FE and experimental analysis of net-shape polymer membrane optics

The Air Force, as well as many other organizations, has considerable interest in developing deployable space-based parabolic membranes. One of the key factors for the success and user acceptance of this technology is 'performance' of the deployed optical membrane. Performance hinges critically on the precision of obtaining a near-net shape parabolic membrane. In a net shape optics concept, these parabolic membranes are maintained by stresses developed due to optical coatings. Continuum-based predictive models of coating requirements must be translated into a prescription for the coating process, which is an atomistic-based activity. In this paper we present some preliminary results of experiments performed to validate the coatings applied to polymer membranes in order to match numerical predictions. Bulge tests were performed to determine the coating stress of a thin film membrane. The bulge tests related the deflection of a pressurized thin film to the film's mechanical proprties (incuding coating stress). A finite element model was created using ABAQUS for comparison with the bulge test data. Vibration tests were also performed to determine the coating stress, since natural frequencies give an estimate of the intrinsic coating properties. An ABAQUS model provided the first few natural frequencies for comparison against the experimental results. In a net shape optics concept, these parabolic membranes are maintained by stresses developed due to optical coatings. Continuum-based predictive models of coating requirements must be translated into a prescription for the coating process, which is an atomistic-based activity. In this paper we present some preliminary results of experiments performed to validate the coatings applied to polymer membranes in order to match numerical predictions. Bulge tests were performed to determine the coating stress of a thin film membrane. The bulge tests related the deflection of a pressurized thin film to the film's mechanical properties (including coating stress). A finite element model was created using ABAQUS for comparison with the bulge test data. Vibration tests were also performed to determine the coating stress, since natural frequencies give an estimate of the intrinsic coating properties. An ABAQUS model provided the first few natural frequencies for comparison against the experimental results.