Abstract: Active Lamb wave damage monitoring methods require a health structural response to act as the baseline. The difference between the damage structural response and the baseline is used to obtain the damage scattering signals in most active Lamb wave damage monitoring methods. Such process will be affected easily by external factors, such as structure and environment variation, etc. This article proposes a no baseline active Lamb wave damage imaging location and monitoring method. Back propagation piezoelectric (PZT) array arrangement method and time reversal window function are purposed to eliminate direct propagation waves and reflections from the boundaries to intercept the inner scattering waves in the structural responses. Based on time reversal theory, current structural responses are used to realize damage location and imaging by suitable piezoelectric array and window function. This method does not need baseline any more. Experiments on a glass fiber reinforced composite board indicate that the location and range of the damage can be expressed well by means of the proposed method.

Key words: structure health monitoring (SHM), Lamb wave, time reversal, no baseline, damage detection