Experimental and numerical investigation of the bending fatigue performance of symmetric and asymmetric polymer gears

2020 ◽  
Vol 234 (6) ◽  
pp. 819-834
Author(s):  
A Karthik Pandian ◽  
Sachin Singh Gautam ◽  
S Senthilvelan
Keyword(s):  
Form Factor ◽  
Correction Factor ◽  
High Stress ◽  
Fatigue Tests ◽  
Multiple Cracks ◽  
Bending Stress ◽  
Element Analysis ◽  
Bending Fatigue ◽  
High Stress Concentration ◽  
Bending Stresses

In this work, the bending fatigue strengths of injection-molded symmetric and asymmetric nylon 66 gears were evaluated experimentally, and the results were substantiated using numerical studies. The symmetric (20°/20°) and asymmetric (34°/20° and 20°/34°) configurations were subjected to bending fatigue tests under a load controlled mode. The bending stresses of the symmetric and asymmetric gears were predicted by quasi-static simulations using a commercial finite element analysis software. The form factor ([Formula: see text]) and the stress correction factor ([Formula: see text]) were computed using an adapted ISO method. The 34°/20° configuration exhibited the lowest bending stress and highest bending fatigue life among the tested configurations. The form factor exerted a decisive influence on the magnitude of the bending stress compared to the stress correction factor. For the considered loading conditions, deflection-induced load sharing occurred in the 20°/20° and 20°/34° configurations but was absent in the 34°/20° configuration. Failure analysis indicated that a high stress concentration caused multiple cracks in the fillets of asymmetric gears.

The Influence of Switch Temperature on Coke Drum Fatigue Life

2010 ◽  
Author(s):  
Fa´bio de Castro Marangone ◽  
Ediberto Bastos Tinoco ◽  
Carlos Eduardo Simo˜es Gomes
Keyword(s):  
Fatigue Life ◽  
Structural Model ◽  
High Stress ◽  
Axial Direction ◽  
Pressure Vessels ◽  
High Stress Concentration ◽  
Short Period ◽  
Bending Stresses ◽  
Switch Temperature ◽  
Lower Temperature

Coke drums are thin-walled pressure vessels that experience severe thermal cycling condition which consists of heating, filling and rapidly cooling the drum in a short period of time. After some years under operation, cracks at the vessel may occur, especially at high stress concentration areas such as the skirt support to shell attachment. During the filling phase of the cycle, when the empty and cooled coke drum is filled with hot oil, the shell and cone temperatures increase rapidly compared to the skirt temperature and the last is pushed outward, since its bottom is at lower temperature and fixed at a concrete base. During quenching (sudden cooling) phase, the coke drum is filled with water at about 80°C and tends to cool faster than the skirt, which is pulled inward until equilibrium is obtained. The skirt expansion and contraction movement results in bending stresses in axial direction on the top of skirt. As lower the switch temperature is, more severe is the bending effect. One of PETROBRAS delayed coke unit presented some operational problems at pre-heating phase, resulting in lower switch temperatures. This paper presents an analysis showing the influence of the switch temperature on coke drum fatigue life. At first, the transient loading conditions were established from thermocouple measurements at skirt attachment weld (hot box region). Later, a transient thermal analysis was performed with FEA and the temperature gradient at the skirt attachment during entire thermal cycle was obtained. The thermal results were then converted to a structural model which was solved for linear elastic stress including other loads such as pressure. Finally, the maximum stress components for both filling and quenching phases were determined and a complete stress range was calculated as per ASME Section VIII, Div 2. The procedure described above was applied for different switch temperatures scenarios in order to show its influence on the fatigue life of the coke drum.

scholarly journals A Novel Method for Tooth Bending Stress Calculation of Gears With Asymmetric Teeth

2021 ◽  
Author(s):  
Oguz DOGAN ◽  
Celalettin YUCE ◽  
Fatih KARPAT
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Bending Stress ◽  
Element Analysis ◽  
Stress Calculation ◽  
Bending Stresses ◽  
New Equation ◽  
Asymmetric Factor

Abstract Today, gear designs with asymmetric tooth profiles offer essential solutions in reducing tooth root stresses of gears. Although numerical, analytical, and experimental studies are carried out to calculate the bending stresses in gears with asymmetric tooth profiles a standard or a simplified equation or empirical statement has not been encountered in the literature. In this study, a novel bending stress calculation procedure for gears with asymmetric tooth profiles is developed using both the DIN3990 standard and the finite element method. The bending stresses of gears with symmetrical profile were determined by the developed finite element model and was verified by comparing the results with the DIN 3990 standard. Using the verified finite element model, by changing the drive side pressure angle between 20° and 30° and the number of teeth between 18 and 100, 66 different cases were examined and the bending stresses in gears with asymmetric profile were determined. As a result of the analysis, a new asymmetric factor was derived. By adding the obtained asymmetric factor to the DIN 3390 formula, a new equation has been derived to be used in tooth bending stresses of gears with asymmetric profile. Thanks to this equation, designers will be able to calculate tooth bending stresses with high precision in gears with asymmetric tooth profile without the need for finite element analysis.

