13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- Quasi-static tests were performed using a classical hydraulic testing machine with the device mentioned above. Dynamic tests were performed using the split Hopkinson of aluminum bars with a diameter of 60mm with 4m long incident bar and 2.5m long transmitted bar. The schematic drawing of the bars is shown in figure 5. Based on the plane shear assumption, the equivalent strain is calculated with measured displacement between the two clamping pieces d (Eqn 1.) and equivalent stress with the force F (Eqn 2). d = 3 eq l ε (1) = 3 eqσ τ , F S τ= . (2) Figure 6 shows first results at various strain rate. The same tendency of stress increases is also Fig.5 Schematic drawing of 60mm aluminum Hopkinson bar and device Fig. 4 Double shear specimen and shear device
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