On testing of charpy specimens using the one-point bend impact technique

Abstract

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

Dynamic mechanical and fracture properties of an infiltrated TiC-1080 steel cermet

“…The procedure has been described in detail, e.g., in Weisbrod and Rittel (2000), and its validity has been assessed e.g., in Rittel and Weisbrod (2001), and Rittel et al (2002a). For the sake of brevity, we will only outline the main characteristics of the procedure.…”

A Simple Methodology to Measure the Dynamic Flexural Strength of Brittle Materials

“…The number of elements, their type and other relevant details are all listed in Table 2. It was previously shown by Giovanola [19] and by Rittel et al [15] that an impacted unsupported structure will not immediately start to propagate away from Rather, a certain amount of time will elapse, during which loading waves travel back and forth in the structure. These authors used in their studies notched/cracked specimens and their conclusion was that the structure fractures long before the specimen takes off from the contact with the incident bar.…”

“…by Weisbrod and Rittel [14], or by Rittel et al [15]. More recently, Belenky et al [16] applied the one-point impact technique to measure the dynamic initiation fracture toughness of nanograined transparent alumina.…”

Size effect on the contact state between fracture specimen and supports in Hopkinson bar loaded fracture test

“…The instrument of Hopkinson bar has been widely used to conduct fracture tests by bending specimens for measuring dynamic fracture toughness under a high loading rate of around ∼ 10 6 M Pa √ m/s (Ruiz and Mines 1985;Bacon et al 1994;Yokoyama 1993;Rizal et al 2002;Rittel et al 2002;Rubio 2003;Popelar et al 1999Popelar et al , 2000Jiang 2004;Jiang and Vecchio 2007a,b). In such high loading rate fracture tests, the dynamic load applied to the bending specimen and the specimen's displacement are necessary parameters for calculating dynamic fracture toughness, which are determined by one-dimensional stress wave theory.…”