Viscoelasticity of Composite Structures for Compulsators

The University of Texas at Austin Center for · Electromechanics (UT-CEM) is a research center which specializes in pulse power technology. DoD's mission for high performance power sources has lead UT-CEM to incorporate advanced composite materials into compulsator designs. However, to achieve these high performance levels, improvements are needed in the thermal and structural properties for armature windings as well as for the surrounding composite structure. In particular, viscoelastic flow can limit compulsator performance life by loss of radial precompression. Composite structures with embedded electrical windings are particularly affected due to the localized, elevated operating temperatures. Under ongoing programs, the viscoelasticity of these composite structures are being characterized by evaluating neat resin behavior. This paper will describe the thermal and structural properties of selected high performance neat resins as well as creep modulus characterization through Dynamic Mechanical Analyzer (DMA) tests. Also documented in this paper will be the results from specialized viscoelasticity tests performed on representative composite windings to determine preload loss versus time, temperature, and stress. Also, in collaboration with the Army Research Laboratory, a nested cylinder code is being developed to predict viscoelasticity induced preload losses.