Design for Additive Manufacturing of a shape-adaptive handle with Joule-heating actuated geometry transformation using shape memory polymers

This study illustrates how the integration of various functional materials via Multi Material Additive Manufacturing (MMAM) can result in the design of smart, user-specific products for human–machine interfaces. The proposed concept focuses on adaptive handgrips that accommodate individual anthropometric characteristics and dynamically adjust their shape under changing load conditions. To achieve reversible shape adaptation, a thermally activated shape-memory polymer (SMP) is integrated into the outer geometry of the grip, allowing for controlled deformation. MMAM is employed to fabricate the required complex geometries from a multitude of functional materials within a single component. A conceptual design phase using the Contact and Channel Approach (C&C 2 -A) is used to define critical functional areas and performance requirements. Mechanical testing characterized inter- layer bonding strength for various material combinations. Thermography is applied to assess the heating system’s capability to induce uniform surface temperatures and thus repeatable deformation. For ensuring uniform deformation of the handle, a bending fin according to DIN EN ISO 178 was employed; to assess form adaptivity, the product geometry was measured using 3D scanning and compared with the initial reference shape. The results highlight the feasibility of personalized, reversible deformation in additively manufactured grips, paving the way for user-specific, adaptive products in ergonomic and functional design.