cancer magister generated transcardiac pressures of about 1000 Pa and beat at 1 Hz, while the sarcomere lengths of fibers changed by 10 % from about 4.0 to 4.4 micrometre during contractions. The total stiffness of all fibers increased from approximately 0.01 MPa to 1 MPa in the sarcomere length range from 3.8 to 6.0 micrometre and increased two- to threefold with a rise in strain rate from 0.01 to 5 rad s-1. In the physiological range of sarcomere length (4.0-4.4 micrometre) and strain rate (0.5-1.2 rad s- 1), single cardiac fibers behaved viscoelastically, with average values for the relative energy dissipation ranging from 0.5 to 0.7. The volume fraction of the extracellular matrix correlated positively with the stiffness of single cardiac fibers. On the basis of these results, I propose a dual role for the viscoelastic behavior of Cancer magister cardiac fibers: (1) the viscous energy dissipation confers dynamic mechanical stability at the level of the single fiber, and (2) the storage and return of elastic strain energy saves energy at the level of the whole heart.

Effect of Graphene Nanoplatelets Content on Dynamic Mechanical Property of GNPs/Ti Composites

2018 ◽  
Vol 910 ◽  
pp. 123-129 ◽  
Author(s):  
X.N. Mu ◽  
H.N. Cai ◽  
Hong Mei Zhang ◽  
Q.B. Fan ◽  
Y. Wu
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Dynamic Compression ◽  
Dynamic Mechanical Properties ◽  
Graphene Nanoplatelets ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Dynamic Mechanical ◽  
Adiabatic Shearing

In this study, the titanium matrix composites (TiMCs) were fabricated by adding graphene nanoplatelets (GNPs). The dynamic compression test was carried out to study the effect of strain-rate and the GNPs content on dynamic mechanical properties of GNPs/Ti. Results show that the GNPs content (0wt%~0.8wt%) correspond to specific microstructure which affect the dynamic mechanical properties of the composites. Under high strain-rate (3500s-1), the 0.4wt%GNPs/Ti has the highest dynamic stress (~1860MPa) and strain (~30%). The adiabatic shearing band (ASB) microstructure of GNPs/Ti with various GNPs content has been observed under 3500s-1 strain-rate and the ASB microstructure evolution of 0.4wt%GNPs/Ti under different strain rate was investigated in particular.

scholarly journals Dynamic Mechanical Properties and Microstructure of an (Al0.5CoCrFeNi)0.95Mo0.025C0.025 High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1154
Author(s):  
Bingfeng Wang ◽  
Chu Wang ◽  
Bin Liu ◽  
Xiaoyong Zhang
Keyword(s):  
Mechanical Properties ◽  
Shear Band ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Dynamic Mechanical Properties ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Dynamic Mechanical

The dynamic mechanical properties and microstructure of the (Al0.5CoCrFeNi)0.95Mo0.025C0.025 high entropy alloy (HEA) prepared by powder extrusion were investigated by a split Hopkinson pressure bar and electron probe microanalyzer and scanning electron microscope. The (Al0.5CoCrFeNi)0.95Mo0.025C0.025 HEA has a uniform face-centered cubic plus body-centered cubic solid solution structure and a fine grain-sized microstructure with a size of about 2 microns. The HEA possesses an excellent strain hardening rate and high strain rate sensitivity at a high strain rate. The Johnson–Cook plastic model was used to describe the dynamic flow behavior. Hat-shaped specimens with different nominal strain levels were used to investigate forced shear localization. After dynamic deformation, a thin and short shear band was generated in the designed shear zone and then the specimen quickly fractured along the shear band.

scholarly journals Dynamic Mechanical Compression Impulse of Lithium-Ion Pouch Cells

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2105 ◽  
Author(s):  
Alon Ratner ◽  
Richard Beaumont ◽  
Iain Masters
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Lithium Ion ◽  
Rate Sensitivity ◽  
Dynamic Mechanical Properties ◽  
Impact Testing ◽  
Significant Feature ◽  
Dynamic Mechanical ◽  
The Impact

Strain rate sensitivity has been widely recognized as a significant feature of the dynamic mechanical properties of lithium-ion cells, which are important for their accurate representation in automotive crash simulations. This research sought to improve the precision with which dynamic mechanical properties can be determined from drop tower impact testing through the use of a diaphragm to minimize transient shock loads and to constrain off-axis motion of the indenter, specialized impact absorbers to reduce noise, and observation of displacement with a high speed camera. Inert pouch cells showed strain rate sensitivity in an increased stiffness during impact tests that was consistent with the poromechanical interaction of the porous structure of the jellyroll with the liquid electrolyte. The impact behaviour of the inert pouch cells was similar to that of an Expanded Polypropylene foam (EPP), with the exception that the inert pouch cells did not show hysteretic recovery under the weight of the indenter. This suggests that the dynamic mechanical behaviour of the inert pouch cells is analogous to a highly damped foam.

