11.4 Common Cushion Methods and Their Features
373
Fig. 11.6 Diameter of
expanding tube is expanded
such process, the impact energy is transformed to elastic-plastic deformation energy
of expanding tubes and the friction heat between conical cylinder and expanding
tubes to be exhausted.
The process that the expanding tubes go through the conical cylinder can be taken
as a plastic molding issue, and the damping force is as follows [5]:
P = 2.3 π σ s
1 −
R 1
R 2
tan α + f
(1− f tanα) · tan α
· e
f l
R 2
R 1 t
(11.3)
where: R 1 is initial central diameter of the expanding tube; R 2 is central diameter of
the expanding tube after deflection; t is thickness of the expanding tube; α is one
half of the taper angle; l is length of the conical cylinder with maximal diameter;
σ s is yield limit of the material of the expanding tube; f is coefficient of the friction
between conical cylinder and expanding tubes.
There are features of deformation of thin-walled metal tube as follows.
1. The damping force of the expanding tube with same material, specification and
deformation is well consistent.
2. Cushioning features are insensitive to environments such as temperature
alternation and humidity, etc.