Mechanical and Thermal Stresses in Clamped, Brazed, and Bonded Carbide Tools

1992 ◽  
Vol 114 (4) ◽  
pp. 377-385 ◽  
Author(s):  
M. A. Younis
Keyword(s):  
Temperature Gradient ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Rupture Strength ◽  
Shear Stresses ◽  
Flow Strength ◽  
Compressive Stresses ◽  
Bond Layer ◽  
Tool Edge ◽  
Carbide Insert

A model based on the finite element method is presented for determining of thermal and mechanical stresses in a carbide insert due to heat and cutting forces induced during metal cutting with a brazed, clamped, and bonded carbide insert. Analysis revealed a high temperature gradient in the brazed insert, thus causing high thermal stresses. For the bonded insert a low temperature gradient but high temperatures were found, leading to possible tool edge chipping and a significant reduction of the bond layer strength. Finally local maxima of tensile and compressive stresses were identified on the rake face just after the chip had lost contact with the tool face. The estimated tensile stresses were close to the transverse rupture strength of sintered carbide. Shear stresses were at a maximum close to the tool edge at levels nearly equal to the shear flow strength of carbides. High compressive stresses can produce chipping at the tool tip.

A Study of the Normal and Shear Stresses on a Cutting Tool

1966 ◽  
Vol 88 (1) ◽  
pp. 51-61 ◽  
Author(s):  
T. C. Hsu
Keyword(s):  
Metal Cutting ◽  
Cutting Tool ◽  
Contact Length ◽  
Depth Of Cut ◽  
Shear Stresses ◽  
Simple Manner ◽  
Tool Edge ◽  
The Coefficient Of Friction ◽  
Tangential Forces ◽  
Normal And Shear Stresses

This paper contains an explanation for the variation of the “coefficient of friction” in metal cutting. The chip partly sticks to and partly slides over the tool and only in the latter region can friction occur. In the experiments, the contact area between the chip and the tool is controlled and the change in the size of the sticking region is observed. The ploughing force acting on the tool edge is taken into account and the force acting on the tool face is determined. It is found that the force on the tool face varies with the depth of cut and the contact length in a simple manner. From the variation of the normal and tangential forces the stress distribution on the tool face is deduced.

scholarly journals Fractographical Analysis and Biomechanical Considerations of a Tooth Restored With Intracanal Fiber Post: Report of the Fracture and Importance of the Fiber Arrangements

2016 ◽  
Vol 41 (5) ◽  
pp. E149-E158 ◽  
Author(s):  
VF Wandscher ◽  
CD Bergoli ◽  
IF Limberger ◽  
TP Cenci ◽  
P Baldissara ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Glass Fiber ◽  
Shear Stresses ◽  
Fiber Post ◽  
Element Analysis ◽  
Parallel Fibers ◽  
Tooth Structure ◽  
Anterior Teeth ◽  
Compressive Stresses

SUMMARY Objective: This article aims to present a fractographic analysis of an anterior tooth restored with a glass fiber post with parallel fiber arrangement, taking into account force vectors, finite element analysis, and scanning electron microscopy (SEM). Methods: A patient presented at the Faculty of Dentistry (Federal University of Santa Maria, Brazil) with an endodontically treated tooth (ETT), a lateral incisor that had a restorable fracture. The treatment was performed, and the fractured piece was analyzed using stereomicroscopy, SEM, and finite element analysis. Results: The absence of remaining coronal tooth structure might have been the main factor for the clinical failure. We observed different stresses actuating in an ETT restored with a fiber post as well as their relationship with the ultimate fracture. Tensile, compression, and shear stresses presented at different levels inside the restored tooth. Tensile and compressive stresses acted together and were at a maximum in the outer portions and a minimum in the inner portions. In contrast, shear stresses acted concomitantly with tensile and compressive stresses. Shear was higher in the inner portions (center of the post), and lower in the outer portions. This was confirmed by finite element analysis. The SEM analysis showed tensile and compression areas in the fiber post (exposed fibers=tensile areas=lingual surface; nonexposed fibers=compression areas=buccal surface) and shear areas inside the post (scallops and hackle lines). Stereomicroscopic analysis showed brown stains in the crown/root interface, indicating the presence of microleakage (tensile area=lingual surface). Conclusion: We concluded that glass fiber posts with parallel fibers (0°), when restoring anterior teeth, present a greater fracture potential by shear stress because parallel fibers are not mechanically resistant to support oblique occlusal loads. Factors such as the presence of remaining coronal tooth structure and occlusal stability assist in the biomechanical equilibrium of stresses that act upon anterior teeth.

