Keywords: design optimisation, model updating, inverse processing, modal optimisation and cascaded targets
Reallocation of system mass and stiffness for achieving target specifications
The development of a system model involves the assemblage of many important components from a dynamic standpoint. The performance of the system is dependent on the dynamic characteristics of each of the components. In an attempt to improve the overall system characteristics, targets are typically specified at the system level. The determination of the component characteristics to achieve these targets are the purpose of this work. Using these targets, an inverse optimisation process can be utilised to determine the adjustment of the mass and stiffness of the system. However, the inverse process will smear the mass and stiffness over all the system degrees of freedom unless all the system equations are utilised in the inverse process or unless some constraints are applied to the set of equations. This smearing tends to confuse the proper mass and stiffness that are needed to achieve the design targets to meet the desired component dynamic characteristics. This work utilises analytical model improvement techniques along with localisation of model change procedures to determine the component target characteristics. As part of the procedure, the existing topology of the finite element model can be modified to restrict or allow additional elemental connectivities in the optimisation process.