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In the project, domestic ventilation concepts with PushPull-Fans were investigated. These ventilation units are characterized by a periodically changing supply and exhaust air operation. To ensure balanced operation, these ventilation units are always used in pairs, with one unit being in the exhaust air mode and the other in supply air mode. Measurements were made in a research apartment. The results were used to validate a CFD simulation model for transient studies. A room-by-room layout with two units in one room and a cross-room ventilation layout with two connected units in two rooms were analysed. The age of air was used as the evaluation parameter. With the room-by-room ventilation layout a lower age of air in the bedroom compared to the cross-room layout was obtained. However, in the room-by-room layout, the air flow through the larger living room with connected corridor was poorer in the rear area. With the cross-room layout, the flow through the rooms was more uniform. With the cross-room layout, the average age of air in the apartment could be slightly reduced compared to the room-by-room layout.
A trend towards lightweight structures, e.g. timber structures, is noticeable in civil engineering, which implies the necessity to predict vibroacoustic characteristics like the transmission of structure-borne sound in order to fulfil requirements regarding serviceability. This contribution focuses on the investigation of junctions of building components e.g. between wall and ceiling. It is part of a joint research project with the aim to catalogue the coupling for a variety of junctions. The resulting database may serve to predict the transmission of structure-borne sound which is typically carried out either using a Finite Element (FEM) approach, suitable for the low frequency range, or by means of energy methods like the Statistical Energy Analysis (SEA) for the high frequency range. Therefore the so-called mid frequency gap emerges, which is examined and attempted to be closed. In this context SEA-averaging techniques are applied in the postprocessing of FEM calculations to obtain an adapted “SEAlike” approach. By varying the subsystems to be excited it is possible to determine Energy Influence Coefficients (EIC), which describe the specific energy content of the different subsystems with respect to the input power. Using this hybrid approach vibroacoustic predictions can be performed also in the mid frequency range. Inverting the EIC-matrix Coupling Loss Factors as well as Damping Loss Factors of the different subsystems can be calculated if the subsystem definition fulfils the SEA-requirements. The application of the method in combination to a classical SEA calculation and to laboratory measurements is presented.
Es wurden Stoßstellendämm-Maße Kij für verschiedene Bauteilverbindungen von BSPH-Elementen gemessen. Diese zeigen eine gute Übereinstimmung zu anderen Werten aus der Literatur.
Bei den Stoßstellen wurde der Einfluss von Elastomerlagern untersucht.
Die Ergebnisse zeigen einen deutlichen Einfluss auf die Kij. Eine Berechnung der Kij mithilfe von Kopplungsverlustfaktoren ηij, welche aus einem SEAModell resultieren, zeigen eine ausreichende Übereinstimmung.
Weitere Schritte der Modellierung zur Überprüfung dieser Erkenntnisse und zur Abbildung von Elastomeren sind notwendig. Der Beitrag ist Teil des gemeinsam von der TU München, der HS Rosenheim und dem ift Rosenheim durchgeführten DFG-AiF Forschungsvorhabens Vibroakustik im Planungsprozess für Holzbauten.
Das IGF-Vorhaben 17328 N/1 der Forschungsvereinigung HS Rosenheim wurde über die AiF im Rahmen des Programms zur Förderung der Industriellen Gemeinschaftsforschung (IGF) vom Bundesministerium für Wirtschaft und Energie aufgrund eines Beschlusses des Deutschen Bundestages gefördert.
Within the scope of the research project "VibWood", operational vibration analyses of timber floor constructions were carried out. In order to understand the vibration behaviour of and the sound transmission through the layers of the constructions the coupling between them was investigated. The transfer function from the point of excitation to a pattern of receiving positions located on each of the layers of the construction was measured using a swept sine excitation. As a result, the frequency range of decoupling between the base floor and the floating floor and between the base floor and the suspended ceiling could be identified and the individual vibration behavior analyzed. The measurements also included the radiated sound power from the suspended ceiling. There is indication that there is not necessarily a correlation between the eigenmodes of the suspended ceiling and the maxima of the radiated sound power
Im Rahmen des AIF-Forschungsprojektes VibWood werden im Deckenprüfstand der HS Rosenheim unterschiedliche Holzdeckenkonstruktionen hinsichtlich ihres Schwingungsverhaltens im Bereich zwischen 4 Hz und 200 Hz untersucht. Parallel dazu werden diese Holzdeckenkonstruktionen an der TU München mittels FE-Berechnungen modelliert. Für die Untersuchungen steht ein Prüfstand zur Verfügung, welcher die Möglichkeit bietet, Decken oder Deckenelemente mit Abmessungen von max. 5,5 m x 5,5 m auf einer Stahlwinkelkonsole aufzulagern. Die Deckenelemente können so durch Messung der Übertragungsfunktionen hinsichtlich ihrer Schwingungsformen untersucht werden. Ein Ziel der Untersuchungen ist es, die tieffrequenten Schwingungen von Holzdecken mit Hilfe von Schwingungstilgern deutlich zu reduzieren. Es werden erste Ergebnisse der Validierung der FE-Modelle vorgestellt, insbesondere der Einfluss der Auflagerung der Deckenelemente auf die Übertragungsfunktion. Weiterhin werden Messergebnisse für unterschiedliche Anregungsarten diskutiert
Experimental investigations on the sound transmission of drywall constructions at low frequencies
(2009)
It is common for timber ceiling constructions to include a suspended ceilings made of plasterboard. In order to minimize the radiation from impact excitation, especially in the low frequency range below 100 Hz, a detailed analysis of the vibration behaviour was necessary.
An experimental modal analysis was carried out and the radiated sound power from the suspended ceiling was measured using a sweep sine excitation by a shaker connected to the top layer of the timber floor construction.
Since the experimental modal analysis was conducted using a high frequency resolution and with a non-stationary sound field, it was necessary to check the validity of the intensity measurements by comparing it with 1/3-octave band measurements. The results show very good agreement.
By this means the radiation efficiency can be measured simultaneously with an experimental modal analysis of a structure.
The multi-disciplinary research project “Vibroacoustic analysis in the planning process of timber constructions“ carried out in cooperation between the University of Applied Sciences Rosenheim, the ift Rosenheim and the Technical University Munich is a comprehensive study of direct as well as flanking structure-borne and airborne sound insulation of Cross Laminated Timber (CLT) elements and their junctions.
The aim is to optimize and simplify the acoustical planning process of wooden multi-storey buildings and thereby to contribute to the increase growth of timber construction industry in Europe. For a prediction of the acoustical performance of solid wood constructions, the vibration reduction index Kij is needed.
The vibration reduction index can be determined i.a. of the direction-averaged junction velocity level difference and the structural reverberation time. Both quantities need to be measured according to EN ISO 10848.
Alternatively, vibration reduction indices for a T- or cross-junction can be derived following the procedures described in prEN ISO 12354-1:2016. However, further knowledge and data of the sound transmission across junctions of CLT is inevitable for a reliable prediction.
In this paper a collection of frequency dependent vibration reduction indices for CLT structures will be presented and compared, involving L-, T- and cross-junctions measured by six international laboratories.