4.3 Design and Verification of Lunar Lander Structure
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test. The object of prediction analysis was test condition and simplified test load and
boundary condition were introduced exactly. In addition, according to the results of
prediction analysis, the layout of test points could be targeted reasonably.
2) Static test of the primary structure in landing state
From the previous static analysis, it could be found that the support of landing
cushion mechanisms could be extracted from the whole lander. By design of the
local structure test parts with applying the corresponding load and certain boundary
constraints, the test could be greatly simplified. The static test of the support of
landing cushion mechanisms and the surrounding structure should accurately reflect
the stress status of the landing gears and the lander structure at installation points
under landing load condition, in order to verify whether the design of the support of
landing gears and the adjacent structure of the lander could meet the requirements.
Therefore, the design of the test parts should include support of landing gears and
the adjacent structure, which were subject to large load under the landing load.
The diagram of the static test parts of landing gears and its support is shown in
Fig. 4.18 for the Chang’E-3 lunar lander.
The loading diagram of structural static test in landing state is shown in Fig. 4.19
for the Chang’E-3 lunar lander.
2. Dynamic Test
The dynamic test is the experimental method to study the mechanical behavior of the
spacecraft structure under dynamic environmental conditions and solve the dynamic
strength issue of the structure. For the lunar lander structure, the landing impact load
environment had been covered by the static state of the landing state. Therefore, only
the dynamic environment in launching state was studied for lunar lander just the
same as common spacecraft. Though due to the great differences in configuration,
especially the fuel tanks in parallel installation and propellant in tanks occupied about
2/3 mass of whole lander, its characteristics was different from common spacecraft.
Usually, the dynamic test of spacecraft structure is not carried out in phase B,
because the design of primary bearing structure is centered on the static load for
structural load. In addition, there might be some uncertainties in system design of
spacecraft and large parts which have a great influence on the dynamic characteristics
of whole spacecraft in phase B. Once the design is changed, it will directly affect the
verification of dynamic characteristics of spacecraft structure.
Usually, the spacecraft primary structure is insensitive to the acoustic environment. However, acoustic environment will cause the spacecraft to generate a random
vibration response, which have a great impact on equipment, cable, pipeline, and
equipment connections on spacecraft. So, the major purpose of the acoustic test
is to verify the ability of equipment, cable, pipeline, and equipment connection
on the spacecraft to withstand the random vibration environment, and to provide
inputs for the random vibration environment conditions of the equipment onboard
the spacecraft.
The major purpose of the sinusoidal vibration test is to verify the rationality of
the spacecraft structure design, to evaluate the ability of the spacecraft structure to
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test. The object of prediction analysis was test condition and simplified test load and
boundary condition were introduced exactly. In addition, according to the results of
prediction analysis, the layout of test points could be targeted reasonably.
2) Static test of the primary structure in landing state
From the previous static analysis, it could be found that the support of landing
cushion mechanisms could be extracted from the whole lander. By design of the
local structure test parts with applying the corresponding load and certain boundary
constraints, the test could be greatly simplified. The static test of the support of
landing cushion mechanisms and the surrounding structure should accurately reflect
the stress status of the landing gears and the lander structure at installation points
under landing load condition, in order to verify whether the design of the support of
landing gears and the adjacent structure of the lander could meet the requirements.
Therefore, the design of the test parts should include support of landing gears and
the adjacent structure, which were subject to large load under the landing load.
The diagram of the static test parts of landing gears and its support is shown in
Fig. 4.18 for the Chang’E-3 lunar lander.
The loading diagram of structural static test in landing state is shown in Fig. 4.19
for the Chang’E-3 lunar lander.
2. Dynamic Test
The dynamic test is the experimental method to study the mechanical behavior of the
spacecraft structure under dynamic environmental conditions and solve the dynamic
strength issue of the structure. For the lunar lander structure, the landing impact load
environment had been covered by the static state of the landing state. Therefore, only
the dynamic environment in launching state was studied for lunar lander just the
same as common spacecraft. Though due to the great differences in configuration,
especially the fuel tanks in parallel installation and propellant in tanks occupied about
2/3 mass of whole lander, its characteristics was different from common spacecraft.
Usually, the dynamic test of spacecraft structure is not carried out in phase B,
because the design of primary bearing structure is centered on the static load for
structural load. In addition, there might be some uncertainties in system design of
spacecraft and large parts which have a great influence on the dynamic characteristics
of whole spacecraft in phase B. Once the design is changed, it will directly affect the
verification of dynamic characteristics of spacecraft structure.
Usually, the spacecraft primary structure is insensitive to the acoustic environment. However, acoustic environment will cause the spacecraft to generate a random
vibration response, which have a great impact on equipment, cable, pipeline, and
equipment connections on spacecraft. So, the major purpose of the acoustic test
is to verify the ability of equipment, cable, pipeline, and equipment connection
on the spacecraft to withstand the random vibration environment, and to provide
inputs for the random vibration environment conditions of the equipment onboard
the spacecraft.
The major purpose of the sinusoidal vibration test is to verify the rationality of
the spacecraft structure design, to evaluate the ability of the spacecraft structure to