Shock energy absorber

Abstract

A shock energy absorber includes, in one example, a cylinder having a closed end and an open end, a sleeve fixed about the open end of the cylinder, and a damping material in the form of an ultra high molecular weight polyethylene material in the cylinder. A plunger is positioned to be driven into the damping material via the sleeve. When the plunger is impacted and driven into the damping material, the damping material changes from a solid to a viscous fluid state thereby enabling absorption of a significant amount of energy.

What is claimed is: 
     
         1 . A crash energy absorber comprising:
 a solid polymer plastic ultrahigh molecular weight damping material body having a critical stress magnitude which varies as crash velocity increases and an ultrahigh molecular weight;   a vessel configured to confine the solid polymer plastic ultrahigh molecular weight damping material body;   a plunger shaft having a distal end proximate the solid polymer plastic ultrahigh molecular weight damping material body; and   the plunger shaft having a cross sectional area and length relative to the vessel and the solid polymer plastic ultrahigh molecular weight damping material body so configured for the plunger to press on the solid polymer plastic ultrahigh molecular weight damping material body seat surface in response to impact energy until said critical stress magnitude of the solid polymer plastic ultrahigh molecular weight damping material body is reached based on the plunger cross sectional area and velocity causing a phase change in the solid polymer plastic ultrahigh molecular weight damping material body to a liquid state ahead of and adjacent the plunger shaft displacing the plunger shaft into the solid polymer plastic ultrahigh molecular weight damping material body until a stroke of the plunger shaft travel is reached or said impact energy is absorbed causing the solid polymer plastic ultrahigh molecular weight damping material body to undergo a phase change back to a solid adjacent the plunger shaft locking said plunger shaft within the solid polymer plastic ultrahigh molecular weight damping material body.   
     
     
         2 . The crash energy absorber of  claim 1  in which the critical stress magnitude of the damping material body is greater than 25 ksi. 
     
     
         3 . The crash energy absorber of  claim 1  in which said impact energy is 82,260 ft-lb or greater. 
     
     
         4 . A crash energy absorption method comprising:
 confining a solid polymer plastic ultrahigh molecular weight damping material body having a critical stress magnitude which increases as crash velocity increases and an ultrahigh molecular weight;   disposing a plunger shaft having a distal end located proximate the solid polymer plastic ultrahigh molecular weight damping material body; and   impacting the plunger shaft at a velocity to press on the solid polymer plastic ultrahigh molecular weight damping material until said critical stress magnitude of the solid polymer plastic ultrahigh molecular weight damping material body is reached based on the plunger cross sectional area and velocity causing a phase change in the solid polymer plastic ultrahigh molecular weight damping material body to a liquid state ahead of and adjacent the plunger shaft displacing the plunger shaft into the solid polymer plastic ultrahigh molecular weight damping material body until a stroke of the plunger shaft travel is reached or impact energy is absorbed causing the solid polymer plastic ultrahigh molecular weight damping material body to undergo a phase change back to a solid adjacent the plunger shaft locking said plunger shaft within the solid polymer plastic ultrahigh molecular weight damping material body.   
     
     
         5 . The method of  claim 4  in which the critical stress magnitude of the damping material is greater than 25 ksi. 
     
     
         6 . The method of  claim 4  in which said impact energy is 82,260 ft-lb or greater.