fracture vs tighten up

fracture

verb
  • To break, or cause something to break. 

  • To amuse (a person) greatly; to split someone's sides. 

noun
  • A break in bone or cartilage. 

  • An instance of breaking, a place where something has broken. 

  • A fault or crack in a rock. 

tighten up

verb
  • To fix something or make it correct. 

  • To become tense and restrained. 

  • To become focused and serious; To stop any vacillation or inconsistency. 

  • To become stringent and ungenerous. 

  • To make sufficiently tight. 

How often have the words fracture and tighten up occurred in a corpus of books? (source: Google Ngram Viewer )