Akihiko Suzuki

Control Characteristics of Shape Memory Alloy Actuator Using Resistance Feedback Control Method

The actuators using shape memory alloys can work as an actuator to control or retain positioning without using sensor devices. In this work, a position control model with a biasing mechanism is produced. The produced model is controlled by resistance feedback using the method of setting off-time and can be set and retained at an arbitrary position. The effects of input current, control distance and off-time on positioning characteristics such as dynamic behavior and position stability are investigated. The results show that high input current for heating is effective for shortening the rise and settling times. However, the overshoot increases with increasing input current. When the recovery strain is below 2.5%, the rise and settling velocities increase with increasing control distance. Furthermore, the off-time affects position stability. In the case of short off-time, fine position stability is performed regardless of the values of input current and control distance.

Transformation/Deformation Behavior and its Constitutive Equation for Ti-Ni-Cu Shape Memory Alloy

This paper describes the transformation and deformation behavior and its constitutive equation for Ti-41.7Ni-8.5Cu (at%) shape memory alloy. Plastic deformation after pre-deformation is investigated using the volume fraction of slip-deformed martensite. New kinetics and constitutive equations are proposed for the reverse transformation process. The material constants in the proposed equationa are determined from the results of tensile and heating/cooling tests of Ti-41.7Ni-8.5Cu (at%) shape memory alloy. The calculated results describe well the deformation and transformation behavior affected by pre-strain.

Bending Fracture Strength of Sintered Silicon Nitride Disks with Shoulder Fillet at Room Temperature

Bending tests were performed on sintered silicon nitride disks with shoulder fillet at room temperature. Experimental fracture probability were compared with analytical predictions obtained by a structural reliability evaluation program, CCPRO. Results showed that; (1)the effective volume concept was applicable to biaxially loaded components, and (2)fracture criteria compared in this analysis gave little effect to fracture predictions.