• A 3D Finite Element Simulation of Ventilated Brake Disc Hot Spotting

      Tang, Jinghan; Bryant, David; Qi, Hong Sheng (2016-06-15)
      Hot spots are high temperature thermal gradients and localisations that are circumferentially distributed on a disc surface which can occur during heavy duty braking. Vibrations and noise can be triggered by hot spotting as well as damage to the disc surface. The experimental investigations suggest that the trigger condition and distribution of hot spots are related to the disc geometry, especially for ventilated discs. To investigate the effects of geometry and structure of a ventilated disc on hot spotting, a 3D finite element model was established. A fast simulation method of hot spotting in 3D was implemented in the model to enable a parametric analysis to be performed more efficiently. The results were validated using experimental data from a laboratory dynamometer.
    • Coupled CFD and FE Thermal Mechanical Simulation of Disc Brake

      Tang, Jinghan; Bryant, David; Qi, Hong Sheng (2014)
      To achieve a better solution of disc brake heat transfer problem under heavy duty applications, the accurate prediction of transient field of heat transfer coefficient is significant. Therefore, an appropriate coupling mechanism between flow field and temperature field is important to be considered. In this paper, a transient conjugate heat transfer co-simulation disc brake model has been presented in order to improve the accuracy and feasibility of conventional coupled FE and CFD method. To illustrate the possible utilizations of this co-simulation method, a parameter study has been performed e.g. geometric, material, and braking application. The results show the advantage of the co-simulation method in terms of computing time efficiency and accuracy for solving complex braking heat transfer problem.
    • FEM and CFD Co-simulation Study of a Ventilated Disc Brake Heat Transfer

      Tang, Jinghan; Qi, Hong Sheng (2013)
      This paper presents a two-way thermally-coupled FEM-CFD co-simulation method for ventilated brake disc rotor heat transfer analysis. Using a third party coupling interface for data mapping and exchange, the FEM and CFD models run simultaneously under a standard heavy duty braking test condition. By comparison with conventional one-way coupling methods and experimental results, the performance of the co-simulation system has been investigated in terms of prediction of the heat transfer coefficient (HTC) and disc temperatures as well as computing time used. The results illustrate that this co-simulation method has good capacity in providing cooling effect and temperature predictions. It also shows that the data exchange between the FEM and CFD codes at every time increment is highly accurate and efficient throughout 10 brake applications. It can be seen that the cosimulation method is more time efficient, convenient and robust compared to previous oneway coupling methods. To utilize the potential of this method, future works are proposed.
    • A Finite Element Simulation of Disc Brake Hot Band Migration

      Tang, Jinghan; Bryant, David; Qi, Hong Sheng (2015)
      The migration of hot banding is the phenomenon whereby hot bands or hot spots on the brake disc surface periodically migrate radially inward and outward. These migrations can cause the undesired brake torque variation (BTV) and further induce vibration problems such as brake judder. To investigate the forming and migration of hot banding problem, transient thermal mechanical finite element models of repetitive braking considering the effects of wear have been performed. The displacement, temperature, stress, and contact pressure distribution against time were obtained in this model. The thermal buckling, thermo-elastic instability (TEI) and hot band migration phenomena have been captured and investigated. The results suggest a cause-effect chain of radial hot band migration. Its determinants include mechanical loading, disc thermal buckling, and most importantly the transient interactions between TEI and wear.
    • A numerical investigation of hot spotting origin of ventilated disc brakes

      Tang, Jinghan; Bryant, David; Qi, Hong Sheng (2015)
      Hot spots are high thermal gradients on the disc surface during brake events which can cause the undesired phenomena of thermal judder and drone. The origin of hot spotting has been presented by various theories such as Thermo elastic instability (TEI) and progressive waviness distortions (PWD). However, majority of the numerical models based on these theories mainly concentrated on solid disc rather than ventilated disc which is the most commonly used nowadays. According to the experimental work done by the authors, disc geometry factors such as vents and pins also have correlations with hot spot distribution; these phenomena are difficult to be predicted analytically. Thus a convenient 2D asymmetric finite element simulation has been performed in order to obtain the correlations observed in experiments. Further parameter studies investigated factors such as uneven initial temperature, vents, pins and pad length. The results have been correlated with the experimental data and demonstrate the contribution of geometric factors in the generation of hot spots and hot judder.
    • Simplified three-dimensional finite element hot-spotting modelling of a pin-mounted vented brake disc: an investigation of hot-spotting determinants

      Tang, Jinghan; Bryant, David; Qi, Hong Sheng; Whiteside, Benjamin R.; Babenko, Maksims (2018-06)
      Hot spotting is a thermal localisation phenomenon in which multiple hot regions form on a brake disc surface during high energy and/or high speed braking events. As an undesired problem, hot spots can result in high order brake judder, audible drone and thermal cracking. This paper presents a finite element model for hot spot modelling which introduces the classical axisymmetric assumptions to the brake pad in 3D by scaling the material properties combined with a subroutine to simulate the heat generation instead of modelling the rotation of the brake pad. The results from the initial feasibility models showed significant improvement in computing efficiency with acceptable accuracy when compared to a traditional FE model without such simplifications. This method was then applied to the 3D simulation of hot spotting on a realistic ventilated brake disc/pad pair and the results showed good correlation with experiments. In order to improve the understanding of the hot spotting mechanism, parametric studies were performed including the effects of solid and ventilated disc geometry, rotational speed and energy, pins, disc run-out, and brake pad length. Based on the analysis of the results, it was identified that the vents and pins affected the hot spot distribution. Speed was shown to be more important on the hot spot generation time and distribution than either the pressure or total energy input. Brake disc run-out was shown to affect the magnitude of both hot spot temperature and height due to the non-linear relationship between local deformation, contact pressure and heat generation. Finally, increasing the brake pad length generated fewer hot spots but the temperature of each hot spot increased.