| 摘要 |
PURPOSE: A crack measuring device is provided to measure a change of crack width precisely, conveniently, periodically and continuously with a varistor or a digital sensor. CONSTITUTION: A crack measuring apparatus with a varistor comprises a first fixed end, a second fixed end, a plunger(12), a varistor(13), a brush(14), a battery(20) and a display unit(19). First and second fixed ends are fastened in both sides of a crack, and the plunger is fastened in the first fixed end and slid in the second fixed end. The varistor is arranged on the plunger, and contacted to the brush fixed in the second fixed end. The plunger slides in cracking, and changes resistance value by sliding between the varistor and the brush. The change of the crack width is measured by detecting the change of the resistance value.
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