Article: The Titan Submarine Implosion - A Probable Fatigue Crack Ruptured the Viewport to Instantly Destroy the Vessel - Fatigue properties of plastics are not well known, and this lack of knowledge likely resulted in implosion of the plastic viewing portal on the Titan Submarine. Fatigue is a complex failure mechanism in all materials, and the likelihood is questionable that fatigue was adequately investigated before submerging this submarine over and over. Most engineers do not well understand this complex failure mechanism.