Videos from UKAN SIG-VA Vibro-Acoustics Masterclass 26, 28, 30 October 2020

Videos from UKAN SIG-VA Vibro-Acoustics Masterclass 26, 28, 30 October 2020

Posted by
Alex Shaida
Thu, 28/01/2021 - 12:05

 

This is a one-day course funded by the UK Acoustics Network on the underlying principles, recent developments and practical applications in structure-borne sound generation and propagation. Whilst the emphasis is on building acoustics, applications to vehicles, white goods and aircraft are included. The course focuses on demonstrations of practical measurements and simplified calculations of the active source quantities, and passive source and receiver quantities, required for estimates of structure-borne power into supporting structures. This power is required for estimates of the radiated sound in spaces remote from the spaces containing the sources. The course is primarily for practitioners, but is relevant to researchers seeking an introduction to this topic.

Below are the three videos recorded from the UKAN Masterclass:

 

Webinar 1.2 – Receiver Structures. Prediction and Measurement.

Receiver structures form an essential part of the acoustic envelope in our built environment. The built structures form the receiver which are exposed to many different sources. These can range from airborne, e.g. Traffic noise to structure borne e.g., plant equipment, gyms. The receiver plays an important role in maintaining the vibroacoustics and need to be considered for isolator selections. For structure-borne vibration, the propagation is complex and receiver mobility must be measured to make meaningful vibroacoustic predictions. Often, within the building acoustics industry, such measurements may be difficult due to logistical, instrumentation or background limitations.  In such cases, one may use infinite plate and beam mobility expressions for heavyweight (e.g. concrete/masonry) and lightweight (e.g. studwall) type receivers forming majority of built structures.  These expressions are useful as a first pass estimate when detailed modelling or in-situ measurements may not be possible. Using infinite receiver characteristics with source and any isolator data allows to make vibroacoustic predictions and isolator selections. Literature shows that such predictions are generally in line with measured mobilities within an accuracy range acceptable within building acoustics domain. The presentation covers these predictive approaches and some measurement considerations. Some real life measurement case studies are also presented to illustrate how infinite receiver mobilities align against measured mobilities.

 

 

Webinar 2.1 – Structure-borne Sources.

This presentation outlines some common types of structure-borne sources and refreshes earlier learning that such sources cannot be fully characterised by observational measurements on the receiving structure alone. Instead, structure-borne sources require active and passive properties to allow full-characterisation, which then allow use in a transferable manner. This presentation focuses on passive properties, specifically the source mobility, where the complexities in direct measurement or simulation are discussed. Despite the difficulties, it is shown that through some relatively simple mathematical expression, an average response can be approximated to good effect. This is demonstrated via a series of case-studies for a variety of source types. The response derived from these simplified expressions are compared to real-world measurement data and finite-element simulation studies, which serve to aid in the understanding of associated benefits such expressions may bring.

 

 

Webinar 3.2 – Back to reality.

In back to reality, we bring together aspects of our learning with a number of possible practical application scenarios for the viewer to consider, in addition to a selection of case studies, both of which serve to emphasise the various ways in which vibroacoustic problems can be approached in real-world scenarios. The presentation ends with a brief discussion on isolators and how traditional single degree of freedom theory can fall short when the intention is to provide full system response. Mobility concepts are presented, with an example illustrating the predictions finite-element simulation of a full assembly to that of a sub-structured version where only the independent mobilities are known .