CRACK DETECTOR

PURPOSE:To obtain a detector which can observe surely and continuously the generation and the advance of a crack by constituting a gauge by bridging and attaching a fine line alternately to each line in two lines of terminal parts attached to an elastic film. CONSTITUTION:The gauge 1 is constituted by arranging and attaching plural pieces of terminal parts 3 in two lines of both sides on an elastic film 2 consisting of an insulating material. To each terminal part 3, the end of a middle lead wire 4 is soldered. Between respective terminal parts 3, a notch 5 is formed, and the elastic film 2 along the sticking shape of the gauge 1 can be deformed. A fine line 6 is attached and formed in a meandering state and alternately to each line so as to bridge two lines of terminal parts 3. In this state, the gauge 1 is stuck to a crack generating part, the fine line 6 for bridging the terminal parts is cut in order by the generation and the advance of a crack, and a resistance value between two lines of terminal parts 3 of the gauge 1 is varied, by which the generation and the advance state of the crack can be obtained surely and continuously without stopping a fatigue testing machine.