Structure Designs Governed by Limited Deformations

Structures governed by distortion design criteria usually support radio telescopes, antennas, and other electronic tracking, observation, and measuring devices. Because measuring and observation errors are magnified in proportion to the distance of the object from the instrument, such instruments require extremely rigid supporting structures. Protection of the structure from environmental distortions may vary from simple sun and wind shields to fully enclosed, thermally controlled environments. In addition, the structure may have to be constructed of low expansion materials, such as invar. Light equipment must be carefully arranged to keep both the overall structure and distortions to the minimum by placing instruments to measure or respond at right angles to the distortions. Computation of distortions by electronic computer within micrometric accuracy must include possible variation of the physical and geometric properties of the material. Extraordinary precaution and controls must be exercised in the erection and fabrication at the mill and shop.