Damping optimization of a fully viscoelastic structure with enforced mass reduction

Abstract

Current damping methods employed in industry, such as Constrained Layer Damping (CLD), all require the introduction of additional mass and a secondary material to the structure. In transportation industries, this weight addition is often correlated with an increase in operational costs. Additionally, in applications with large temperature changes, such as in space, the secondary material introduces an additional source of stress during thermal expansion and contraction. This work presents a methodology to significantly improve the damping performance of a fully viscoelastic, single material structure while also enforcing a mass reduction. The work expands upon the modal strain energy (MSE) method to calculate the damping performance of a fully viscoelastic structure and develops a novel weighting scheme to make the optimization more robust. The methodology is then implemented on a technology demonstration thermoplastic lunar rover. This implementation demonstrates the ability to optimize a fully viscoelastic structure to significantly improve the damping performance while also achieving a large decrease in mass. The implementation also demonstrates the robustness of the weighting scheme as it allows the natural frequencies to shift between iterations. The skin thickness of the rover’s base panel was optimized. After optimization, the base panel of the rover achieved a 20% damping improvement for Mode 1 with a 9% mass reduction. The skin thickness of the full rover was optimized and achieved a 15% damping improvement for Mode 2 with an 11% mass reduction.