The optimal design for fatigue life using biological method

A methodology for structural shape optimization is presented. It can be applied to problems with fatigue life, as the design objective,. Initial cracks, of a user specified size, are automatically generated perpendicular to a (user) specified boundary. The software allows the rapid and accurate calculation of the fatigue life associated with each of the (user) specified cracks by using the new and simple method developed in [2] for estimating the stress intensity factor for cracks at a notch. These quantities are then used to determine the optimum shape. This method is ideal for use in structural optimisation as accurate results are obtained without the need to explicitly model a crack, i.e. it is only necessary to model the uncracked structure. This work confirms earlier findings that a stress optimized structure does not necessarily give the longest fatigue life. The importance of non destructive inspection (NDI) and the role it plays in determining optimum structural geometries is also revealed.