G.S. Pisarenko Institute for Problems of Strength of the National Academy of Sciences of Ukraine, Kyiv, Ukraine (
EFFECT OF TRANSIENT HEATING OF THE OUTER SURFACE OF THE RING SPECIMEN WITH RADIAL CRACKS ON BRITTLE FRACTURE RESISTANCE
Abstract. The urgency of the problem of increasing resistance to fracture of the most critical structures and their elements causes the need for research and development of the new design and technologically possible solutions. Currently, efficiency of “warm prestressing” (WPS) is out of question, however, its use as a separate process step is controversial. For further research of the possible technological processes based on the WPS effect, it is necessary to develop special experimental techniques that directly model the WPS technology using a simple model of the structural element with cracks. In this paper, results of studies on increasing the resistance to fracture of a simple model of thick-walled shell (ring specimen with radial cracks on the inner surface) by transient heating of the outer surface are presented. An 11% increase of resistance to brittle fracture of the ring specimen at low temperature due to the influence of transient heat is shown experimentally. From the numerical simulations results it can be concluded that as a result of transient heating of the outer surface of the specimen tensile stresses occur on its inner surface, whose values at the crack tip exceeds the yield point. A localized plastic flow that occurs will lead to strain hardening of the material and the crack tip blunting. Experiments and numerical simulations show that according to the proposed implementation of WPS on the design element
(specimen) the level of stress and strain at the crack tip can be easily controlled.
Keywords: resistance to brittle fracture, transient heating, finite element method, fracture toughness.
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