{HEAD ~ A structure} having {TAIL ~ a normal position}, and a deformed position in which the structure is subject to strain resulting from external application of stress forces, the structure being adapted to respond to the strain induced by the external stress forces and to restore itself to the normal position, the structure comprising: 
{ HEAD ~ A structure } having { TAIL ~ a normal position } , and a deformed position in which the structure is subject to strain resulting from external application of stress forces , the structure being adapted to respond to the strain induced by the external stress forces and to restore itself to the normal position , the structure comprising :
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH