MEMS sensor fusion: Acoustic emission and strain

In this paper, Micro-Electro-Mechanical-Systems (MEMS) based device accommodating acoustic emission (AE) and strain sensors is presented for damage detection in structures. The MEMS AE sensors have the transduction principle of capacitance change while the MEMS strain sensors have the transduction principle of piezoresistivity. Two aluminum 7075 coupon samples with existing notches are tested under fatigue loading. The performance of MEMS sensors is compared with conventional piezoelectric AE sensors, and strain gauges. The MEMS AE sensors detect the damage initiation and evolution while their sensitivities are lower than piezoelectric AE sensors. The MEMS strain sensors can detect the fatigue cycles while they are influenced by thermal drift, which affects the measurement of true strain. The relevant AE signals released by active flaw occur at high strain levels. The combination of AE and strain sensors on the same device can be utilized to define active and idle modes of AE data acquisition using strain as controlling variable.