13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- solid flat specimen was carried out. It concludes that an elliptical coil with its centre axis perpendicular to the middle axis of the specimen gives a smallest thermal gradient on the solid flat specimen. In addition, it was recommended in [10] that a longitudinal opposite direction working coil is for better axial temperature gradients. An experimental investigation of effect of working coil configurations on thermal gradient along a flat specimen was first carried out, as shown in Fig. 3-3. Figure 1 Configuration of working coil on flat specimen Fig. 1 A-C shows the one direction longitudinal configuration with different turns. The temperature increases up to 500°C, and the dynamic temperature was recorded. The results shows that the working coil configuration C (4 turns with 25 mm gap in the middle) gives the minimal thermal gradients (10°C) at 500°C. Figure 2 Configuration of working coil on thin-walled tubular specimen Fig. 2 shows the two different working coil configurations on thin-walled tubular specimen. The temperature increases up to 500°C, and the dynamic temperatures were recorded. The results shows that the working coil configuration A (4 turns with gap in the middle) gives larger thermal gradients (50°C) at 500°C. If the number of turns increases to 6 with gap in the middle, the thermal gradients greatly reduced to 10°C at 500°C. Figure 3 Configuration of working coil on cylindrical solid specimen
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