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This study aims to compare the friction and wear performance of commercial brake pads for four wheelers among metallic, semimetallic and non-asbestos organic (NAO) formulations to identify one with the right combination of properties for optimal performance.

Three commercially available brake pads for four-wheeler automotive applications were acquired. Samples were cut from the brake pads to study their physical and mechanical properties. The effects of friction and wear were analyzed using a pin-on-disk tribotester. Surface morphology on the worn-out surface of the brake pads was studied.

It was observed that the frictional properties remained stable and less fluctuating in the semimetallic and NAO pads, whereas the coefficient of friction of all the pads varied between 0.35 and 0.55. The wear rate of the metallic pads is less than that of NAO and semimetallic pads. The surface morphology studies revealed that the metallic pads contained more primary plateaus and smaller amounts of secondary plateaus compared to semimetallic and NAO pads, resulting in better wear resistance characteristics.

Because the market is flooded with various options for brake pad materials, it is imperative that the vehicle manufacturers choose the right pad material with great care not only to ensure the optimal functioning of the braking system but also passenger safety. Mechanical and tribological properties of brake pads contribute greatly to their effectiveness. There is a requirement to choose the proper material for a certain application that has a consistent friction coefficient and reduced wear.

The tenting of via holes has been a controversial issue in the military arena for several years. This issue has gained importance with MIL‐STD‐2000's requirement that all circuitry and vias under components be coated to preclude entrapment of flux. This paper addresses this issue by evaluating the MIL‐Spec thermal shock reliability of solder mask as a hole fill material and as a via tent cover. The relationship of via hole to pad size on tent reliability and solder mask thickness is also investigated. This paper concludes that solder mask as a hole fill material will not pass military thermal shock requirements and that standard dry film solder mask is very sensitive to via hole and pad dimensions. The thinner and more flexible high conformance solder mask is the only material capable of passing MIL‐Spec thermal shock requirements for all via hole to pad relationships.

To propose a solution procedure to minimize/eliminate tombstoning defects in small chip components with different micro via‐in pad designs for high density module assembly.

Four different micro via‐in pad designs were compared (via‐hole diameter): ultra small via‐in pads (10 μm), small via‐in pads (20 μm) and large via‐in pads (60 μm), as well as designs with no via‐in pads and capped via‐in pads. Two process variables were also evaluated for the goal of achieving a high‐yield assembly solution in micro via‐in pad and lead‐free solder conditions. Potential factors such as the preheat conditions of the reflow profile and stencil aperture size, which might affect tombstoning in components with micro via‐in pads, were investigated.

The results indicated that the micro via‐in pad design significantly increased the tombstoning; thus, tombstoning did not occur in components with both no via‐in pads and capped via‐in pads. Capped via‐in pads exhibited the best results in preventing tombstoning and provided a wide process window for the selection of process parameters. The results showed that tombstoning was found to decrease with both increasing stencil opening ratio and use of reflow profile with long‐preheat condition.

The paper's findings provide certain process guidelines for high density module assemblies with via‐in pad design. The strategy is to prevent tombstoning by adopting capped via‐in pad design if possible when employing micro via‐in pad technology.

The purpose of this paper is to investigate the friction coefficients of aramid and acrylic fibers on brake pads.

Fiber components used in the present pads are aramid and acrylic fibers, respectively, while keeping other components, such as binders, lubricants, abrasives, fillers the same. Disk FC25 and disk FC17 are used for rotor rubbing test to investigate the friction coefficients with brake pads. The pads are tested by 1/5 scale brake dynamometer, and test mode is modified JASO C406‐P1. The results are analyzed with the friction coefficient and the temperature, transfer film, roughness, and photomicrograph of worn surface on rotors.

The friction coefficient was mainly determined by the pad material rather than the rotor material, and pads made of aramid fiber had high‐friction coefficient, while pads made of acrylic fiber had low‐friction coefficient, especially under high temperature. Temperature change during braking process was directly related to the initial speed only, and was indifferent to materials or decelerations imposed. In the fade test, the reversal of friction coefficients between the aramid fiber and acrylic fiber pads is determined by the amount of remained amount of respective fiber above 520°C.

Effect of different fiber components, aramid and acrylic fibers, on friction characteristics of pad is sought. Reversal of friction coefficients is determined by the thermal stability of fibers used for pads.

This paper aims to design a new surface profile with simpler processing technology, which makes the bearing load carrying capacity (LCC) close to that of conventional tilting-pad thrust bearing.

