Developments in tyre design for lower rolling resistance:a state of the art review

Future sustainability of road transportation will require substantial improvement in the efficient use of energy by road vehicles. As new technologies being deployed reduce total vehicle energy consumption, the contribution of tyre rolling resistance to total energy consumption continues to increase. For this reason tyre rolling-resistance is starting to drive the focus of many tyre developments nowadays. This is because the rolling-resistance can be responsible for 20–30% of the total vehicle fuel consumption. Thus, lowering the rolling-resistance would help to reduce the fuel consumption (i.e. CO2, NOx and hydrocarbon emissions) and hence improve the environment greatly given the large number of vehicles used globally. It is found that the primary source of the rolling-resistance is the tyre deformational behaviour (i.e. hysteresis damping) which can account for 80–95% of the total rolling-resistance. This paper reviews the state of the art in tyre design, research and development for lower rolling-resistance, with focus on the primary source for the rolling-resistance (i.e. mechanical hysteresis damping), from three perspectives: the structural lay-up; the dimensional features; and the materials compound(s) of the tyre. </jats:p

Computer aided engineering prediction of brake noise: modeling of brake shims

Brake shims, applied to brake pads, are used for suppressing high frequency noise in disc brake units. Also called brake insulators, they do this mainly by adding more damping to the system in the brake pad area. This reduces the likelihood of the energy transfer between the components which would cause modal coupling. Finite element analysis (FEA), as a simulation and analysis technique, is widely used in the industry to perform squeal analysis as a part of the virtual development of new brake units. However, in most computer aided engineering (CAE) simulations of brake noise, shims are modeled as thin sheets of steel or are not modeled at all. This introduces some inaccuracy because the damping effect and flexibility of the rubber and adhesive material are ignored. Such inaccuracy in predicting system behavior, in the virtual design stage, means the analyst may not be able to locate the right frequencies of any occurring instability in order to decide on a noise fix. Also, the over-prediction of instabilities by complex eigenvalue analysis (CEA) adds to the inaccuracy of the process. This paper introduces a simplified CAE model for the brake shim, which when implemented in brake system modeling helps in highlighting the actual frequencies at which instability occurs in the system by taking into account the correct level of damping in the system in the virtual design stage. The method is confirmed by correlating the analysis predictions with the noise performance of a brake unit in dynamometer tests. </jats:p

The effects of tyre material and structure properties on relaxation length using finite element method

This study investigates the influence of tyre structural layup and material properties on the relaxation length of a rolling tyre using finite element analysis. Relaxation length for rolling tyre under different operating conditions has been studied recently. However, the effects of tyre structural layup and material properties on relaxation length were ignored. In this present work, a finite element (FE) tyre model was built based on the material and geometry properties obtained from measurements of the tyre provided by a vehicle company. Rather than the common method (steady state rolling analysis) used for cornering behaviour simulations, ABAQUS/Explicit program was used for prediction of the cornering performance and relaxation length for a constant slip angle of the rolling tyre. Two different steer inputs were applied to the rolling tyre in terms of slip angle variation, namely step input and ramp input. The effects of various factors, including cross-section area, spacing, crown angle and strength of the tyre reinforcement cords, on relaxation length of the rolling tyre were investigated by numerical experiments using the design of experiment (DOE) method

Nutrients, Phytochemical, Antioxidant and Antimicrobial Analysis of Pterocarpus osun Stem Bark and Leaf for Their Nutritional, Medicinal Capacity

Plants play a crucial role in human well-being and health. They provide some of the essential nutrients that humans require as well as act as medications to alleviate and cure various health problems. The purpose of this study is to look into the nutritional value, mineral composition, and the overall contributions of Pterocarpus osun to human nutrition and health.&nbsp;The result of the proximate analysis showed that protein is 9.52% in stem bark and 13.63% in the leaf, while the crude fiber in the stem bark is 37.89% and 46.03%, in the leaf. Ash, 6.74% and 7.46% in the stem bark and leaf respectively while carbohydrate content is 15.37% (stem bark) and 3.26% (leaf). Alkaloids, flavonoids, terpenoids, steroids, and tannins were detected in both organs of the plant tested. The mineral elements present include Ca, Mn, Fe, Ni, Mg, Zn, Cr, Co, Cd, Sulphur, and phosphorus. The antioxidant effect compared favorably well with that of the ascorbic acid used as standard. The extracts were screened for antimicrobial activities using eleven human pathogens. Each of the extracts successfully killed six microbes.&nbsp