Mechanical behavior of ultrafine grained OFHC Cu at high strain rates

Author(s):  
L. J. Park ◽  
H. W. Kim ◽  
C. S. Lee ◽  
K.-T. Park
2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo

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.


2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Huiyang Luo ◽  
Chenkai Dai ◽  
Rong Z. Gan ◽  
Hongbing Lu

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.


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