Toward on-orbit structural health monitoring of inflatablestructures using electromechanical impedance method

Inflatable structures are promising candidates for a wide range of aerospace vehicles due to their volume/weight savings, high storage rate, low cost, and easy deployment. However, space survivability is a major concern for such structures. Therefore, structural health monitoring (SHM) of inflatable structures has been increasingly studied. Electromechanical impedance (EMI) method is one of the most-popular SHM methods, which can promptly and accurately identify early structural damage. Nevertheless, the necessary of using bulky, expensive and high-power commercial impedance analyzer hampers electromechanical impedance method from being used in-situ and online. In recent years, several miniature impedance measurement devices have been developed for practical applications. However, the aerospace application of such devices is still absence. In this paper, a miniature integrated impedance measurement printed circuit board (PCB) prototype toward on-orbit SHM of inflatable structures is developed. The proposed PCB prototype consists of impedance measurement module, in which the AD5933 chip and the ADG708 chip were adopted to achieve impedance signals. In this case, the PCB prototype can effectively measure the electrical impedance of up to six channels of the piezoelectric transducers at 0.2 ∼2V excitation voltage in the frequency range of 10 ∼100kHz. Moreover, an inflatable boom was taken as the inspected structure, and a PZT-5H was used as the piezoelectric transducer for experimental validation. The results demonstrate that the proposed PCB prototype works functionally and can accurately quantify the simulated damage on the inflatable boom. In addition, it is found that the miniature integrated impedance measurement PCB prototype developed in this paper has the advantages of low bulk and less weight, which can be further enhanced to satisfy the demands of on-orbit SHM of inflatable structures.