The influence of crack propagation of the bended beam on propagation performace of vibration energy

Abstract

Possibilities of using the vibroacoustic diagnostic methods for monitoring condition of concrete pre-stressed structures have been researched by the Laboratory of Vibroacoustics, Faculty of Automobiles and Heavy Machinery Engineering. An active experiment was carried out in order to examine the relations between loading (up to damage) of a concrete beam and its vibrations. The research methodology has given an opportunity to assess the possible use of descriptors reflecting propagation of vibration energy for evaluating the stage of failure development or the level of crack propagation. The concept of these descriptors (measures) is based on variable in time energy of processes, proportional to the square of instantaneous value of amplitude. As another assumption of this simple equation is that the defined measures are inversly proportional to the force of impact, it results easy to process the descriptors on the basis of synchronically recorded time signals. The preliminary results have shown that the proposed method can be considered as a supplementary way of detecting damages at an early state of propagation. At the current, preliminary stage of research it can be said that the location of both the impact point and the accelerometer, as well as direction of measured vibrations of the object have proved to be important for diagnostic utility of detectors.