Building standards incorporating quantitative acoustical criteria to ensure adequate sound insulation are now being implemented. Engineers are making great efforts to design acoustically efficient double-wall structures. Accordingly, efficient simulation models to predict the acoustic insulation of double-leaf wall structures are needed. This paper presents the development of a numerical tool that can predict the frequency dependent sound reduction index R of stud based double-leaf walls at one-third-octave band frequency range. A fully vibro-acoustic 3D model consisting of two rooms partitioned using a double-leaf wall, considering the structure and acoustic fluid coupling incorporating the existing fluid and structural solvers are presented. The validity of the finite element (FE) model is assessed by comparison with experimental test results carried out in a certified laboratory. Accurate representation of the structural damping matrix to effectively predict the R values are studied. The possibilities of minimising the simulation time using a frequency dependent mesh model was also investigated. The FEA model presented in this work is capable of predicting the weighted sound reduction index Rw along with A-weighted pink noise C and A-weighted urban noise Ctr within an error of 1 dB. The model developed can also be used to analyse the acoustically induced frequency dependent geometrical behaviour of the double-leaf wall components to optimise them for best acoustic performance. The FE modelling procedure reported in this paper can be extended to other building components undergoing fluid–structure interaction (FSI) to evaluate their acoustic insulation

Experimental and finite element (FE) plastic load results of cracked piping elbows under opening in-plane bending are presented and compared with data from similar defect-free components. The elbows used were short-radius components with an outside diameter of 88.9 mm and thickness 5.49 mm. Axial (at the crown) and circumferential (at the intrados) blunt crack-like defects were produced using electric discharge machining (EDM) procedures. Both short (è 218 axial or 2â 468 circumferential) and long (è 758 axial or 2â 1208 circumferential) defects were investigated with three depth±thickness ratios a=t 0:5, 0.75 and 1.0. The FE simulations employed the measured true stress±strain properties for the elbow material and included geometric non-linear behaviour.The results obtained show that piping elbows under opening bending can tolerate substantial defects, with reductions in plastic loads compared with the defect-free component of the order of 15 per cent or less in most cases, except when the defect is through-wall and circumferential and covers an angle 2â 1208 or more, in which case the reduction in plastic load can be as high as 40 per cent.

Finite element analyses of cracked short-radius piping elbows are reported. Both axial and circumferential cracks, centred about the bend crown or intrados respectively, are considered. The defects are internal, with depth±thickness ratios a=t in the range 0:25 < a=t < 1:0. Since the aim is to assess limit loads, the analysis assumes elastic±perfectly plastic material behaviour with no geometric non-linearities. The loadings considered are (a) opening bending moment, (b) internal pressure and (c) combined loading of steady pressure, set at the design value of the pipe elbow, with a superimposed monotonically increasing opening bending moment.For each type of loading, the general component behaviour, by consideration of the global deformation with increasing load, is reported. Limit load values for each case are presented and the relative reductions in load-carrying capacity, compared with that predicted for a defect free elbow of the same material and dimensions, are given. NOTATION a crack depth A, n constants bradius ratio R=r m D o pipe outside diameter h bend characteristic tR=r 2 m K r measure of proximity to failure by linear elastic fracture mechanics L r measure of proximity to plastic limit load failure m normalized moment for an uncracked pipe M=4S y r 2 m t M moment M L limit moment of elbow M S limit moment of straight pipe p normalized pressure for an uncracked pipe Pr m =S y t P pressure P d design pressure P L limit pressure for an elbow P S limit pressure for a straight pipe r m pipe mean radius r ml

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