| 1. |
- Bergstedt, Edwin, et al.
(författare)
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Gear micropitting initiation of ground and superfinished gears : Wrought versus pressed and sintered steel
- 2021
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 160
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the resistance of micropitting on two materials, using an FZG back-to-back test rig with CPT gears. The materials are wrought steel (16MnCr5) and a commercial powder metallurgical material (AstaloyTM Mo). Two finishing methods were studied: grinding and superfinishing. Experimental results show that the superfinishing prevented micropitting, but led to premature failure due to cracks in the root caused by tip-to-root interference. Micropitting was initiated at a higher load stage for the powder metallurgical steel compared to the ground wrought steel. The failure mechanisms were similar between materials with the same surface finish. The powder metallurgical steel showed subsurface initiated fatigue compared to the wrought ground steel having surface-initiated fatigue. Testing new finishing methods and materials, one has to be aware of the influence of the gear micro geometry.
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| 2. |
- Bergstedt, Edwin, 1986-, et al.
(författare)
-
Gear Micropitting Initiation of Ground and Superfinished Gears: Wrought versus Pressed and Sintered Steel
-
Ingår i: Tribology International. - 0301-679X .- 1879-2464.
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the resistance of micropitting on two materials, using an FZG back-to-back test rig with C-PT gears. The materials are wrought steel (16MnCr5) and a commercialpowder metallurgical material (AstaloyTM Mo). Two finishing methods were studied: grinding andsuperfinishing. Experimental results show that the superfinishing prevented micropitting, but ledto premature failure due to cracks in the root caused by tip-to-root interference. Micropitting wasinitiated at load stage 8, and 9 for the ground wrought, and powder metallurgical steel respectively.The failure mechanisms were similar between materials with the same surface finish. The powdermetallurgical steel showed subsurface initiated fatigue compared to the wrought groundsteel having surface-initiated fatigue. Testing new finishing methods and materials, onehas to be aware of the influence of the gear micro geometry.
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| 3. |
- Bergstedt, Edwin, et al.
(författare)
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Influence of gear surface roughness on the pitting and micropitting life
- 2020
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications Ltd. - 0954-4062 .- 2041-2983. ; 234:24, s. 4953-4961
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Tidskriftsartikel (refereegranskat)abstract
- Pitting and micropitting are the two main gear rolling contact fatigue modes. It is widely accepted that micropitting will lead to pitting; however, the relationship between pitting and micropitting life needs further investigation. In this work, micropitting and pitting tests were performed on an FZG back-to-back test rig using standard FZG PT-C and GF-C gears. The gear tooth profile change due to micropitting and pitting damage was measured in situ in the gearbox using a profilometer after each test. The gear surface roughness parameters were calculated from the measured tooth profile. A Gaussian low pass filter with cut off length (Formula presented.) mm was applied to the measured tooth profile to obtain the waviness. The calculated roughness parameters and the obtained tooth profile with waviness for each test were imported into the KISSsoft software to calculate the contact stress and specific film thickness at the corresponding load stage. Experimental results show that smooth gear surface can reduce or even avoid micropitting damage, but could lead to a reduction in pitting life.
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| 4. |
- Lin, Jiachun, et al.
(författare)
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A quantitatively distributed wear-measurement method for spur gears during micro-pitting and pitting tests
- 2021
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- FZG gear testing is widely used to evaluate the performance of lubricants, gear materials, and gear-tooth geometries under different loads. During these tests, gear tooth wear results in the loss of gear profile in the form of micro-pitting, pitting and scuffing, can be observed. However, gear wear is usually measured by weighting. This method cannot be used to study the wear depth on a specific point on the gear-tooth surface. In this study, tooth profiles were measured via a profilometer during the FZG gear-pitting test. Moreover, an algorithm was developed to quantitatively evaluate the distributed cumulative wear and wear progress at a certain test stage. Simultaneously, the real tooth profile was obtained. Experiments were performed to validate the proposed method, and the results showed that gear-tooth-surface wear can be quantitatively determined. Thus, the proposed method can be used for further gear-failure-prediction experiments.
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| 5. |
- Lin, Jiachun, et al.
(författare)
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Compensation of mounting error in in-situ wear measurement during gear pitting test
- 2022
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Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 191
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Tidskriftsartikel (refereegranskat)abstract
- A profilometer can be used to monitor the tooth surface topography evolution during gear pitting tests. Due to the mounting relationship variation between the instrument and the gear, the tooth profile's measurement position deviation from its theoretical location will introduce a measurement error. In this study, the tooth profile measurement error introduced by mounting using a tactile profilometer was theoretically analysed and experimentally confirmed as a fish shape. A mounting error compensation method based on projection onto the perpendicular plane to the gear's datum axis was proposed. The results show that the fish-shaped tooth profile measurement error can be effectively compensated, benefitting the evaluation of the gear tooth surface wear during gear pitting tests.
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| 6. |
- Lin, Jiachun, et al.
(författare)
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Gear wear prediction based on the theorem of degradation entropy generation
- 2024
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 191
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Tidskriftsartikel (refereegranskat)abstract
- Tooth surface material loss caused by gear wear alters the surface morphology of gears, which impacts their vibration, noise, and remaining lifespan. Although gear wear modeling and prediction have been extensively studied, this paper proposes a novel approach based on the theorem of degradation entropy generation (DEG). A point-by-point calculation method is introduced to determine the degradation coefficient for each measurement point on the tooth profile, accounting for varying working conditions along the tooth profile during the actual meshing process of the gear pair. First, the FZG gear's bearing capacity is tested. Next, a surface roughness profilometer is employed to in-situ measure the tooth profile after each load stage. The profile deviation curve and the amount of profile wear following each load stage are obtained by processing the measured profile morphology data. Then, the pitting safety factor for each point on the tooth surface is calculated according to the ISO 6336–22:2018 standard and used to correct the degradation coefficient for that point. Finally, the entropy generation of the system during each load stage of the FZG gear is calculated. The degradation coefficient suggested in the DEG theorem is employed to link gear wear with system entropy generation, realizing gear wear modeling and prediction. The results demonstrate that the gear wear calculation method based on the DEG theorem can accurately predict the evolution of tooth profile surface morphology during the experimental process. This research provides a unified calculation method for surface morphology evolution caused by gear wear during service.
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| 7. |
- Lin, Jiachun, et al.
(författare)
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In situ measurement of gear tooth profile during FZG gear micropitting test
- 2019
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Ingår i: SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES. - : IOP PUBLISHING LTD. - 2051-672X. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- According to the GFKT-C/8.3/90 FZG gear micropitting test procedure, the average value of gear tooth profile deviation is used as the failure criterion. Typically, gear tooth profile deviation is measured using a gear measuring machine. In order to do that during the FZG gear test, the gears tested have to be disassembled from, and assembled to the test rig. This process is tedious, time-consuming and is likely to add uncertainty to the testing results. An in situ gear tooth profile measurement method has been developed and applied in FZG gear micropitting tests. The tooth profile of the tested gear was measured in-situ in the gearbox before, during and after each load stage of the gear micropitting test. An algorithm was developed to fit the measured profile to its theoretical shape. Furthermore, a tooth profile change evaluation algorithm was developed for monitoring the evolution of the tooth profile during the duration of the test. The whole methodology was exemplified with a wrought gear test case run to pitting damage.
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| 8. |
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