The stress in riveted panels subjected to acoustic loading can be reduced in magnitude by reinforcement of the edges of the panels. The benefit from the reinforced edges or doublers has been directly confirmed by tests carried out by Koenig et al on coupons made from aluminium alloy which were subjected to simulated acoustic loading. Tests on a titanium alloy coupon with a reinforcement indicated a similar reduction in stress. A method for estimating the stress reduction in riveted panels from reinforcement is provided by ESDU 67029. According to a numerical investigation by Koenig et al, the stress reduction indicated by ESDU 67029 is overestimated and, consequently, the fatigue life predicted would be less. Both the ESDU method and that of Koenig et al are discussed in the Memorandum.