Concordia researcher looks to 4D printing to develop composite materials
Curved composite piece can be 4D printed quickly and economically and include long continuous fibres that have high mechanical properties.
As 3D printing becomes more advanced, researchers are looking for new ways to push the boundaries of this technology. Enter 4D printing — a method that enables users to create objects with a 3D printer that change shape over time once they’re removed from the printer.
“4D printing allows us to make curved composite structures without the need to make curved moulds,” says Suong Van Hoa, professor in the Department of Mechanical, Industrial and Aerospace Engineering in Concordia’s Faculty of Engineering and Computer Science (ENCS).
This 4D printing method allows Hoa to make a curved composite piece quickly and economically, where the part includes long continuous fibres that have high mechanical properties. Not only that, but building composite structures using Hoa’s method eliminates the need for expensive and complex molds. His findings show how the manufacturing process can be significantly streamlined.
“4D printing of composites utilizes the shrinkage of the matrix resin, and the difference in coefficients of thermal contraction of layers with different fibre orientations to activate the change in shape upon curing and cooling,” he says.
This means that parts with curved geometries can be made without the need for a complex mold. Hoa cautions that the degree of shape-changing depends on the material properties, the fibre orientation, the lay-up sequence and the manufacturing process.
One of the key considerations for this project was the anisotropic properties of composite layers — how a material acts while bearing loads along different axes. Hoa outlines the anisotropic properties at play in building a composite structure.
Resin shrinkage can cause materials to be deformed. Temperature changes can cause fibres to expand or contract. Ha argues that understanding and controlling these changes is key to making curved laminates without curved molds.
“Anisotropic properties have been looked at as a liability in the past,” he says. “Now I look at them as an asset.”
Hoa believes his research is well suited for the aerospace industry, where composites are widely used. He also thinks this will be useful for space applications where there is significant temperature fluctuation.
“The structure can open up during the day (when the temperature is high) to collect the solar energy, and close up at night to provide protection for its interiors,” he adds.
Last fall, Hoa became the first Canadian to be named a fellow of the American Society for Composites for his “outstanding contributions to the composites community through research, practice, education and service.”
He announced his latest discovery in the journal Advanced Manufacturing: Polymer & Composites Science.