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Destruction mechanics: self-destruction

Cherepanov G. P., Esparragoza I. E.

International Journal of Applied Mechanics and Engineering

2007

Vol. 12, no 2

565-570

Fracture meehanics studies the cracking of a material while destruction is the fraeturing/separation of a material into smali debris by very many cracks. In the latter case, a fraeture front or wave separates the intact material from that destructed into smali particles. As distinct from fracture mechanies, destruction mechanies does not concern about how and where each crack grows. Its main interest is to study the location and motion of the fracture front. The present paper is a brief presentation of destruction mechanics and, especially, self-destruction, or selfsustaining fracture in former terminology, as its most interesting subject. Destruction in this approach is treated like a specific phase transition of an intact material into a destructed one. The general condition of destruction is formulated in terms of energy. Some problems of destruction mechanies are briefly reviewed, including quasistatie problems of local destruction in stress concentration zones, stability and instability of destruction process, flame drilling, a theory of Tungus meteorite destruction, and dynamic problems such as the problems of underground explosion, collision of brttle bodies, and propagation of a plane fracture wave from a free boundary. The dynamic, explosive growth of the destruction zone occurring by itself, uncontrollably, is called the selfdestruction. Self- destruction starts from a small change in the boundary or loading playing the part of a trigger initiating a fracture wave that propagates at the speed of sound and destructs all material being at the metastable, overstressed condition. The destruction of Batavian tears is a well-known example of self-destruction. Coal bursts and rock bursts as self-destruction phenomena in deep rnines have been known for a long time. Some old but forgotten experiments on explosive self-destruction of glass specimens are described in the paper, as well as some calculations of fraeture waves and an estimate of the size of destructed particles.

Physical and structural characterization of mismatched welded joints by dynamic fracture toughness test.

Ranatowski E., Sadowski J.

Inżynieria Materiałowa

2001

R. XXII, nr 5

753-756

An assessment of dynamic fracture parameters such as KId, JId, total failure energy K and their parts Kz, Kr for the experimented conventional and pre-cracked specimens tested by dynamic fracture test were made. The additional investigations by X-ray diffractometer and scanning electron microscope were made to reveal the structural sources of scatter of the results in the Charpy test.

Wykonano ocenę dynamicznych parametrów procesu pękania, takich jak KId, JId, energię zniszczenia K oraz jej składowe Kz, Kr poprzez dynamiczne badania konwencjonalnych próbek oraz z karbem zakończonym pęknięciem. Ponadto wykonano dodatkowe badania na dyfraktometrze rentgenowskim oraz mikroskopie skaningowym w celu ujawnienia strukturalnych źródeł rozrzutu badań obserwowanych w próbce Charpy V.