Anisogrid thermoplastic composite lattice structure by innovative out-of-autoclave process

An innovative manufacturing process for thermoplastic composite structures is proposed for the production of three-dimensional cylindrical lattice structures. An out-of-autoclave compaction process has been designed by using the compression of a heat-shrink tube during its shape recovery in oven. Thermoplastic prepreg tapes are wound on a metallic cylindrical-patterned mold at room temperature, and the full assembly is inserted in the heat-shrink tube before heating in oven. In this study, anisogrid lattice structures have been prototyped in E-glass/polypropylene composite. Circular composite rings were manufactured as well to measure for technology assessment. Finite element (FE) modeling has been used to predict mechanical performances of anisogrid lattice structures. Model calibration and validation was carried out by using the results from mechanical tests on rings. Numerical models were developed with a batch-type parametric approach to quickly evaluate combined effects of geometry and material parameters. Numerical results are in good agreement with experimental data, having less than 8% of maximum difference in the case of the complex anisogrid lattice structure.