Reliability of statistical energy analysis (SEA) models depends on good estimates of coupling loss factors (CLFs), modal densities, and damping loss factors. Statistical modal energy distribution analysis (SmEdA), a finite element based method to compute CLFs from uncoupled finite elements models of subsystems, is used to generate SEA CLF for general subsystems. This method is based on the basic SEA relations for coupled oscillators and on a dual modal formulation to describe the vibration of coupled subsystems. Previous works have demonstrated the use of the SmEdA method for structure-to-structure couplings. The current work extends the SmEdA process to structure-to-cavity couplings. The estimation of CLF using the SmEdA approach is compared, for a simple test case, to analytical results and a classical expression obtained with a wave approach. Results show good comparison with analytical results even below critical frequency, where the wave approach underestimates CLF. Finally, an industrial application has been carried out to demonstrate that the SmEdA approach can be used in the case of complex structures.

This paper is a discussion of the equivalence between rain-on-the-roof excitation, diffuse field and modal energy equipartition hypotheses when using statistical energy analysis (SEA). A first example of a simply supported plate is taken to quantify whether a field is diffuse or the energy is equally distributed among modes. It is shown that the field can be diffuse in a certain region of the frequency-damping domain with a single point force but without energy equipartition. For a rain-on-the-roof excitation, the energy becomes equally distributed, and the diffuse field is enforced in all regions. A second example of two plates coupled by a light spring is discussed. It is shown that in addition to previous conclusions, the power exchanged between plates agrees with the statistical prediction of SEA if and only if the field is diffuse. The special case of energy equipartition confirms this observation.

Statistical modal Energy distribution Analysis (SmEdA) can be used as an alternative to Statistical Energy Analysis for describing subsystems with low modal overlap. In its original form, SmEdA predicts the power flow exchanged between the resonant modes of different subsystems. In the case of sound transmission through a thin structure, it is well-known that the non resonant response of the structure plays a significant role in transmission below the critical frequency. In this paper, we present an extension of SmEdA that takes into account the contributions of the non resonant modes of a thin structure. The dual modal formulation (DMF) is used to describe the behaviour of two acoustic cavities separated by a thin structure, with prior knowledge of the modal basis of each subsystem. Condensation in the DMF equations is achieved on the amplitudes of the non resonant modes and a new coupling scheme between the resonant modes of the three subsystems is obtained after several simplifications. We show that the contribution of the non resonant panel mode results in coupling the cavity modes of stiffness type, characterised by the mode shapes of both the cavities and the structure. Comparisons with reference results demonstrate that the present approach can take into account the non resonant contributions of the structure in the evaluation of the transmission loss.

Self sensing techniques allow the use of a piezoelectric transducer simultaneously as an actuator and as a sensor. Such techniques are based on knowledge of the transducer behaviour and on measurements of electrical quantities, in particular voltage and charge. Past research work has mainly considered the linear behaviour of piezoelectric transducers, consequently restricting the operating driving voltages to low values. In this work a new self sensing technique is proposed which is able to perform self sensing reconstruction both at low and at high driving voltages. This technique, in fact, makes use of a hysteretic model to describe the nonlinear piezoelectric capacitance necessary for self sensing reconstruction. The capacitance can be measured and identified at the antiresonances of a vibrating structure with a good approximation. After providing a mathematical background to deal with the main aspects of self sensing, this technique is compared theoretically and experimentally to a typical linear one by using an aluminum plate with one bonded self sensing transducer and a positive position feedback (PPF) controller to verify the performance in self sensing based vibration control.

The forced response of the structure-water-filled cavity system is investigated from the Patch Transfer Functions method. In such a case, a poor convergence of the PTF method is observed when using standard mode expansion to build the cavity-PTF. To improve its convergence and maintain the advantages of substructuring, residual shapes are introduced in the cavity-PTF computation, which is the new material of this article. This technique is successfully applied on numerical examples, highlighting the interest of such an approach, especially in heavy fluid.