ABSTRACT
This chapter determines the intensive distribution of forces and moments in the membrane, which result from external forces applied to the membrane. The membrane will be assumed to support the external forces without acceleration, i.e., we assume equilibrium between the forces applied to the membrane surface and the forces and moments within the material itself. The surface force resultants are made up of tension and shear components along any exposed edge. Equilibrium equations relate the external forces applied to a membrane to the force and moment resultants within the membrane. The equilibrium equations follow from the requirement that for any body in steady motion, the sum of all forces and the sum of all moments that act on the body must be zero. The equations of mechanical equilibrium may usually be applied to biological membranes even if they do experience acceleration because the product of the membrane mass times the acceleration is negligible compared to other forces.
