What is Bending Stress?
Bending is the stress that combines tension and compression. You put a bending stress on a bar when you grasp it with both hands and push the ends together or when you bend a paper clip. The wing spars (interior structural members) are subjected to bending while the aircraft is in flight. The lower side of the spar is subjected to tension, while the upper side is subjected to compression. Obviously, some materials will break before they bend and often are unacceptable for aircraft construction.
