During a water impact the CM deceleration force will vary from 12 to 40 G's, depending on the shape of the waves and the CM's rate of descent. A major portion of the energy (75 to 90 percent) is absorbed by the water and by deformation of the CM structure. The module's impact attenuation system reduces the forces acting on the crew to a tolerable level.
The impact attenuation system is part internal and part external. The external part consists of four crushable ribs (each about 4 inches thick and a foot in length) installed in the aft compartment. The ribs are made of bonded laminations of corrugated aluminum which absorb energy by collapsing upon themselves at impact. The main parachutes suspend the CM at such an angle that the ribs are the first point of the module that hits the water.
The internal portion of the system consists of eight struts which connect the crew couches to the CM structure. These struts (two each for the Y and Z axes and four for the X axis) absorb energy by deforming steel wire rings between an inner and an outer piston. The struts vary in length from 34 to 39 inches and have a diameter of about 2½ inches.
Question: What did the internal and external parts look like? Are there photos available? I'm especially interested in the "steel wire rings between an inner and an outer piston" of the inner section, as I can't envision what that is at all.