International Journal of Aerospace and Lightweight Structures

doi: 10.3850/S2010428615100138

Checking Combustion Chamber Of Liquid Rocket Using Ect With AMR Sensor

Dongfeng He^1,a, Mitsuharu SHIWA¹, Shinichi Moriya², Naoki Nagao³ and Teiu Kobayashi^{3 1}National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, Japan. ^ahe.dongfeng@nims.go.jp ²Japan Aerospace Exploration Agency, 1 Koganezawa, Kakuda, Miyagi, Japan. ³Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki, Japan.

ABSTRACT

Eddy current testing (ECT) system with high sensitive anisotropic magneto resistive (AMR) sensor was developed. The magnetic field resolution of the AMR sensor was 12 pT/pHz at the frequencies above 1 kHz. To reduce the influence of lift off variance during scanning, a dual frequency excitation method was used. A circular coil with 20 turns and the diameter of 3 mm was used to produce the excitation field. Two probes were made with the sensing direction of the AMR sensor perpendicular to the coil or parallel with the coil. A chamber type specimen made of copper alloy was prepared to simulate the cooling grooves of the combustion chamber of liquid rocket. Artificial defects with the left wall thickness of 0mm, 0.2mm, 0.4mm, 0.6mm. were made in the bottom of some cooling grooves. The width of the defects was 0.2mm and the lengths of the defects were 3mm, 5mm and 10mm respectively. Using the dual frequency ECT system with AMR sensor, all the artificial defects were successfully detected.

Keywords: ECT, AMR, Combustion chamber.

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