Low-Deflection Loss And Hysteresis Measurements On A Spacecraft Test Joint

Item

Title
Low-Deflection Loss And Hysteresis Measurements On A Spacecraft Test Joint
Report Number
WL-TR-91-3078 Volume III, p. IBC-1 thru IBC-19
Creator
Austin, Eric M.
Flora, Timothy L.
Goodding, James C.
Corporate Author
CSA Engineering, Inc.
Lockheed Missiles and Space Company, Inc.
Date
1991
Date Issued
1991-08
Extent
19
Identifier
ADA241313
Format
1 online resouce
Abstract
Passive damping has been demonstrated to be an effective and efficient means
for limiting the effects of on-board excitations on the dynamics of space vehicles.
High-precision applications require these treatments to both be effective at very low
excitation levels and not affect the dimensional stability of the structure under quasistatic
and thermal-mechanical loads. This work documents a study of two important
issues facing structures damped with viscoelastic materials: hysteresis and loss at low
deflection levels.
The test article is an I-beam-like structure designed to simulate an experimental
method of fabricating graphite-epoxy /honeycomb structures without using any
mechanical fasteners. After identifying the most critical vibrational modes from a
separate system-level analysis, a damping treatment was designed for the test joint
using standard finite element techniques. A modal test using very low random excitation
levels was performed on the resulting damped structure. Statistical methods
were used to determine that the maximum displacement level of the free-free structure
was of the order of nano-meters. Subsequently, hysteresis tests were performed on the
same damped beam. Laser interferometry was used to measure displacements of the
joint after undergoing cyclic static loads of varying magnitudes. Percent hysteresis
was measured while the joint was loaded in three-point bending. Hysteresis behavior
during displacements as small as 150 nano-meters was recorded.
Description
Passive damping has been demonstrated to be an effective and efficient means
for limiting the effects of on-board excitations on the dynamics of space vehicles.
High-precision applications require these treatments to both be effective at very low
excitation levels and not affect the dimensional stability of the structure under quasistatic
and thermal-mechanical loads. This work documents a study of two important
issues facing structures damped with viscoelastic materials: hysteresis and loss at low
deflection levels.
The test article is an I-beam-like structure designed to simulate an experimental
method of fabricating graphite-epoxy /honeycomb structures without using any
mechanical fasteners. After identifying the most critical vibrational modes from a
separate system-level analysis, a damping treatment was designed for the test joint
using standard finite element techniques. A modal test using very low random excitation
levels was performed on the resulting damped structure. Statistical methods
were used to determine that the maximum displacement level of the free-free structure
was of the order of nano-meters. Subsequently, hysteresis tests were performed on the
same damped beam. Laser interferometry was used to measure displacements of the
joint after undergoing cyclic static loads of varying magnitudes. Percent hysteresis
was measured while the joint was loaded in three-point bending. Hysteresis behavior
during displacements as small as 150 nano-meters was recorded.
Distribution Classification
1
Distribution Conflict
No
DTIC Record Exists
No
Illinois Tech Related
No
Photo Quality
Not Needed
Report Availability
Full text available
Type
article
Is Part Of
Proceedings of Damping '91: 13-15 February 1991 San Diego, California (GCA-1 through JCB-17)
Media
articleIBC

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Items with "Has Part: Low-Deflection Loss And Hysteresis Measurements On A Spacecraft Test Joint"
Title Class
Proceedings of Damping '91: 13-15 February 1991 San Diego, California (GCA-1 through JCB-17)