Challenges of friction reduction of engine plain bearings – Tackling the problem with novel bearing materials

Summer, Florian; Grün, Florian; Offenbecher, Martin; Taylor, Stuart

doi:10.1016/j.triboint.2018.10.042

Cited by 49 publications

(16 citation statements)

References 26 publications

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“…Test strategies, which define the test program, are adapted for the respective goal of research [10]. Examples can be found in [11] for research on the seizure resistance of journal bearing materials in engine applications and in [12] for the assessment of lifetime due to mild wear during start/stop operation.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

et al. 2020

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Optimizing the surface topography of cast iron crankshafts offers the opportunity to use this material as an alternative to steel in high-performance combustion engines. In the past, this was not possible due to the higher wear on bearing shells and the higher friction losses in relation to forged steel shafts. In order to find an optimized shaft micro topography, the friction and wear behavior of steel and cast iron shafts with different surface treatments were compared to each other, using a combined physical (experimental) and a virtual (computational) simulation approach. The experiments were carried out with a rotary tribometer using a journal bearing test configuration with the possibility to test real-life bearing shells and shaft specimens, manufactured from real-life crankshafts. In the experiments, a polished steel shaft with low bearing wear was effective. The optimization of cast iron crankshafts by a novel surface treatment showed a significant reduction of bearing wear in relation to the classical surface finishing procedures of cast iron shafts. A computational simulation approach, considering the real-life micro topography by using the Navier–Stokes equations for the calculation of micro hydrodynamics, supports the assessment of fluid friction. The virtual simulation shows, in accordance to the experimental results, only a minor influence of the investigated shaft topographies on the fluid friction. Further optimization of shaft surfaces for journal bearing systems seems possible only by the usage of patterned micro topographies.

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Section: Introductionmentioning

confidence: 99%

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

et al. 2020

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“…Al-Si alloys are often used in several engineering applications owing to their high strength-to-weight ratio, low coefficient of thermal expansion, and better wear resistance as compared to other aluminum alloys [1][2][3][4]. However, the porosity and needle or acicular morphology of the Si are detrimental to its mechanical properties [5,6]. Al-Si alloys can be tailored by alloying, microstructural modification, or reinforcing with suitable reinforcements to improve their performance in engineering applications [7].…”

Section: Introductionmentioning

confidence: 99%

Tribological characteristics of friction stir processed graphite and tin/LM24 surface composites

2020

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Friction stir processing (FSP) is an emerging solid-state technique for preparing surface composites using various reinforcements. Ceramics and metallic particles are easily reinforced in a matrix by this technique. Surface composites made from an LM24 alloy reinforced with graphite and tin, with good wettability and material flow owing to the low melting point of tin, were fabricated by FSP at two rotational speeds of 1,400 and 1,000 rpm. Despite its low hardness, the graphite/LM24 surface composite fabricated at a higher rotational speed of 1,400 rpm exhibited better wear resistance. However, its frictional behavior was not significantly affected by the reinforcement. The fabricated surface composites with graphite and tin reinforcement as well as graphite-only reinforcement exhibited contradicting behaviors under sliding wear conditions. The post wear analysis indicated that abrasion, adhesion, layer formation, and delamination occurred on the composite surfaces.

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“…Low friction for the desired lifetime is a key requirement for engine bearings [5][6][7]. In sliding bearings, methods to improve the frictional performance range from improved mechanical design [8] over different lubricant formulation [8,9] and novel bearing material solutions [1,2,10] to modern surface engineering [11][12][13]. Furthermore, the frictional losses of sliding bearings can be reduced by wear-induced change of the contact geometry-hereafter referred to as wearing-in-under boundary or mixed-friction conditions [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

2020

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With the increased use of automotive engine start-stop systems, the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important issue. In engineering practice, numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface parameters. The aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop operation. For this purpose, the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment (mixed-EHL/MBS). In mixed-EHL/MBS, the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to Herbst. The detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and simulation. The actual distribution and position of surface roughness, as used in deterministic contact modelling, is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

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Challenges of friction reduction of engine plain bearings – Tackling the problem with novel bearing materials

Cited by 49 publications

References 26 publications

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

Tribological characteristics of friction stir processed graphite and tin/LM24 surface composites

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

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