Study of brittle fracture by acoustic emission from indentation cracks

This paper describes a novel approach for investigating the fracture of brittle solids by combining a theory of acoustic emission (AE) with the Dugdale–Barenblatt model. An example is provided with indentation‐produced, half‐penny‐shaped cracks that were generated by pressing a Vickers indenter onto the surface of a glass plate and that produced AE signals. These were detected using four capacitive displacement transducers, one at epicenter and the other three at off‐epicentral positions. Assuming that a mode I type of crack was generated and using indentation fracture mechanics, a mode I stress intensity factor KIc=7.44×105 N/m3/2 was obtained. Both dipole strength and source‐time function associated with crack formation were determined from the AE theory. Assuming that an effective gauge length can be interpreted equal to a dipole linkage distance and using the Dugdale–Barenblatt model for the fracture of brittle solids, it is shown that all the other important parameters on crack formation can be deter...

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