Particles formation due to the wear of tires and measures for the wear reduction: A review

Tires are a very important part of a vehicle, necessary for the vehicle driving. During the vehicle exploitation, due to the friction which appears in the contact between the tire and the road, it comes to the formation of so called non-exhaust particles. The particles formed during the vehicle exploitation can be composed of heavy metals and they are harmful for people’s health and for the environment. Several factors influence the size of the wear of tires. The investigations about the tires behavior as well as the size of the wear can be conducted on the road, in the laboratory, as well as by application of modern software. The paper shows the applied methodologies applied by other researchers during the investigation of tires particles formation, the applied materials for the tires manufacturing, influential parameters on the wear of tires, as well as methods for the wear of tires reduction. After analyzing other researches in the subject field, the authors have come to the conclusions related to the factors which can reduce the wear of tires and these factors should be given proper attention in further studies.

Role of Eco-Friendly Bio-Based Graphene-Oil Nanofluids on Friction Reduction for Wind Turbine Application

Sustainable energy such as wind turbine is known as a green technology that minimize the carbon emission into environment. However, unwanted friction and wear in journal bearing of a wind turbine’s gearbox leads to reduction of power efficiency and increase the reliance onto fossil-fuel powered electricity. Lubricating oils are used in journal bearing to provide the hydrodynamic lubrication film. However, commercially available lubricants are petroleum-based, which are non-replenishable and toxic. Thus, the bio-degradable vegetable oil, high oleic palm oil-based methyl ester (high oleic POME) was used as a base oil synthesized with graphene nanoplatelets (GNP), multi-walled carbon nanotubes (MWCNT) and nanostructured graphite (NSG), respectively, to enhance the friction and wear reduction. The tribological performance of each type of bio-based graphene-oil nanofluid was studied using pin-on-ring tribo-tester. It is concluded that NSG in high oleic POME shows 52.03% friction coefficient reduction and 59.27% pin specimen weight loss reduction. With this significant friction and wear reduction, power efficiency of wind turbine will be improved significantly. Thus, the reliance of society depending on fossil-fuel powered electricity can be reduced and minimize the carbon emission into the environment.

Analysis of the Impact Factor of Rail Grinding on Their Condition

The Doctoral Thesis “Analysis of the impact of rail grinding on their condition” is developed by Viktors Ivanovs to obtain a Doctoral Degree in Engineering. The scientific supervisor is Assoc. Professor Dr. sc. ing. Pāvels Gavrilovs. In this Doctoral Thesis rail steels are considered according to standards EN 13674-1:2011 and GOST R 51685-2013. Rail steel defects and reasons for their causes are reviewed. The statistics of damaged and heavily damaged rails in the network “Latvijas dzelzceļš” in the period 2011–2019 is studied and analysed in detail. The statistics of rail grinding train operation in “Latvijas dzelzceļš” within the year period 2011–2019 is gathered and analysed. A research of hardness of 60 E1 type rail running surface, of metal chemical composition of the damaged rail with code X 10.1., and structure analysis was performed. Likewise, statistics of wheelset rejection in the network “Latvijas dzelzceļš” in the period 2016–2019 are gathered and analysed, as well as the number of wheel rim defects in the railway of Russian Federation. The main defects of wheelsets are reviewed. The actual wear of wheels and rails in Latvia and the stated wear in the railway of Russia are modelled. Repair profiles of rail head grinding for Latvian rail ways are modelled and their influence on side wear determined due to the rail and wheel surface interaction. Calculations regarding the wheels with flange angle of 66.8° from worn out profile durability coefficient were performed for Latvian railway according to the entry conditions on rail profiles, developed in this dissertation. A rail grinding method was developed. The wheelset repair and wheel grinding economic expenses were calculated. Recommendations for wheel and rail side wear reduction are presented.

A Systematic Review of Compliant Mechanisms as Orthopedic Implants

Currently available motion-preserving orthopedic implants offer many advantages but have several limitations to their use, including short device lifetime, high part count, loss of natural kinematics and wear-induced osteolysis and implant loosening. Compliant mechanisms have been used to address some of these problems as they offer several potential advantages - namely wear reduction, reduced part count, and the ability to achieve complex, patient-specific motion profiles. This article provides a systematic review of compliant mechanisms as orthopedic implants. Based on the PRISMA guidelines for an efficient review, this work identified fourteen implantable orthopedic devices that seek to restore anatomical motion by utilizing mechanical compliance. From reviewing these implants and their results, advantages and consequences for each are summarized. Trends were also identified in how these devices are capable of mitigating common challenges found in orthopedic design. Design considerations for the development of future compliant orthopedic implants are proposed and discussed.

Wheel profile optimization procedure to minimize flange wear considering profile wear evolution

This study aims to develop a wheel profile optimization procedure to minimize flange wear considering the wear evolution. To this end, the wheel wear simulation capability is integrated into the profile optimization framework such that a total material loss can be minimized under design constraints. This allows for the wear reduction to be maintained over an extended traveling distance, while an optimized profile, minimizing the frictional energy for only the initial profile, would not ensure the optimum performance after the profile wear becomes significant. Furthermore, to enable a balanced mitigation of the profile wear and surface damage, the damage index model is introduced to the weighted objective function, considering profile wear evolution. Using flange wear tests with a scaled roller test rig, wear reduction of the optimized profile is experimentally validated. The wear simulation results agree with the test data. It is demonstrated that the flange wear and tread surface damages are reduced simultaneously over an extended traveling distance using the profile optimization procedure developed in this study.