Analysis Method for Bending Deflection of the Inner Frame System in an Airborne Optoelectronic Platform

The inner frame is a primary load-bearing component of an airborne electro-optical pod, and its structural mechanical characteristics directly influence imaging quality and attitude stability under complex operating conditions. During the early design stage, structural assessment mainly relies on high-fidelity finite element analysis (FEA), which is computationally intensive and inefficient for rapid parameter screening and scheme comparison. To address this issue, a simplified analytical method for preliminary evaluation of the inner-frame structure is proposed, and its engineering applicability is systematically assessed. The relationship between inner-frame axis rotation and structural loading conditions is first established. Under the assumption that the loading direction is approximately perpendicular to the curvature direction, curved frame members are equivalently modeled as straight beams of equal length, and analytical expressions for bending deflection are derived. Finite element simulations are then performed to evaluate the accuracy and applicability of the method under different structural parameters. Results show that when curvature and geometric conditions satisfy the limits defined in this study, the deviation between the simplified model and numerical results remains within an engineeringly acceptable range. The method provides an efficient analytical tool for rapid structural evaluation in the early design stage.