Smart Material Actuated Fasteners

Abstract

A smart material actuated fastener is provided. In another aspect, a fastener includes a shape memory material and a non-shape memory material with the shape memory material being a minority of the total fastener materials. A further aspect provides a fastener having workpiece-engaging surfaces made of an inactive and non-shape memory material.

1 . A fastener comprising:
 a shape memory material;   a non-shape memory material, the shape memory material being a minority of the total fastener materials;   a laterally enlarged head;   an elongated stem longitudinally extending from the head, the head and the stem being made of the non-shape memory material;   a plunger coupled to the stem;   a flexible outer member coupled to the plunger and surrounding a leading end of the stem opposite the head;   one of the plunger and the outer member being made of the shape memory material; and   the shape memory material longitudinally moving the plunger and the outer member toward the head and laterally expanding the outer member, when an activation state changes.   
     
     
         2 . The fastener of  claim 1 , wherein the stem is hollow and the non-shape memory material is located on at least an external surface thereof. 
     
     
         3 . The fastener of  claim 2 , wherein the shape memory material is the plunger and is at least partially located internally within the stem. 
     
     
         4 . The fastener of  claim 1 , wherein the shape memory material is entirely internal within the non-shape memory material, and the shape memory material causes a width dimensional change of the non-shape memory material when the actuation state changes. 
     
     
         5 . The fastener of  claim 1 , wherein the shape memory material is polymeric and the non-shape memory material is polymeric. 
     
     
         6 . The fastener of  claim 1 , wherein the non-shape memory material creates a hole-sealing grommet, and the shape memory material is internally located within the grommet. 
     
     
         7 . The fastener of  claim 1 , wherein the shape memory material moves the plunger within a hollow section of the stem made of the non-shape memory material which is polymeric. 
     
     
         8 . The fastener of  claim 1 , further comprising an umbrella extending from the stem, the shape memory material contacting the umbrella in a fastening condition. 
     
     
         9 . The fastener of  claim 1 , wherein the outer member is made of the shape memory material and includes an internal cup-shape adjacent a distal end of the plunger. 
     
     
         10 . A fastener comprising:
 a laterally enlarged head, the head including non-shape memory material;   an elongated stem longitudinally extending from the head;   a plunger coupled to the stem, the plunger including a longitudinally elongated portion and a laterally enlarged portion in at least one condition;   an outer member coupled to the plunger and the stem;   one of the plunger and the outer member including shape memory material; and   the shape memory material longitudinally moving the outer member toward the head and laterally expanding the outer member, when an activation state changes.   
     
     
         11 . The fastener of  claim 10 , wherein the shape memory material is the plunger and is at least partially located internally within the stem. 
     
     
         12 . The fastener of  claim 10 , wherein the shape memory material is entirely internal within the non-shape memory material, and the shape memory material causes a width dimensional change of the non-shape memory material when the actuation state changes. 
     
     
         13 . The fastener of  claim 10 , wherein the outer member includes a laterally enlarged ring extending from a cylindrical outside surface, the ring being laterally enlargeable when the shape memory material is activated. 
     
     
         14 . The fastener of  claim 10 , wherein the outer member is made of the shape memory material and includes an internal cup-shape adjacent the laterally enlarged portion of the plunger. 
     
     
         15 . The fastener of  claim 10 , further comprising an automotive vehicle, interior trim panel secured to the head, and the outer member securing the stem to a sheet metal panel. 
     
     
         16 . A fastener comprising:
 a laterally enlarged head, the head including non-shape memory material;   an elongated stem longitudinally extending from the head;   a plunger coupled to the stem;   an outer member coupled to the plunger;   one of the plunger and the outer member including shape memory material;   the shape memory material moving a portion of the outer member when an activation state changes;   a frustoconical umbrella, the shape memory material moving toward the umbrella if changed from an unfastening condition to a fastening condition; and   the outer member acting as a workpiece hole-sealing grommet when in a fastened condition.   
     
     
         17 . The fastener of  claim 16 , wherein the shape memory material is the plunger and is at least partially located internally within the stem. 
     
     
         18 . The fastener of  claim 16 , wherein the shape memory material is entirely internal within the non-shape memory material, and the shape memory material causes a width dimensional change of the non-shape memory material when an actuation state changes. 
     
     
         19 . The fastener of  claim 16 , wherein the outer member is made of the shape memory material and includes an internal cup-shape adjacent a laterally enlarged distal end of the plunger. 
     
     
         20 . The fastener of  claim 16 , further comprising an automotive vehicle, interior trim panel secured to the head, and the outer member securing the stem to a sheet metal panel.