Weight Estimation Of Fuselage Structure In Preliminary Aircraft Design

Fuselage weight estimation is one of the most important issues in aircraft preliminary design. Thispaper is mainly engaged in the large aircraft fuselage structural weight estimation of the preliminarydesign stage. In order to obtain a more accurate fuselage structural weight, we study two methods toestimate the weight for a typical aircraft fuselage: one is semi-analytical method based on beamtheory analysis; the other method is based on the finite element analysis and structural optimization.1) A method of estimating the civil aircraft fuselage weight based on beam theory has beendeveloped. It simplifies the fuselage structure to a thin-walled tubular beam structure. The landing andmaneuvering loads then is imposed the on the structure. According to the stress checking formula, thefuselage strength on these two conditions is evaluated and the minimum amount of material requiredis calculated in order to calculate the load-bearing structures weight. A correction relationshipbetween the body weight and body structure weight is used to get the total fuselage weight. The A320aircraft is taken as an example to verify this method. The results show that the method based on thebeam theory to estimate the fuselage weight has a reasonable accuracy.2) A method of estimating the fuselage structural weight of civil aircraft based on finite elementmethod and structural optimization has been developed. This process includes establishing fuselageshape CAD model, loads calculation, automatically generating finite element model of the bodystructure, structural size optimization and fuselage weight correction. The fuselage parameters shapemodel is automatically created by the use of CATIA advanced programming interface (API) throughVisual Basic (VB). A Matlab program is written to calculate several typical loads and the most seriouscase as the design load is selected, and also the inertial load and the cabin floor load are calculated. APatran/Nastran’s script is written to establish the fuselage structure model and structural finite elementmodel. The size of fuselage structure to obtain the least structure weight can be optimized. Thefuselage structure weight is corrected by related formula to receive the reasonable result. The abovemethod is applied to estimate different cabin layout fuselage weight. The impact of the width of thefuselage cross-section on the fuselage structure weight is obtained.The results show that fuselage weight estimation based on the beam theory method has quick andeasy characteristic, and has relatively high accuracy. The finite element method, which combines theadvanced computer-aided design software CATIA and structural analysis software MSC.Pastran tocalculate fuselage weight, has the advantage of high automation. Both methods are feasible and effective, and is convenient method and rapid automatic tools to estimate the fuselage structuralweight.