Health monitoring anaylsis of cracked plate based on static deflection and natural frequencies

Abstract EN

This research presents a SHM (Structural Health Monitoring) techniques that are based on static and modal analyses of cracked plate structure.

Finite element models (FEMs) for the different cracked steel plate have been created by considering the length and the orientations of the crack, and a cantilever supported plates (parallel to the crack) are used.

The finite element models are examined under the action of static concentrated lateral load.

It is found that the maximum deflections of cracked plate increases when there is an increase in the crack length.

The highest value of the maximum deflection is at (0.12 m) of half-crack length.

The reason of this behavior is attributed to the decrease in material's stiffness causing structure deformation.

However, this deflection decreases when the orientation of crack increases until it reaches the minimum value at 90 of crack angle.

Modal analysis is also performed to each FEM to extract the values of the natural frequencies.

It is noticed that the values of natural frequencies decrease with an increasing of crack length, and they increase with the increasing of crack orientation angle.

An experimental test has been done to check the validity of the intact plate.

The results obtained is the fundamental natural frequency.

A comparison between the natural frequency and finite element result is made an error of less than (10 %) is found.

Finally, SHM analysis is applied in order to predict the early behavior of the plates in accordance with the results above.

The extrapolation for certain symbols of the results is performed to derive numerical formulas of the natural frequencies and static deflections.

The natural frequencies and static deflections' formulas are used as a function for the half-crack length, however, there is a formula for each orientation angle.