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Title: Prediction of impact sound transmission with heavy impact sources in heavyweight buildings
Author: Hirakawa, Susumu
ISNI:       0000 0004 7659 0764
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2018
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In heavyweight buildings, impact sound insulation from heavy impacts such as footsteps in bare feet, or children running and jumping can be a significant problem. Hence it is useful to be able to predict the Fast time-weighted maximum sound pressure level (Lp,Fmax) in a room due a transient impact on the floor above. This thesis extends an existing prediction model using Transient Statistical Energy Analysis (TSEA) to include the effect of a floating floor on top of the concrete base floor, and through comparison with measurements. Time-domain Finite Element Methods (FEM) have been used to incorporate the rubber ball (a heavy impact source) within the model and to investigate the accuracy of TSEA and measurement procedures in the low-frequency range. Experimental and lump parameter models have been used to investigate the structural dynamics of the rubber ball, and the blocked force on impact. Experimental determination of modal parameters identified the fundamental frequency in order to estimate the Young's modulus of the rubber for FEM models. A single degree-of-freedom (dof) model for the ball gave reasonable estimates of the blocked force but for modelling purposes more accurate data was needed from force plate measurements. An idealised floating floor was investigated using small mass-spring systems that would fit on top of a force plate for which experiments and two dof models indicated a single peak or a double peak in the time domain blocked force depending on whether the resilient material was soft or stiff respectively. To incorporate the effect of a floating floor on a heavyweight base floor in a TSEA model, an inverse approach to TSEA (ITSEA) has been developed. Using laboratory measurements this gives the normalised transient power input into the base floor for a heavy impact source impacting the floating floor. Experimental assessment of ITSEA was carried out in test laboratories using small mass-spring systems and a full-size floating floor which validated the approach to experimentally quantify transient power with ITSEA and incorporate this in TSEA to predict Lp,Fmax in a receiving room. FEM models were validated against measurements from which comparisons of TSEA and FEM at low-frequencies show sufficiently close agreement (i.e. < 2.5dB) to recommend that TSEA be used in design work due to its fast computation time. FEM was also used to investigate and suggest improvements to measurement procedures by using corner measurement positions of Lp,Fmax.
Supervisor: Hopkins, Carl ; Lee, P. J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral