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Abstract: The commercial automotive mufflers are generally of a complicated shape with multiply connected parts and complex acoustic elements. The analysis of such complex mufflers has always been a great challenge. In this paper, an Integrated Transfer Matrix method has been developed to analyze complex mufflers. Integrated transfer matrix relates the state variables across the entire cross-section of the muffler shell, as one moves along the axis of the muffler, and can be partitioned appropriately in order to relate the state variables of different tubes constituting the cross-section. The paper presents a generalized one-dimensional (1-D) approach, using the transfer matrices of simple acoustic elements, which are available from the literature. The present approach is robust and flexible owing to its capability to construct an overall matrix of the muffler with the transfer matrices of individual acoustic elements and boundary conditions, which can then be used to evaluate the transmission loss, insertion loss, etc. Results from the present approach have been validated through comparisons with the available experimental and three-dimensional finite element method (FEM) based results. The results show good agreement with both measurements and FEM analysis up to the cut-off frequency. [Copyright &y& Elsevier]

Abstract: This paper proposes a hybrid method for the prediction of vibrational and acoustic responses of low-damping system in the medium-to-high frequency ranges by using the power flow analysis (PFA) algorithm and statistical energy analysis (SEA) coupling concepts. The main part of this method is the application of the coupling loss factor (CLF) of SEA to the boundary condition of PFA in reverberant system. First, for hybrid PFA, the hybrid boundary conditions on 1-D and 2-D cases were derived in the general form. To verify the derived boundary conditions, numerical analyses for each case were performed. The hybrid PFA solutions using derived boundary conditions were compared with the classical PFA solutions with various reverberance factors including the effects of the characteristic length, excitation frequency and group velocity besides damping loss factor of the subsystem. Additionally, the hybrid PFA on 3-D case and the hybrid power flow finite element method (PFFEM) for hybrid PFA of built-up structures are described in the other companion paper. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental procedure for the axial load identification of slender prismatic beams with unknown boundary conditions by making use of one vibration frequency and of five amplitudes of the corresponding mode shape. In fact, this method does not require the knowledge of the effective length of the beam under examination, but only the flexural rigidity and mass per unit length. The proposed algorithm was verified by means of many numerical and experimental tests on tie-rods having different boundary conditions. Excellent estimates of the axial forces were obtained. Finally, the influence of the location of the instrumented sections on the estimation of the axial load was analyzed using a simply supported beam model. [Copyright &y& Elsevier]

Abstract: In this paper the transverse vibration characteristics of piezoceramic rectangular plates, with completely free and completely clamped boundary conditions, are investigated by theoretical analysis, experimental measurement, and numerical calculation. Using Ritz''s method together with the equivalent material constants carries out the theoretical evaluations for resonant frequencies. Two optical techniques, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), based on the displacement measurement are employed to determine the transverse vibration modes. In addition, the impedance analyzer is also used to measure the electrical impedance variation. From the experimental results, it is found that the transverse vibration modes cannot be obtained by impedance analysis for the completely free piezoceramic plate; however, certain modes can be unexpectedly measured for the completely clamped piezoceramic plate owing to the imperfect boundary simulation in experiments. Numerical calculations using the finite element method (FEM) are performed and good agreement is obtained when comparing the theoretical analysis and experimental measurements. According to the theoretical analysis, frequency parameter versus equivalent Poisson''s ratios ranging from 0.25 to 0.6 with different aspect ratios and material types are also presented for the first three transverse modes. [Copyright &y& Elsevier]

Abstract: In this paper, the dynamic analysis of 3-D composite beam elements restrained at their edges by the most general boundary conditions and subjected in arbitrarily distributed dynamic loading is presented. For the solution of the problem at hand, a boundary element method is developed for the construction of the 14×14 stiffness matrix and the nodal load vector of a member of an arbitrarily shaped composite cross section, taking into account both torsional warping and shear deformation effects, which together with the corresponding mass and damping matrices lead to the formulation of the equation of motion. To account for shear deformations, the concept of shear deformation coefficients is used, defining these factors using a strain energy approach. Eight boundary value problems with respect to the variable along the bar angle of twist, to the primary warping function, to a fictitious function, to the beam transverse and longitudinal displacements and to two stress functions are formulated and solved employing a pure BEM approach. Both free and forced vibrations are considered, taking also into account effects of transverse, longitudinal, rotatory, torsional and warping inertia and damping resistance. Numerical examples are presented to illustrate the method and demonstrate its efficiency and accuracy. [Copyright &y& Elsevier]

This paper derives a new class of modal decompositions of Somigliana's identities for a certain class of problems displaying symmetry and uniformity such as, for instance, elastic vibration problems including the effect of fluid loading. The decompositions are shown to lead to a number of new analytical results relating to homogeneous and inhomogeneous boundary value problems in whichever realm of physics, for example, free and forced vibration problems in a bounded domain, and also to unify many known results which have previously been obtained by other methods. At every stage, the mathematical analysis is shown to correspond to physical concepts relating to standing waves, transmission of energy and bi-orthogonality. Details are given for a number of examples in elastodynamics and vibro-acoustics, of which the fluid-loaded membrane provides particularly clear demonstrations of the power of the method in a non-trivial setting. • Bi-orthogonality is used to solve boundary value problems in linear dynamics. • Boundary Integral Equations are converted to simple boundary identities. • A novel modal projection technique is used to handle boundary conditions. • Analytical solutions are found for certain sets of boundary conditions. [ABSTRACT FROM AUTHOR]