Wave Measurements on Truss Model.
Technical rept. 1 Jan 84-1 Sep 85,
WEA CAMBRIDGE MA
Pagination or Media Count:
Large space structures LSS are large periodic lattice structures being considered for space applications in earth orbit. The vibration and wave propagation characteristics of these structures can affect their performance, integrity and the ability to nondesctructively assess that integrity. In this preliminary study, the wave propagation characteristics of a tetrahedral truss model consisting of fiberglass reinforced composite rods and aluminum joints are observed experimentally. Longitudinal ultrasonic transducers are coupled to the joints of the truss model. The input signal consists of a gated sinusoid having a center frequency of 280 kHz. Because a tetrahedral truss, a commonly proposed LSS configuration can be constructed from basic repeating units of tetrahedrons and pyramids, only tetrahedrons and pyramids are considered. Tetrahedrons and pyramids are constructed by inserting fiberglass reinforced polyester rods 0.193 cm 0.076 in in diameter and 18.72 cm 7.37 in in length into machined 2024-T4 aluminum joints. Because a tetrahedral truss requires only two types of joints, the tetrahedrons and pyramids are constructed using the two types of joints. The cutting of the fiberglass rods, the machining of the aluminum joints and the final assembly of tetrahedrons and pyramids are done with great care to minimize structure variability.
- Unmanned Spacecraft