TESTING THE HYPOTHESIS OF THE COSINE DISTRIBUTION OF STRESSES IN THE SHAFT-HOLE CONTACT

2021 ◽  
pp. 42-47
Author(s):  
DMITRY A. BEZIK ◽  
Keyword(s):  
Stress Distribution ◽  
Contact Zone ◽  
Stress Raiser ◽  
Central Zone ◽  
Angular Distance ◽  
Mechanical Stresses ◽  
Nite Element ◽  
Stress Raisers ◽  
Cosine Law ◽  
Slight Discrepancy

One of the most common connection types in mechanical engineering and construction is the shaft-hole connection. The mechanical stresses caused by its loading are distributed in the contact zone of the loaded parts of the joint. In some cases, they can lead to destruction. Therefore, while designing, it is important to analyze the mechanical stresses in the contact zone. Traditionally, calculations assume that the contact stresses are distributed according to the cosine law. However, this is not entirely true, especially with diff erent shaft and hole diameters. The authors examined theoretical studies of the contact zone of the shaft and the hole (including the cases of diff erent diameters) and the stress distribution in the contact zone. Based on the studies, they performed numerical calculations in the APMWinMachine environment to determine the stresses in the volume of the shaft and the plate with a hole when loading the shaft-hole connection. The analyses were performed for the two-dimensional case by the fi nite element method in the APMStructure program. The results show that when the diameters in the connection are equal, the stress distribution is close to the cosine law. In this case, only one stress raiser occurs in the contact zone, which is located on the line of action of the loading force. However, if there is a slight discrepancy in the shaft and hole diameters, there are three stress raisers in which the connection may break – the central zone and two side zones. The angular distance between them can be determined based on the known theoretical formulas. The authors made an experiment with a plexiglass model, which qualitatively confi rmed the correctness of the analysis performed.

Effect of Bubble Inclusions on the Mechanical Properties of Cast Poly-Methyl Metacrylate

1972 ◽  
Vol 94 (4) ◽  
pp. 847-852 ◽  
Author(s):  
J. D. Stachiw
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Loading Condition ◽  
Stress Raiser ◽  
Compressive Yield Strength ◽  
Compressive Test ◽  
Acrylic Plastic ◽  
Methyl Metacrylate ◽  
As Stress ◽  
Stress Raisers

Bubble inclusions present in cast acrylic plastic generally degrade the mechanical properties of the material. To evaluate the effect of bubbles on the mechanical strength of acrylic plastic, 120 tensile and compressive test specimens were machined from massive acrylic castings with bubble inclusions. The specimens were tested under uniaxial loading condition and effect of bubbles on tensile and compressive strength noted. The stress raiser effect of bubbles caused the tensile specimens to fail at stresses 7 to 30 percent lower than observed in specimens without bubbles. The compressive yield strength was not affected by bubbles. However, here the bubbles served as stress raisers also and caused cracks to initiate at the bubble surfaces when the yield strength of acrylic plastic was reached.

Contact Stress Analysis of Multilayered Strands

2011 ◽  
Vol 130-134 ◽  
pp. 1230-1233 ◽  
Author(s):  
Xin Ze Zhao ◽  
Wei Peng ◽  
Shao Qing Zhang ◽  
Ming Song Yang
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Contact Zone ◽  
Contact Stress ◽  
Contact Surface ◽  
Gaussian Quadrature ◽  
Arbitrary Point ◽  
Fretting Wear ◽  
Adjacent Layer ◽  
Analytical Expressions

The calculation method of contact force in contact-zone between adjacent layer wires has been analyzed. The principal radii of curvatures of wires were taken into consideration while obtaining the analytical expressions for contact stesses and sizes of contact surface. Meanwhile, a formular for shear stress of arbitrary point in half-space under contact-zone was derived on basis of the Boussinesq problem and it was simplified by using Gaussian quadrature. According to the results, the stress distribution could be unsderstood more thoroughly and the results is of great importance for studying looseness, fatigue and fretting wear of multilayered strands.

