On alternative approaches to linearization and Morison's equation for waveforces

The limitations of the 'equivalent linearization' approach are discussed an d an alternative approach is advocated based on the idea of 'corresponding linear forms' which give unbiased estimates for the output quantity require d from an analysis. The application of the alternative approach is illustra ted by developing corresponding linear forms for Morison's equation applica ble to the estimation of extreme wave loading and the estimation of wave-in duced fatigue loading. These corresponding linear forms differ only in a li nearization factor and expressions for this are obtained for both cases. It is shown that the linearization factor varies not just with the nature of the output but also with the relative magnitudes of the drag and inertia te rms in Morison's equation. The application of the alternative approach to t he oscillatory motion of bodies is discussed briefly.