A Three-Dimensional Finite Difference Solution for the Thermal Stresses in Railcar Wheels

1969 ◽  
Vol 91 (3) ◽  
pp. 891-896 ◽  
Author(s):  
G. E. Novak ◽  
B. J. Eck
Keyword(s):  
Computer Program ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Shear Stresses ◽  
Radial Temperature ◽  
Closed Form Solutions ◽  
Brake Application ◽  
History Of ◽  
Thin Disks

A numerical solution is presented for both the transient temperature and three-dimensional stress distribution in a railcar wheel resulting from a simulated emergency brake application. A computer program has been written for generating thermoelastic solutions applicable to wheels of arbitrary contour with temperature variations in both axial and radial directions. The results include the effect of shear stresses caused by the axial-radial temperature gradients and the high degree of boundary irregularity associated with this type of problem. The program has been validated by computing thermoelastic solutions for thin disks and long cylinders; the computed values being in good agreement with the closed form solutions. Currently, the computer program is being extended to general stress solutions corresponding to the transient temperature distributions obtained by simulated drag brake applications. When this work is completed, it will be possible to synthesize the thermal history of a railcar wheel and investigate the effects of wheel geometry in relation to thermal fatigue.

Steady-State Thermal Stresses in Wedge-Shaped Cutting Tools

1975 ◽  
Vol 97 (3) ◽  
pp. 1060-1066
Author(s):  
P. F. Thomason
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Equivalent Stress ◽  
Cutting Tools ◽  
Thermoelastic Stress ◽  
Plastic State ◽  
Steady State Heat

Closed form expressions for the steady-state thermal stresses in a π/2 wedge, subject to constant-temperature heat sources on the rake and flank contact segments, are obtained from a conformal mapping solution to the steady-state heat conduction problem. It is shown, following a theorem of Muskhelishvili, that the only nonzero thermal stress in the plane-strain wedge is that acting normal to the wedge plane. The thermal stress solutions are superimposed on a previously published isothermal cutting-load solution, to give the complete thermoelastic stress distribution at the wedge surfaces. The thermoelastic stresses are then used to determine the distribution of the equivalent stress, and this gives an indication of the regions on a cutting tool which are likely to be in the plastic state. The results are discussed in relation to the problems of flank wear and rakeface crater wear in metal cutting tools.

Conjugated Heat Transfer in Skirt Hot Box in Pressure Vessels

2006 ◽  
Author(s):  
Hossein Shokouhmand ◽  
Manoochehr Bozorgmehrian
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Temperature Gradient ◽  
Thermal Stresses ◽  
Weld Line ◽  
Pressure Vessels ◽  
Conductive Heat ◽  
Air Pocket ◽  
Cyclic Operation ◽  
Conjugated Heat Transfer

