Search Results

Disc brake noise is recognized as a major problem of the automotive industry. Various experimental and numerical techniques have been developed to model the noisy brake and investigate possible solutions. Developing a virtual model of the disc brake which can accurately reproduce the behavior of the brake unit under different conditions is a considerable step forward towards reaching this goal. Among various aspects of the analytical model of a disc brake, application of the correct value of damping based on the material properties and functional frequency range of each component is a significant factor in ensuring correct prediction of the brake system behavior. Complex Eigenvalue Analysis is well established as a tool for predicting brake instabilities which can potentially lead to brake noise. However, it is known to over-predict instabilities i.e. predict instabilities which do not occur in the real brake system.

Government regulations and consumer needs are driving automotive manufacturers to reduce vehicle energy consumption. However, this forms part of a complex landscape of regulation and customer needs. For instance, when reducing aerodynamic drag or vehicle weight for efficiency other important factors must be taken into account. This is seen in vehicle bonnet design. The bonnet is a large unsupported structure that is exposed to very high and often fluctuating aerodynamic loads, due to travelling in the wake of other vehicles. When travelling at high speed and in close proximity to other vehicles this unsteady aerodynamic loading can force the bonnet structure to vibrate, so-called “bonnet flutter”. A bonnet which is stiff enough to not flutter may be either too heavy for efficiency or insufficiently compliant to meet pedestrian safety requirements. On the other hand, a bonnet which flutters may be structurally compromised or undermine customer perceptions of vehicle quality.

Complex events such as a ballistic impact are influenced by number of parameters. Simulation of such events need a number of material parameters to be defined. These parameters are difficult to be quantified and considered in finite element analysis. Due to this, the physics of the event is not accurately captured in numerical simulation. Considering these parameters require extensive experimentation which incurs huge costs. Due to advances in the explicit finite element codes and material models, it is possible to determine these parameters by reducing the dependence on experiments. In this study, a method is depicted to determine Johnson-Cook material and failure model parameters. An example of a projectile hitting the armor plate is used to depict this method and to determine these material parameters for the target armor plate by performing a DOE study with minimal experimental test data.

Finite Element Analysis (FEA) is a numerical method to find solutions to real world problems and is now commonly used for product development. Various finite element analyses are performed to validate the system performance. Many finite element codes are also available for this purpose. Now-a-days, product development not only deals with the validation of design performance, but also focuses on design optimization. Methods such as one-factor-at-a-time (OFAT) experiments are generally used in which one input factor is varied at a time and its effect on system performance is studied. Design of Experiments (DOE) is a systematic approach in which more than one input factors are purposefully varied to study their effect on system performance. Finite Element Analysis and Design of Experiments approach can be used in combination for design optimization. This paper deals with the process for design optimization that can be followed using FEA and DOE in conjunction.

Dimensional distortion, cosmetic distortion issues can arise during heating and cooling in the paint shop processing of car bodies. A car body can be in perfect cosmetic condition as it leaves the BIW facility, yet develop distortion defects during painting. Traditionally such issues have only been detectable on new car body designs by building and painting prototypes of a new design. The timing of such activities, by their very nature, mean that precious little time is available to address these issues by design changes in today's condensed new vehicle programmes. The result is often a vehicle entering production with partial resolution of an issue, accompanied by on-going product rework and rectification activities throughout the lifecycle of the product. This created the need for developing a CAE simulation tool which could predict these issues very early during the virtual CAE build phases of a vehicle program itself.

The rotor and stator of electric motors consist of multiple materials, of which steel forms the majority of mass and volume. Steel in electric motors is commonly in the form of thin sheets (laminations), stacked along the axis of the rotor. The structural integrity of such a stack can be ensured using bolting, welding or bonding of the laminations. Predictive mechanical finite element simulations of these laminated stacks can become computationally intense because the steel sheets are thin, and the motor often contains hundreds of them. If the laminations are modelled individually, the size of the elements is very small compared to the overall dimensions and the interface between the laminations need to be modelled as well. In this paper, we present an alternate method of modelling this laminated stack as a single solid body using homogeneous and orthotropic material property, instead of representing each lamination.