Experimental and theoretical evaluation of the behavior of a shape memory alloy Belleville washer under different operating conditions

The high-temperature sensitivity of shape memory alloys (SMA) provides them with the ability to vary the load-deflection curve with temperature when used as Belleville washers. This paper describes the properties and behavior of a SMA Belleville washer made of CuAlNiMnTi under different testing conditions. In addition, a mathematical model was developed to describe and predict the behavior of SMA devices. The results show that the mechanical and electrical integrity of bolted connections is strongly affected by the metallurgical state of the SMA washer. Variations in the loading and/or operating conditions may induce substantial changes in the washer behavior and, in some cases, complete loss of the beneficial shape-memory effect. This fact is significant, since it imposes very strict conditions on the fabrication of SMA washers for electrical applications.