Virtual Point

This study focuses on quantifying road noise performance using complex power (structural) on the main body connection points of rear axle of an SUV. It shows how this quantity can be calculated using measured data. The power in mechanical systems is calculated by the product of forces and velocity. The compatibility of the forces/ body velocities are achieved by the application of the virtual point transformation.

Many OEMs use dedicated test bench setups for testing and developing of components separately from their vehicle platforms. Relating these results to full-vehicle assemblies is not immediately possible, because of the difference in boundary conditions and incompatibility between test bench and vehicle measurement points. This study focuses on the use of tire noise test benches in the engineering of full-vehicle NVH. We show how virtual points, easily obtained using DIRAC, ensure compatibility between various test assemblies.

Before performing a transfer path analysis (TPA), the engineer needs to think about the right modeling of the source’s interface with the receiver. In practice, the vibration transfer from the source to the receiver is often modeled with three translational forces in each connection point. Mechanically this corresponds to a ball joint connection, which cannot transfer any moments. This study compares different complexities of interface descriptions on the industrial example of an electro-magnetic roll control (ERC) in a passenger car.

Hydraulic testing machines can be used to obtain frequency dependent dynamic stiffnesses of rubber isolators in translational degrees of freedom (DoF). Alternatively, dynamic substructuring based methods can be used. Results of two substructuring methods will be compared to those from a hydraulic machine.

Due to the lack of masking noise from combustion engines in electric vehicles, the noise of auxiliary components is becoming a relevant topic. One of these components is the electric refrigerant compressor (ERC). This paper addresses the airborne sound transmission of the compressor, using the methods of component-based transfer path analysis (TPA).

Currently two ISO standards are proposed for source characterisation. In this paper it is shown how the different approaches can be derived and compared using the general framework for Transfer Path Analysis (TPA).

This paper presents a practical study on popular Experimental Dynamic Substructuring topics. A series of substructures is designed of such complexity to fit in right between “real life” structures and “academic” structures.

This paper presents a Transfer Path Analysis (TPA) method to predict the transmission of steering gear vibrations of BMW vehicles in a multi-kHz range. The blocked-force TPA concept is used.

Component-based Transfer Path Analysis allows us to analyse and predict vibration propagation between an active source and passive receiver structures. The forces that characterise the active source are determined using sensors placed on the connected passive substructure.

Sound and vibration have a defining influence on our perception of product quality. They are especially well-known aspects in the automotive industry. While traditional combustion engines are gradually getting replaced by hybrid or full-electric drive-lines, other electromechanical (so-called mechatronic) systems make their entrance. As a consequence, the sound experience shifts from low-frequent engine roar to high-frequent humming and whining – a yet unfamiliar experience that calls for redefinition of the soundscape. This thesis presents techniques that aim to implement measurements of structural dynamics and active vibration sources into development processes. This simulation is facilitated by use of Experimental Dynamic Substructuring: a methodology that determines structural dynamic aspects of complete products based on individually measured components.

Transfer Path Analysis (TPA) designates the family of test-based methodologies to study the transmission of mechanical vibrations. Since the first adaptation of electric network analogies in the field of mechanical engineering a century ago.

This paper presents a comparison of two component Transfer Path Analysis methods to predict the transmission of steering gear vibrations into the vehicle.

This paper presents a validation study of several experimental Frequency Based Substructuring (FBS) techniques that were developed recently. Advances in the techniques up to 2009 were already applied and validated using the rear axle differential – vehicle interaction as a test case.

Crucial in Dynamic Substructuring is the correct definition of the interfaces of the subsystems and the connectivity between them. Although this is straightforward practice for numerical finite element models, the experimental equivalent remains challenging.