An Exit Burr Model for Drilling of Metals

2000 ◽  
Vol 123 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. Ken Lauderbaugh Saunders ◽  
Craig A. Mauch
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Temperature Effects ◽  
Material Removal ◽  
Burr Formation ◽  
Failure Condition ◽  
Formation Model ◽  
Varying Thickness ◽  
Exit Burr ◽  
Thrust Forces

The mechanics of the formation of exit burrs for drilling metals are analyzed. A burr formation model is developed where the material in front of the drill is modeled as an axi-symmetric, circular plate of varying thickness. The drilling thrust forces are distributed as a pressure along the top surface of this plate. The stress state is then calculated. Material removal continues until a failure condition is reached. At the point of failure of the plate the remaining material is bent out to form the burr. The model also includes temperature effects. Experimental verification was conducted on 2024-T351 aluminum and on 7075-T561 aluminum. Two types of drill geometry were considered. The experiments were conducted with feeds from 0.05 to 0.35 mm/rev. The model accurately predicts the experimental data.

scholarly journals A Study of Yielding and Plasticity of Rapid Prototyped ABS

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1495
Author(s):  
Dan-Andrei Șerban ◽  
Cosmin Marșavina ◽  
Alexandru Viorel Coșa ◽  
George Belgiu ◽  
Radu Negru
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Plastic Flow ◽  
Plane Stress ◽  
Yield Criterion ◽  
Numerical Analyses ◽  
Flow Potential ◽  
Stress States ◽  
State Configuration

In this article, the yielding and plastic flow of a rapid-prototyped ABS compound was investigated for various plane stress states. The experimental procedures consisted of multiaxial tests performed on an Arcan device on specimens manufactured through photopolymerization. Numerical analyses were employed in order to determine the yield points for each stress state configuration. The results were used for the calibration of the Hosford yield criterion and flow potential. Numerical analyses performed on identical specimen models and test configurations yielded results that are in accordance with the experimental data.

scholarly journals MODELLING CHLORIDE DIFFUSION IN CONCRETE WITH INFLUENCE OF CONCRETE STRESS STATE

2017 ◽  
Vol 23 (7) ◽  
pp. 955-965 ◽  
Author(s):  
Jian WANG ◽  
Pui-Lam NG ◽  
Weishan WANG ◽  
Jinsheng DU ◽  
Jianyong SONG
Keyword(s):  
Experimental Data ◽  
Diffusion Coefficient ◽  
Stress State ◽  
Diffusion Model ◽  
Stress Ratio ◽  
Chloride Diffusion ◽  
Influence Coefficient ◽  
Chloride Diffusion Coefficient ◽  
Stress Influence ◽  
Concrete Stress

Under coastal or marine conditions, chloride erosion is the major accelerating factor of reinforcement corrosion. Therefore, it is of vital importance to investigate the chloride diffusion model. Research reveals that the concrete stress state has great influence on chloride diffusion; therefore a stress influence coefficient was incorporated in chloride diffusion coefficient model by many researchers. By referring to the experimental data from eight different researchers, the law between stress influence coefficient and concrete stress ratio is studied in detail, and equations relating the stress influence coefficient with the concrete stress ratio are established. Compared with three typical existing groups of equations, it is found that the proposed equations give the most accurate estim.ation of the stress influence coefficient. Hence, the proposed equations can be adopted to improve the valuation of chloride diffusion coefficient, and a modified chloride diffusion model is put forward. Three groups of experimental data are used to validate the modified chloride diffusion model, which is shown to be reasonable and having high prediction accuracy.

Initial Investigation Into Helical Milling of Laminated Stacks of Electrical Steel

2012 ◽  
Author(s):  
Howard Liles ◽  
J. Rhett Mayor
Keyword(s):  
Electrical Steel ◽  
Thrust Force ◽  
Initial Study ◽  
Helical Milling ◽  
Burr Formation ◽  
Spring Back ◽  
Plunge Milling ◽  
Axial Thrust ◽  
Electrical Steels ◽  
Thrust Forces

This paper serves to report the findings of an initial study on the holing of laminated stacks of electrical steels. Three different holing methods were considered: plunge milling, helical milling (orbit milling), and drilling. Stack delamination, axial thrust force, and burr formation were measured at various feed rates for each process and utilized as comparison metrics. Results from the initial experimental investigation indicate that drilling produces significant burr and plunge milling, whilst reducing burr formation compared to drilling, led to delamination of the stack. Helical milling minimized thrust forces, avoided delamination and minimized burr formation. An interesting spring back effect was also observed during the cutting of the laminated stacks. It is concluded that helical milling is a viable and effective processing method for making holes in laminated stack of hard electrical steels.

