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Abstract In order to investigate the regularity of crack propagation under blasting dynamic loads，polymethyl methacrylate(PMMA) plates are employed to make samples containing a single crack and a borehole. The borehole is designed along the quadrant of a circle centered at one crack tip with radius of 60 mm. A detonator inside the borehole is fired to produce dynamic stress waves. The effects of incident angles of stress waves on crack initiation angles and propagation angles have been studied experimentally. The results show that：(1) As incident angle is 0°，crack initiation angle is 0°，i.e. the cracks propagate along the crack surface plane；(2) As incident angle is greater than 15° and less than 75°，wing-cracks occur along the pre-existing crack tips；(3) The wing-crack property is related to the incident angle of stress waves；(4) As incident angle is greater than 75°，new developed cracks are very small.
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Received: 05 November 2012
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2013, Vol. 32 
