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11 Landing Gear Technology of Lunar Lander
There were features of aluminum honeycomb as follows.
(1) Aluminum honeycomb material with same size and foil gauge showed
remarkable consistency.
(2) The damping force was almost same when the aluminum honeycomb material
deformed.
(3) Occasional instability of some part of honeycomb material would lead to a
fierce oscillation of the damping force, which should be avoided in application.
The application of aluminum honeycomb absorption technology was very mature,
such as the landing gear system of Apollo lunar module and Viking Mars lander.
2. Aluminum Foam
Aluminum foam is one kind of light material with specific mechanical properties.
The difference of damping feature for different aluminum foam material is significant. Compared with aluminum honeycomb, the density and crushing strength of
aluminum foam is higher. Unlike aluminum honeycomb, the load of aluminum foams
varies with stroke when compressed. The highlighted advantage of aluminum foam
is its isotropic damping capability, which is fit to application on the occasion that the
direction of impact force is not certain.
11.4.2 Deformation of Thin-Walled Metal Tube
The thin-walled metal tube can deform in different patterns. Various energy absorption buffers can be designed by different patterns of deformation. An absorber of
metal plastic deformation is shown in Fig. 11.5. It absorbs the impact energy by
both friction and radial plastic deformation of metal tube. The buffer components
consist of a hollow conical cylinder and a series of expanding tubes with diverse
thickness. When the input load exceeds specific threshold, the buffer is activated
with every expanding tube successively going through the conical cylinder. Because
the diameter of outer conical cylinder with larger end is greater than the diameter
of inner expanding tubes, the diameter of conical cylinder is expanded when the
expanding tubes are getting through the conical cylinder, as shown in Fig. 11.6. In
Fig. 11.5 Aluminum honeycomb absorber
11 Landing Gear Technology of Lunar Lander
There were features of aluminum honeycomb as follows.
(1) Aluminum honeycomb material with same size and foil gauge showed
remarkable consistency.
(2) The damping force was almost same when the aluminum honeycomb material
deformed.
(3) Occasional instability of some part of honeycomb material would lead to a
fierce oscillation of the damping force, which should be avoided in application.
The application of aluminum honeycomb absorption technology was very mature,
such as the landing gear system of Apollo lunar module and Viking Mars lander.
2. Aluminum Foam
Aluminum foam is one kind of light material with specific mechanical properties.
The difference of damping feature for different aluminum foam material is significant. Compared with aluminum honeycomb, the density and crushing strength of
aluminum foam is higher. Unlike aluminum honeycomb, the load of aluminum foams
varies with stroke when compressed. The highlighted advantage of aluminum foam
is its isotropic damping capability, which is fit to application on the occasion that the
direction of impact force is not certain.
11.4.2 Deformation of Thin-Walled Metal Tube
The thin-walled metal tube can deform in different patterns. Various energy absorption buffers can be designed by different patterns of deformation. An absorber of
metal plastic deformation is shown in Fig. 11.5. It absorbs the impact energy by
both friction and radial plastic deformation of metal tube. The buffer components
consist of a hollow conical cylinder and a series of expanding tubes with diverse
thickness. When the input load exceeds specific threshold, the buffer is activated
with every expanding tube successively going through the conical cylinder. Because
the diameter of outer conical cylinder with larger end is greater than the diameter
of inner expanding tubes, the diameter of conical cylinder is expanded when the
expanding tubes are getting through the conical cylinder, as shown in Fig. 11.6. In
Fig. 11.5 Aluminum honeycomb absorber