DEVICE AND METHOD FOR INDICATING IF A FASTENING ELEMENT HAS REACHED A TENSILE YIELD LIMIT LOAD.

摘要

A device and method for indicating if a fastening element upon fastening to a piece has reached a tensile yield limit load. The fastening element includes a threaded shaft having a magnetostrictive material. The device includes a mechanism for generating an alternating magnetic field that penetrates the shaft, a mechanism for measuring a physical quantity that depends on the momentary magnetic susceptibility of the shaft and a control unit adapted to detect a significant change of the physical quantity and determine and indicate if the shaft of the fastening element has reached the tensile yield limit load.