Issue 40

Z. Zhang et alii, Frattura ed Integrità Strutturale, 40 (2017) 149-161; DOI: 10.3221/IGF-ESIS.40.13 159 The thermal energy variation for SPB with different opening ratios during the hysteresis loading process is compared in Fig. 10, in which Fig.10a and Fig. 10b show the thermal dissipation energy based on Heat characterization formula and the thermal convection energy variation trend during the hysteresis process. Similarly, Similarly, In Fig.10, the blue line is the temperature signal; the green line is the energy dissipation; the orange line is the bearing capacity; and the pink line is the strength degradation of the different dampers. From which we could see that the yield point for SPB would appear much earlier than in SPA under the case of same opening ratio. Similarly, the inflection point of temperature rise corresponds with the yielding point of the skeleton curve. Also, the local temperature would have a larger rise as the opening ratio increases under the same maximum displacement load, and the location with larger temperature rise would transfer from two fixture sides to the central opening. And the temperature rise happens earlier for larger opening ratio, and the local stress concentration would induce the obvious improvement of average temperature rise. The hysteresis dissipation energy performance behaves much better with smaller opening ratio, for which the temperature rise is not very obvious even if reaching the yielding point, this is because that the bearing capacity would decrease due to out-of- plane of the specimen instead of local damage. By comparing Fig.9 and Fig. 10, we can see that SPA behaves much better in hysteresis energy dissipation performance than SPB. a. Thermal Energy of SPA b. Convection dissipation energy of SPA c. Thermal energy of SPB d. Convection dissipation energy of SPB Figure 11 : The change of thermal energy during the hysteresis loading. As shown in Fig.11, the average temperature rise changes earlier and earlier as the opening ratio increases. The thermal energy and convection energy could be calculated according to the temperature rise. The maximum of    Q t for SP25 is about 12500J, which holds almost 53% of    W t . Thus,    Q t holds a really significant percentage of    W t during the low-cycle hysteresis loading process. Plastic Energy Fig.12 shows the plastic damage energy based on the energy conservation law. As can be seen from this figure, the inflection point of thermal dissipation energy would happen earlier as the opening ratio increases, the thermal dissipation 0 2 4 6 8 10 0.0 5.0E3 1.0E4 1.5E4 2.0E4 2.5E4 3.0E4 Displacement(mm) SPA10 SPA15 SPA20 SPA25 Heat energy Q q (J) 0 2 4 6 8 10 0 20 40 60 80 100 120 SPA10 SPA15 SPA20 SPA25 Energy of thermal disslpation Q h (J) Displacement(mm) 0 2 4 6 8 10 0.0 5.0E3 1.0E4 1.5E4 2.0E4 2.5E4 3.0E4 SPB10 SPB15 SPB20 SPB25 Heat energy Q q (J) Displacement(mm) 0 2 4 6 8 10 0 20 40 60 80 100 120 SPB10 SPB15 SPB20 SPB25 Energy of thermal disslpation Q h (J) Displacement(mm)