Dynamic Friction Measurements at Sliding Velocities Representative of High-Speed Machining Processes

2000 ◽  
Vol 122 (4) ◽  
pp. 834-848 ◽  
Author(s):  
H. D. Espinosa ◽  
A. J. Patanella ◽  
M. Fischer
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Experimental Methodology ◽  
Stress Wave Propagation ◽  
Fracture Mechanisms ◽  
Dynamic Friction ◽  
High Speed Machining ◽  
Machining Processes ◽  
Friction Coefficients ◽  
Al 6061

Understanding high speed machining processes requires knowledge of the dynamic friction response at the tool-workpiece interface, the high strain rate response of the workpiece material and its fracture mechanisms. In this paper, a novel experimental technique, consisting in the independent application of an axial static load and a dynamic torque, is used to investigate time resolved dynamic friction. Shear stress wave propagation along an input bar, pressing statically against an output bar, is analyzed. The quasi-static and kinetic friction coefficients of Ti-6Al-4V sliding against 1080 Steel, Al 6061-T6 sliding against 1080 Steel, and Al 6061-T6 sliding against Al 7075-T6, with various surface characteristics, are investigated. Sliding velocities up to 6.9 m/s are achieved. Surface roughness is varied to understand its role on the frictional response of the sliding interfaces. The dependence of friction coefficient on material strain-rate sensitivity is also assessed. Measured friction coefficients compared well with values reported in the literature using other experimental techniques. The experimental methodology discussed in this article provides a robust method for direct measurement of the quasi-static and dynamic friction coefficients representative of high-speed machining, metal-forming and ballistic penetration processes. [S0742-4787(00)01304-7]

The Effect of Strain Rate on the Material Characteristics of Nickel-Based Superalloy Inconel 718

2007 ◽  
Vol 340-341 ◽  
pp. 283-288 ◽  
Author(s):  
Jung Han Song ◽  
Hoon Huh
Keyword(s):  
Dynamic Response ◽  
High Strain Rate ◽  
Strain Rate ◽  
Turbine Blade ◽  
Inconel 718 ◽  
High Speed ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Experimental Results ◽  
Stress Wave Propagation

The dynamic response of the turbine blade materials is indispensable for analysis of erosions of turbine blades as a result of impulsive loading associated with gas flow. This paper is concerned with the dynamic material properties of the Inconel 718 alloy which is widely used in the high speed turbine blade. The dynamic response at the corresponding level of the strain rate should be acquired with an adequate experimental technique and apparatus due to the inertia effect and the stress wave propagation. In this paper, the dynamic response of the Inconel 718 at the intermediate strain rate ranged from 1/s to 400/s is obtained from the high speed tensile test and that at the high strain rate above 1000/s is obtained from the split Hopkinson pressure bar test. The effects of the strain rate on the dynamic flow stress, the strain rate sensitivity and the failure elongation are evaluated with the experimental results. Experimental results from both the quasi-static and the high strain rate up to 3000/s are interpolated in order to construct the constitutive relation that should be applied to simulate the dynamic behavior of the turbine blade made of the Inconel 718.

scholarly journals Investigation on the Effects of Prefabricated Crack and Strain Rate on Uniaxial Compressive Properties of Frozen Silty Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dongdong Ma ◽  
Ezra Esanju Kaunda ◽  
Kun Huang
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Shear Failure ◽  
Rapid Change ◽  
Stress Wave Propagation ◽  
Peak Strain ◽  
Soil Specimen ◽  
Silty Soil ◽  
Fracturing Process ◽  
Deformation Properties

