In-depth analysis of crack area characteristics of fisheye failures influenced by the multiaxial stress condition in the tooth root fillet of high-strength gears

2021 ◽  
pp. 095440622110616
Author(s):  
Daniel Fuchs ◽  
Sascha Rommel ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Residual Stresses ◽  
Stress Condition ◽  
Bending Strength ◽  
High Strength ◽  
Tooth Root ◽  
Multiaxial Stress ◽  
Depth Analysis ◽  
Standard Specimens ◽  
Compressive Residual Stresses ◽  
Model Approach

Modern high-strength gears have to satisfy many requirements, such as improved tooth root bending strength. The process of shot-peening is correlated to the introduction of compressive residual stresses in the surface layer of a gear to achieve a higher tooth root bending strength. However, due to the compressive residual stresses fisheye failures can occur and can have a determining effect on the endurance of high-strength gears. By preventing such failures, it should be possible to increase further the tooth root bending strength of high-strength gears. However, this requires a deeper understanding of the crack initiation and propagation processes. Especially the unique multiaxial stress condition in the tooth root fillet of a gear could influence the crack area characteristics significantly. Though, in the literature there is no proper characterization of crack area characteristics in the tooth root fillet of gears in detail, so far. Furthermore, in previous work a model approach for the evaluation of the tooth root bending strength of gears was presented, which is based on the results of Murakami. A first comparison with experimental data showed a basic applicability of the model approach on gears. However, the derived model approach showed some room for improvement. Questions arose as to whether the approach is really fully applicable to gears, whether further modifications are needed, or whether further extension is even practical, since the fisheye fracture characteristics of gears might differ significantly from those of standard specimens. The aim of this paper is therefore to present an extensive in-depth analysis of the crack area characteristics in the event of tooth root fracture damages caused by a fisheye failure in high-strength gears. Furthermore, a case study is used to verify whether a detailed evaluation of the characteristics of non-metallic inclusions leads to more accurate results of the model approach.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

Short Crack Propagation Model Applied to Shot Peened Aluminium Alloys

2009 ◽  
Vol 65 ◽  
pp. 53-61 ◽  
Author(s):  
J. Solis ◽  
J. Oseguera-Peña ◽  
I. Betancourt
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Aluminium Alloys ◽  
Micromechanical Model ◽  
High Strength ◽  
Crack Arrest ◽  
Propagation Model ◽  
Safe Load ◽  
Compressive Residual Stresses

The Navarro-Rios micromechanical model was used to assess the bounds of two different damage zones: crack arrest region and crack propagation region of controlled shot peening (CSP) of high strength aluminium alloys. Performance of CSP in terms of fatigue resistance was investigated. This comparison indicated that CSP in terms of fatigue depends on the competition between its beneficial and detrimental products, i.e. surface roughness and compressive residual stresses respectively. The gathered information can be used for safe load determinations in design.

High Toughness Ceramic Laminates by Design of Residual Stresses

2001 ◽  
Vol 702 ◽  
Author(s):  
Nina A. Orlovskaya ◽  
Jakob Kuebler ◽  
Vladimir I. Subotin ◽  
Mykola Lugovy
Keyword(s):  
Fracture Toughness ◽  
Residual Stresses ◽  
Damage Tolerance ◽  
High Strength ◽  
Ceramic Composites ◽  
Tensile Stresses ◽  
High Toughness ◽  
Apparent Fracture Toughness ◽  
Layered Ceramics ◽  
Compressive Residual Stresses

ABSTRACTMultilayered ceramic composites are very promising materials for different engineering applications. Laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with the high strength and reliability. The control over the mechanical behavior of laminates can be obtained through design of residual stresses in separate layers. Here we report a development of tough silicon nitride based layered ceramics with controlled compressive and tensile stresses in separate layers. We design laminates in a way to achieve high compressive residual stresses in thin (100-150 micron) Si3N4 layers and low tensile residual stresses in thick (600-700 micron) Si3N4-TiN layers. The residual stresses are controlled by the amount of TiN in layers with residual tensile stresses and the layers thickness. The fracture toughness of pure Si3N4(5wt%Y2O3+2wt%Al2O3) ceramics was measured to be of 5 MPa m1/2, while the apparent fracture toughness of Si3N4/Si3N4-TiN laminates was in the range of 7-8 MPa m1/2 depending on the composition and thickness of the layers.

scholarly journals Effect of Laser Peening with a Microchip Laser on Fatigue Life in Butt-Welded High-Strength Steel

