The nuts act to stop {HEAD ~ cracks} formed in {TAIL ~ the structure} when the structure is impacted 
formed in
The nuts act to stop { HEAD ~ cracks } formed in { TAIL ~ the structure } when the structure is impacted
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH