SMAs are attractive damping elements for structural control systems.

1
Semi-Active Control of SMA Tendons for Seismic
Isolation of Structural Systems B.A. Davis
(Ph.D. Student, ME), Advisor Stefan Seelecke
NC STATE UNIVERSITY
Introduction
SMA Dynamic Modeling
Simulation Results

• Capable of single crystal and polycrystalline
  material modeling.

Sinusoidal Excitation Frequency Response
Austenite
Martensite
x(t)
Varying Sine Sweep Frequency Paths
Single crystal SMA constitutive behavior.
SMA oscillator representing 1st bending mode of
12-story building.

• SMAs are attractive damping elements for
  structural control systems.
• Provides strain recovery of up to 8.
• Inherent energy dissipation.
• Damping capacity is controlled by SMA geometry.
• Provides coupled nonlinear damping/stiffness
  effects.

Stress Strain Relation
Strain-Displacement
Optimal radius evident in acceleration frequency
response. The optimal radius differs for sweep
direction, and amplitude.

• Study of jump phenomenon, and frequency
  variation.
• Optimal SMA radius size varies with excitation
  frequency path, and amplitude.

SMA shear building model, taking into account the
geometry.
Polycrystalline SMA constitutive behavior
dynamically coupled model..
Research Goals/Scope
Prototype Experimental Setup
Random Excitation Building Prototype
Building Simulations RMS accelerations for
multiple SMA radius sizes.
Building Simulation Displacement response of
optimal SMA diameter and without SMA.

• Quantify general mechanisms for optimal SMA
  diameter response.
• Provide high fidelity model of SMA dynamic
  response behavior.
• Design/fabricate bench top experimental SMA
  building prototype for validation.
• Implement semi-active control mechanism into
  model/experiment.

• Prototype parameter design.
• LabVIEW data acquisition development.
• Shaker control.

• Simulations of building prototype response show
  optimal behavior at 115 micron SMA diameter.