Structural Design And Damage Identification Of Filament-Wound Toroidal Vessels

Recently, filament-wound toroidal pressure vessels have emerged as an attractive alternative in the aircraft where space-saving, weight reduction and non-drift of barycenter are required. For winding toroial vessels, a design-oriented method for the pattern parameters demanding both structural characteristics and winding stability is described systematically in this paper. Furthermore, an improved structural damage identification method based on modal strain energy change is developed.Chapter 1 outlines filament winding and states background and important significance of developing CAD/CAM system and damage identification method for composite toroidal vessels.Chapter 2 gives pattern equations for geodesic winding toroidal vessels based on differential geometry, obtains the necessary and sufficient condition of non-bridging winding, indicates the deficiency of geodesic pattern for toroidal vessels winding.Chapter 3 presents concept and design method for equicohesive pattern of filament-wound toroidal vessels. The equicohesive pattern parameters considering the initial winding conditions and the variation of laminated thickness are obtained. The general criterions for fiber bridging and slippage on torus are derived by differential geometry. The relationship among the slippage resistance, the relative bend radius and the thickness matching of helical and hoop winding plies are given. Moreover, the initial winding angle and the thickness of helical winding plies are optimized using SQP algorithm. The minimum structural mass is treated as optimization objective while the strength and winding stability are treated as constraint conditions. Chapter 4 presents a new class of trajectory—non-geodesic pattern, which have more freedom than geodesic and equicohesive pattern aforementioned. The differential equations of non-geodesic pattern on torus are derived from differential geometry. A pattern design proposal considering structural optimization and winding stability is presented. Furthermore, the transmission relationship between the toroidal mandrel and the payout eye is given by the arrangement rule of the winding pattern on torus. The optimum pattern is adjusted based on the conditions of uniform and full coverage.Chapter 5 briefly outlines the operating system of the winding machine for the toroidal vessels, obtains movement equations of winding torus and the nonlinear equation for solving the rotation angle of mandrel.In chapter 6, CAD technology is applied to filament winding process according to the analysis of the winding pattern. The main frame and the implement of CAD system were investigated and the simulations ofgeodesic and non-geodesic winding are performed. It can be confirmed that the comprehensive structural performance of the toroidal pressure vessel could be improved by using this pattern.Chapter 7 develops an improved structural damage identification method based on modal strain energy. The structural modal perturbation considering second-order terms are given to obtain the change of the mode parameters before and after damage in the structure. A modes division method is put forward by expressing the higher modes in terms of series expansion of the lower modal parameters. The damage quantification approach based on second-order modal perturbation and modes division method is derived.