Improving adhesion strength analysis by the combination of ultrasonic and mechanical tests on single lap joints.

International audienceThe aim of this paper is to improve knowledge about adhesion strength in single-lap joints by comparison of data from both Non Destructive Testing (NDT) and standard mechanical tests. study presents a high-frequency ultrasonic imaging of aluminum-epoxy-aluminum joints that carefully chemically prepared using two different surface treatments of the aluminum substrate: silanization and chromic-sulfuric etching. The surface energy of the treated substrate is complete set of ultrasonic data are obtained using high-frequency focused transducers. After inspection, single-lap shear tests were performed, and the mechanical strength of each joint is determined. The good cor relations among the surface measurements, the mechanical tests and ultrasonic results are presented and discussed. The demonstration of a close correlation between ultrasonic images obtained at high frequency and the fracture surface is promising

Determination of Acoustic Attenuation in Composites by the Time Frequency Method

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Interference-filter-stabilized external-cavity diode lasers

International audienceWe have developed external cavity diode lasers, where the wavelength selection is assured by a low loss interference filter instead of the common diffraction grating. The filter allows a linear cavity design reducing the sensitivity of the wavelength and the external cavity feedback against misalignment. By separating the feedback and wavelength selection functions, both can be optimized independently leading to an increased tunability of the laser. The design is employed for the generation of laser light at 698, 780 and 852 nm. Its characteristics make it a well suited candidate for space-born lasers

Towards evaluating variable adhesion on single lap shear joints using high-frequency ultrasonic analysis

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Towards evaluating variable adhesion on single lap shear joints using high-frequency ultrasonic analysis

International audienc

An optical lattice clock with spin-polarized 87Sr atoms

International audienceWe present a new evaluation of an <SUP>87</SUP>Sr optical lattice clock using spin polarized atoms. The frequency of the <SUP>1</SUP>S<SUB>0</SUB>--><SUP>3</SUP>P<SUB>0</SUB> clock transition is found to be 429 228 004 229 873.6 Hz with a fractional uncertainty of 2.6×10<SUP>-15</SUP>, a value that is comparable to the frequency difference between the various primary standards throughout the world. This measurement is in excellent agreement with a previous one of similar accuracy [Phys. Rev. Lett. 98, 083002 (2007)]