Measurement of Young’s Modulus of Human Tympanic Membrane at High Strain Rates

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Huiyang Luo ◽  
Chenkai Dai ◽  
Rong Z. Gan ◽  
Hongbing Lu
Keyword(s):  
Mechanical Behavior ◽  
Tympanic Membrane ◽  
Young’S Modulus ◽  
High Strain ◽  
Young's Modulus ◽  
Strong Dependence ◽  
Strain Rates ◽  
Loading Conditions ◽  
High Strain Rates ◽  
Human Tympanic Membrane

The mechanical behavior of human tympanic membrane (TM) has been investigated extensively under quasistatic loading conditions in the past. The results, however, are sparse for the mechanical properties (e.g., Young's modulus) of the TM at high strain rates, which are critical input for modeling the mechanical response under blast wave. The property data at high strain rates can also potentially be converted into complex modulus in frequency domain to model acoustic transmission in the human ear. In this study, we developed a new miniature split Hopkinson tension bar to investigate the mechanical behavior of human TM at high strain rates so that a force of up to half of a newton can be measured accurately under dynamic loading conditions. Young’s modulus of a normal human TM is reported as 45.2–58.9 MPa in the radial direction, and 34.1–56.8 MPa in the circumferential direction at strain rates 300–2000 s−1. The results indicate that Young’s modulus has a strong dependence on strain rate at these high strain rates.

scholarly journals Applicability of Mechanical Tests for Biomass Pellet Characterisation for Bioenergy Applications

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1329 ◽  
Author(s):  
Orla Williams ◽  
Simon Taylor ◽  
Edward Lester ◽  
Sam Kingman ◽  
Donald Giddings ◽  
...  
Keyword(s):  
Strain Rate ◽  
Young’S Modulus ◽  
High Strain ◽  
Young's Modulus ◽  
Mechanical Tests ◽  
Strain Rates ◽  
High Strain Rates ◽  
Dynamic Mechanical ◽  
Pellet Strength ◽  
Biomass Pellet

In this paper, the applicability of mechanical tests for biomass pellet characterisation was investigated. Pellet durability, quasi-static (low strain rate), and dynamic (high strain rate) mechanical tests were applied to mixed wood, eucalyptus, sunflower, miscanthus, and steam exploded and microwaved pellets, and compared to their Hardgrove Grindability Index (HGI), and milling energies for knife and ring-roller mills. The dynamic mechanical response of biomass pellets was obtained using a novel application of the Split Hopkinson pressure bar. Similar mechanical properties were obtained for all pellets, apart from steam-exploded pellets, which were significantly higher. The quasi-static rigidity (Young’s modulus) was highest in the axial orientation and lowest in flexure. The dynamic mechanical strength and rigidity were highest in the diametral orientation. Pellet strength was found to be greater at high strain rates. The diametral Young’s Modulus was virtually identical at low and high strain rates for eucalyptus, mixed wood, sunflower, and microwave pellets, while the axial Young’s Modulus was lower at high strain rates. Correlations were derived between the milling energy in knife and ring roller mills for pellet durability, and quasi-static and dynamic pellet strength. Pellet durability and diametral quasistatic strain was correlated with HGI. In summary, pellet durability and mechanical tests at low and high strain rates can provide an indication of how a pellet will break down in a mill.

Mapping the Young's modulus distribution of the human tympanic membrane by microindentation

2019 ◽  
Vol 378 ◽  
pp. 75-91 ◽  
Author(s):  
Huiyang Luo ◽  
Fang Wang ◽  
Chen Cheng ◽  
Don U. Nakmali ◽  
Rong Z. Gan ◽  
...  
Keyword(s):  
Tympanic Membrane ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Human Tympanic Membrane

Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Orthopedic Implants ◽  
Strain Rates ◽  
High Strain Rates ◽  
Static Compression ◽  
Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

Sign in / Sign up

Export Citation Format

Share Document