Finite Element Analysis of Residual Stresses in Threaded End Closures

1991 ◽  
Vol 113 (3) ◽  
pp. 398-401 ◽  
Author(s):  
A. Chaaban ◽  
U. Muzzo
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Bauschinger Effect ◽  
High Stress ◽  
Empirical Method ◽  
Pressure Vessels ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Proof Testing ◽  
Pressure Cycle

Due to the high stress concentration at the root of the first active thread in threaded end closures of high pressure vessels, yielding may occur in this region during the application of the first pressure cycle or proof testing. This overstraining introduces residual stresses that influence the fatigue performance of the vessel. This paper presents a parametric analysis of threaded end closures using elastic and elasto-plastic finite element solutions. The results are used to discuss the influence of these residuals on the estimated fatigue life when the vessel is subjected to repeated internal pressure. A simple empirical method to allow for the Bauschinger effect of the material is also proposed.

The Weight Reduction Design of the Regenerator CA Nozzle in FCC Unit Using the FEA

2013 ◽  
Vol 658 ◽  
pp. 345-349
Author(s):  
Il Taek Lee ◽  
Hyun Sik Kim ◽  
Namr Young Choi ◽  
Dong Pyo Hong
Keyword(s):  
Weight Reduction ◽  
Catalytic Cracking ◽  
Equivalent Stress ◽  
High Stress ◽  
Fluid Catalytic Cracking ◽  
Code Design ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Unit Energy ◽  
Asme Code

Recently, due to the rising of oil prices, interest in FCC Unit (Fluid Catalytic Cracking Unit) energy recycling is increasing. FCC Unit (Fluid Catalytic Cracking Unit) is a mechanical used to convert bunker C oil into high quality gasoline. Pressure vessel of FCC Unit is that refining the crude oil when is operating in high-temperature and high-pressure environment. So it needs analysis of structure carefully. In this paper, FEA (Finite element analysis) of the FCC unit was performed to evaluate its structural stability and weight reduction. The equivalent stress of the FCC unit was investigated and compared against the ASME code design specifications. The area of high stress concentration with maximum stress higher than the prescribed value was analyzed locally to carefully evaluate the stress. Finally, we were reduces the thickness of the CA nozzle in FCC unit, and it was satisfied structural stress.

Dislocation Dynamics Simulations in the Presence of Interacting Cracks

1999 ◽  
Vol 121 (2) ◽  
pp. 151-155 ◽  
Author(s):  
I. Demir ◽  
A. N. Gulluoglu
Keyword(s):  
Plastic Zone ◽  
High Stress ◽  
Dislocation Dynamics ◽  
Failure Behavior ◽  
Multiple Cracks ◽  
Accurate Analysis ◽  
High Stress Concentration ◽  
History Of ◽  
Reasonable Description ◽  
Dynamics Simulations

For an understanding failure behavior of crystalline solids, considerable interest is given to investigating interaction effects between the main crack and microcracks in the presence of mobile dislocations. Accurate analysis of these types of interaction problems may lead to accurate models for failure prevention and the history of plastic zone development. High stress concentration areas such as crack tips are the places where dislocations are subjected to higher forces. Therefore, a computer simulation technique based on dislocation dynamics has been developed to investigate the movement of dislocations in the presence of multiple cracks. Dislocation structures, dislocation distribution and strain rate results are presented as functions of applied stresses for different microcrack positions and orientations. Simulation results give a reasonable description of dislocation pattern development during deformation around the cracks and explain the shape and development of the plastic zone.

scholarly journals Contribution In Determining The Fatigue Endurance of Slide Diamond Burnishing AISI52100 Steel Components

2021 ◽  
Author(s):  
Ouahiba Taamallah ◽  
Hamid Hamadache ◽  
Abdelaziz Amirat ◽  
Ouzine Boussaid
Keyword(s):  
Fatigue Resistance ◽  
Maximum Stress ◽  
High Stress ◽  
Ultimate Tensile Stress ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Diamond Burnishing ◽  
Slide Diamond Burnishing ◽  
Fatigue Endurance ◽  
Good Agreement

Abstract The present paper is an investigation on the effect of slide diamond burnishing on the fatigue endurance of a component made of AISI52100 steel. Burnishing operation has been performed on cylindrical specimens using optimal parameters statistically selected such as burnishing force, burnishing feed and number of tool passes. Bending fatigue tests in air at R= -1 and S-N curves have been plotted by incrementing the applied stress from a maximum stress level of about 66% of the ultimate tensile stress to a stress value below which fatigue does not occur. Results show that slide diamond burnishing has increased the fatigue resistance comparing to unburnished specimens. The fatigue endurance is respectively 222 MPa and 190 MPa. At high stress levels, the fatigue resistance improvement is clearly observed and the fatigue trends are in good agreement with those reported in literature. However, the present results are slightly lower and that is attributed to the shoulder fillet value of the specimen. For small fillet radius, fatigue resistance is lowered.

