| 摘要 |
PCT No. PCT/FI94/00540 Sec. 371 Date May 30, 1996 Sec. 102(e) Date May 30, 1996 PCT Filed Nov. 30, 1994 PCT Pub. No. WO95/15443 PCT Pub. Date Jun. 8, 1995A plate-like washer of generally annular shape and a method of using the washer for pre-tensioning. The washer is adapted to be placed between a fastening element, used to attach two pieces to form a coupling, and a piece to be fastened. The washer is manufactured from a shape-memory metal whose upper transformation temperature is higher than the highest use and assembly temperature of the coupling. The thickness of the washer is adapted in view of the length and pre-tensioning need of the fastening element, as well as the expansion of the washer at the upper transformation temperature. The washer is actively heated to its upper transformation temperature and undergoes a phase transformation which expands the washer and pre-tensions the coupling to the desired degree.
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