Beata Świeczko-Żurek

Road texture influence on tyre rolling resistance

Tyre performance, one of the critical factors for vehicle users, is strongly related to the road surface characteristics, most notably to the pavement texture. Phenomena that occur at the tyre/road interface affect tyre friction (skid resistance), rolling resistance, tyre wear and tyre/road noise. This article deals with relationship between surface texture and rolling resistance of light and heavy vehicle tyres. Mean profile depth (MPD) is one of the most common descriptors of road surfaces and in many studies it is correlated with rolling resistance of tyres. Results of measurements performed by the Technical University of Gdańsk show that although the correlation exists, it is not very strong and regression between MPD and rolling resistance is not linear. The key reason for this is partial enveloping of the tyre tread interacting with pavement texture. The article presents results of laboratory and road measurements of rolling resistance performed on road surfaces characterised by MPD from 0.20 up to 4.75 mm and the correlation of the rolling resistance coefficient with MPD. Certain aspects of texture enveloping and influence of this phenomenon on rolling resistance are discussed.

Rolling resistance and tyre/road noise on rubberised asphalt pavement in Poland

The paper presents results of tyre/road noise and rolling resistance measurements performed on stone mastics asphalt (SMA) that contains rubberised asphalt, developed and produced by a refinery in Poland. Bituminous binder was modified with polymer and addition of crumb rubber. The first observations of asphalt mixture with the new kind of modified bitumen used on the field section are presented. Rolling resistance of passenger car tyres was measured by test trailer R2 Mk.2. Tyre/road noise was measured by a Tiresonic Mk.4 trailer using the close proximity method. Measurements were performed for 50 and 80 km/h and the results obtained on test and reference sections covered with conventional SMA 11 were compared.

Tyre rolling resistance and its influence on fuel consumption

Rolling resistance of tyres is one of the major resistive forces acting on any wheeled vehicle. Unfortunately, it is also one of the forces very difficult to measure. It is estimated that in certain traffic conditions (like for example constant speed driving with slow or moderate speed) so called Rolling Resistance Impact Factor may be as high as 0.3. This means that reduction of rolling resistance by 50% would lead to 15% of energy savings. The paper presents road measuring method of tyre rolling resistance and unique equipment used by the Technical University of Gdansk designed to perform measurements of passenger car tyres. It also discusses road pavement, tyre and environmental conditions influence on rolling resistance. Also selected data describing current situation related to rolling resistance on different road pavements and rolling resistance of modern passenger car tyres including tyres specially designed for electric and hybrid vehicles are presented.

Antimicrobal and ostheointegration activity of bone cement contains nanometals

Purpose: One of the major problems in bone surgery are infections – especially thoseoccurring in the course of the operating on the patients with lowered immunity system,because they carry the danger of complications. In the Mechanical Department of TechnicalUniversity of Gdansk, there has been carried the research with the use of bone cement andmetal nanoparticles.Design/methodology/approach: The bone cement was used without supplement orwith one or two drugs. These experiments are the latest, because include pure bone cement(without drugs) with nanometals. The titanium specimens was covering with such composecoating. The implant was inserted into rat`s thigh for six weeks. Afterwards the implantwas removed from the body and examined by means of scanning electron microscope.Simultanously biological research was carried out. Bonless samples were placed intobacterial liquid, generated by the researcher (the Patent number P 409082 ) containing fivemost frequently occurring bacteria in human body.Findings: Result of the SEM research was positive – there was good adhesion ofostheoblasts to the surface and there were no traces of infection.Practical implications: The research concerns bone cement with nanoparticles proves,that nanoparticles are the alternatives to antibiotics.