Development of Design Curve for Sweepolet Subjected to Acoustic Induced Vibration

2016 ◽  
Author(s):  
Yuqing Liu ◽  
Philip Diwakar ◽  
Dan Lin ◽  
Ismat Eljaouhari ◽  
Ajay Prakash
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Acoustic Energy ◽  
Piping System ◽  
Element Analysis ◽  
Design Curve ◽  
High Stress Concentration

High acoustic energy has the potential to cause severe Acoustic Induced Vibration (AIV) that leads to fatigue failure at high stress concentration regions such as fittings in a piping system. Sweepolet fittings have been extensively used as mitigation to counteract the risk of fatigue failure caused by AIV. The advantages of a sweepolet are its integrally reinforced contoured body and low stress concentration. However, there are inconsistencies in published standards and regarding the design limits for sweepolet subjected to AIV. In this paper, Finite Element Analysis is conducted to simulate high frequency pipe shell wall vibration caused by acoustic energy inside the pipe. Peak stress and the associated minimum fatigue life are calculated for sweepolet and sockolet under the same acoustic excitation. By comparing the stress level to that of a sockolet whose design limit to AIV had been published, the design curve and fatigue life equation for sweepolet are developed.

The Evolution of Surface Damage in Press-Fitted Shaft According to the Bending Stress

2007 ◽  
Vol 26-28 ◽  
pp. 1353-1356
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Fatigue Life ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Fretting Wear ◽  
Small Scale ◽  
Multiple Cracks ◽  
Bending Stress ◽  
Propagation Process ◽  
Fatigue Crack Nucleation ◽  
Bending Load

Fretting damage is a critical problem to prevent failure of press-fitted shaft such as the rotor of a steam turbine, railway axles or coupling. To clarify the characteristics of surface damage due to fretting in press-fitted shaft, experimental methods were applied to small-scale specimen with different bending load conditions. Fatigue tests and interrupted fatigue tests of press-fitted specimen were carried out by using a rotate bending fatigue test machine. Macroscopic and microscopic characteristics were examined using scanning electron microscope (SEM), optical microscope or profilometer. It is found that small fatigue cracks are nucleated early in life regardless of bending stress, and thus the most portion of fatigue life on press fits can be considered to be crack propagation process. Most of surface cracks are initiated near the contact edge, and multiple cracks are nucleated and interconnected. Furthermore, the fretting wear rates at the contact edge increase rapidly at the initial stage of total fatigue life. It is thus suggested that the fatigue crack nucleation and propagation process is strongly related to the evolution of surface profile by fretting wear in press fits.

scholarly journals Effects of Rim Thickness on Spur Gear Bending Stress

1994 ◽  
Vol 116 (4) ◽  
pp. 1157-1162 ◽  
Author(s):  
G. D. Bibel ◽  
S. K. Reddy ◽  
M. Savage ◽  
R. F. Handschuh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Power ◽  
Design Parameter ◽  
Gear Tooth ◽  
Spur Gear ◽  
Bending Stress ◽  
Element Analysis ◽  
Bending Stresses

Thin rim gears find application in high-power, lightweight aircraft transmissions. Bending stresses in thin rim spur gear tooth fillets and root areas differ from the stresses in solid gears due to rim deformations. Rim thickness is a significant design parameter for these gears. To study this parameter, a finite element analysis was conducted on a segment of a thin rim gear. The rim thickness was varied and the location and magnitude of the maximum bending stresses reported. Design limits are discussed and compared with the results of other researchers.

Acoustic Vibration Induced Fatigue in Pipe Joints

2015 ◽  
Author(s):  
Ajay Prakash ◽  
Philip Diwakar ◽  
Dan Lin ◽  
Paul Deane ◽  
Yuqing Liu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sound Pressure ◽  
High Stress ◽  
Acoustic Vibration ◽  
Acoustic Energy ◽  
Piping System ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Pipe Joints

High acoustic energy has the potential to cause severe acoustic induced vibration (AIV) that can lead to fatigue failure at high stress concentration locations (discontinuities) in a piping system. AIV at pipe junctions (Lateral, Tee, and Wye) and welded support attachments (trunnions and shoes) is evaluated using Finite Element Analysis. At different size pipe junctions, branch and header pipe shells may be subjected to different sound pressure. Also, inertia associated with different wall thickness(s) can lead to very different dynamic response of the two shell walls. The effect of these differences on AIV response is analyzed. Resulting response for different junction reinforcement designs is evaluated and compared to an unreinforced ‘stub-on’ configuration to assess the designs.

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