3D-Printed Porous Structure and Polymer Infiltration for Fabrication of Functionally Gradient Material with Complex Shape

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Additive manufacturing includes a variety of 3D fabrication technologies. Starting from early powder-based 3D printing, commercial machines are now capable of producing thermoplastics using fused deposition modeling, ultraviolet curable polymers using stereolithography, and metals using laser sintering techniques. However, additive manufacturing of composites or bi-materials remains challenging, particularly for two materials with significantly different properties that can be combined in various ratios to create different mechanical behaviors. This research aims to develop a manufacturing method, in which 3D printing is utilized to make specific scaffold structures, allowing polymer to infiltrate and reinforce the part. This new method will enable development of functionally gradient materials, light-weight design, and reinforced structures for applications of additive manufacturing in rapid prototyping, healthcare, automotive and aerospace. Outcomes of this research will stimulate the next-generation additive manufacturing technology and provide education and research opportunities for students of many different backgrounds. This research focuses on understanding the infiltration mechanism of the polymer through certain parameters, such as viscosity and surface tension, and mechanical behaviors of the polymer infiltrated composite in order to customize material properties, including stiffness, hardness, strength, and isotropy or anisotropy. To this end, this research includes two tasks. First, the research team will study and simulate the infiltration phenomenon using computational fluid dynamics and validate with design of experiments. The results will define the structural limits to capsulate or drain liquid polymers prior to solidification. In the second task, they will investigate the rule of mixtures for composite mechanics under a variety of scaffold structures and the non-linear behavior of the composite under extreme loads. Results from this research can be used to establish a material decomposition algorithm. This algorithm can thus be used to define scaffold structure and polymer selection given a set of desired material properties.