brittleness vs fragility

brittleness

noun
  • The state of being brittle; aptness to break; fragility. 

  • The property by virtue of which a material is fractured without appreciable deformation by the application of load. 

fragility

noun
  • The condition or quality of being fragile; brittleness; frangibility. 

  • Weakness; feebleness. 

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