Slim pressure rods such as thin piston rods may buckle outwards if the compressive force F exceeds a permissible value (Figure K 12). This value is referred to as the buckling force F K. Cylinders with a large stroke and/or a thin piston road should undergo further calculations with regard to possible buckling. Euler's formula applies in this regard to cylinders arranged vertically and to the application of centric forces.
where l = the smallest axial planar moment of inertia
s = free buckling length (see Figure K 12)
S K = safety factor (safety in terms of buckling)
In addition to the basic scenario (scenario 1), another three buckling scenarios are possible in this context (Figure K 12). Mounting scenario 2 applies in most cases, so that s = l.
Particularly thorough calculations are required for horizontal cylinders or those tilted at a considerable angle, since the bending stress associated with the component's own weight is added to the compressive stress in such cases (Figure K 13).
Figure K 12: Buckling scenarios involving vertical cylinders
Figure K 13: Buckling involving horizontal cylinders