To investigate the uniaxial compressive strength and deformation properties of frozen silty soil with prefabricated crack under various strain rates, the static uniaxial compressive tests were conducted for frozen silty soil using three kinds of binder materials to select the suitable prefabricated crack manufacturing method. Afterward, the static and dynamic stress-strain curves of frozen silty soil with different prefabricated crack numbers were obtained based on static and splitting Hopkinson pressure bar (SHPB) tests. In addition, the high-speed camera was employed to record the fracturing process of frozen silty soil under impact loads. Results indicated that the frozen silty soil specimens with no binder showed higher static strength compared with other two binder materials (plaster and Vaseline). The strength growth rate of frozen silty soil showed three-stage (fast-slow-rapid) change characteristics. The peak strain of frozen silty soil under static loads scope was higher compared with that under dynamic loads, while its dynamic peak strain with various prefabricated crack numbers was remarkably rate-dependent. The absorbed energy density of frozen silty soil was subject to a negative (positive) relationship with the prefabricated crack numbers (strain rate). The dominated crack of intact frozen silty soil specimen finally presented Y-shaped shear failure. However, tensile cracks parallel to stress wave propagation direction were observed for the frozen silty soil specimen with prefabricated crack.

Reduction of Vibrations due to Unbalance with Anti-Vibration Clearance Angle in High Speed Milling

2016 ◽  
Vol 836-837 ◽  
pp. 161-167
Author(s):  
Anna Thouvenin ◽  
Xin Li ◽  
Ning He ◽  
Liang Li
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Removal Rate ◽  
Machining Process ◽  
High Speed Machining ◽  
Machining Processes ◽  
High Speed Milling ◽  
Clearance Angle ◽  
Fast Solution ◽  
Considerable Problem

High speed milling is one of the most commonly used machining processes in many fields of the industry. It is regarded as a simple and fast solution to achieve a high material removal rate, which allows an important production of parts. Unbalance is a problem in any machining process but becomes a considerable problem when reaching high speed machining. The vibrations due to an unbalanced tool or tool holder can result in a poor surface quality and a damaged tool. The damping of the vibrations can be achieved with a specially designed tool showing an anti-vibration clearance angle. This paper shows the influence of the anti-vibration clearance angle by a computational model and a set of experiments to see if it can reduce or suppress the vibrations due to unbalance in high speed milling.

Networked sensing for high-speed machining processes based on CORBA

2005 ◽  
Vol 119 (2) ◽  
pp. 418-426 ◽  
Author(s):  
Rodolfo E. Haber ◽  
Karina Cantillo ◽  
Jose E. Jiménez
Keyword(s):  
High Speed ◽  
High Speed Machining ◽  
Machining Processes

Finite Element Simulation of Extremely High Speed Machining of Ti6Al4V Alloy

2011 ◽  
Vol 141 ◽  
pp. 293-297 ◽  
Author(s):  
Yang Tan ◽  
Yi Lin Chi ◽  
Ya Yu Huang ◽  
Ting Qiang Yao
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Void Nucleation ◽  
Chip Morphology ◽  
Ti6al4v Alloy ◽  
Material Behavior ◽  
Fracture Mechanisms ◽  
High Speed Machining ◽  
Damage Initiation ◽  
Damage And Fracture

The finite element modeling and simulation of extremely high speed machining of Ti6Al4V alloy are presented in the paper. The Johnson-Cook’s constitutive model is used to describe the material behavior. The Johnson-Cook damage initiation criterion is used to predict the onset of damage due to void nucleation in ductile fracture. A damage evaluation law based on plastic strain energy and a fracture criterion combining the effect of different fracture mechanisms are proposed to model the progressive damage and fracture, respectively. Simulation results show that the predicted chip morphology agrees well with the experimental one. The distribution of temperature and specific cutting force are discussed later.

Dynamic Tensile Characteristics of DP600 Steel Sheets for Automotive Applications

2012 ◽  
Vol 509 ◽  
pp. 40-45
Author(s):  
Dan Yang Dong ◽  
Yang Liu ◽  
Lei Wang ◽  
Chang Sheng Liu
Keyword(s):  
Strain Rate ◽  
Tensile Testing ◽  
High Speed ◽  
Greenhouse Gas Emission ◽  
Testing Machine ◽  
Fracture Mechanisms ◽  
Strain Rates ◽  
Automotive Applications ◽  
Tensile Testing Machine ◽  
Steel Sheets