Pressure vessels are common equipment in oil, gas and petrochemical industries. In a hot containing fluid vessel, excessive temperature gradient at junction of skirt to head (weld line), can cause unpredicted high thermal stresses; Thereby fracture of the vessel may occur as a result of cyclic operation. Providing a hot box (air pocket) in crotch space is a economical, applicable and easy mounted method in order to reduce the intensity of thermal stresses. Natural convection due to temperature difference between the wall of pocket, will absorb heat near the hot wall (head of the vessel) and release that near the cold wall (skirt of the vessel), then the skirt wall conducts heat to the earth as a fin. This conjugated heat transfer removes the temperature gradient boundary at welded junction. This phenomena will lead the temperature gradient on the weld line from a sudden to smooth behavior, thereby the skirt-head junction, that is a critical region, could be protected from excessive thermal stresses. In this paper the profit of hot box and conjugated heat transfer in cavity has been demonstrated experimentally. As a result it is shown that the conductive heat transfer through the skirt (which acts as a fin) ensures the continuation of natural convection in the box. Also the governing equations has been solved numerically and compared with experimental results.

Thermal Stresses in Moderately Thick Elastic Plates

1959 ◽  
Vol 26 (3) ◽  
pp. 432-436
Author(s):  
B. E. Gatewood
Keyword(s):  
Temperature Gradient ◽  
Plane Stress ◽  
Thermal Stresses ◽  
Plate Thickness ◽  
Three Dimensional ◽  
Elastic Plates ◽  
Plate Length ◽  
Moderately Thick Plates ◽  
Thick Elastic Plates ◽  
Thickness Variable

Abstract The three-dimensional stresses in the plate are investigated without using the plane-stress or plane-strain assumptions, the thickness of the plate being limited so that the normal stress in the thickness direction can be taken as a polynomial in the thickness variable. The temperature is taken as a polynomial in the thickness variable but with relatively large, though restricted, gradients with respect to the co-ordinates of the plane of the plate. For the case of the temperature constant in thickness variable, the stresses in the plane of the plate are presented as the plane-stress solution plus correcting terms due to the plate thickness, where the correcting terms involve the product of the temperature gradient and the ratio of the plate thickness to the plate length in the direction of the temperature gradient. In many cases the corrections are small even for moderately thick plates.

scholarly journals Tribological wear of Fe-Al coatings applied by gas detonation spraying

2021 ◽  
Author(s):  
Tomasz Chrostek
Keyword(s):  
Dry Friction ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Detonation Spraying ◽  
Gas Detonation ◽  
Compressive Stresses ◽  
Spraying Parameters ◽  
Thin Oxide Films ◽  
Pin On Disc ◽  
The Coefficient Of Friction

Comparative tests of gas detonation (GDS) coatings were carried out in order to investigate the influence of spraying parameters on abrasive wear under dry friction conditions. The tests were carried out using the pin-on-disc (PoD) method at room temperature. The microstructure of the coatings was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM / EDS) methods. The results showed that with specific GDS process parameters, the main phases in both coatings were FeAl and Fe3Al involving thin oxide films Al2O3. The tribological tests proved that the coatings sprayed with the shorter barrel of the GDS gun showed higher wear resistance. The coefficient of friction was slightly lower in the case of coatings sprayed with the longer barrel of the GDS gun. During dry friction, oxide layers form on the surface, which act as a solid lubricant. The load applied to the samples during the tests causes shear stresses, thus increasing the wear of the coatings. During friction, the surface of the coatings is subjected to alternating tensile and compressive stresses, which lead to delamination and is the main wear mechanism of the coatings.

Residual Stress Analysis in Different Thickness TiN Coatings on High-Speed-Steel Substrates

2011 ◽  
Vol 239-242 ◽  
pp. 2331-2335 ◽  
Author(s):  
Fang Mei ◽  
Guang Zhou Sui ◽  
Man Feng Gong
Keyword(s):  
Residual Stresses ◽  
High Speed ◽  
Thermal Stresses ◽  
High Speed Steel ◽  
X Ray Diffraction ◽  
Tin Coatings ◽  
Compressive Stresses ◽  
M2 High Speed Steel ◽  
Steel Substrates ◽  
Different Thickness

