地震波に含まれる衝撃波動の計測

Against the theory that the main causes of collapse of structures in past large earthquakes depend on bending moment and shear force due to extraordinary loads, the authors have another opinion that they shall be impact in seismic waves unable to measure with the seismograph of SMAC type. To prove the presence of impact in seismic waves the authors devised a new seismograph with wide-range up to 2,000 Hz and installed it at Tsukuba City. The records measured near field earthquakes, approved that the seismic waves include waves with very short periods but showed small acceleration. A series of dropping tests brought out the possibility of impact waves with large acceleration and very short periods

Stress relaxation of TiNi shape memory alloy in subloop loading

"The transformation-induced stress relaxation and stress recovery of TiNi shape memory alloy (SMA) in the stress-controlled subloop loading were investigated based on the local variation in temperature and transformation band on the surface of the SMA tape in the tension test. The results obtained are summarized as bellows. (1) In the loading process, temperature increases due to the exothermic martensitic transformation (MT) till the holding strain under a constant stress rate and thereafter temperature decreases during holding the strain constant, resulting in stress relaxation due to the MT. (2) In the unloading process, temperature decreases due to the endothermic reverse transformation till the holding strain under a constant stress rate and thereafter temperature increases during holding the strain constant, resulting in stress recovery due to the reverse transformation. (3) Stress varies markedly in the initial stage followed by gradual change during holding the strain constant. (4) If stress rate is high till the holding strain in the loading and unloading processes, both stress relaxation and stress recovery are large. (5) It is important to take account of these behaviors in the design of SMA elements since the force of SMA elements can vary under constant strain even if temperature is kept constant around SMA elements.

Discharge Characteristics in Facing Targets Type of Sputtering Method and Properties of Deposited Thin Films

Article信州大学工学部紀要 76: 13-20 (1995)departmental bulletin pape