Papers by Keyword: Impact Position

Abstract: Damage behavior of composite stiffened plates of structure I and structure II at different positions and under different impact energy subjected to low-velocity impact testing was studied in this paper. Visual observation and ultrasonic C-scanning were also employed to inspect the damage size. The results showed that damage behavior of composite stiffened plates was not only related to damage behavior of laminates, but also related to damage between stringer and laminate and damage of stringer itself. It was found that the mechanism of absorbing energy varies with the impact position, as well as the damage behavior. When the impact position was near stringer, partial energy was absorbed by stringer to make stringer and laminate disengage and damage area of laminates was smaller. Damage behavior of composite stiffened plates varies with the structure. Damage area of samples of structure II was smaller than that of samples of structure I. It was estimated preliminarily that design of structure II was better than that of structure I.

Abstract: This study is to forecast the impact force and impact position of free over-fall flow in the downstream by using artificial neuron networks (ANN). A simulation procedure for the ANN algorithm was established to train and validate numerical samples with the experimental data. The outcomes of simulation show the ANN method can properly estimate the impact force and position.

Abstract: In mechanical structures, the impact force is related to the structural damage. To identify the location where impact force occurs, the triangle method has long been used. This method requires three acceleration signals or strain signals to be measured on the mechanical structure. Time delay among these signals is useful information to estimate the location of the impact force. It is very difficult to estimate time delay by using the raw data of three signals because the propagation wave of the structure is a dispersive wave. Therefore, three signals should be analyzed in the time and frequency domain in order to estimate the time delay at each frequency. For the time-frequency analysis of highly non-stationary signals like impulse signals, time-frequency methods or time scale methods have been used. These methods use the first or second order statistical characteristics of the signal. This paper outlines the higher order Wigner method to obtain time and frequency information of a signal. Since it uses the high order statistics of signals, this method is useful for identifying the impact signal embedded in the background. It has a better time-frequency resolution for a non-linear signal than other time-frequency and time scale methods. This method can be applied to estimate the location of an impact force, which becomes a cause of damage of mechanical plants. Finally, in order to prove this method, experimental work was conducted on an aluminum plate in the laboratory.