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- Higashitani, Yuko, et al.
(författare)
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A traction coefficient formula for EHL line contacts operating in the linear isothermal region
- 2023
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Ingår i: Tribology International. - : Elsevier Ltd. - 0301-679X .- 1879-2464. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Many mechanical products including rolling/sliding parts are used with various lubricants and operating conditions. Increasing the efficiency and reliability of products requires an essential understanding of the traction characteristics of the rolling/sliding parts. Many researchers have investigated the traction characteristics of rolling/sliding EHL contacts considering shear-thinning, thermal effects, and roller compliance. There are, however, only a few papers concerning the modeling of traction characteristics in the linear isothermal region at low slide-to-roll ratios. We propose a prediction formula for the dimensionless traction coefficient for EHL line contacts in the linear isothermal region. The formula was obtained by numerical simulations using a fully-coupled finite-element EHL line contact solver, and it is applicable for the piezoviscous rigid/elastic, and the isoviscous rigid/elastic regimes.
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| 2. |
- Higashitani, Yuko, et al.
(författare)
-
A traction coefficient formula for EHL point contacts operating in the linear isothermal region
- 2024
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Ingår i: Tribology International. - 0301-679X .- 1879-2464. ; 193
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Tidskriftsartikel (refereegranskat)abstract
- Many mechanical systems including rolling/sliding parts, require traction data across a spectrum of operating conditions to predict their motion effectively. Numerous studies have examined the thermal effects and shear-thinning concerning the traction curve, but only a few have focused on the traction coefficient in the linear isothermal regime for low SRR. In this work, we investigate traction coefficient characteristics of EHL point contacts in the linear isothermal regime, over a wide range of operational conditions. To this end, we conduct numerical simulations utilizing a fully-coupled finite element-based model, resulting in a prediction formula for the traction coefficient slope. With this formula, the traction coefficient slope could be predicted for the operating conditions considered.
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| 3. |
- Higashitani, Yuko, et al.
(författare)
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An Inlet Computation Zone Optimization for EHL Line Contacts
- 2022
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Ingår i: Tribology letters. - : Springer. - 1023-8883 .- 1573-2711. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- Most EHL numerical calculation methods considering both starved and flooded conditions, employ a fixed multiple of the Hertzian radius for the normalization of the computational domain. These methods are often used to investigate the influence of the lubricant supply on friction etc., but the solutions obtained might be numerically starved. The present numerical calculation method utilizes an optimized normalization of the computational domain to ensure that the solutions obtained are not numerically starved. With this normalization method, the computational domain can be appropriately meshed, regardless of the variability in the inlet length due to changes in the operating conditions. This method can, therefore, be used to obtain accurate EHL film thickness and pressure data over a wide range of operating conditions.
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| 5. |
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| 6. |
- Higashitani, Yuko
(författare)
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Prediction of traction in EHL contacts operating in the linear isothermal region
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The vehicle industry plays an important role in moving people and goods all over the world. Unfortunately, the vehicular transportation has a huge (negative) impact on the climate. Improved fuel-efficient vehicle technologies are therefore required to reduce emissions and address environmental concerns. The introduction of alternative fuels and the use of high-pressure fuel injection systems in vehicle engines are some of the approaches that are employed to enhance the fuel efficiency of automobiles. However, in the case of high-pressure fuel injection systems, the tribological interfaces such as those of cam–roller followers are subjected to severe operating conditions (including high contact pressures and sliding motion) and consequently high frictional losses and risk of wear-related failures. This thesis’s objective is to establish a prediction formula for the traction coefficient slope to analyze the motion of the roller follower. This prediction formula is derived based on numerical calculations performed using a fully-coupled finite-element based model of the elliptical elastohydrodynamically lubricated contact specifically designed for operational conditions within the isothermal linear regime.
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