A MICROSTRUCTURE-BASED MECHANISTIC MODEL FOR BONE SAWING: PART 2 - ACOUSTIC ENERGY RATE PREDICTIONS

2021 ◽  
pp. 1-19
Author(s):  
Roshan Mishra ◽  
Michael Conward ◽  
Johnson Samuel
Keyword(s):  
Cutting Force ◽  
Mechanistic Model ◽  
Cutting Edge ◽  
Acoustic Energy ◽  
Depth Of Cut ◽  
Energy Rate ◽  
Edge Geometry ◽  
Woven Bone ◽  
Ae Energy ◽  
Ae Signal

Abstract Part-2 of this paper is focused on modeling the acoustic emission (AE) energy rate as a function of the specific cortical bone microstructures (viz., osteon, interstitial matrix, lamellar bone, and woven bone) and the depth-of-cut encountered by the bone sawtooth. First, the AE signal characteristics from the sawing experiments (in Part-1) are related to the pure haversian and pure plexiform regions of the cut. Using the cutting force predictions from Part-1 as input, the AE energy rate is then modeled in terms of the energies dissipated in the shearing and ploughing zones encountered by the rounded cutting edge. For this calculation, the rounded edge geometry of the sawtooth is modeled as a combination of (i) shear-based cutting from a negative rake cutting tool; and (ii) ploughing deformation from a round-nose indenter. The spread seen in the AE energy rate is captured by modeling the variations in sawed surface height profile, tool cutting edge geometry, and porosity of the bone. The model calibration and validation protocols are similar to those used in Part-1. The validated AE model is useful for process planning both in terms of its ability to predict AE energy rate trends and cutting force variations, based on the differences in the underlying bone microstructures.

scholarly journals The Chemical Softening Effect and Mechanism of Low Rank Coal Soaked in Alkaline Solution

2019 ◽  
Vol 17 (1) ◽  
pp. 1449-1458
Author(s):  
Gao Zhixiang ◽  
Guo Hongyu ◽  
Dong Zhiwei ◽  
Luo Yuan ◽  
Xia Daping
Keyword(s):  
Alkaline Solution ◽  
Count Rate ◽  
Coal Sample ◽  
Low Rank ◽  
Stress Strain ◽  
Softening Effect ◽  
Energy Rate ◽  
Ae Energy ◽  
Ae Signal ◽  
Chemical Softening

AbstractIn order to analyze the feasibility of chemical softening on low rank coals, bituminous coal was collected from the Qianqiu mine in Henan Province, China, and soaked in water and alkaline solution for different lengths of time. The complete stress-strain and acoustic emission (AE) experiments on the coal samples under uniaxial compression were tested on the RMT-150B Rock Mechanics Testing System and DS2 series AE signal analyzer. The results showed that the coal samples soaked in the water and alkaline solution present different characteristics in the deformation and failure process. As we increase the soaking time, the uniaxial compressive strength and deformation degree of the soaked coal samples in the alkaline solution and water decreased by 42.7% and 94.8% respectively. In the loading test, an AE signal is generated in all coal samples and the maximum ringing count rate and AE energy rate are present near the stress maximum for a short time. Moreover, the ringing count rate and AE energy rate have a good consistency with the stress-strain of the coal samples. The cumulative ringing count of the two groups soaked in water and alkaline solution decreased by 51% and 89% compared to the original coal sample. However, the decreased degree of the samples soaked in the alkaline solution is much higher than that of those soaked in water and the results showed that the alkaline solution has a better softening effect on the coal sample. With the increase of the alkaline solution concentration, the contact angle decreased from 112.5° to 41°. Through microscope and scanning electron microscopy (SEM) analysis of the soaked coal samples, we found that the pores and fissures increased, the structure of coal became loose, and the mechanical strength decreased sharply after soaking in the alkaline solution, thus achieving a chemical softening effect.

Mechanistic Model Based on the Actual Removal Volume during Simultaneous Five-Axis Milling

2011 ◽  
Vol 223 ◽  
pp. 713-722 ◽  
Author(s):  
Seok Won Lee ◽  
Andreas Nestler
Keyword(s):  
Cutting Force ◽  
Process Model ◽  
Tool Path ◽  
Mechanistic Model ◽  
Cutting Tools ◽  
Rake Angle ◽  
Milling Process ◽  
Cutting Edge ◽  
Nc Code ◽  
Five Axis

In this paper we present a novel mechanistic model of cutting process of the cylindrical tool by using the actual removal volume per tooth via NC simulation. The simulation kernel enables “virtually” cutting the workpiece in milling process per NC code, as well as calculating the removal volume per tooth which leads to predict the actual cutting force during simultaneous five-axis machining. Combined with the material removal simulation, the advanced mechanistic process model, which can enable the prediction of the cutting force and adjust the trajectory velocity of the cylindrical tools undergoing five-axis movement, is presented by applying the line integral along the cutting edge and taking the rake angle and cutting edge roundness into consideration. The novel methodology to adjust the cutting force by prevailing cutting tools undergoing multi-axis motion is to be validated by experiment and integrated into tool path planning systems.

