scholarly journals Inverse Identification of the Ductile Failure Law for Ti6Al4V Based on Orthogonal Cutting Experimental Outcomes

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1154
Author(s):  
Andrés Sela ◽  
Daniel Soler ◽  
Gorka Ortiz-de-Zarate ◽  
Guénaël Germain ◽  
François Ducobu ◽  
...  
Keyword(s):  
Numerical Models ◽  
Orthogonal Cutting ◽  
Constitutive Models ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Ductile Failure ◽  
Average Error ◽  
Workpiece Temperature ◽  
Inverse Simulation ◽  
Infrared Measurements

Despite the prevalence of machining, tools and cutting conditions are often chosen based on empirical databases, which are hard to be made, and they are only valid in the range of conditions tested to develop it. Predictive numerical models have thus emerged as a promising approach. To function correctly, they require accurate data related to appropriate material properties (e.g., constitutive models, ductile failure law). Nevertheless, material characterization is usually carried out through thermomechanical tests, under conditions far different from those encountered in machining. In addition, segmented chips observed when cutting titanium alloys make it a challenge to develop an accurate model. At low cutting speeds, chip segmentation is assumed to be due to lack of ductility of the material. In this work, orthogonal cutting tests of Ti6Al4V alloy were carried out, varying the uncut chip thickness from 0.2 to 0.4 mm and the cutting speed from 2.5 to 7.5 m/min. The temperature in the shear zone was measured through infrared measurements with high resolution. It was observed experimentally, and in the FEM, that chip segmentation causes oscillations in the workpiece temperature, chip thickness and cutting forces. Moreover, workpiece temperature and cutting force signals were observed to be in counterphase, which was predicted by the ductile failure model. Oscillation frequency was employed in order to improve the ductile failure law by using inverse simulation, reducing the prediction error of segmentation frequency from more than 100% to an average error lower than 10%.

Finite Element Modeling of Chip Formation in the Domain of Negative Rake Angle Cutting

2003 ◽  
Vol 125 (3) ◽  
pp. 324-332 ◽  
Author(s):  
Y. Ohbuchi ◽  
T. Obikawa
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Undeformed Chip Thickness ◽  
Element Modeling ◽  
Single Grain ◽  
Serrated Chips

A thermo-elastic-plastic finite element modeling of orthogonal cutting with a large negative rake angle has been developed to understand the mechanism and thermal aspects of grinding. A stagnant chip material ahead of the tool tip, which is always observed with large negative rake angles, is assumed to act like a stable built-up edge. Serrated chips, one of typical shapes of chips observed in single grain grinding experiment, form when analyzing the machining of 0.93%C carbon steel SK-5 with a rake angle of minus forty five or minus sixty degrees. There appear high and low temperature zones alternately according to severe and mild shear in the primary shear zone respectively. The shapes of chips depend strongly on the cutting speed and undeformed chip thickness; as the cutting speed or the undeformed chip thickness decreases, chip shape changes from a serrated type to a bulging one to a wavy or flow type. Therefore, there exists the critical cutting speed over which a chip can form and flow along a rake face for a given large negative rake angle and undeformed chip thickness.

scholarly journals Prediction of Surface Quality Based on the Non-Linear Vibrations in Orthogonal Cutting Process: Time Domain Modeling

2019 ◽  
Vol 3 (3) ◽  
pp. 53
Author(s):  
Kibbou ◽  
Dellagi ◽  
Majdouline ◽  
Moufki
Keyword(s):  
Surface Quality ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Cutting Conditions ◽  
Process Time ◽  
Mean Deviation ◽  
Non Linear ◽  
Linear Vibrations

This work presents an analysis of relationships between the non-linear vibrations in machining and the machined surface quality from an analytical model based on a predictive machining theory. In order to examine the influences of tool oscillations, several non-linear mechanisms were considered. Additionally, to solve the non-linear problem, a new computational strategy was developed. The resolution algorithm significantly reduces the computational times and makes the iterative approach more stable. In the present approach, the coupling between the tool oscillations and (i) the regenerative effect due to the variation of the uncut chip thickness between two successive passes and/or when the tool leaves the work (i.e., the tool disengagement from the cut), (ii) the friction conditions at the tool–chip interface, and (iii) the tool rake angle was considered. A parametric study was presented. The correlation between the surface quality, the cutting speed, the tool rake angle, and the friction coefficient was analyzed. The results show that, during tool vibrations, the arithmetic mean deviation of the waviness profile is highly non-linear with respect to the cutting conditions, and the model can be useful for selecting optimal cutting conditions.