Cutting Process of Double Angle Drill

2015 ◽  
Vol 651-653 ◽  
pp. 1211-1216
Author(s):  
Shouichi Tamura ◽  
Takashi Matsumura
Keyword(s):  
Flow Direction ◽  
Wedge Angle ◽  
Burr Formation ◽  
Force Model ◽  
Workpiece Material ◽  
Fiber Reinforced Plastic ◽  
Chip Flow ◽  
Reinforced Plastic ◽  
Cutting Processes ◽  
Thrust Forces

Double angle drills have recently been used to improve the surface finish in drilling. The double angle drill consists of lower edges at a large wedge angle and upper edges at a small wedge angle on the lips. The paper discusses the cutting processes of the double angle drill in analysis and experiment. A force model is applied to simulate the cutting force and the chip flow direction. The cutting tests are conducted to verify the force model in drilling of carbon fiber reinforced plastic (CFRP) and aluminum alloy (A7075) with a single and a double angle drills. The double angle drill is effective in control of delamination in drilling of CFRP due to reduction of the thrust force. Meanwhile, in drilling of A7075, the small wedge angle of the upper edges on the double angle drill is not effective in reduction of the thrust forces. The curved edge at the end of the lip, in turn, promotes burr formation in drilling of A7075. The effectiveness of the double angle drill depends on the workpiece material.

Application of the concept of criterion of a complex stress state to a simple tension for appraisal of resistance of fatigue of structural materials. Part 2. Drawing up criterion and its checking on compliance to experimental data

2021 ◽  
pp. 41-45
Author(s):  
P.N. Kozlov
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Structural Material ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Regular Change ◽  
Regular Cycle ◽  
Simple Tension ◽  
Dangerous Point

The criterion for appraisal of resistance of fatigue of structural material at action on it of repeatedly variables loads and static loads in the form of a bend or tensioncompression together with torsion, and also at action of loads, which create two-axis regular change of stress state in a dangerous point of material is constructed. The received criterion will acceptable be coordinated with the known experimental data. Keywords: dangerous point of material, regular cycle of loading, equivalent amplitude, equivalent average stress, chart of extreme amplitudes of stresses. [email protected]

Reliability Evaluation of Structural Ceramics Under Multiaxial Stress State

1998 ◽  
Author(s):  
Takashi Ono ◽  
Masaki Kaji ◽  
Michiaki Nishimura
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Stress State ◽  
Fracture Probability ◽  
Test Method ◽  
Structural Ceramics ◽  
Multiaxial Stress ◽  
Fatigue Lifetime ◽  
Empirical Parameter ◽  
Multiaxial Stress State

Strength and fatigue lifetime of structural ceramics under multiaxial stress state have been estimated and compared with experimental data. Biaxial strength tests were done by an anticlastic bending test method at room temperature. Biaxial fatigue tests were done by anticlastic bending and also ring-on-ring test method at 1200°C in air. Fracture probability and lifetime were predicted on the basis of a Weibull multiaxial distribution function and subcritical crack growth, using the results of stress analyses by the finite element method. Modified maximum hoop stress theory including an empirical parameter, T, was applied to the equivalent normal stress in the multiaxial distribution function. The empirical parameter T represents a shear stress sensitivity to mixed-mode fracture due to a grain interlocking effect. It has been confirmed that the predicted fracture probability and the fatigue lifetime agrees well with the experimental data if grain interlocking effects are taking into account.

Vibrational Dephasing and Collision Induced Scattering in Molecular Liquids

1983 ◽  
Vol 22 ◽  
Author(s):  
Jiri Jonas
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Temperature Effects ◽  
Essential Role ◽  
Theoretical Models ◽  
Molecular Liquids ◽  
Vibrational Dephasing

ABSTRACTThe results of several Raman studies of vibrational dephasing in polyatomic molecular liquids at high pressure are reviewed. The density and temperature effects on vibrational dephasing of isotropic Raman bands for different vibrational models are reported for the following liquids: C(CH3)4; Si(CH3)4; Ge(CH3)4; ; Sn(CH3)4 and isobutylene CH2; = C(CH3) 2.The experimental data are used to test the current theoretical models of vibrational dephasing. Selected results of our high pressure experiments on collision induced scattering in polyatomic molecular liquids demonstrate well the essential role of high pressure in studying these phenomena.

Time and temperature effects on geomembrane strain from a gravel particle subjected to sustained vertical force

2012 ◽  
Vol 49 (3) ◽  
pp. 249-263 ◽  
Author(s):  
A. Sabir ◽  
R.W.I. Brachman
Keyword(s):  
Experimental Data ◽  
Temperature Effects ◽  
High Density Polyethylene ◽  
Measured Data ◽  
Vertical Force ◽  
Temperature Superposition ◽  
Measured Strain ◽  
Time Temperature Superposition ◽  
Tensile Strains

Experimental data is reported that quantifies how time (up to 10 000 h) and temperature (from 22 to 85 °C) impact tensile strains in a 1.5 mm thick high-density polyethylene geomembrane — with a compressible clay liner beneath it — that are induced by an overlying gravel particle when subjected to a sustained vertical force. At an average applied stress of 250 kPa and clay water content of 16%, tensile strains were found to increase by 1.25 times as the temperature was increased from 22 to 55 °C after 1000 h. Similarly, strains were found to increase by factors between 1.2 to 1.3 as time was increased from 10 to 1000 h. Based on the measured data, time–temperature superposition (tTS) was then used to develop an approach to predict long-term geomembrane strains from gravel indentations. The tTS approach was validated against independent experiments conducted for 10 000 h (1.14 years) as it was found that the predicted strain of 19% was very close to the measured strain of 18%. Provided that the physical properties of the geomembrane do not decrease abruptly, the results suggest that the tTS approach developed can be used to provide estimates of long-term geomembrane strains.

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