| Integrated process is an important technique of cure process for composites to reduce parts and fasteners and meet the needs of structure performance. Fabrication cost can be reduced in integrated process. Cure-induced deformation is key problem to improve process quality of large-scale and complex structural composite integrated structure. For reducing cure-induced deformation, conventional method is that adjust and correct the skin of mold and cure system again and again according as experiences and process tests. But the conventional method increases fabricate cost. So it is important to guarantee a product and reduce fabrication cost that the method of analyzing and predicting deformation is developed for integrated composite structure.In this paper, analysis models and three-dimensional finite element method (FEM) for cure process of composite integrated structure were developed. Thermal deformation and cure shrink were considered in analysis models and the evolution of residual stresses in the entire cure process was studied. Numerical predictions compared quite well with experimental measurements for the development of cure temperature and cure-induced deformations.During autoclave integrated process, the mismatch between coefficients of thermal expansion of metal mold and composite part, flexible auxiliary mold, temperature distribution and deformation of framed-mold are important mold influencing factors for cure-induced deformation of composite structures. In this paper, fiber Bragg grating sensor was used to monitor residual stresses development in the unidirectional laminate. According as stress gradient in the direction of thickness obtained by experimental measurement mold/part interaction was studied. Shear-layer model was introduced and an associated model between shear-layer parameters, the dimension and cure pressure of composite structure was developed. Simulated results for laminate by shear-layer model could accurately predict cure-induced deformation compared with experimental measurements. Non-uniform pressure distribution on the surface of part transferred by flexible mold will influence cure-induced deformation, and flexible mold also has an effect on cure temperature distribution of composite part. In this paper, the performance of transferring cure pressure of flexible mold was studied with experiment and simulation. Non-uniform pressure distribution transferred by L-Shape flexible mold was obtained. The pressure from flexible mold on the part was as boundary condition to predict residual stresses and cure-induced deformation. And in thermal-chemistry model cure temperature of flexible mold and composite part are simulated together. Then cure-induced deformation of L-shape part was predicted and using flexible mold increased deformation. Framed-mold deformation and temperature distribution are important factors of cure-induced deformation for integrated structures. In this paper, framed-mold deformation and temperature distribution was obtained with FEM and numerical predictions compared quite well with experimental measurements. Structural parameters of flat-plate framed-mold have an effect on framed-mold deformation and the regularity was studied. Then deformation and temperature distribution of framed-mold were as boundary condition of cure-induced deformation simulation. Cure-induced deformation of unidirectional laminate induced by framed-mold was obtained.In this paper, cure temperature and cure-induced deformation for Carbon/BMI5428 T-Shape stiffened panel were investigated with considering mold factors during co-curing process and glue joint co-curing process. The results showed that tool/part interaction was the major mold factor to induce deformation for T-Shape stiffened panel, framed-mold temperature distribution and deformation was the secondary mold factor, and flexible mold was the third mold factor. And cure temperature distribution in glue joint co-curing was more uniform than in the co-curing. Cure-induced deformation in glue joint co-curing was less than in the co-curing.Lastly, in this paper, four control factors were presented to reduce cure-induced deformation by selecting processes and mold design. And the regularities of four factors were obtained to direct deformation control. |
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