Material Ductile Failure-Based Finite Element Simulations of Chip Serration in Orthogonal Cutting of Titanium Alloy Ti-6Al-4V

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Guoliang Liu ◽  
Suril Shah ◽  
Tuğrul Özel
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Ductile Failure ◽  
Ductile Deformation ◽  
Ductile Material ◽  
Damage Initiation ◽  
Coated Carbide

Titanium alloy Ti-6Al-4V, an alpha-beta alloy, possesses ductile deformation behavior and offers advantageous properties, light weight but high strength, good resilience, and resistance to corrosion, becoming highly suitable for aerospace and biomedical applications. However, its machinability is still considered a limiting factor in improving productivity. This paper presents a finite element modeling methodology for orthogonal cutting titanium alloy Ti-6Al-4V by considering material constitutive modeling together with material ductile failure in combination with damage initiation and cumulative damage-based evolution to simulate not only ductile material separation from workpiece to form chips but also chip serration mechanism by applying an elastic–viscoplastic formulation. The finite element model is further verified with orthogonal cutting experiments (using both uncoated and TiAlN-coated carbide tools) by comparing simulated and acquired forces and simulated and captured chip images at high cutting speeds. The effects of cutting speed, feed, tool rake angle, and tool coating on the degree of chip serration are studied through the simulation results. The cutting temperature and strain distributions are obtained to study the chip serration mechanism under different cutting conditions. It is confirmed that the material failure, crack initiation, and damage evolution are of great significance in the chip serration in cutting titanium alloy Ti-6Al-4V.

scholarly journals Influence of Constitutive Models and the Choice of the Parameters on FE Simulation of Ti6Al4V Orthogonal Cutting Process for Different Uncut Chip Thicknesses

2021 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Nithyaraaj Kugalur Palanisamy ◽  
Edouard RiviÈre LorphÈvre ◽  
Pedro-José Arrazola ◽  
François Ducobu
Keyword(s):  
Constitutive Model ◽  
Orthogonal Cutting ◽  
Constitutive Models ◽  
Chip Thickness ◽  
Material Model ◽  
Machining Process ◽  
Uncut Chip Thickness ◽  
Dependent Strain ◽  
Important Input

The constitutive model and its pertinent set of parameters are important input data in finite element modeling to define the behavior of Ti6Al4V during machining process. The present work focusses on comparing different constitutive models and the parameters sets available in literatures and investigating the quality of the predictions when varying uncut chip thickness (40 µm, 60 µm, 100 µm and 280 µm). In addition, temperature-dependent strain hardening factor along with strain softening phenomenon based reconstructed material model is proposed. The results from the numerical simulations are compared with experimental results available in literature. The comparison shows that the force values are highly influenced by constitutive models and the choice of parameters sets, whereas the chip morphologies are mainly influenced by the uncut chip thickness and constitutive models. This work justifies the need for an appropriate set of parameters and constitutive model that replicate the machining behavior of Ti6Al4V alloy for different cutting conditions.

scholarly journals An investigation of force components in orthogonal cutting of medical grade cobalt–chromium alloy (ASTM F1537)

2017 ◽  
Vol 231 (4) ◽  
pp. 269-275 ◽  
Author(s):  
Szymon Baron ◽  
Eamonn Ahearne
Keyword(s):  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Lifestyle Changes ◽  
Ageing Population ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Undeformed Chip Thickness ◽  
Force Components ◽  
Medical Grade

