ABSTRACT--This paper reports our methodology and results for the assessment of the dynamic fracture energy of notched Charpy A508 steel specimens. The fracture tests consist of one-point bend impact applied to the specimen in contact with an instrumented bar. Fracture is caused by the inertia of the unsupported specimen only. The fracture energy is determined from the incident, reflected and single wire fracture gage signals. High-speed photographic recordings show that for all the specimens investigated in the "lower shelf" temperature regime, fracture occurs relatively early and prior to "taking off" of the bar by rigid body motion. It also confirms that the fracture gage readings indeed coincide with the formation of a crack from the notch tip.The present methodology is relatively easy to implement, and it allows the investigation of the fracture properties of materials at loading rates (and velocities) that are substantially higher than those achieved in a conventional Charpy test. Moreover, this test is attractive for modeling purposes since its boundary conditions are simple and well defined. KEY WORDS--Charpy, dynamic fracture, one point bend impact, instrumented bar, high-speed photography
Un d i s p o s i t i f expérimental basé s u r l e principe des b a r r e s d'Hopk i n s o n a é t é développé a f i n d ' é t u d i e r l e ccmportement en f a t i g u e par chocs d'éprouvettes de t r a c t i o n .
Des aciers à haute limite d'élasticité présentant des modes de durcissement différents sont considérés. Dans tous les cas on note un accroissement de la limite d'élasticité quand la vitesse de sollicitation passe de 10-3 à 5.103s-1. Les ténacités obtenues à des vitesses de chargement de 106 MPa[MATH].s-1 sont supérieures à celles obtenues à 100 MPa[MATH].s-1
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