scholarly journals Application of Mechanistic Force Models to Features of Arbitrary Geometry at Low Material Removal Rate

2021 ◽  
Author(s):  
Grael Sebastian Stevenson Miller ◽  
Rishad A. Irani ◽  
Mojtaba Ahmadi
Keyword(s):  
Cutting Force ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Mechanistic Model ◽  
Depth Of Cut ◽  
Discretization Method ◽  
Arbitrary Geometry ◽  
Radial Depth ◽  
Machining Operations

Abstract This paper presents a workpiece discretization method to apply existing cutting force models to predict the forces generated during low material removal rate robotic machining operations of features with arbitrary geometry. Two machining operations along a straight edge are modelled using this feature discretization method are shown, a chamfer pass on a sharp corner and the removal of a trapezoidal cross section. The workpiece features are measured using a high resolution laser profile scanner to obtain the volume of the features to be removed. The identified features are discretized into rectangular sections such that the cutting force models can be applied to predict the cutting forces. A linear and an exponential mechanistic model which relate tool immersion and feed rate to the cutting force are applied to the scanned workpiece features. The linear and nonlinear models show good agreement with the measured data, with the exception that the linear model occasionally over predicts the forces depending on the radial depth of cut.

scholarly journals Machinability of Scots pine during peripheral milling with helical cutters

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 8172-8183
Author(s):  
Dong Jin ◽  
Kejun Wei
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Scots Pine ◽  
Inclination Angle ◽  
Cutting Speed ◽  
Cutting Edge ◽  
Resultant Force ◽  
Orthogonal Experimental Design ◽  
Depth Of Cut ◽  
Peripheral Milling

Scots pine (Pinus sylvestris L.) is a fast-growing wood that has been widely manufactured into various furnishing products. To improve the machinability of Scots pine, the cutting force and surface roughness during peripheral milling with helical cutters was assessed via an orthogonal experimental design. Experimental results revealed that the resultant cutting force is positively related to the depth of cut, but negatively correlated with inclination angle of cutting edge and cutting speed. However, surface roughness first declines and then increases with increasing inclination angle, and it also shows an increasing trend with the increasing depth of cut and decreasing cutting speed. Furthermore, the depth of cut significantly contributes to the resultant force and surface roughness, while both the cutting speed and inclination angle have insignificant impacts on the resultant force and surface roughness. Finally, the optimized milling parameters were determined as 62° inclination angle of cutting edge, 45 m/min cutting speed, and 0.2 mm depth of cut, and these parameters are proposed for the quality finishing of Scots pine machining.

Rounded Cutting Edge Model for the Prediction of Bone Sawing Forces

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Thomas P. James ◽  
John J. Pearlman ◽  
Anil Saigal
Keyword(s):  
Cutting Force ◽  
High Speed ◽  
Orthogonal Cutting ◽  
Friction Model ◽  
Cutting Edge ◽  
Resultant Force ◽  
Hertzian Contact ◽  
Depth Of Cut ◽  
Force Magnitude ◽  
Variable Friction

A new analytical model to predict bone sawing forces is presented. Development of the model was based on the concept of a single tooth sawing at a depth of cut less than the cutting edge radius. A variable friction model was incorporated as well as elastic Hertzian contact stress to determine a lower bound for the integration limits. A new high speed linear apparatus was developed to simulate cutting edge speeds encountered with sagittal and reciprocating bone saws. Orthogonal cutting experiments in bovine cortical bone were conducted for comparison to the model. A design of the experiment’s approach was utilized with linear cutting speeds between 2600 and 6200 mm/s for depths of cut between 2.5 and 10 μm. Resultant forces from the design of experiments were in the range of 8 to 11 N, with higher forces at greater depths of cut. Model predictions for resultant force magnitude were generally within one standard deviation of the measured force. However, the model consistently predicted a thrust to cutting force ratio that was greater than measured. Consequently, resultant force angles predicted by the model were generally 20 deg higher than calculated from experimental thrust and cutting force measurements.

scholarly journals An investigation on the cutting force of milling Inconel 718

2018 ◽  
Vol 169 ◽  
pp. 01039 ◽  
Author(s):  
Jhy-Cherng Tsai ◽  
Chung-Yu Kuo ◽  
Zing-Ping Liu ◽  
Kelvin Hsi-Hung Hsiao
Keyword(s):  
Cutting Force ◽  
Inconel 718 ◽  
Rapid Change ◽  
Chip Thickness ◽  
Spindle Speed ◽  
Cutting Edge ◽  
Depth Of Cut ◽  
Force Model ◽  
Dry Cutting ◽  
Specific Cutting Force

