Mechanical properties of additively manufactured multi-material stiff-soft interfaces: Guidelines to manufacture complex interface composites with tunable properties.

[Display omitted] • The TSIC model facilitates the design of complex interface composites with stiff and compliant materials. • Control of the tensile and shear interface thickness allows tuning of the composites' stiffness and strength, respectively. • Fracture analysis reveals non-columnar fractures as a key to enhancing interface hardening in TSICs. • UV curing during printing results in a gradient elastic modulus at stiff-soft interfaces, enhancing strength compared to non-UV-cured samples. The rapid growth of polyjet additive manufacturing has propelled the 3D printing of multi-material polymer composites toward unprecedented applications. Interfaces in such composites play a paramount role in determining mechanical performance. This study delves into the crucial role of interfaces, employing VeroWhite and Agilus30Black materials to scrutinize the tensile and shear properties of stiff-soft interfaces. By applying these layers strategically, composites with multi-oriented interfaces were created, revealing the impact of soft material thickness and orientation on stiffness and strength. We identified columnar and non-columnar fracture mechanisms, shedding light on their correlation with interface hardening. Nanoindentation tests unveil the local interface properties, emphasizing the gradient change in elastic modulus when printed on the x -axis and the sharp drop on the z -axis. These findings offer valuable insights into material selection and interface optimization, providing a roadmap for achieving tailored mechanical properties in complex interface composites. [ABSTRACT FROM AUTHOR]