I’m excited to share that my technical note, “Three-node torsional spring element formulation for the analysis of reconfigurable bar-linked structures,” has been accepted for publication in the ASME Journal of Applied Mechanics!
In this work, I introduce a three-node torsional spring element with closed-form expressions for both internal forces and tangent stiffness. The key idea is to model joint rotational stiffness in bar-linked structures without adding rotational degrees of freedom, so the element drops directly into the same global DOF system as a standard truss. That makes it compact, easy to implement, and computationally efficient, while still capturing how joint stiffness affects buckling behavior and actuation forces.
Beyond reconfigurable trusses, this formulation is broadly applicable to compliant mechanisms, architected metamaterials, kirigami lattices, and biomechanics-inspired assemblies. It provides a minimal, first-principles description of joint rotational stiffness that is decoupled from axial behavior, making it a useful building block for many kinds of nonlinear structural analyses. An open-source implementation of the spring element in a nonlinear structural solver accompanies the paper to make it straightforward for others to adopt and build on this work.
A huge thank you to my advisor and co-author, Dr. Evgueni T. Filipov, for his constant support and guidance throughout this project.
Check out the paper here.