Moving support technique for delaminatoin detection in laminated composite beams using the first natural frequency

A new practical procedure is presented for delamination detection in beam-like composite structures. This technique identifies the delamination axial location and its length accurately based on the only first natural frequency. An additional simply support condition besides the boundary conditions is defined and it is moved along the beam length. When this support is located on delamination, especially its tips, the frequency reduction will be noticeable. Simulating this idea in ABAQUS finite element software shows that the location and size of delamination can be detected accurately. To verify the numerical results, some experiments are conducted and a new fixture is designed and manufactured for simulating the additional moving support along the length of the beam. Both finite element and experimental results show the ability of the proposed method in delamination detection for different boundary conditions. Also, this new simple and applicable technique can be used even for small delamination lengths by monitoring only the first natural frequency, unlike the available methods in the literature.