Over the years, numerous studies have been conducted for the development of alternative materials for better performance of brake pads. With a huge selection of materials, automobile manufacturers must prioritize the performance standards, safety, cost and environmental factors of the brake pads. To improve the friction performance of brake pads, maintain customers comfort level and environment safety, design engineers test and verify the best materials to satisfy the federal performance standards. Raw materials of brake pads compose of different categories such as organic, semi metallic and low-metallic. Besides the difference in composition, these materials affect the brake pads in terms of friction properties, wear rates and noise levels. It is crucial for engineers and manufacturers to improve friction stability while minimizing vibration by manipulating the composition of different raw materials and additive materials. Automotive brake pads normally consist of numerous metallic and composite materials that are formed by hot compression which can result in various mechanical properties [14]. This research proposes to investigate different composition of metallic raw materials and how their frictional performance is affected under different environmental testing standards. This research investigates the frictional performance of six types of raw materials with different mechanical properties and morphology using a universal mechanical tester (Bruker UMT). This paper examines the overall friction performance, coefficient of friction and creep groan behavior of six different raw materials under different humidity levels. By scrutinizing the static and kinetic coefficient of friction(COF) at different humidity levels, humidity-induced friction instability at low speed is studied and presented in this paper. After performing friction tests for each material, it was concluded that the friction performance and kinetic coefficient of friction of the brake pad samples were drastically affected by longer exposure to humid air.

Driving with tyres not appropriate for the actual conditions can not only lead to accidents related to the tyres, but also cause detrimental effects on the environment via emission of rubber particles if the driving conditions are causing an unexpectedly high amount of tread wear. Estimating tyre performance in an online setting is therefore of interest, and the feasibility to estimate friction performance, velocity performance, and tread wear utilizing available information from the automotive grade sensors is investigated in this thesis. For the friction performance, a trend analysis is performed to investigate the correlation between tyre stiffness and friction potential. Given that there is a correlation, a model is derived based on the trend having a stiffness parameter as an input in order to predict the friction performance. Tendencies for a linear trend is shown, and a linear regression model is fitted to data and is evaluated by calculating a model fit and studying the residuals. Having a model fit of $80\%$, the precision of the expected values stemming from the proposed model is concluded to be fairly low, but still enough to roughly indicate the friction performance in winter conditions. A tread wear model that can estimate the amount of abrasive wear is also derived, and the proposed model only utilizes available information from the automotive grade sensors. Due to the model having a parameter that is assumed to be highly tyre specific, only a relative wear difference can be calculated. The model is evaluated in a simulation environment by its ability to indicate if a tyre is under the influence of a higher wear caused by a higher ambient temperature. The results indicates that the model is insufficient in an online setting and cannot accurately describe the phenomena of softer tyres having a larger amount of wear caused by a high ambient temperature compared to stiffer tyres. Lastly, a double lane change test (ISO 3888-2) is conducted to determine the critical velocity for cornering manoeuvres, which defines the velocity performance. The test was executed for six different sets of tyres, two of each type (winter, all-season, and summer). The approach to estimate the velocity performance in an online setting is analogue to that of the friction performance, and a trend analysis is performed to investigate the correlation between longitudinal tyre stiffness and the critical velocity. The results are rather unexpected and shows no substantial differences in velocity performance, even though the tyre-road grip felt distinctively worse for the softer tyres according to the driver. It is concluded that the bias stemming from the professional driver's skills might have distorted the results, and that another approach might need to be considered in order to estimate this performance.