Structural limitations of additively manufactured building panels

Abstract

An experimental study on the performance of structural panels designed to serve as roofing and walls in low-cost Costa Rican homes manufactured with additive manufacturing of recycled polymers. Designs were simulated iteratively in Solidworks and performance was measured based on weight, print time, and deflection under loading. Loads were calculated based on standards from the Housing and Urban Development Council and Costa Rican weather patterns. A slicer provided by Oakridge National Laboratory was used to calculate an estimated print time for each design.

The results from simulation were then plotted to find an optimal design minimizing weight, deflection and print time. As expected, the optimal roof panel design used a small minimum feature size of 0.2” while maintaining stiffness by maximizing the distance between the outer casing of the panel with a thin i-beam inspired inner structure. The optimal roof panel design was used as inspiration for design iterations of the walls.

With the optimal geometry selected from iteration, the designs were then evaluated for printing on the BAAM using the design constraints laid out by ORNL. Strict limitations in terms of possible print path required changes to the geometry of the structure that increased deflection under loading by a factor of 10.

Tensile tests in accordance with ISO 527-2 were run on samples of rPET printed on an Ultimaker 2 Extended+ to get the material properties of the plastic depending on print direction. The results of these tests can be used to add rigor to previous Solidworks simulations of the house.