The material properties of an oxygen-free high thermal conductivity (OFHC) film with a thickness of 0.1 mm were evaluated at strain rates ranging from 10 −3 /s to 10 3 /s using a high-speed material micro-testing machine (HSMMTM). The high strain-rate material properties of thin films are important especially for an evaluation of the structural reliability of micro-formed parts and MEMS products. The high strain-rate material testing methods of thin films, however, have yet to be established to the point that the testing methods of larger specimens for electronics, auto-body, train, ship, and ocean structures are. For evaluation, a new type of HSMMTM was developed to conduct high-speed tensile tests of thin films. This machine is capable of testing at a sufficiently high tensile speed with an electromagnetic actuator, a novel gripping mechanism, and an accurate load measurement system. The OFHC copper film shows high strain-rate sensitivity in terms of the flow stress, fracture elongation, and strain hardening. These measures increase as the tensile strain rate increases. The rate-dependent material properties of an OFHC copper film are also compared with those of a bulk OFHC copper sheet with a thickness of 1 mm. The flow stress of an OFHC copper film is relatively low compared to that of a bulk OFHC copper sheet in the entire range of strain rates, while the fracture elongation of an OFHC copper film is much larger than that of a bulk OFHC copper sheet. A quantitative comparison would provide material data at high strain rates for the design and analysis of microappliances and different types of micro-equipment.
We investigate a six-air-hole bismuth-oxide-based photonic crystal fiber (Bi-PCF) in terms of Brillouin characteristics. One huge challenge in measuring the Brillouin properties of the Bi-PCF is the nonnegligible beam reflection at the splicing points, which can be attributed to the mirroring effect caused by different refractive indices of silica and bismuth fibers. To solve the problem we propose a method that is based on the combination of a pump-probe beat lock-in scheme and a normalized gain curve-fitting technique. Using this method, successful characterization of Brillouin properties for a 1.16-m-long Bi-PCF is experimentally demonstrated. With the measured Brillouin gain coefficient and the known chi((3)) nonlinearity parameters, the Kerr nonlinearity figure-of-merit (F(nl-SBS)), including the stimulated Brillouin scattering-caused pump-power limit, is also estimated for the Bi-PCF.
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