Advanced Materials Research Vol. 498

Abstract: Improving the cutting processes by optimizing operating parameters necessarily involves understanding the thermo-mechanical mechanisms generated during chip formation. For this, numerical simulations are used to obtain the strain, stress and thermal fields near the tool tip. Nowadays, the validation of numerical simulation models of cutting is based on macroscopic results such as chip geometry and cutting forces generated by the machining process. However, it is not appropriate to validate local fields by macroscopic results. So, it is important to validate numerical cutting simulations on the bases of measured local strain fields. This article aims to study the feasibility of strain field measurement in orthogonal machining of the titanium alloy Ti64. A high-speed camera was used to provide data for segmented chip formation analysis. A microscope was related to the camera to observe an area of about 0.7x0.7mm² around the tool tip. An optimum adjustment of camera settings, lighting, workpiece surface preparation and cutting conditions allowed to obtain an acceptable image quality for analyzing with Correli [1] software. At low cutting speed, Correli qualitatively identify the position of the primary shear band and its evolution over the time.

Abstract: A comparative study of different material modeling strategies in deformability analysis of rectangular cups is presented in this paper. The article focuses on application of dynamic explicit and static implicit approaches in Finite Element Methods (FEM) for metal forming simulation where different material models and contact conditions with friction are involved. The simulated results are verified using results from experimental study of the deformation on the same material. Further, a comparison between a quadratic Hill anisotropic yield criterion and von Mises yield criterion with isotropic hardening has been studied. The results confirm that the dynamic explicit method is more efficient in simulating sheet metal forming processes. The study shows also that the finite element analysis undoubtedly gives good approximate numerical results to real processes when the material and friction anisotropy are considered.

Abstract: This paper aims to establish a direct relationship between the value of the acceleration and the roughness profile. To this end, a system of testing has been designed to link the value of the acceleration to the position of the tool on the surface of the piece at each time step. In order to allow a more detailed monitoring, rather than measuring a generatrix of the piece, readings are taken on a machined surface which is comprised of widths, between 7 and 10 mm, and lengths, between 20 and 100 mm, where segments of the helical path of the tool on the piece are observed, thereby linking the path to specific values of the readings by the accelerometer.

Abstract: Despite of the efforts focused on the improvement of simulation of machining processes, this problem remains still open. In the case of metal cutting, 2D (two dimensional) modeling has been extensively used for decades in the prediction of difficult to measure variables in metal cutting. Although more complex 3D (three dimensional) approaches have been carried out they have still high computational cost. On the other hand long fiber reinforced composites are extensively used in industry; however the numerical modeling of composite cutting is still poorly developed, and mainly focused on 2D approach. Two dimensional approaches imply some simplifying hypotheses and limitations those could influence the results obtained from the analysis. This paper focuses on phenomena involved during cutting of metals and composite those should modeled using three dimensional approaches.