Concept
Stress block
2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
Bending is a pair of forces, pushing and pulling
A bending moment is not a mysterious twisting. It is a push near the top of a section and a pull near the bottom, separated by a lever arm — a couple, made out of stress.
When half the section has given up
Bending theory puts the neutral axis through the centroid. That is a consequence, not a rule — and when the tension side cracks, the same reasoning moves the axis somewhere else entirely.
Named alongside it
The objects these essays reach for when they reach for this one.
Lever armNeutral axisCentroidCracked sectionElastic limitFirst moment of areaModular ratioPlane sectionsPlastic momentSecond moment of areaSection modulusTransformed section