Tunable impedance load-bearing structures

Abstract

A tunable impedance load bearing structure includes a support comprising an active material configured for supporting a load, wherein the active material undergoes a change in a property upon exposure to an activating condition, wherein the change in the property is effective to change an impedance characteristic of the support.

1 . A tunable impedance load bearing structure, comprising:
 a support comprising an active material configured for supporting a load, wherein the active material undergoes a change in a property upon exposure to an activating condition, wherein the change in the property is effective to change an impedance characteristic of the support.   
     
     
         2 . The tunable impedance load bearing structure of  claim 1 , wherein the active material comprises a shape memory polymer, a shape memory alloy, a ferromagnetic shape memory alloy, an electroactive polymer, a piezoelectric material, a magnetorheological elastomer, an electrorheological elastomer, or combinations comprising at least one of the foregoing active materials. 
     
     
         3 . The tunable impedance load bearing structure of  claim 1 , wherein the change in a property comprises a change in an elastic modulus, a shape, a dimension, a shape orientation, a component location, a phase change, or combinations comprising at least one of the foregoing properties. 
     
     
         4 . The tunably compliant load bearing structure of  claim 1 , wherein the change in an impedance characteristic comprises a change in a stiffness, a damping capability, a yield strength, a shear strength, a force-deflection behavior, a preferred mode of deformation, a load-carrying capacity, a load path within the structure, an energy absorption capacity, or combinations comprising at least one of the foregoing characteristics. 
     
     
         5 . The tunable impedance load bearing structure of  claim 1 , further comprising an activation device in operative communication with the active material, to provide the activating condition to the active material, wherein the activating condition comprises a thermal activation signal, an electric activation signal, a magnetic activation signal, a chemical activation signal, a mechanical signal, or a combination comprising at least one of the foregoing activation signals. 
     
     
         6 . The tunable impedance load bearing structure of  claim 1 , wherein the support further comprises a first portion, a second portion, and a third portion, wherein the second portion comprises the active material and is disposed between the first portion and the second portion. 
     
     
         7 . The tunable impedance load bearing structure of  claim 1 , wherein the support further comprises a flat portion having a first aperture in physical communication with an angular portion having a second aperture coaxially aligned with the first aperture, and a pin disposed in the first and the second apertures, wherein the active material is adapted to actuate the pin. 
     
     
         8 . The tunable impedance load bearing structure of  claim 7 , wherein the pin comprises the active material. 
     
     
         9 . A tunable impedance load bearing structure, comprising:
 a support configured for supporting a load, comprising.
 an upper portion having a first flat surface and a second flat surface, wherein a canted beam element is disposed between the first flat surface and the second flat surface; 
 a first disc comprising an active material in physical communication with the second flat surface of the upper portion, wherein the active material undergoes a change in a property upon exposure to an activating condition, wherein the change in the property is effective to change a compliance characteristic of the support; and 
 a second disc in physical communication with the first disc. 
   
     
     
         10 . The tunable impedance load bearing structure of  claim 9  wherein the active material comprises a shape memory polymer, a shape memory alloy, a ferromagnetic shape memory alloy, an electroactive polymer, a piezoelectric material, a magnetorheological elastomer, an electrorheological elastomer, or combinations comprising at least one of the foregoing active materials. 
     
     
         11 . The tunable impedance load bearing structure of  claim 9 , wherein the change in a property comprises a change in an elastic modulus, a shape, a dimension, a shape orientation, a component location, a phase change, or combinations comprising at least one of the foregoing properties. 
     
     
         12 . The tunable impedance load bearing structure of  claim 9 , wherein the change in a compliance characteristic comprises a change in a stiffness, a damping capability, a yield strength, a shear strength, a force-deflection behavior, a load-carrying capacity, an energy absorption capacity, or combinations comprising at least one of the foregoing characteristics. 
     
     
         13 . The tunable impedance load bearing structure of  claim 9 , further comprising an activation device in operative communication with the active material, to provide the activating condition to the active material, wherein the activating condition comprises a thermal activation signal, an electric activation signal, a magnetic activation signal, a chemical activation signal, a mechanical signal, or a combination comprising at least one of the foregoing activation signals. 
     
     
         14 . A method for changing an impedance characteristic of a load bearing structure, the method comprising:
 disposing a load bearing structure intermediate a substrate and a load, wherein the load bearing structure comprises a support configured for supporting the load, wherein the support comprises an active material; and   activating the active material to effect a change in a property of the active material, wherein the change in the property is effective to change an impedance characteristic of the load bearing structure.   
     
     
         15 . The method of  claim 14 , wherein the active material comprises a shape memory polymer, a shape memory alloy, a ferromagnetic shape memory alloy, an electroactive polymer, a piezoelectric material, or combinations comprising at least one of the foregoing active materials. 
     
     
         16 . The method of  claim 14 , wherein the change in a property comprises a change in an elastic modulus, a shape, a dimension, a shape orientation, a component location, a phase change, or combinations comprising at least one of the foregoing properties. 
     
     
         17 . The method of  claim 14 , wherein the change in an impedance characteristic comprises a change in a stiffness, a damping capability, a yield strength, a shear strength, a force-deflection behavior, a load-carrying capacity, an energy absorption capacity, or combinations comprising at least one of the foregoing characteristics. 
     
     
         18 . The method of  claim 14 , wherein activating the active material is accomplished using an activation device in operative communication with the active material, wherein the activation device is operable to selectively apply an activation signal to the active material. 
     
     
         19 . The method of  claim 18 , wherein the activation signal comprises a thermal activation signal, an electric activation signal, a magnetic activation signal, a chemical activation signal, a mechanical signal, or a combination comprising at least one of the foregoing activation signals. 
     
     
         20 . The method of  claim 14 , wherein the disposing the load bearing structure intermediate a substrate and a load further comprises activating the active material to position the load relative to the substrate, and deactivating the active material to maintain the load in the position.