Dynamic Substructuring

An exciting new development is the mixed indicator Blocked Force determination, which uses both acceleration-based measurements and force gauges as indicators for the Blocked Force calculation. This study focuses on comparing the acceleration-based in-situ and new mixed indicator Blocked Force determination methods using measurements of an artificially excited electric power steering (EPS). 

This thesis is the result of a 4-year collaboration between the Technical University of Munich and the BMW Group. The goal was to apply substructuring methods to the Noise Vibration Harshness (NVH) engineering needed for integrating electric climate compressors in upcoming vehicles. Specifically, the aim was to simulate the compressor noise in the cabin for different, virtual design variants of the isolation concept. Therefore, the methods from two broader fields were applied: First, the excitation of the compressor was modeled with component transfer path analysis (TPA) methods. Second, the full transfer path from the compressor to the driver’s ear is assembled from multiple subcomponent models, via dynamic substructuring (DS).

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.

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 page provides an accessible overview of Dynamic Structuring, the interface conditions required and the applications of Dynamic Substructuring in different domains

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.

This thesis deals with new methods, which can determine the dynamic response of a complex system identified in operation, based on the knowledge of its subsystem dynamics and excitation.

In this paper a vision on substructuring methods is proposed, by recalling important historical milestones that allow us to understand substructuring as a domain decomposition concept.