Estudo da rigidez complexa de um sistema vibratório incorporando atuador com memória de forma.

Abstract

The shape memory alloys (Shape Memory Alloys - SMA) are materials able to return to their original geometric shape after deformation by heat. Beyond that these alloys exhibit significant variations in mechanical properties such as stiffness and damping. In this context, the shape memory alloys (SMA) can be used to develop vibration absorbers able to act on structures in which they are installed, providing proper tuning between the excitation frequency and the natural frequency of the system. This study aims to analyze the behavior of the stiffness and damping parameters of a helical spring with shape memory, attached to a mechanical system of one degree of freedom subjected to an unbalanced force by harmonic excitation and to a temperature control system. Analyzing the effect of these parameters on the structural response, bounded to the concept of complex stiffness, it is possible to predict the system's behavior within certain acceptable ranges of vibrations frequency already in the design phase. The theoretical and experimental results show the influence of the temperature and excitation frequency on the behavior of the elastic modulus, the stiffness and damping of these alloys, and also demonstrate that the application of shape memory actuators in a structural system can reduce the vibration amplitudes significantly.