2021 ◽  
Vol 2 (4) ◽  
pp. 878-890
Author(s):  
Tomoharu Kato ◽  
Yoshihiro Sakino ◽  
Yuji Sano
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
High Strength Steel ◽  
Welded Joint ◽  
Base Material ◽  
High Strength ◽  
Microchip Laser ◽  
Laser Peening ◽  
Near Surface ◽  
Compressive Residual Stresses

Laser peening introduces compressive residual stresses on the surfaces of various materials and is effective in enhancing fatigue strength. Using a small microchip laser, with energies of 5, 10, and 15 mJ, the authors applied laser peening to the base material of an HT780 high-strength steel, and confirmed compressive residual stresses in the near-surface layer. Laser peening with a pulse energy of 15 mJ was then applied to fatigue samples of an HT780 butt-welded joint. It was confirmed that laser peening with the microchip laser prolonged the fatigue life of the welded joint samples to the same level as in previous studies with a conventional laser.

A Study on Grinding Parameter Optimization of Reaction Bonded Silicon Carbide

2013 ◽  
Vol 631-632 ◽  
pp. 660-665 ◽  
Author(s):  
Yao Wang ◽  
Zha Yan Feng
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Silicon Carbide ◽  
Residual Stresses ◽  
Compressive Residual Stress ◽  
Bending Strength ◽  
Grinding Parameters ◽  
Depth Analysis ◽  
Cut Depth ◽  
Full Factorial

In order to enhance the efficiency and the surface smooth degree of the RBSiC grinding, a three factors two levels full factorial design was utilized to optimize the process. Combined with the effects of grinding parameters on surface roughness, the grit cut depth analysis was employed to choose the appropriate grinding parameters. The strength reliability and the residual stresses of the RBSiC ground using the optimized parameters were investigated. The results show that comparing to the polished RBSiC the ground ones have higher compressive residual stress, lower crack scatter and similar average bending strength.

The Effect of Surface Enhancement on Improving the Fatigue and Sour Service Performance of Downhole Tubular Components

2012 ◽  
Author(s):  
Jeremy E. Scheel ◽  
Douglas J. Hornbach
Keyword(s):  
Carbon Steel ◽  
Residual Stresses ◽  
High Strength ◽  
Steel Alloys ◽  
Surface Enhancement ◽  
Tensile Stresses ◽  
High Magnitude ◽  
Sour Service ◽  
Tubular Components ◽  
Compressive Residual Stresses

Sulfide stress cracking (SSC) and hydrogen embrittlement (HE) prevent the use of high strength carbon steel alloys in the recovery of fossil fuels in H2S containing ‘sour’ environments commonly experienced in deep well fossil fuel recovery efforts. Couplings are a common weak point in casing strings as high magnitude mean tensile stresses are generated by connection interferences created during power make-up of downhole tubular components. When subject to service loads both mean and alternating stresses are increased further providing the high tensile stresses necessary for SSC initiation. Since high strength carbon steel alloys are not typically suited for sour service environments, the current solution is to use or develop much more expensive alloys with increased corrosion-cracking resistance, or limit their use to significantly weaker sour environments, or higher operating temperatures. Failure due to fatigue is another major problem in downhole tubular components. Likelihood of fatigue failure is further exacerbated in corrosive environments (such as H2S and NaCl), commonly encountered in service. The cost for detecting the impending failure before final separation is dramatic at a factor 10X. A cost effective method of mitigating failure from SSC and corrosion fatigue would greatly reduce operational costs and extend component life. Introduction of stable, high magnitude compressive residual stresses into less expensive carbon steel alloys alleviates the tensile stresses, and mitigates SSC, while also improving fatigue performance. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance. The effects of LPB on high cycle fatigue (HCF) and SSC were evaluated on quench and tempered API P110 grade steel. LPB processed specimens had an increase in fatigue life greater than an order of magnitude over untreated specimens. LPB was successful in completely mitigating SSC in all test specimens at tensile stresses up to 90% specified minimum yield strength (SMYS). The initial results indicate that LPB processing of P110 steel provides an economical means of SSC mitigation and fatigue strength improvement in sour environments.

