Probabilistic uncertainty analysis of laser/material thermal interactions

Performance of a system during heat-flux (laser-type) irradiation is of increasing importance to a variety of defense and commercial applications. For laser irradiation of spacecraft components, such as a laser power or propulsion system receiver, predicting with accuracy the moment (time) and type of failure of it is difficult. These difficulties arise from the inherent nonlinear nature of the problem, because surface reradiation heat transport mechanisms come into play as the system is heated. Additionally, there are uncertainties associated with the irradiation source intensity, interaction cross-section and view angle; the property state of the material(s) that are being heated; and the effective emissivity/absorptivity and surface radiation view factor(s). The physical properties of the materials on a spacecraft may also change greatly over time due to exposure to the space environment. To better understand the uncertainties associated with these issues, a study was performed at the University of New Mexico's Institute for Space and Nuclear Power Studies, under U. S. Air Force Phillips Laboratory sponsorship, to develop and apply uncertainty computer model for generic laser heating problems that incorporate probabilistic design (Monte Carlo sampling based) assessment methods.; This work discusses in detail: the background associated with the laser irradiation/material thermal interaction process; past work in related technical areas; the research objectives of the study; the technical approach employed; as well as the development and application of the generic one- and two-dimensional laser/material heating uncertainty interaction analysis models. This study successfully demonstrated an efficient uncertainty assessment methodology to assess simple laser irradiation/material thermal heating process problems. Key parameter uncertainties were characterized and ranked for numerous example problem applications, and the influence of various Monte Carlo sampling approach parameters on the assessment results were also examined. Additionally, a two-dimensional analysis was performed that demonstrated the utility of the assessment process to characterize parameter uncertainties associated with heating of a material that has been exposed to a space environment over a period of time. The usefulness of the overall uncertainty analysis methodology to efficiently support the preliminary design assessment process of complex systems from a practical engineering standpoint, is also addressed.