Internal Stress of ZnO thin Films Caused by Thickness Distribution and Crystallinity

1998 ◽  
Vol 518 ◽  
Author(s):  
M. Takeuchi ◽  
K. Inoue ◽  
Y. Yoshino ◽  
K. Ohwada
Keyword(s):  
Thin Films ◽  
Stress Distribution ◽  
Thickness Distribution ◽  
Zno Thin Films ◽  
Optimum Thickness ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray ◽  
Argon Ions ◽  
Cosine Law

AbstractThe improvement of thickness distribution and crystallinity in ZnO thin films prepared by radio frequency (rf) planer magnetron sputtering has been studied. Optimum thickness distribution of less than ± 2.2% in a 3-inch wafer is obtained by changing the substrate angle to the ZnO target and is in accordance with cosine law. The c-axis orientation perpendicular to the silicon substrate is confirmed by x-ray diffraction. The stress of ZnO thin films is larger than 0.3GPa and its distribution is independent of the substrate angle that is set at a slant to the optimum angle for thickness distribution. These results indicate that thickness distribution of ZnO thin films heavily depends on the substrate angle, while the stress and its distribution are independent of the setting angle of the substrate. Stress distribution is attributed to the distribution of argon ions and sputtered molecules impinging a wafer.

scholarly journals Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
César A. Vázquez Jiménez ◽  
Vignaud Granados Alejo ◽  
Carlos Rubio González ◽  
Gilberto Gómez Rosas ◽  
Sergio Llamas Zamorano
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Duplex Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Stress Raiser ◽  
Residual Stress Distribution ◽  
Laser Shock

Two different stress raiser geometries (fillets and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.

Infrared Photoelastic Study of Thin-Film-Edge-Induced Stresses in Silicon Substrates

2001 ◽  
Vol 695 ◽  
Author(s):  
H. J. Peng ◽  
S.P. Wong ◽  
Shounan Zhao
Keyword(s):  
Thin Film ◽  
Stress Distribution ◽  
Oxide Thin Film ◽  
Geometrical Parameters ◽  
Silicon Substrates ◽  
Substrate Thickness ◽  
Concentrated Force ◽  
Window Width ◽  
Fringe Patterns ◽  
Slight Discrepancy

ABSTRACTThe stress distribution in silicon substrates under a silicon dioxide thin film edge, long oxide thin film stripes and long oxide window structures have been studied using the infrared photoelastic (IRPE) method. The experimental IRPE stress fringe patterns were compared with the simulated patterns based on an analytic solution we obtained recently for the stress distribution under a thin film edge in isotropic substrates. Dependence of the stress distribution in these structures on the geometrical parameters such as the stripe width, window width, and substrate thickness were also studied. The implication of a slight discrepancy between the experimental and simulated IRPE patterns on the singular behavior of stress field in the substrate at the film edge and the concentrated force assumption are discussed.

scholarly journals The Structural Design of a High-Performance WBD Brake Disc

R&D Journal ◽  
2021 ◽  
Author(s):  
A. Chen ◽  
K-J. Kang ◽  
F. Kienhöfer
Keyword(s):  
Stress Distribution ◽  
High Performance ◽  
Mechanical Stresses ◽  
Core Material ◽  
Brake Disc ◽  
Shear Stresses ◽  
Compressive Stresses ◽  
Braking Torque ◽  
Bulk Diamond ◽  
Sufficient Strength

ABSTRACT A high performance, newly-developed wire-woven bulk diamond (WBD) ventilated brake disc is introduced to reduce the operating temperatures and mass of conventional brake discs. The use of the highly porous material requires a deeper understanding of the mechanical stresses developed within a brake disc to be developed to improve the disc core strength to withstand the high stresses developed during braking. In this study, experimentally determined solid brake disc stress distribution results, separated into the compressive stresses due to the pad clamping force and the shear stresses due to the applied brake torque, were applied to the reinforcement ofthe WBD core brake disc. The analysis was based on the maximum predicted deceleration conditions of a medium sized truck (Mercedes-Benz Atego). While the WBD core material possessed sufficient strength to withstand the shearing due to the braking torque, the pad clamping load was predicted to cause disc failure. Consequently, straight radial ribs were designed to reinforce the ventilated core, with final rib dimensions of 74x14x2.5 mm, manufactured from mild steel (SAE1006). A total of 10 ribs at 36° intervals were added to reinforce the core, increasing the mass by 0.20 kg compared to the original disc. The newly reinforced WBD brake disc remains lighter than a commercially available pin-finned disc, and is expected to maintain superior thermal performance while possessing the required mechanical strength. Additional keywords: Ventilated disc, mechanical stresses, braking, stress distribution

scholarly journals Monitoring and Analysis of Stress Distribution of the Interaction between Rock and Backfill and the Influence of Geometric Features of the Backfill Boundary