Inconel alloy has been widely used in industry but is difficult to machine due to its rapid change in cutting force during machining. This paper investigated the cutting force for milling Inconel 718 as conventional force model is unable to handle the above situation. Theorectical force model is first reviewed and two-phase experiments of slot milling based on dry cutting are designed to measure the cutting force and the specific cutting force. Experiments in phase I are designed based on Taguchi method with spindle speed, feedrate per cutting edge and depth of cut as experimental parameters. The results showed that the first two parameters play more important roles in the cutting force. A phase II exhaust experiments is designed with spindle speed set from 400 to 800 rpm while the feedrate per cutting edge is set from 0.04 to 0.08 mm/tooth. The results are concluded as the following. (i) There exists a strong size effect in milling Inconel 718 as the cutting force changed with the chip thickness. Specific cutting force is larger at small thickness of cut and become smaller when the thickness increases. (ii) A 2nd order non-linear cutting force model, which takes spindle speed N and feedrate fz into account, for milling Inconel 718 is derived from the measured data and represented as Ft(N, fz )= (13910 -3.1N - 109900fz - 0.0028N2 +23.9Nfz+434500fz2) xapxh. The derived force model compensates the inaccuracy of conventional force model.

scholarly journals Numerical analysis of different cutting edge radii in hot micro-cutting of Inconel 718

2019 ◽  
Vol 234 (1) ◽  
pp. 196-210
Author(s):  
Xin Liu ◽  
Xu Zhang ◽  
Dazhong Wang
Keyword(s):  
Cutting Force ◽  
Nickel Alloy ◽  
Cutting Edge ◽  
Machining Process ◽  
Depth Of Cut ◽  
Flow State ◽  
Micro Cutting ◽  
Micro Parts ◽  
Tip Radius ◽  
Cutting Speeds

Mechanical micro-cutting is one of the advanced processes for manufacturing of micro-parts. During the micro-cutting process, the thickness of the uncut chip is very close to the tip radius of the tool. The cutting edge is used to cut and extrude the workpiece. In this paper, the experiments and simulations of macro-machining nickel alloy are compared, and the process of micro-cutting nickel alloy is simulated and analyzed. In this study, four cutting edge radii, three cutting speeds, six hot cutting temperatures, and a constant depth of cut are used. The radius of the cutting edge of different sizes is theoretically analyzed and verified by simulation of material flow state, temperature, stress, strain, and cutting force. The results show that the material separation points are very close together at different cutting edge radii. The change in the radius of the cutting edge changed the contact state of the material in the cutting area, which has a large influence on the temperature and cutting force. The effects of different cutting speeds and hot working temperature on the machining process are also discussed.

scholarly journals Analysis of the influence of the cutting edge geometry on parameters of the perforation process for conveyor and transmission belts

2018 ◽  
Vol 157 ◽  
pp. 01022 ◽  
Author(s):  
Dominik Wojtkowiak ◽  
Krzysztof Talaśka ◽  
Ireneusz Malujda ◽  
Grzegorz Domek
Keyword(s):  
Mechanical Properties ◽  
Cutting Force ◽  
Material Properties ◽  
Polyester Fabric ◽  
Cutting Edge ◽  
Reinforced Polymers ◽  
Edge Geometry ◽  
Different Types ◽  
Conveyor Belts ◽  
Different Thickness

Perforated belts, which are used in vacuum conveyor belts, can have significantly different mechanical properties like strength and elasticity due to a variety of used materials and can have different thickness from very thin (0,7 mm) to thick belts (6 mm). In order to design a complex machine for mechanical perforation, which can perforate whole range of belts, it is necessary to research the influence of the cutting edge geometry on the parameters of the perforation process. Three most important parameters, which describe the perforation process are the cutting force, the velocity and the temperature of the piercing punch. The results presented in this paper consider two different types of punching (a piercing punch with the punching die or with the reducer plate) and different cutting edge directions, angles, diameters and material properties. Test were made for different groups of composites belts – with polyurethane and polyester fabric, polyamide core or aramid-fibre reinforced polymers. The main goal of this research is to specify effective tools and parameters of the perforation process for each group of composites belts.

Tool Failure Mechanism in High-Speed Milling of Inconel 718 by Use of Ceramic Tools

2014 ◽  
Vol 8 (6) ◽  
pp. 837-846 ◽  
Author(s):  
Norikazu Suzuki ◽  
◽  
Risa Enmei ◽  
Yohei Hashimoto ◽  
Eiji Shamoto ◽  
...  
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
Inconel 718 ◽  
High Speed ◽  
Estimation Error ◽  
Contact Stresses ◽  
Cutting Edge ◽  
High Speed Milling ◽  
Ceramic Tools ◽  
Edge Geometry

A series of high-speed milling tests of Inconel 718 were carried out utilizing SiAlON ceramic tools, and the transitions of the cutting edge geometry and cutting forces were investigated. Through the experimental investigations, it was confirmed that the cutting edge is worn rapidly and a round shape is formed at the initial stage of machining. The radius of the round cutting edge becomes considerably large with respect to the uncut chip thickness, and thus the ploughing process is dominant in ceramic milling like general micro cutting operations. Based on the observed phenomena, a quasi-mechanistic model for cutting force prediction was proposed, where the measured cutting edge geometry and the contact stress distribution at the toolworkpiece interface are taken into account. The estimated cutting force by the proposed model showed a good agreement with the measured one. Minimizing the estimation error in the cutting forces, contact stresses of the cutting edge to the workpiece are identified. Stress field analysis using the estimated contact stresses revealed that the large tensile stress instantaneously generates around the stagnation point. This mechanism may contribute to the generation of the rake face flaking, which determines the end of the tool life.

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