Original paper(Vol.46 No.9 pp.1017)
Mechanical behavior in Al2O3FRP and metal sleeve joint of insulating load support for superconducting magnet
Ejima Hidehiro; Usami Saburo; Suzuki Fumio; Watanabe Hiroyuki
Abstract:A Rod type and a cylinder-rod type load supports are developed for superconducting magnets of magnetic levitation vehicles. The load supports act as thermal insulators and, at the same time, are required to sustain vibrating loads. The supports are made of Al2O3FRP and have joints contacting with metal sleeve. The material of rod is unidirectional Al2O3FRP, while that of cylinder is satin woven laminating Al2O3FRP. The results obtained in this study on mechanical behavior of the load support are as follows:
(1)The Unidirectional Al2O3FRP rod and the metal sleeve can be tightly joined by pulling them to opposite directions, each of which has a matching taper fce with solid lubricant before assembling.
(2)The impregnation resin of Al2O3FRP should have a high glass transition temperature, i.e. 453K, for reverting a decrease in joint force due to stress relaxation of the resin at room temperature. By using a sufficiently large circumferential elastic strain to both the rod and the sleeve than the cooling thermal strain of Al2O3FRP, high joint force remains even at a cryogenic temperature and the joint can sustain high vibrating loads.
(3)The replenishment resin, which forms a wedge shape at both ends of cylinder in the wedge shape groove of the metal sleeve, should have the glass transition temperature of 398 K, so as to prevent the joint from stress relaxation at room temperature. By curing the replenishment resin in the cylinder-rod type load support, the relaxation in the rod is kept as low as 10% because of high enough glass transition temperature of rod resin.
Key Words:superconducting magnet, load support, Al23 FRP, impregnation resin, joint force, stress relaxation