The Dynamic Mechanical Properties of CBF Composite Plate and its Sandwich Structure with Aluminum Foam Core

2010 ◽  
Vol 452-453 ◽  
pp. 281-284
Author(s):  
Zhong Liang Chang ◽  
Guang Ping Zou ◽  
Wei Ling Zhao ◽  
Yang Cao ◽  
Rui Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Composite Plate ◽  
Sandwich Structure ◽  
Aluminum Foam ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Mechanical Properties ◽  
Alkali Resistance ◽  
Foam Core ◽  
Dynamic Mechanical

The continuous basalt fiber (CBF) as inorganic fiber obtained from the basalt melt. It has high elastic modulus, low bulk density, low thermal conductivity, low moisture absorption rate and excellent alkali resistance, etc. In this paper, the split Hopkinson pressure bar (SHPB) technique is used for testing the CBF composite plate and its sandwich structure with aluminum foam core dynamic mechanical properties, and then to study the dynamic properties of CBF composite plate and its aluminum foam sandwich structure under different high strain rate. From the test results we can see that the CBF-foam aluminum sandwich structure has superior energy absorption properties, and also from the experiment results we can obtain that the sandwich structure dynamic stress-strain curves has a typically "three-phase" characteristics and strain rate effect.

Effect of Electromagnetic Force on Dynamic Mechanical Properties of the Magnetorheological Elastomer Under Compression Mode

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Xinxin Shi ◽  
Shaogang Liu ◽  
Dan Zhao ◽  
Zhenghang Zhao ◽  
Jin Cui ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Strain Amplitude ◽  
Electromagnetic Force ◽  
Dynamic Mechanical Properties ◽  
Loading Frequency ◽  
Magnetorheological Elastomer ◽  
Change Rate ◽  
Dynamic Mechanical ◽  
Energy Dissipation Capacity

Abstract Under the compression mode, the direction of force on the magnetorheological elastomer (MRE) is parallel to the direction of electromagnetic force, so the effect of electromagnetic force on its dynamic mechanical properties cannot be ignored. Therefore, this paper focuses on the effect of electromagnetic force on the dynamic mechanical properties of MRE under compression mode. A new type of testing device was designed and processed. Under a different loading frequency, strain amplitude and external magnetic field, dynamic mechanical properties of MRE were tested, respectively. The result shows that the stiffness and energy dissipation capacity of MRE increase with the current and loading frequency. The stiffness of MRE decreases with the increase in the strain amplitude, but the energy dissipation capacity increases. Comparing the force-displacement curve of MRE with or without the effect of the electromagnetic force, it shows that the electromagnetic force has a great effect on the stiffness of MRE and little effect on its energy dissipation capacity. When the electromagnetic force is removed, the stiffness of MRE decreases, and the change rate of stiffness increases with current. The maximum change rate of stiffness is 5.65%.

scholarly journals SHPB Testing and Analysis of Bedded Shale under Active Confining Pressure

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Guoliang Yang ◽  
Jingjiu Bi ◽  
Xuguang Li ◽  
Jie Liu ◽  
Yanjie Feng
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Peak Stress ◽  
Confining Pressure ◽  
Dynamic Mechanical Properties ◽  
Dynamic Elastic Modulus ◽  
Peak Strain ◽  
Dynamic Mechanical ◽  
Bedding Angle

Shale gas is the most important new energy source in the field of energy, and its exploitation is very important. The research on the dynamic mechanical properties of shale is the premise of exploitation. To study the dynamic mechanical properties of shale from the Changning-Weiyuan area of Sichuan Province, China, under confining pressure, we used a split Hopkinson pressure bar (SHPB) test system with an active containment device to carry out dynamic compression tests on shale with different bedding angles. (1) With active confining pressure, the shale experiences a high strain rate, and its stress-strain curve exhibits obvious plastic deformation. (2) For the same impact pressure, the peak stress of shale describes a U-shaped curve with an increasing bedding angle; besides, the peak stress of shale with different bedding angles increases linearly with rising confining pressure. The strain rate shows a significant confining pressure enhancement effect. With active confining pressure, the peak strain gradually decreases as the bedding angle increases. (3) As a result of the influence of different bedding angles, the dynamic elastic modulus of shale has obvious anisotropic characteristics. Shale with different bedding angles exhibits different rates of increase in the dynamic elastic modulus with rising confining pressure, which may be related to differences in the development of planes of weakness in the shale. The results of this study improve our understanding of the behavior of bedded shale under stress.

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