Dimensionally Stable Optical Metering Structures With NiTi Composites Fabricated Through Ultrasonic Additive Manufacturing

High performance optical metering structures in airborne and space applications need to exhibit dimensional stability in demanding thermal and mechanical environments. Materials for this application should have a low coefficient of thermal expansion, high thermal diffusivity, high specific stiffness and exhibit good ductility. Current materials are limited in one or more of these properties. Common choices are invar, carbonfiber composite, and silicon-carbide. The former has low specific stiffness and thermal diffusivity and the latter choices are brittle materials that require special care and have slow manufacturing processes. In this work, the development of a thermally invariant metal matrix composite will be described along with its incorporation into a high performance optical metering structure. The material is a composite of super-elastic NiTi ribbons and aluminum, where the ribbons are embedded using ultrasonic additive manufacturing. Measurements and modeling of the thermo-elastic response will be presented followed by the design and manufacture of a metering structure. The metering structure design eases integration with an optical bench and lens bezels while leveraging the advantageous properties of this new metal matrix composite.