Irreversible and Repeatable Shape Transformation of Additively Manufactured Annular Composite Structures.

Area of Science:

• Materials Science
• Additive Manufacturing
• Polymer Science

Background:

• Four-dimensional (4D) printing, an extension of additive manufacturing (AM), offers time-dependent shape transformations.
• Current 4D printing faces challenges in cost-competitiveness and achieving high dimensional accuracy and repeatability in shape transformations.

Purpose of the Study:

• To develop an irreversible and repeatable thermoresponsive shape transformation method for 4D printing.
• To overcome limitations of existing 4D printing techniques using a non-shape-memory polymer.
• To demonstrate the application of the developed method in fabricating complex composite structures.

Main Methods:

• Utilized a material extrusion additive manufacturing process with acrylonitrile butadiene styrene (ABS) thermoplastic.
• Programmed printing paths along a circular direction to induce circumferential anisotropy.
• Applied heat treatment as a thermal stimulus for shape transformation, comparing constrained and unconstrained deformations for accuracy and repeatability.

Main Results:

• Achieved a unique 2D-to-3D shape transformation in annular discs in response to thermal stimulus due to programmed anisotropy.
• Demonstrated that geometric constraints enhance the predictability and repeatability of thermal deformations.
• Successfully applied the method for in-situ assembly of a composite frame-membrane structure without additional assembly steps.

Conclusions:

• The developed thermoresponsive shape transformation method offers a viable approach for cost-effective and accurate 4D printing.
• The technique enables the integration of functional components into complex 3D structures during the printing process.
• This advancement holds potential for practical applications requiring precise, time-dependent shape changes in AM.