Exposure to noise constitutes a health risk. The present paper is related to activities performed to test emerging technologies aimed to characterise noise sources. In particular, acoustic acquisitions have been achieved on a complex laboratory equipment composed by different machines including a rotor serving as blower. Advanced noise measurement techniques based on acoustic holography and beamforming have been employed to realise a deep characterisation of the noise sources. This analysis could fix, in effective way, the possible mitigation strategies and, if extended to the other noise sources, a comprehensive management of the workplace noise exposure.

This paper presents a new approach to evaluating the mistuning effects on turbomachinery blades that is classified as neither deterministic nor statistical — it is based on the employment of genetic algorithms. A genetic algorithm has been exploited to find the structurally mistuned configuration that leads to the maximum value of blade vibration amplitude for an assigned domain of variations. A test case has been fixed and subjected to an assigned forcing field; the target of the test case was to perform a smart search of the worst mistuned configuration. The test case was a twenty-blade disc on which one thousand forced frequency response analyses have been performed. A comparison with the results, based on the Monte Carlo methods, proved the suitability and the relevance of the proposed approach. The investigation has demonstrated the applicability of this new possible engineering approach to the study of systems with uncertain properties.

In this paper a simple approach based on the Carlson's method will be presented to define a supersonic conguration optimized in terms of sonic boom properties. The Carlson's method provides a simplified procedure for the calculation of sonic boom characteristics for supersonic airplane congurations and spacecrafts. The information required for the signature predictions are: aircraft shape factor KS, aircraft operating conditions and atmospheric data. Unfortunately, there is not an analytic expression of the shape factor. Nevertheless, a graphic representing the relationship between KS and parameters related to the aircraft geometry, can be used. In this paper KS have been approximated through a linear and a quadratic interpolation as a function of other parameters and its minimization problem has been formulated. Computational results show the optimal values to be assigned to the aircraft geometry parameters in order to obtain the minimal value of the shape factor and in consequence of the sonic boom overpressure.

The structural behaviour of bolted joints of composite laminates for aerospace applications was modelled comparing the shape, amplitude and phase of stress–strain cycles. This study proposes a model for the bolted joints resulting in a typical load–displacement curve, under cyclic loading, significantly affected by hysteretic effects. From the data gathered through the experimental activities, a constitutive relationship between strain and stress was proposed, starting from simple physical models. The assumption of a rigid shift between the laminates was used to correlate load and displacement curves in the different phases of the load cycle. The hysteretic behaviour was attributed to friction phenomena and interpreted using damping coefficients characterizing the global dynamic response of the structural joint.

Non-Destructive Testing of aircraft structures is of paramount relevance leading to key information regarding the structural characteristics and the residual life of a component. This paper is focused on the experimental and modeling activities related to vibrational analysis carried out on a typical aeronautical composite sample. A flap section of a regional aircraft has been studied applying the conventional tools of the modal analysis. The aeronautical component has been at first characterized in terms of natural frequencies and normal modes. Then it has been damaged using a drop tower that induced a controlled impact in the structural component. The vibrational analyses have been repeated and the normal modes in the two conditions have been compared. Then other approaches based on vibrational properties of the structures have been investigated to detect defect and damage.