Experimental research of self-regularities of ceramics fracture under shock wave loading

A series of UEWE (underwater electrical wire explosion) experiments were carried out to study the fragmentation of ceramic tubes under shock wave (SW) loading caused by explosion of the axial conductor. The amplitude of shock wave loading of the samples in the UEWE setup was regulated by varying the energy of the battery of capacitors charged by high voltage source. Duration of the discharge was 0,3-0,8 µs. The statistical distribution of the tube fragments was determined by gathering fragments from the bottom of the explosion chamber. The mass of the collected fragments was about 98 % of the mass of the original sample. The size of fragments estimated by two methods is “weighing” and “photography”. The “photography” method was based on the form factor of fragments, which was calculated separately. The distributions obtained by both techniques were in good agreement. Since the mass of the tubes was varied, the parameter of the specific energy of the loading pulse was introduced in order to correlate the data. The collected fragments can be divided into two classes: quasi-two dimensional objects (2D) with characteristic fragment size d* is greater or equal to the thickness d of the tube wall and three-dimensional (3D) with characteristic size less than the wall thickness. It was found that the distribution of the 3D objects could be described by a power law, in which the value of the power remains constant and does not depend on the specific energy. Distribution of the 2D fragments obeys an exponential law. It is shown that the inflection point of the fragment distribution curve is shifted toward smaller scales with increasing of the specific energy. The existence of different distributions for the different scale of the fragments is explained.