Application Of Shape Memory Alloy In The3-D Adaptive Variant Structure

As a new type of smart material, shape memory alloy (SMA) is widely used in the aerospace,biomedicine, civil engineering and so on due to its unique mechanical and physical properties suchlike the shape memory effect, Pseudoelasticity and good biological compatibility. The utilization ofthe SMA material to automatically change the aerodynamic shape of the aircraft in flight whichimproves the flight efficiency and optimizes the adaptability in different flight environments withvariable tasks has become an important research topic. Many scholars at home and abroad havecarried on the related research about the application of the SMA material and achieved certain results.This thesis presents a study and analysis of the SMA material and its application for the adaptive inletstructure around the establishing of the SMA constitutive relation and the method of the finite elementrealization, and the attempts that have been done are as follow:1. The SMA constitutive models which have been generally applied in the engineering aresummarized and discussed in this paper. Lagoudas constitutive model which is based on the basictheory of thermodynamics is derivate in this thesis. The unified constitutive model is foundedwhich can explain completely the thermodynamic behavior of the phase transformation byintroducing Tanaka, Liang and Brinson’s relations of the martensitic volume, the stress and thetemperature into the framework of this model.2. The research about methods of the finite element realization for the SMA material is carried outin this thesis. The user material subroutine (UMAT) of the ABAQUS software package is used torealize the finite element simulation of SMA by adopting fully implicit stress updating algorithmand tangent stiffness matrix which is deduced. The UMAT is verified through the computationalexample.3. The character of the phase transformation and the thermodynamic behavior of the3-D structures:strip and bump, in the temperature loading are discussed. The result shows that the strip andbump can undergo large deflection in the vertical. This thesis provides certain reference value tothe research about the application of the SMA in the adaptive inlet structure.