Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: crack monitor

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Wet paper stretches. It also does not tear suddenly. Glass microscope slides makes a better telltale as it is brittle and has little elongation, however, uneven surfaces make adhesion difficult. Both will only show enlarging of a crack, not closure, and the paper will be restricted to planar movement. Across uneven surfaces it will be wavy/creased which will allow additional movement before tearing. Additionally, it will not stick effectively unless the surfaces are very clean. The same problem (regarding surface cleanliness) occurs with epoxy. At a collapse site theodolites are preferred as they also allow remote monitoring. While in the collapsed building falling dust and noise make an excellent telltale.