The concept of 4D printing is used in recent works by Suong Van Hoa, to develop complex composite springs and stiffeners without the need for complex curved molds.
Van Hoa, Suong. “Development of composite springs using 4D printing method” Composite Structures 210 (2019): 869-876.
Hoa, Suong, Bhargavi Reddy, and Daniel Rosca. “Development of omega stiffeners using 4D printing of composites” Composite Structures 272 (2021): 114264.