Abstract
The natural frequencies of the bar subjected to tensile or compression load varied in proportion to the magnitude of the axial stress. Vibration equation of a bar with fixed-end supports or with simple-end supports subjected to an axial stress was analyzed and theoretical relation between applied stress and natural frequency was obtained. A round bar with fixed-end supports or with simple-end supports was subjected to tensile or compression load and impacted by a small ball. By laser beam displacement detector, natural frequencies of the bar were measured by using the eigen deflection modes, and working stress in the bar was estimated by the natural frequencies. The relation between applied axial stress and natural frequency of the bar by the experiment and by the theory was compared. Eigen deflection modes may be one of effective and promising method to measure working stress in a bar subjected to an axial stress.