The paper analyzes the LCC of the thrust pad with crown profile and designs a new profile, whose performance is similar to the crown profile. The laser method is introduced to fabricate the new profile. The profile with tiny crown height can be fabricated by the laser with the proper parameters.

It was found that there is an optimum value, which is best in terms of the capacity of tilting-pad thrust bearing reach. The new profile with proper parameters can replace the crown profile.

The new profile can replace the crown profile and is easier to be made. The new design method could be adopted for designing the pad surface profile of the tilting-pad thrust bearing.

This study aims to investigate the performance characteristics of an externally adjustable bearing with multiple pads in steady state conditions. The proposed adjustable bearing geometry can effectively control the hydrodynamic operation in bearing clearances by adjusting the pads in radial and tilt directions. These pad adjustments have a significant role in improving the bearing characteristics such as load capacity, attitude angle, side leakage, friction variable and Sommerfeld number, which will be analysed in this paper.

The adjustable bearing is designed with circumferentially spaced four bearing pads subjected to similar radial and tilt adjustments. Tilt angles are applied along the leading edges of bearing pads. A modified film thickness equation is used to incorporate the pad adjustments and accurately predict the variation in film profile. Finite difference approximation is adopted to solve the Reynolds equation and discretize the fluid film domain.

For negative radial and tilt adjustments, higher hydrodynamic pressures are generated in bearing clearances, which increases the bearing load capacity at different eccentricity ratios. From comparative analysis for different pad adjustments, superior bearing performance is observed for bearing pads under negative radial and negative tilt adjustments.

This research presents a detailed theoretical approach to analyse the performance capability of a four pad adjustable bearing geometry, which is not available in literatures. Improved bearing performances with negative pad adjustments can attract bearing designers to implement the proposed adjustability-bearing concept in rotating machineries.

This paper aims to present the theoretical and experimental investigation of the temperature of high speed and heavy haul tilting pad journal bearing.

The bearing is 152.15 mm in diameter with three slenderness ratios (L/D) and three clearance ratios. The equations that govern the flow and energy transport are solved by the finite difference method, and the experimental tests are conducted in a test rig of high speed and heavy haul tilting pad journal bearing. The shaft speed ranges from 3,000 to 16,500 r/min (the highest linear-velocity equals 131.4 m/s), and the three static loads are 10, 20 and 30 KN.

The comparisons between numerical results and experimental results show better correlations. It is shown in the theoretical and experimental results that the temperature increases with static load and shaft speed and decreases with clearance ratio and L/D.

The theoretical models presented in this paper can be used to predict the temperature of tilting pad journal bearing when the shaft’s linear velocity is up to 130 m/s.

Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This paper aims to simplify the calculation of the journal bearing performance, and to reduce the workload.

On the basis of previous research, a general performance calculation model of journal bearing is proposed in this paper. Eccentricity ratio and attitude angle of axis to each pad are calculated by coordinates of spindle center and each pad center by establishing the unified coordinate system. The surface deformation of journal bearing is taken into consideration, and a correction value is added to the dimensionless oil film thickness.

The performance calculation results of various fix-pad and tilting-pad journal bearings match the results of the existing references very well, revealing the validity of the model. The general model can greatly reduce programming workload, and increase adaptability to different bearings.

Geometric descriptions of both fix-pad and tilting-pad journal bearings are unified in this model, which can be applied to both standard and non-standard journal bearings with different preload ratios. In addition, due to the unification of different bearings types, this model is more conducive to performance comparison among different bearing types, and promotes the development of new structural forms for journal bearings.

Inductive power transfer (IPT) is a hands free user charging system, which allows the transfer of energy over a large air gap without physical contact. The purpose of this paper is to evaluate two magnetic coupling structures and its applicability to EVs charging systems.

A brief introduction of IPT systems is initially presented, with the characterization of the chosen resonant topologies, series uncompensated (SU) and series parallel (SP). The magnetic coupling structures (MCSs) are then investigated and the principal characteristics required for EVs applications are outlined. The circular and the DD magnetic coupling structures are chosen due to its inherent advantages and a description of both physical and electrical most important aspects are made. Finally, different simulation and experimental results are analyzed and discussed for both magnetic structures.

The SU topology is suitable for applications with low voltages sources at the cost of a more attuned control. The DD pad allows a higher power transfer when compared with the circular pad, with better efficiency for the same working conditions. The DD pad is more tolerant to misalignment in the axis y while the circular pad is independent of the misalignment direction. Both modeled pads can transfer at least 5 kW without saturating the core.

This paper analyzes and compares the power transfer capability, misalignment tolerance and core saturation levels of the selected pads.