Determination of the dynamic fracture toughness using a new stress pulse loading method

Dynamic Effects in Hopkinson Bar Four-Point Bend Fracture

“…6-Typical dynamic loads (P I and P II ) comparison for small and large un-notched high-strength HT-1 steel specimens; the loads were computed by Eqs. [5] and [6]. reflected by the interface between the loading pins and the specimen, and they appear on the reflected pulse.…”

“…The average dynamic load applied on the specimen and the specimenÕs loading point displacement can be derived using Eqs. [1] through [6] as…”

“…[5] and [6], i.e., comparing the loads applied on two sides of the bending specimen. A similar method has been employed in impact wedge-loaded compact tension specimens by Harding et al [22,23] Typical results of the small and larger uncracked steel HT-1 specimen, from the tests with and without a pulse shaper, are shown in Figures 6(a) and (b).…”

“…[5]), shows large variations and high-frequency oscillations, while the load (P II ) by a transmitted pulse (Eq. [6]) shows a Fig. 7-Typical dynamic loads (P I and P II ) obtained from small precracked and notched specimens; the loads were computed by Eqs.…”

“…Among Hopkinson bar loaded fracture tests, the compressive stress wave is more commonly employed compared to the tensile stress wave, because it is straightforward to perform and the bend specimen employed is easier to prepare (fabrication and fatigue precrack). The loading methods adopted for the Hopkinson compression pulse fracture test are numerous, including a single incident bar setup, referred to as 1-bar (only incident bar) impact; [4][5][6][7][8][9][10][11][12][13] 2-bar (including incident and transmission bars) setups; [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and 3-bar (one incident bar and two transmission bars [each transmission bar as a support]/three-point bend) impact. [30][31][32] In such Hopkinson pressure bar loaded fracture tests, both the dynamic loads applied on the specimen and the specimenÕs displacement are determined by the one-dimensional stress wave theory, while the methods to determine load and displacement are different.…”