To reduce fuel consumption and greenhouse gas emission, dual phase (DP) steels have been considered for automotive applications due to their higher tensile strength, better initial work hardening along with larger elongation compared to conventional grade of steels. In such applications, which would create potential safety and reliability issues under dynamic loading, the mechanical behavior of DP steel considering the strain rate must be examined. In the present study, the dynamic tensile behavior of DP600 steel sheets was investigated using a high-speed tensile testing machine at various strain rates. And the quasi-static tensile testing was also conducted on the steel to understand the effect of the strain rate on the tensile property. The fracture mechanisms of the steel were also analyzed. The results show that the mechanical properties of DP600 steel are noticeably influenced by the strain rates. As the strain rate increases, the strength of the steel increases and the obvious yield phenomenon can be observed when the strain rate is above 0.01 s-1. The fracture elongation of DP600 steels decreases with increasing strain rate from 0.001 to 1 s-1, then increases up to the strain rate of 100 s-1 and reaches the lowest value at the strain rate of 1000 s-1. DP600 steel sheet exhibit typical ductile fracture characteristics with dimples morphology of the facture surface when tensile deformed at various strain rates.

Prediction of Cutting Forces in High Speed Machining of Ti6Al4V Using SPH Method

2015 ◽  
Author(s):  
Alaa A. Olleak ◽  
Hassan A. El-Hofy
Keyword(s):  
Cutting Forces ◽  
High Speed ◽  
Orthogonal Cutting ◽  
Chip Morphology ◽  
3D Models ◽  
Material Behavior ◽  
Coupled Analysis ◽  
High Speed Machining ◽  
Machining Processes ◽  
Sph Method

Over the last few decades, the interest in modeling of machining processes has been growing. In this regard, the smoothed particle hydrodynamics (SPH) method is one of the latest powerful techniques used for that purpose. The strength of SPH lies behind its accuracy in stress calculations and the ability to handle situations involving large amount of deformation, which is difficult to be tackled using traditional finite element methods. This work aims to present and evaluate the use of SPH method in modeling of high speed machining (HSM). A thermo-mechanical coupled analysis of both 2D and 3D models is performed using LS-DYNA. The simulation aims to predict the cutting forces and chip morphology during high speed orthogonal cutting of Ti6Al4V alloy. In order to accurately simulate the material behavior during cutting, Johnson-Cook material constitutive model is used. The results from SPH model are validated using published experimental data.

scholarly journals Simulation of Grain Refinement Induced by High-Speed Machining of OFHC Copper Using Cellular Automata Method

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Jun Zhang ◽  
Xiang Xu ◽  
José Outeiro ◽  
Hongguang Liu ◽  
Wanhua Zhao
Keyword(s):  
High Temperature ◽  
Cellular Automata ◽  
High Strain Rate ◽  
Strain Rate ◽  
Grain Refinement ◽  
High Speed ◽  
High Strain ◽  
Machining Process ◽  
Ofhc Copper ◽  
High Speed Machining

Abstract During high-speed machining (HSM), the microstructure of materials evolves with significant plastic deformation process under high strain rate and high temperature, which affects chip formation and material fracture mechanisms, as well as surface integrity. The development of models and simulation methods for grain refinement in machining process is of great importance. There are few models which are developed to predict the evolution of the grain refinement of HSM in mesoscale with sufficient accuracy. In this work, a cellular automata (CA) method with discontinuous (dDRX) and continuous (cDRX) dynamic recrystallization (DRX) mechanisms is applied to simulate the grain refinement and to predict the microstructure morphology during machining oxygen-free high-conductivity (OFHC) copper. The process of grain evolution is simulated with the initial conditions of strain, strain rate, and temperature obtained by finite element (FE) simulation. The evolution of dislocation density, grain deformation, grain refinement, and growth are also simulated. Moreover, cutting tests under high cutting speeds (from 750 m/min to 3000 m/min) are carried out and the microstructure of chips is observed by electron backscatter diffraction (EBSD). The results show a grain refinement during HSM, which could be due to the occurrence of dDRX and cDRX. High temperature will promote grain recovery and growth, while high strain rate will significantly cause a high density of dislocations and grain refinement. Therefore, HSM contributes to the fine equiaxed grain structure in deformed chips and the grain morphology after HSM can be simulated successfully by the CA model developed in this work.

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