Abstract

This qualitative study develops morphological design principles for thermally formed passive adaptive grippers within an accessible 4D-printing approach. A practice-based morphological exploration was conducted through 18 PLA+ prototypes fabricated by Fused Deposition Modeling and thermally formed through controlled hot-water immersion. The study treats the two-dimensional pre-forming sheet geometry as the central design variable and examines how variations in flat-pattern organization affect the activated three-dimensional gripper. This shifts attention from optimizing a single predefined gripper toward understanding how form variations generate design knowledge. The prototypes were organized into two morphological families: a convergence-based radial gripping family and a guided cylindrical wrapping family. Functional and morphological readings of the catalogue showed that flat-pattern decisions shape grasp typology, functional role distribution, approach geometry, structural continuity, and the behavioral envelope of the activated form. The study proposes seven morphological design principles linking flat-pattern operations to three-dimensional gripping consequences, while also showing that the two families form a continuum of morphological possibilities rather than discrete categories. Across the prototype lineage, design knowledge accumulates through comparison and can be recombined into more resolved configurations. This paper offers a planning vocabulary for developing passive adaptive gripping structures before performance optimization or application-specific engineering begins.

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