Since the Great Hanshin Earthquake in 1995, many investigations on the seismic damper have been made. On the other hand, it also theoretically projected that ultra fine grained Zn-Al alloys could show superplasticity ...Since the Great Hanshin Earthquake in 1995, many investigations on the seismic damper have been made. On the other hand, it also theoretically projected that ultra fine grained Zn-Al alloys could show superplasticity at low temperatures [1-4]. Authors tried to make a massive ultra fine grained Zn-22 mass % Al alloy by means of TMCP (thermo-mechanical controlling process). The superplastic Zn-Al alloy is not susceptible to strain deterioration because it has a low work-hardening rate and, thus, does not accumulate strain significantly when deformed plastically. On the other hand, since its work hardening rate is low, plastic deformation proceeds locally, required plastic energy can’t be sufficiently obtained and local fracture and local deformation instability can take place easily. The structural designer must overcome the strain localization resulting from the low work-hardening rate. Several types of seismic dampers were successfully developed with overcoming the local deformation instability. Three types of seismic dampers were finally developed.展开更多
文摘Since the Great Hanshin Earthquake in 1995, many investigations on the seismic damper have been made. On the other hand, it also theoretically projected that ultra fine grained Zn-Al alloys could show superplasticity at low temperatures [1-4]. Authors tried to make a massive ultra fine grained Zn-22 mass % Al alloy by means of TMCP (thermo-mechanical controlling process). The superplastic Zn-Al alloy is not susceptible to strain deterioration because it has a low work-hardening rate and, thus, does not accumulate strain significantly when deformed plastically. On the other hand, since its work hardening rate is low, plastic deformation proceeds locally, required plastic energy can’t be sufficiently obtained and local fracture and local deformation instability can take place easily. The structural designer must overcome the strain localization resulting from the low work-hardening rate. Several types of seismic dampers were successfully developed with overcoming the local deformation instability. Three types of seismic dampers were finally developed.
