Eventos Anais de eventos
CONEM 2022
XI Congresso Nacional de Engenharia Mecânica - CONEM 2022
A Phenomenological Description of Shape Memory Alloy Fatigue
Submission Author:
Vanderson Dornelas , RJ
Co-Authors:
Vanderson Dornelas, Marcelo Savi, sergio oliveira, Pedro Manuel Calas Lopes Pacheco
Presenter: Vanderson Dornelas
doi://10.26678/ABCM.CONEM2022.CON22-0040
Abstract
Shape memory alloys (SMAs) belong to smart materials which can recover their shape when subjected to an appropriate thermomechanical field. These materials can be used in several applications considering different fields including biomedical, automotive, aerospace, civil engineering, and robotics, many of which involve cyclic loading conditions. In this regard, the fatigue phenomenon is an important subject that needs to be investigated. In general, SMAs exhibit two kinds of fatigue: functional fatigue related to the reduction of functional properties; and structural fatigue associated with the material failure due to the growth and propagation of microcracks. This contribution presents a numerical investigation of fatigue on shape memory alloys. A macroscopic three-dimensional constitutive model with internal variables is employed to describe functional and structural fatigue adopting a continuum damage perspective. The proposed model considers several phenomena related to SMAs, including transformation induced plasticity (TRIP), classical plasticity, phase transformation plasticity coupling, pseudoelasticity, and shape memory effect (SME), allowing an appropriate representation of the main aspects of the thermomechanical behavior of shape memory alloys. An equivalent critical damage is proposed to define the fatigue life of SMAs, considering different behaviors of martensitic and austenitic phases. In order to demonstrate the capabilities of the model, numerical simulations are compared with experimental data. Results show that the model responses are in close agreement with experimental data, including fatigue life predictions and loss of performance. In addition, numerical simulations considering different peak stress are proposed to evaluate the degradation of the functional parameters. Conclusions point out that the increase of the maximum stress promotes a reduction of the functional properties of the material due to the evolution of the TRIP strain and fatigue. These results are qualitatively similar to experimental results available in the literature, attesting to the model capability to describe the evolution of functional and structural fatigue in SMAs.
Keywords
Shape memory alloys (SMA), Functional fatigue, Structural fatigue, constitutive model, numerical simulations
