Comparative Analysis of Temperature Fields in Railway Solid and Ventilated Brake Discs

A new approach to numerical simulation using the finite element method (FEM) for the rotational motion of discs for railway vehicle disc brake systems was proposed. For this purpose, spatial models of transient heating due to the friction of such systems with solid and ventilated discs were developed. The performed calculations and the results obtained allowed justification of the possibility of simplifying the shape of the ventilated brake disc through elimination of ventilation channels. This contributes to a significant reduction in computational time, without compromising the accuracy of the results. The spatial and temporal temperature distributions in the ventilated and the solid disc of the same mass were analyzed. The share of energy dissipated due to convection and thermal radiation to the environment in relation to the total work done during a single braking was investigated. The maximum temperature values found as a result of computer simulations were consistent with the corresponding experimental results.

Friction Stir Consolidation of Aluminum AA5052 Alloy Machining Wastes

The purpose of this paper is to develop aluminum AA5052 alloy solid disc from machining wastes via friction stir consolidation (FSC) process & optimize its parameters: die rotational speed, pre-compact aspect ratio and processing time for better performance characteristics. At first, the required dedicated tooling are designed and built for the specific process. Then, the solid discs are fabricated from aluminum AA5052 alloy machining chips through FSC process in which the experimental parameters considered are rotational speed (315, 400 and 500 rpm), pre-compact aspect ratio (25.4/7, 25.4/5 and 25.4/3) and processing time (30, 45 and 60 sec). Based on the experiment, the compressive strength, hardness and microstructure of the consolidated solid disc are evaluated. Taguchi’s L9 orthogonal array is used to analyze and optimize the process. The results revealed that solid disc is successfully fabricated using FSC process using dedicated tooling, and rotational speed (500 rpm), compact aspect ratio (25.4/3) and processing time (60 sec) are optimal FSC processing conditions. The microsturcture of the solid disk shows finer and fully recrystallized grains in axial cross section orientation of the disc particularly in the central region. Moreover, the results show, the compressive strength and hardness of the solid disc are comparable to that of forged or cast disc and suitable for most engineering structural applications.

High-Spatial-Resolution Position-Sensitive Plastic Scintillation Optical Fiber Bundle Detector

We fabricated a 5 m long position-sensitive plastic scintillation optical fiber (PSOF) bundle detector composed of a sensing probe, two photomultiplier tubes (PMTs), two fast amplifiers, and a digitizer. Seven PSOFs in a bundle were used as sensing probes to estimate the gamma-ray source position, and 60Co, an uncollimated solid-disc-type radioactive isotope, was used as a gamma-ray emitter. To improve on the spatial resolution of previous studies, the transit time spread (TTS) was reduced by using a high-timing-response PMT and a bundle type of multi-cladded PSOFs. Noise was filtered out of the data. In addition, the accuracy of the data was improved through cubic spline interpolation. We determined the measurement time and measured the full width at half maximum (FWHM) considering the spatial resolution. We obtained the best spatial resolution—compared to the results of earlier studies—using our proposed bundle detector. Moreover, the sensitivity of the PSOF bundle detector was evaluated at several positions in the sensing probe. Based on the results of this study, a position-sensitive PSOF bundle detector could be used to measure gamma-ray source positions accurately over a wide contaminated area and in a shorter period of time.

Thermo-Structural Analysis of Ventilated and Non – Ventilated Disc Brake using Different Materials.

Every year Automobile industry is evolving. Significant inventions and improvements are occurring day by day. One of the important inventions in an automobile industry is the braking system. Disc brakes are widely used for maintaining and controlling speed of the vehicle by hindering the rotation of the shaft or any mechanical member. Material selection and design are one of the important factors, which plays an important role in the dissipation of heat generated. This paper compares three different materials i.e. C/C-SiC ceramic, Titanium grade 5 alloy, Tungsten Carbide, with two of the popular designs i.e. Ventilated disc and Solid disc (non-ventilated disc)

Heat Dissipation from Stationary Passenger Car Brake Discs

The paper presents experimental investigation of the heat dissipation from stationary brake discs concentrated on four disc designs, a ventilated disc with radial vanes, two types of ventilated discs with curved vanes - a non-drilled and cross-drilled disc, and a solid disc. The experiments were conducted on a purpose built Thermal Spin Rig and provided repeatable and accurate temperature measurement and reliable prediction of the total, convective and radiative heat dissipation coefficients. The values obtained compare favourably with Computational Fluid Dynamics results for the ventilated disc with radial vanes and solid disc, though the differences were somewhat pronounced for the ventilated disc. The speeds of the hot air rising above the disc are under 1 m/s, hence too low to experimentally validate. However, the use of a smoke generator and suitable probe was very useful in qualitatively validating the flow patterns for all four disc designs. Convective heat transfer coefficients increase with temperature but the values are very low, typically between 3 and 5 W/m2K for the disc designs and temperature range analysed. As expected, from the four designs studied, the disc with radial vanes has highest convective heat dissipation coefficient and the solid disc the lowest, being about 30% inferior. Convective heat dissipation coefficient for the discs with curved vanes was about 20% lower than for the disc with radial vanes, with the cross drilled design showing marginal improvement at higher temperatures.

Troweling of Concrete Surfaces – Contemporary Methods

The paper presents an analysis of the process of troweling concrete surfaces using the disc power trowel machines. The quantitative parameter of the disc effect of the disc is its geometric efficiency Sg . The algorithm for calculation of geometric efficiency Sg by simulation method is presented. The analytical formulas for calculation of geometric efficiency Sg for the solid disc and the ring for uniform linear motion at constant rotational velocity are presented.The possibility of converting geometry of the working element to approximate geometry (in terms of geometric efficiency) with the form of concentric rings with center in the middle of the rotation of the disc is presented. The size of the ring was determined by a parameter called the filling factor w. This record allows to calculate the value of the geometric efficiency of the disc's effect by the analytical method as the sum of the geometric efficiency of all. The methodology of numerical calculation of the widths of overlapping of machining areas for neighboring disc tracks has been presented to ensure the highest homogeneity of machining. The adopted objective function to optimize the uniformity of machining is to minimize the index of standard deviation of the geometric efficiency εSg . The geometry of the real working elements most often used for troweling in the aspect of uniformity of machining was analyzed. The method of the optimization of geometry with the assumed kinematic parameters was indicated in order to obtain the best quality of surface machining.

Effect of Materials and Designs of Brake Rotor Discs on Factor of Safety and Displacement Assessed using Auto Desk Fusion360

Brake rotor is one of the top safety elements in many rotating machines and automobile. The temperature distribution in the rotor, the displacement of the rotor and factor of safety during braking are important parameters which will decide about the safety of vehicle and life of the brake rotor. It is very important to study the influence of materials and design on the factor of safety and displacement for better selection of materials and design of brake rotor discs. In this investigation, three designs of rotor namely a solid disc, a ventilated rotor disc with radial slots and a newly designed rotor consisting aero foil grooves and fins are used which are made of cast iron, titanium alloy and C/C-SiC dual matrices composite material. These discs are modeled in Autodesk Fusion 360. The mechanical behavior such as variation of factor of safety and displacement of the rotor discs are analyzed using Autodesk Fusion360. It is found that titanium alloy seems to provide better distribution of factor of safety in all the three designs of rotor discs. It also gives minimum displacement whereas cast iron rotor gives maximum displacement under the gradually applied static load.