An ageing population, increased physical activity and obesity are identified as lifestyle changes that are contributing to the ongoing growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt–chromium–molybdenum (Co-Cr-Mo) alloys, due to their mechanical properties and excellent biocompatibility, qualify as a class of materials that meet the stringent functional requirements of these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers rely on high-precision machining. However, a comprehensive literature review has shown that there has been limited research into the fundamental mechanisms in mechanical cutting of these alloys. This article reports on the determination of the basic cutting-force coefficients in orthogonal cutting of medical grade Co-Cr-Mo alloy ASTM F1537 over an extended range of cutting speeds ([Formula: see text]) and levels of undeformed chip thickness ([Formula: see text]). A detailed characterisation of the segmented chip morphology over this range is also reported, allowing for an estimation of the shear plane angle and, overall, providing a basis for macro-mechanic modelling of more complex cutting processes. The results are compared with a baseline medical grade titanium alloy, Ti-6Al-4V ASTM F136, and it is shown that the tangential and thrust-force components generated were, respectively, ≈35% and ≈84% higher, depending primarily on undeformed chip thickness but with some influence of the cutting speed.

scholarly journals Partition of Primary Shear Plane Heat in Orthogonal Metal Cutting

2020 ◽  
Vol 4 (3) ◽  
pp. 82
Author(s):  
Lars Langenhorst ◽  
Jens Sölter ◽  
Sven Kuschel
Keyword(s):  
Metal Cutting ◽  
Numerical Models ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Shear Plane ◽  
Machining Processes ◽  
Heat Partition ◽  
Realistic Representation ◽  
Cutting Velocity ◽  
Cutting Processes

When assessing the effect of metal cutting processes on the resulting surface layer, the heat generated in the chip formation zone that is transferred into the workpiece is of major concern. Models have been developed to estimate temperature distributions in machining processes. However, most of them need information on the heat partition as input for the calculations. Based on analytical and numerical models, it is possible to determine the fraction of shear plane heat transferred into the workpiece for orthogonal cutting conditions. In the present work, these models were utilized to gain information on the significant influencing factors on heat partition, based on orthogonal cutting experiments, experimental results from the literature, and a purely model-based approach. It could be shown that the heat partition does not solely depend on the cutting velocity, the uncut chip thickness, and the thermal diffusivity—combined in the dimensionless thermal number—but the shear angle also has to be taken into account, as already proposed by some researchers. Furthermore, developed numerical models show that a more realistic representation of the process kinematics, e.g., regarding chip flow and temperature-dependent material properties, do not have a relevant impact on the heat partition. Nevertheless, the models still assume an idealized orthogonal cutting process and comparison to experimental-based findings on heat partition indicates a significant influence of the cutting edge radius and the friction on the flank face of the tool.

Chatter When Machining Aluminium Alloy: An Investigation Using a Structural Model

1968 ◽  
Vol 183 (1) ◽  
pp. 17-29 ◽  
Author(s):  
B. M. Johnson ◽  
C. Andrew
Keyword(s):  
Machine Tool ◽  
Aluminium Alloy ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Regenerative Chatter ◽  
Tool Vibration ◽  
Undeformed Chip Thickness ◽  
Machining Force ◽  
Conventional Tool

This paper describes an experimental investigation of machine tool chatter, in which the machine tool structure was replaced by a model, two-degrees-of-freedom structure with adjustable and consistent vibration characteristics. Primarily non-regenerative chatter, and secondarily regenerative chatter, were investigated for orthogonal cutting of an aluminium alloy with both conventional and restricted-contact cutting tools. The results are presented in the form of stability charts; these show the limiting widths of cut which can be machined without chatter, for given sets of machining and structural conditions. For non-regenerative chatter, it was found that the limiting width of cut: increases with a decrease in the structure's cross-receptance between the directions normal and tangential to the cut surface; increases with a decrease in cutting speed, but in a manner depending on the structural characteristics; is substantially independent of the mean undeformed chip thickness; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. For regenerative chatter it was found that the limiting width of cut: was approximately one half of the limiting width for non-regenerative chatter, for the otherwise similar machining and structural conditions investigated; increases with a decrease in cutting speed; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. Theoretical predictions of non-regenerative chatter with a conventional tool, based on independent measurements of machining force oscillations during tool vibration, agree well with experimental results. For regenerative chatter with a conventional tool, the theory was based on the superposition of machining force oscillations arising from tool vibration and from removing a wavy surface. The predictions were in error at low cutting speeds, indicating that the force oscillations are not superposable at this condition.

