The Effect of a Damping Compound on Jet‐Efflux Excited Vibrations: An Article in Two Parts Presenting Theory and Results of Experimental Investigation

The modes of fuselage vibration that could be excited by jet‐efflux pressure fields are first discussed, and consideration is given to (he initial acoustic and structural damping of the modes. A simplified theory is presented for the acoustic damping of flat (or nearly flat) panels set in a much larger body, such as a fuselage. Using the results of Part I, an estimate is then made of the effect of Aquaplas damping compound on the vibration stresses, amplitudes and rivet loads of a structure subjected to random jet‐efflux excitation. It is assumed that the structure and the damping compound together constitute a linear system. In the two particular cases considered, the maximum possible reduction of rivet load is found to be about 40 per cent and 70 per cent respectively, and it is concluded that this is insufficient to outweigh the possible adverse effects of certain factors which cannot be introduced into a simplified investigation.