What are the most effective methods for inspecting and monitoring ship structures?

3 Eddy current testing

Eddy current testing is another non-destructive method that uses electromagnetic induction to inspect ship structures. It works by applying an alternating current to a coil, which generates a magnetic field that induces eddy currents in the structure. The eddy currents are affected by the conductivity, permeability, and geometry of the structure, and they can be measured by a sensor. The changes in the eddy currents can reveal the presence and location of cracks, corrosion, or other defects. Eddy current testing can be applied to both ferromagnetic and non-ferromagnetic materials, and it does not require direct contact or surface preparation. However, eddy current testing is sensitive to noise, lift-off, and orientation, and it has limited penetration depth and resolution.

4 Acoustic emission testing

Acoustic emission testing is a non-destructive method that uses the sound waves generated by the deformation or fracture of ship structures. It works by attaching sensors to the structure, which detect and record the acoustic signals emitted by the structure under stress or load. The frequency, amplitude, and duration of the signals can indicate the type, severity, and location of the damage. Acoustic emission testing can monitor the structure in real time and in service, and it can detect active and growing defects. However, acoustic emission testing is complex, expensive, and prone to interference, and it requires baseline data and signal analysis.

5 Fiber optic sensing

Fiber optic sensing is a novel method that uses optical fibers to measure the strain, temperature, pressure, or vibration of ship structures. It works by embedding or attaching the optical fibers to the structure, which act as sensors that modulate the light signals passing through them. The changes in the light signals can reflect the changes in the physical parameters of the structure. Fiber optic sensing can provide continuous and distributed monitoring of the structure, and it can withstand harsh environments and electromagnetic interference. However, fiber optic sensing is still under development, and it faces challenges such as installation, durability, and cost.