Material Characterization of SMA Actuators Under Nonproportional Thermomechanical Loading

The application of SMA actuators in smart structures usually involves thermally induced phase transformation with a variable applied stress in SMA actuators, resulting in thermomechanical nonproportional loading of SMAs in stress-temperature space. To investigate the constitutive response of SMAs under thermomechanical nonproportional loading, experiments for thermally induced phase transformation of binary NiTi SMA wires loaded by an elastic linear spring are performed in the Active Materials Laboratory at Texas A&M University A constitutive model developed by Bo and Lagoudas (1998a, b, c) and lagoudas and Bo (1998) is used as the basis for the theoretical prediction of the response of SMA line actuators loaded by springs with different elastic constants. Model predictions are compared with experimental results.

[1]  L. Brinson.  One-Dimensional Constitutive Behavior of Shape Memory Alloys: Thermomechanical Derivation with Non-Constant Material Functions and Redefined Martensite Internal Variable , 1993 .

[2]  Qingping Sun,et al.  Micromechanics modelling for the constitutive behavior of polycrystalline shape memory alloys. I: Derivation of general relations , 1993 .

[3]  V. Levitas.  Phase transitions in elastoplastic materials: Continuum thermomechanical theory and examples of control. Part II , 1997 .

[4]  L. E. Malvern.  Introduction to the mechanics of a continuous medium , 1969 .

[5]  D. Lagoudas,et al.  A UNIFIED THERMODYNAMIC CONSTITUTIVE MODEL FOR SMA AND FINITE ELEMENT ANALYSIS OF ACTIVE METAL MATRIX COMPOSITES , 1996 .

[6]  Stephen David Howard,et al.  The thermomechanical constitutive experimentation of NiTi shape memory alloy strips and rods , 1995 .

[7]  D. Lagoudas,et al.  A thermodynamical constitutive model for shape memory materials. Part I. The monolithic shape memory alloy , 1996 .

[8]  Dimitris C. Lagoudas,et al.  Thermomechanical modeling of polycrystalline SMAs under cyclic loading, Part III: evolution of plastic strains and two-way shape memory effect , 1999 .

[9]  J. Shaw,et al.  Thermomechanical aspects of NiTi , 1995 .

[10]  J. Krumhansl,et al.  Nonlinear and nonlocal continuum model of transformation precursors in martensites , 1988 .

[11]  Stelios Kyriakides,et al.  Initiation and propagation of localized deformation in elasto-plastic strips under uniaxial tension , 1997 .

[12]  K. Tanaka.  A THERMOMECHANICAL SKETCH OF SHAPE MEMORY EFFECT: ONE-DIMENSIONAL TENSILE BEHAVIOR , 1986 .

[13]  D. Lagoudas,et al.  Thermomechanical modeling of polycrystalline SMAs under cyclic loading, Part IV: modeling of minor hysteresis loops , 1999 .

[14]  Craig A. Rogers,et al.  One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials , 1990 .

[15]  Etienne Patoor,et al.  Micromechanical Modelling of Superelasticity in Shape Memory Alloys , 1996 .

[16]  Dimitris C. Lagoudas,et al.  Thermomechanical modeling of polycrystalline SMAs under cyclic loading, Part I: theoretical derivations , 1999 .

[17]  C. Lexcellent,et al.  RL-models of pseudoelasticity and their specification for some shape memory solids , 1994 .

[18]  Dimitris C. Lagoudas,et al.  Thermomechanical modeling of polycrystalline SMAs under cyclic loading, Part II : material characterization and experimental results for a stable transformation cycle , 1999 .

[19]  Michael Ortiz,et al.  An analysis of a new class of integration algorithms for elastoplastic constitutive relations , 1986 .

[20]  C. Truesdell,et al.  The Non-Linear Field Theories of Mechanics , 1965 .

[21]  Dominic G.B. Edelen,et al.  On the characterization of fluxes in nonlinear irreversible thermodynamics , 1974 .