TiN coatings were deposited on AISI M2 high-speed-steel (HSS) substrates by multi-arc ion plating technique. The thickness of substrate was 1.0 mm and five thicknesses of TiN coatings were 3.0, 5.0, 7.0, 9.0 and 11.0 μm, respectively. X-ray diffraction (XRD) has been used for measuring residual stresses. The stresses along five different directions (Ψ=0°, 20.7°, 30°, 37.8° and 45°) have been measured by recording the peak positions of TiN (220) reflection for each 2θ at different tilt angles Ψ. Residual compressive stresses present in the TiN coatings. Furthermore, the results revealed that the value of the residual stresses in TiN coatings was high. While the coatings thickness changed from 3 to 11 μm, the residual stresses varied from -3.22 to -2.04 GPa, the intrinsic stresses -1.32 to -0.14 GPa, the thermal stresses -1.86 to -1.75 GPa. The residual stresses in TiN coatings showed a nonlinear change. When the coatings thickness was about 8 μm, the residual stresses in TiN coatings reached to the maximum value.

Invsetigation about Residual Stresses of Plasma-Spraying Sm2Zr2O7/YSZ Thermal Barrier Coatings of Different Substrate Conditions

2011 ◽  
Vol 308-310 ◽  
pp. 1177-1181 ◽  
Author(s):  
Hong Song Zhang ◽  
Gang Yi Cai ◽  
Shu Sen Yang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plasma Spraying ◽  
Thermal Stresses ◽  
Thermal Barrier ◽  
Shear Stresses ◽  
Substrate Thickness ◽  
Optimum Thickness ◽  
Slight Effect ◽  
Axial Residual Stress

Effect of substrate conditions, including material type, thickness and radius of substrate, on residual thermal stresses of plasma spraying Sm2Zr2O7/YSZ TBCs was analyzed through finite element method in this paper. The radial and shear stresses of the coating decrease with increasing of distance from the center to edge, and they decrease abruptly at the edge of the specimen, while the axial residal stress increase abruptly at the edge of substrate. All residual stresses increase with increasing of thermal expansion coefficient of substrate. The thickness of substrate has slight effect on the radial residual stress, axial residual stress and shear stress are almost uneffected by substrate thickness. The optimum thickness of substrate is 10mm. Radius of substrate have no effect on radial stress when it is greater than 28mm.

Temperature-dependent stability of deep wells in the Cooper Basin

2010 ◽  
Vol 50 (2) ◽  
pp. 734
Author(s):  
Fermin Fernandez-Ibañez ◽  
David Castillo ◽  
Doone Wyborn ◽  
Dean Hindle ◽  
Adrian White
Keyword(s):  
Thermal Stresses ◽  
High Heat ◽  
In Situ Stress ◽  
Silica Content ◽  
Granitic Rocks ◽  
Drilling Fluids ◽  
Radiogenic Heat ◽  
Collapse Pressure ◽  
Compressive Stresses ◽  
Cooper Basin

The Cooper-Eromanga Basin is characterised by high heat flow that has been related to the presence of high radiogenic heat-producing granites. Several wells have been drilled in the area to exploit the heat from the fractured granitic rocks of the basement. Drilling through the hot formations in the Cooper Basin (max. temperature ca. 250 °C) with relatively cool drilling fluids induces an almost instantaneous cooling of the wellbore wallrock. Cooling of the hole (the usual case) increases the tensile stresses (and decreases the compressive stresses) at the wellbore wall. The magnitude of the thermal stresses is also dependent on the silica content of the formation. Modelling of the in situ stress tensor and mechanical properties of the wellbore rocks has revealed the time-dependent effect that the borehole collapse pressure has on the stability of the wells. Narrow breakouts form at the time of drilling. Afterwards, the temperature difference (ΔT) decays with time, and as the hole warms up compressive stresses increase and breakouts become enhanced. Therefore, if a high ΔT and a short well exposure time are achieved, it would be possible to inhibit breakout development, drill with a lower mud weight (eventually underbalanced), and, thus, minimise the risk of formation damage.

Sign in / Sign up

Export Citation Format

Share Document