There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Calculations of the impact of friction and wear on energy consumption, economic expenditure, and CO2 emissions are presented on a global scale. This impact study covers the four main energy consuming sectors: transportation, manufacturing, power generation, and residential. Previously published four case studies on passenger cars, trucks and buses, paper machines and the mining industry were included in our detailed calculations as reference data in our current analyses. The following can be concluded:

 Fifty years ago, wear and wear-related failures were a major concern for UK industry and their mitigation was considered to be the major contributor to potential economic savings by as much as 95% in ten years by the development and deployment of new tribological solutions. The corresponding estimated savings are today still of the same orders but the calculated contribution to cost reduction is about 74% by friction reduction and to 26% from better wear protection. Overall, wear appears to be more critical than friction as it may result in catastrophic failures and operational breakdowns that can adversely impact productivity and hence cost.

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Influence of tribology on global energy consumption, costs and emissions

Surface composites by friction stir processing: A review

Emerging trends in manufacturing such as light weighting, increased performance and functionality increases the use of multi-material, hybrid structures and thus the need for joining of dissimilar materials. The properties of the different materials are jointly utilised to achieve product performance. The joining processes can, on the other hand be challenging due to the same different properties. This paper reviews and summarizes state of the art research in joining dissimilar materials. Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes. Methods for process selection are described and future challenges for research on joining dissimilar materials are summarized.

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Joining of dissimilar materials

https://cyberleninka.org/article/n/403409.pdf

A review of numerical analysis of friction stir welding

In this experiment, copper-base composites reinforced with 30 nm and 5 μm SiC particles are fabricated on the surface of a purecopper sheetvia friction stir processing (FSP). Microstructure, mechanical properties and wear resistance of friction stir processed (FSPed) materials are investigated as a function of volume fraction of SiC particles. Results show that, applying FSP, without SiC particles, increases the percent elongation significantly (more than 2.5 times) and decreases copper's strength. Adding micro- and nano-sized SiC particles decreases the tensile strength and percent elongation. Increasing the volume fraction or decreasing the reinforcing particle size enhances the tensile strength and wear resistance and lowers the percent elongation.

Investigation of mechanical properties of Cu/SiC composite fabricated by FSP: Effect of SiC particles’ size and volume fraction

Friction stir processing (FSP) was used to fabricate SiC/AZ91 composite layer. Effect of process parameters such as rotational and traverse speeds, tool penetration depth and tilt angle on the formation of defects such as cracks, tunnelling cavity and also on sticking of matrix material to the tool was investigated. Also, effect of these parameters was studied on the mechanical properties and microstructures of specimens. Microstructure studies were carried out by optical and SEM. Results showed that FSP is an effective process to fabricate SiC/AZ91 composite layer with uniform distribution of SiC particles, good interfacial integrity and significant grain refinement. Increasing the rotational speed leads to a decrease in the grain size and an increase in the traverse speed leads to a decrease in the grain size. There are upper and lower limitations for these speeds which were determined. PD is a more effective parameter to produce sound surface layer. PD value was affected by traverse and rotational speeds and the tilt angle values. This study shows that by using 5 μm SiC particles, the stir zone grain size reduces from 150 to 7.17 μm and stir zone hardness increases from 63 to 96 Hv.

Producing of AZ91/SiC composite by friction stir processing (FSP)

The microstructures, wear property and micro-hardness of AZ91 Mg alloy/alumina particle reinforced nano-composite produced by friction stir processing (FSP) were investigated. The initial microstructures of the AZ91 were composed of irregularly distributed β-phases (Al12Mg17), while the FSPed specimens were characterized by the homogeneous distribution of alumina particles, the recrystallized grain structure and the dissolution of β-phase. The results showed an improvement in the hardness, wear property of the FSPed zone as results of more grain refinement and pinning effect of nano-alumina particles as compared to those of the base metal. The hardness of the FSPed zone was a higher and more homogeneously distributed and the wear resistance as evaluated by Dry sliding wear tests, was superior, as compared with the base metal.

Characterization of AZ91/alumina nanocomposite produced by FSP

Applications Material and heat flow Microstructural evolution Mechanical properties Corrosion behaviour, wear properties Mechanical alloying by FSP, FSP as a welding and casting repair technique, welding forces Artificial neural network, optimization and simulation FSW and FSP of polymers

Parviz Asadi

Papers

Investigation of mechanical properties of Cu/SiC composite fabricated by FSP: Effect of SiC particles’ size and volume fraction

Producing of AZ91/SiC composite by friction stir processing (FSP)

Characterization of AZ91/alumina nanocomposite produced by FSP

Advances in Friction-Stir Welding and Processing

Simulation of material flow in friction stir processing of a cast Al–Si alloy