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Rong Lu ◽  
Fengshan Ma ◽  
Jie Zhao ◽  
Jianbo Wang ◽  
Guilin Li ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Contact Zone ◽  
Local Stability ◽  
Horizontal Stress ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Geometric Features ◽  
Deep Mining ◽  
Boundary Part ◽  
Distribution Of Stress

Backfill mining methods are widely used in metal mines. The boundary part of the backfill has a direct effect on the local stability in mining engineering. The distribution of stress on the boundary part of the backfill and surrounding rock had their own features. To study the characteristics of stress distribution of backfill and surrounding rock on the boundary part, we conducted a field investigation, field monitoring, and numerical simulation. According to the underground monitoring, the overall characteristics of the boundary part of the backfill were that the accumulated horizontal stress was larger than the accumulated vertical stress on the deep sublevel and the accumulated horizontal stress was smaller on the shallow sublevel. On the contact zone (i.e., the boundary part), the stress of the surrounding rock was larger than the stress of the backfill. Combined with the numerical model analysis, we determined that the geometric features of the backfill boundary had an influence on the stress distribution of stress. The multistep boundary helped the integrity of the contact zone and local stability in deep mining.

The Effect of Nonuniform Interfacial Pressures on the Heat Transfer in Bolted and Riveted Joints

1990 ◽  
Vol 112 (3) ◽  
pp. 174-182 ◽  
Author(s):  
C. V. Madhusudana ◽  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Stress Distribution ◽  
Contact Zone ◽  
Plate Thickness ◽  
Interfacial Area ◽  
Interfacial Pressure ◽  
Riveted Joints ◽  
Flow Through ◽  
Contact Spots

In bolted or riveted joints where the interfacial pressure is not uniform, the total resistance to heat flow in a vacuum is the result of two separate components: the microscopic resistance, which arises due to the constraint of the heat flow through the actual microscopic contact spots, and the macroscopic resistance, which exists because the contact zone, over which these microscopic contact spots are located, is only a fraction of the total interfacial area. Presented here is a review of the recent literature addressing the interfacial pressure distribution and the size of the contact zone, in so far as they affect the heat transfer at these interfaces. A survey of the experimental work on contact pressure and the associated heat transfer in bolted joints is presented, along with the size of the actual contact zone which was identified as an important parameter affecting both the microscopic and the macroscopic resistances. An analysis is performed in which it is formally shown that the exact form of the stress distribution within the contact zone is immaterial for the computation of the total microscopic conductance if the available theoretical results for local solid spot conductance are used. If experimental correlations for local solid spot conductance are used, however, the computed total microscopic conductances may differ about 5 to 10 percent, depending on the type of stress distribution chosen. It is also shown that, for a given load, the total microscopic conductance may be increased by increasing the loading radius and/or the plate thickness.

Effect of Laser Shock Peening on Fatigue Life at Stress Raiser Regions of a High-Speed Micro Gas Turbine Shaft: A Simulation Based Study

2019 ◽  
Vol 45 ◽  
pp. 15-27
Author(s):  
Jan G. Pretorius ◽  
Dawood A. Desai ◽  
Glen C. Snedden
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
High Speed ◽  
Stress Raiser ◽  
Element Model ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Residual Stress Field ◽  
Shock Peening ◽  
Stress Raisers

Fatigue failure due to stress raiser regions on critical rotating components in gas turbine engines, such as the shaft, is a crucial aspect. Methods to reduce these stresses and improve fatigue life are a source of ongoing research. Laser shock peening is a method where compressive residual stresses are imparted on the stress raisers of such components. However, numerical based studies on multiple laser shock peening applied to stress raisers is under-researched. Hence, this study will attempt to predict the fatigue life at fillet radii step induced stress raiser regions on a high-speed gas turbine engine shaft by utilization of laser shock peening. The objective of this study was achieved by developing a more computational efficient finite element model to mimic the laser shock peening process on the fillet radii step induced stress raiser regions of a shaft. A modified laser shock peening simulation method for effective prediction of the residual stress field was introduced. Furthermore, the fatigue life improvement due to laser shock peening was predicted by employing Fe-safe fatigue software. From the results, the modified laser shock peening simulation method provided accurate prediction of the residual stress field with a reduced computational time of over 68% compared to conventional methods. The fatigue life revealed an improvement of 553% due to laser shock peening, which is comparable to similar findings in the literature. Hence, from the findings and results achieved, the developed finite element model can be an appropriate tool to assist in the fatigue life estimation of laser shock peening applied to stress raisers.

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