| In recent years, the technique of structural intensity has been an efficient means of solving sound and vibration problems. As a tool of diagnosing defect and identifying the source of vibration, it can judge the magnitude of structural intensity and make out the main route of vibration transmission. In consideration of the direct relationship between structural intensity and vibration, active control that took structural intensity as cost function was developed in the late 1980s.Based on the theory of elasticity mechanics, structural intensity formula for beams is deduced in this paper. Taking structural intensity as cost function, we study the active control of infinite beam and non-homogeneous beam and present the result of active control under the condition of different location of error sensors and different distance between control force and primary force in the beam. At the same time, we compare the result of active control that take structural intensity and displacement as cost function respectively, and conclude that the first kind of method is more efficient. When using structural intensity as cost function, a control strategy expressing the relationship between control force and primary force is presented.Error sensor is the main part of active control system, and the whole active control efficiency depends much on the message measured by error sensors. Therefore, getting exact measured message is very important. It is well-known that traditional acceleration transducers method has some default when measuring structural intensity. So, PVDF film, a new material of piezoelectrical macromolecule is brought up. According to its integral characteristic, particular shaped PVDF sensors are designed and the finite difference error in the result can be avoided by using them. Finally, an experiment that compares the two kind of methods is done,and conclusion that: PVDF sensors is feasible to measure structural intensity.
|
PDF Full Text Request