CALCULATION OF BENDING VIBRATIONS IN SHIPS' LINE-SHAFTING

In their introduction, the Authors mention that calculation of bending vibration in ships' shafting is a problem of finding input values rather than a computation problem. Factors that influence the result of bending-vibration calculations are then discussed; they include propeller thrust, mass, point of support in stern tube, and shaft and bearing stiffness. Prediction of stiffness by calculation, by experimental investigation and by dimensionless diagrams is discussed in further detail. A three-stage method for calculating bending vibration in ships' shafting is presented. There is a pre-design stage, a design stage, and a third stage which is required when it is seen that there is a danger of resonance and a consequent need for calculating the natural frequency as accurately as possible. If it is found that the natural frequency has to be shifted, this can be done in several ways; these are discussed.