Stress Analysis in Multi-head Large Scale Additive Manufacturing

Large-scale additive manufacturing is a rapidly evolving field that offers unique opportunities for manufacturing massive structures such as full-size prototypes of the submarine hull, wind turbine molds, and multi-story buildings. Commercially available large-scale 3D printers, such as big-area additive manufacturing or large-format additive manufacturing, can work with a wide range of materials, from metals and polymer/composites in the automotive and aerospace sectors to cementitious materials in the construction sector. Characterizing residual or yield stress development in these processes is key to understanding the part distortion during the print towards real-time quality monitoring, error compensation, and effective process control. This analysis would become further complicated as multiple heads are adopted for collaborative large-scale printing either to enhance efficiency or facilitate multi-material or multi-resolution printing. The adoption of multiple printing heads introduces variables such as changes in interlayer gap or bonding time, affecting stress distribution in the final printed part, and eventually the deformation or structural integrity of the end product. To systematically investigate and characterize this intricate relationship, this study employs a fast and efficient analytical approach to evaluate the stress distribution and potential point of collapse in a printed concrete wall by a multi-head large-scale 3D printer. The maximum shear stress distribution is calculated from the equilibrium of forces and compared with concrete yield stress to determine point of collapse and potential failures. This criterion is then evaluated for both single-head and multiple-headed large-scale 3D printing across various print lengths and layer heights.