Behavior of Compressive Residual Stresses in High Strength Steel Welds Induced by High Frequency Mechanical Impact Treatment

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mansoor Khurshid ◽  
Zuheir Barsoum ◽  
Gary Marquis
Keyword(s):  
Residual Stresses ◽  
Welded Joints ◽  
High Frequency ◽  
Fatigue Testing ◽  
Research Work ◽  
High Strength ◽  
Fatigue Loading ◽  
Element Analysis ◽  
Mechanical Impact ◽  
Compressive Residual Stresses

Residual stress state plays an important role in the fatigue life of welded structures. The effect can be beneficial or detrimental, depending on the nature of residual stresses. High frequency mechanical impact (HFMI) treatment is a postweld fatigue improvement technique for welded joints. In this research work the behavior of compressive residual stresses induced in welded joints in high strength steels (HSS) by HFMI treatment has been investigated. Longitudinal nonload carrying attachments in HSS are tested with constant amplitude (CA) and variable amplitude (VA) fatigue loading. Stress concentration factors have been calculated using finite element analysis (FEA). Residual stresses have been measured at different cycles during fatigue testing using X-ray diffraction technique. It is observed that the induced residual stresses are quite stable with some relaxation in CA and VA loading. The overloads in VA loading seem to be more detrimental. Relaxation of residual stresses is more obvious in VA tests.

Enhanced Surface Residual Compression of Carburized Steel Parts Using Laser Peening Process With Preload

2014 ◽  
Author(s):  
Zhichao (Charlie) Li ◽  
B. Lynn Ferguson
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Laser Peening ◽  
X Ray Diffraction ◽  
Carburized Steel ◽  
Initiation And Propagation ◽  
Quench Hardening ◽  
Enhanced Surface ◽  
Compressive Residual Stresses ◽  
Residual Compression

Residual stresses are critical to the fatigue performance of parts. In general, compressive residual stress in the surface is beneficial, and residual tension is detrimental because of the effect of stress on crack initiation and propagation. Carburization and quench hardening create compressive residual stresses in the surface of steel parts. The laser peening process has been successfully used to introduce residual compression to the surface of nonferrous alloy parts. However, the application on carburized steel parts has not been successful so far. The application of laser peening on carburized steel parts is limited due to two main reasons: 1) the high strength and low ductility of carburized case, and 2) the compressive residual stresses in the surface of the part prior to laser peening. In this paper, the carburization, quench hardening, and laser peening processes are integrated using finite element modeling. The predicted residual stresses from quench hardening and laser peening are validated against residual stresses determined from X-ray diffraction measurements. An innovative concept of laser peening with preload has been invented to enhance the residual compression in a specific region of laser peened parts. This concept is proved by FEA models using DANTE-LP.

scholarly journals Numerical Investigations of the Crack Resistance of Ion-Strengthened Sheet Glass Under Bending Strains

2021 ◽  
Vol 24 (3) ◽  
pp. 27-34
Author(s):  
Pavlo P. Hontarovskyi ◽  
◽  
Natalia V. Smetankina ◽  
Serhii V. Ugrimov ◽  
Nataliia H. Garmash ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Residual Stresses ◽  
Crack Resistance ◽  
Sheet Glass ◽  
Surface Crack ◽  
Bending Strength ◽  
Surface Defects ◽  
High Strength ◽  
Structural Element ◽  
Compressive Stresses

The safety of reliable operation of aircraft and their durability essentially depend on the strength of the glazing, which is a critical structural element. There are a number of different requirements for glazing. To provide the necessary parameters, high-strength silicate glass is widely used, and special technologies for its strengthening are used. The analysis of the problem showed that the insufficient strength of aircraft glazing elements and the complexity of methods for monitoring the state of glass during production and operation due to the presence of microscopic surface defects, as well as the need for a reliable assessment of residual stresses, require that there be used new approaches and technical solutions for the development of modern technologies for creating structures. Ion exchange is one of the glass strengthening mechanisms, which makes it possible to reduce the negative effect of surface defects by artificially creating residual compressive stresses and reducing the thickness of the damaged layer. Computational studies, under bending strains, of the crack resistance of ion-exchange strengthened sheet glass were carried out using an in-house FEM-based software package developed to study the thermally stressed states of structures. The results obtained showed that the strength of real sheet glass fracture due to tensile stresses in bending is determined by crack-like surface defects. The creation of residual compressive stresses on the glass surface by ion exchange strengthening provides an increase in bending strength. With an increase in residual stresses and the depth of their distribution, the effect of ion-exchange treatment increases. If the depth of the zone of compressive stresses due to ion-exchange strengthening is much less than the depth of the surface crack, then the strength of the glass depends little on the maximum compressive stresses on the surface. The effect of ion-exchange strengthening increases significantly in the case of a decrease in the depth of the surface crack. The expediency of further research and comparison of calculation results with experimental data are shown. The developed technique will make it possible to solve important practical problems in studying the strength of the aircraft multilayer glazing and determining the optimal methods for eliminating defects.

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