Identification of the stiffening and structural damping effects of cryogenic support structures in milling thin-walled components

Abstract

When machining thin-walled components, low structural rigidity frequently leads to dynamic instabilities such as chatter. The application of cryogenically generated support structures formed by expanding liquid CO₂ and a lubricant emulsion to create a temporary ice layer has emerged as a promising approach to stabilize the workpiece. While previous research has successfully demonstrated the phenomenological feasibility and focused on process control during the support structure generation, the predictive design of such milling processes requires a quantification of the support’s macroscopic material properties. Because the resulting ice is a multiphase, porous composite, standard literature values are inapplicable. Therefore, the core scientific challenge addressed in this study is decoupling the purely mass induced inertial effects of the ice structure from its actual stiffening and damping contributions to establish a reliable material model. Using Finite Element Method (FEM) for parameter identification, the macroscopic material properties were determined. The findings reveal that cryogenic support structures exert a dual stabilizing mechanism: they provide critical added rigidity and effectively dissipate vibrations, particularly in the high-frequency range, by significantly increasing the inherent damping of the system.