This paper deals with the method in which the material damping of a hinged-hinged beam in terms of the mode of vibration can be expressed by loss factor. The loss factor expressing the material damping was obtained by B. J. Lazan using the stress-distribution function and the energy-absorption function. In Lazan's method, the stress-distribution function of a member was obtained on the basis of the quasistatic deformation of the member. Therefore, the stress-distribution function of the higher mode of vibration cannot be obtained. In this paper, the stress-distribution function is obtained from the dynamic deformation which is determined by analyzing undamped vibration of the beam and the material damping considering the mode of vibration is estimated by the loss factoer. As the result, it is become clear that the stress-distribution function is not dependent on the mode of vibration but on stress level, and the loss factor of stress state in the practice is the value in the range from 0. 004 to 0. 008
It is an essential feature in surface acoustic wave(SAW) device applications to know the propagation characteristics. In this paper, the characteristics of Rayleigh waves on LiTaO_3 are computed by changing arbitrarily both cut and propagation direction. The results are shown in a set of maps of equal velocity, equal power flow angle, equal electro-mechanical coupling constant and equal temperature coefficient of delay time. From these maps it is possible to know the characteristics of SAW propagation for every substrate with arbitrary cut and propagation direction. Therefore these maps are very useful for the selection of new substrate of LiTaO_3. Also the computed results of temperature coefficients for X-cut, Y-cut and Z-cut LiTaO_3 are compared with the reported experimental values, and these are in good agreement with each other.