scholarly journals Influences of Cutting Speed and Material Constitutive Models on Chip Formation and their Effects on the Results of Ti6Al4V Orthogonal Cutting Simulation

2021 ◽  
Author(s):  
Nithyaraaj Kugalur-Palanisamy ◽  
Edouard Rivière-Lorphèvre ◽  
Pedro-José Arrazola ◽  
François Ducobu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Constitutive Models ◽  
Cutting Speed ◽  
Element Model ◽  
Cutting Process ◽  
Machine Material ◽  
On Chip

The highly used Ti6Al4V alloy is a well know hard-to-machine material. The modelling of orthogonal cutting process of Ti6Al4V attract the interest of many researchers as it often generates serrated chips. The purpose of this paper is to show the significant influence of cutting speed on chip formation during orthogonal cutting of Ti6Al4V along with different material constitutive models. Finite element analyses for chip formation are conducted for different cutting speeds and are investigated with well-known Johnson-Cook constitutive model, a modified Johnson–Cook model known as Hyperbolic Tangent (TANH) model that emphasizes the strain softening behavior and modified Johnson-Cook constitutive model that consider temperature dependent strain hardening factor. A 2D Lagrangian finite element model is adopted for the simulation of the orthogonal cutting process and the results from the simulations such as calculated forces, chip morphologies are analyzed and are compared with the experimental results to highlight the differences. The results analysis shows that, the temperature in the secondary deformation zone is directly proportional to the cutting speed.

Thin Film Stress Sensor on the Tool Rake Face for Orthogonal Cutting

2020 ◽  
Author(s):  
Toshiyuki Obikawa ◽  
Kenji Yagi ◽  
Mamoru Hayashi
Keyword(s):  
Thin Film ◽  
Silicon Nitride ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Film Stress ◽  
Rake Face ◽  
Stress Sensor ◽  
Thin Film Stress

Abstract The evaluation of stress and temperature on the tool faces during machining is very important for understanding the fundamental mechanism of machining processes, developing cutting tools, optimizing cutting conditions. Although cutting temperature has been often measured using the tool-chip thermocouple method, a two-color pyrometer, etc., measurement of stress on the tool face has been hardly reported. For this reason, a cutting tool with a thin film stress sensor in the surface layer of the rake face was developed for orthogonal cutting. The film sensor was made of manganin, a copper-manganese-nickel alloy having piezoresistance effect. The manganin was coated on the rake face of polished silicon nitride matrix by magnetron sputtering in a specific pattern having a line 30 micrometer wide and 0.2 micrometer thick along the cutting edge. Then, the rake face was further coated with silicon nitride for protecting the thin stress sensor. After the calibration of the sensor, the tool was applied to orthogonal cutting experiment, in which MC Nylon and polyvinyl chloride were machined at a very low cutting speed. For four levels of uncut chip thickness from 0.05 to 0.20 mm the stress was measured for MC Nylon. The measured stress seems consistent with stress distributions measured by photoelasticity method reported so far.

Study on Temperature Effect in Micro-Cutting Process

2011 ◽  
Vol 268-270 ◽  
pp. 2077-2080
Author(s):  
Zi Yang Cao ◽  
Hua Li
Keyword(s):  
Temperature Effect ◽  
Orthogonal Cutting ◽  
Temperature Drop ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Cutting Process ◽  
Material Strength ◽  
Uncut Chip Thickness ◽  
Micro Cutting

A coupled thermo-mechanical model is used to simulate two-dimensional orthogonal cutting process based on simulation model of micro-cutting. The temperature effect in micro-cutting process is studied deeply through FEM combined with micro-cutting experiments. The results indicate that cutting temperature decreases at the tool-chip interface with reduction in uncut chip thickness at high cutting speed and large uncut chip thickness. The temperature drop tends to have a hardening effect on the material strength, which in turn causes an increase in the specific cutting energy.

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