Topology-Optimized PLA Test Fixture for Cyclic Testing of Lattice-Based Hysteretic Dampers

1. Introduction

Reliable experimental characterization of architected lattice materials requires specialized fixture systems that ensure accurate load transfer. Traditional metallic fixtures are often prohibitively expensive and slow to produce, hindering rapid, iterative material research. This study addresses this challenge by presenting the design, finite element validation, and topological optimization of a cost-effective test fixture made from Fused Filament Fabrication (FFF) Polylactic Acid (PLA). The fixture is designed to enable the cyclic mechanical characterization of LPBF-manufactured Kelvin-type lattices.

1. Methods

The fixture's design process was iterative, combining CAD modeling and Finite Element Analysis (FEA) to refine its geometry and performance. The supports were designed for axial load transfer compatible with an Instron 8801 testing machine. The loading protocol was proportionally scaled from a recognized standard for Steel Plate Shear Yielding Dampers (SPSYDs). A density-based topology optimization was performed to minimize mass while maintaining structural rigidity, targeting a mass reduction constraint of 60%.

1. Results

The iterative design and optimization process successfully improved the safety factor from an initial 2.08 to a final value of 4.25, confirming its structural integrity under the maximum load of 5.3 kN. The topology optimization achieved a mass reduction of 40% compared to the initial design. Preliminary experimental analysis and numerical simulations confirmed that the optimized PLA supports exhibited minimal deformation, with displacements around 0.73 mm, which was significantly lower than the machine clamps.

1. Conclusions

This research demonstrated that combining numerical analysis and topological optimization can produce cost-effective, FFF-manufactured PLA components that are capable of replacing traditional metal devices in cyclic mechanical testing applications. The developed methodology can be extended to other test devices where stiffness and precision are crucial. The validated fixture provides a reliable platform for future experimental tests of lattice-based hysteretic dampers.