On the Stabilization of 2D FE Simulations of Chip-Formation: The Role of Process-Dependent Mesh Patterns and Kinematic ALE Mesh Constraints

The Arbitrary Lagrangian-Eulerian (ALE) method is well-established in modeling chip-formation. However, high strains and strain rates within the chip challenge this approach, often causing inadmissible element distortions that lead to premature simulation termination. This issue is especially evident when simulating variable chip thickness, such as in milling, compared to the more consistent conditions in turning. Several models have implemented a method to maintain mesh quality within the chip-formation zone using advanced ALE. This involves defining a compact control volume that covers the workpiece process zone, including a relevant part of the chip. Kinematic ALE mesh constraints are applied to its boundaries, which then move in sync with the cutting tool edge, thereby preserving mesh granularity in the deformation region. This method enables precise modeling of milling kinematics without requiring path transformations. In this work, the strategy is enhanced by incorporating a key feature. The control volume is now discretized with 2D quadrilateral patches. A library of patches is available, with each patch distinguished by the nodes along its four edges. A configuration of patches is generated automatically to mesh the control volume according to the requirements, ensuring mesh compatibility. The chip-formation simulation is divided into two milling stages, and during transitions, the mesh is adapted by exchanging patches and adjusting internal nodes as needed for mesh healing. This approach handles spatial and transient deformations through a two-level granularity: first, at the control volume level using patches, and second, at the patch level using elements. This work introduces the new strategy, with an emphasis on modeling and model reduction related to chip-formation.