Smoothed Particle Hydrodynamics (SPH), a particle-based, meshless method originally developed in the 1970s for modeling astrophysical problems, is being increasingly used for modeling fluid mechanics and solid mechanics problems. The method has several advantages over grid-based methods including better handling of large deformations and the availability of an intrinsic material separation method for chip separation and crack formation. Due to these advantages, several researchers have applied the SPH method to model materials removal processes such as cutting. However, one drawback of SPH method is that it is computationally expensive, since each particle interacts with all the particles that are within its support domain and the number of particles within this domain can be significant. One way to reduce the computational time is to partition the domain into two parts, where in one segment undergoing large deformations and material separation, the SPH method is used and in the second segment, the conventional finite element (FE) mesh is used.

In this work, the accuracy of this approach is investigated in the context of orthogonal cutting. The high deformation zone (where chips form and curl) is meshed with the SPH method, while the rest of the workpiece is modeled using the FE method. At the interface, SPH particles are coupled with finite element mesh for smooth transfer of stress and displacement. The boundary conditions are applied to tool and FE zone of the workpiece. For comparison purposes, the work-piece model based fully on SPH discretization is also considered. First, the SPH model is validated by comparing with the work by Mandaj et al. \[1\], who studied orthogonal machining of aluminum A2024-351 using the SPH method. This is followed by a comparison of the results from the coupled SPH-FE model with the SPH model. The coupled SPH-FE model is developed using the same material parameters and machining conditions. A comparison of the chip profile, the cutting force and various field variables such as the von Mises stress and the damage parameter show that the coupled SPH-FE model reproduces the SPH model results accurately. However, the SPH-FE model takes almost 40% less time to run, a significant gain over the SPH model. Similar reduction in computation time is observed when the coupling is applied to micro-cutting model of Zhao et al. \[2\], with depth of cut in range of 300nm. This result is useful for extending the machining model to three-dimensional oblique cutting, where the number of particles are large.


A Comparison of Smoothed Particle Hydrodynamics (SPH) and Coupled SPH-FEM Methods for Modeling Machining

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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