Load monitoring of aerospace structures utilizing micro-electro-mechanical systems for static and quasi-static loading conditions

Abstract

The National Research Council Canada (NRC) has worked on the development of structural health monitoring (SHM) test platforms for assessing the performance of sensor systems for load monitoring applications. The first SHM platform consists of a 5.5 m cantilever aluminum beam that provides an optimal scenario for evaluating the ability of a load monitoring system to measure bending, torsion and shear loads. The second SHM platform contains an added level of structural complexity, by consisting of aluminum skins with bonded/riveted stringers, typical of an aircraft lower wing structure. These two load monitoring platforms are well characterized and documented, providing loading conditions similar to those encountered during service. In this study, a micro-electro-mechanical system (MEMS) for acquiring data from triads of gyroscopes, accelerometers and magnetometers is described. The system was used to compute changes in angles at discrete stations along the platforms. The angles obtained from the MEMS were used to compute a second, third or fourth order degree polynomial surface from which displacements at every point could be computed. The use of a new Kalman filter was evaluated for angle estimation, from which displacements in the structure were computed. The outputs of the newly developed algorithms were then compared to the displacements obtained from the linear variable displacement transducers connected to the platforms. The displacement curves were subsequently post-processed either analytically, or with the help of a finite element model of the structure, to estimate strains and loads. The estimated strains were compared with baseline strain gauge instrumentation installed on the platforms. This new approach for load monitoring was able to provide accurate estimates of applied strains and shear loads.

Load monitoring and compensation strategies for guided-waves based structural health monitoring using piezoelectric transducers

“…As mentioned in [16], load monitoring and measurements are essential tasks for design certification of structural component. The certification tasks are costly and have to cater to uncertainties in the actual loads a structure is subjected to during its intended operation, which may be widely different from the calculated design loads.…”

“…Currently load monitoring task is typically carried out using strain gages, accelerometers, micro-electro-mechanical systems (MEMS) or combinations of these. Recently Martinez et al [16] proposed the use of MEMS based sensors for load monitoring on aerospace structures. They demonstrated accurate estimation of strains and shear forces on simple structure; however for complex structure an accurate FE model is required.…”

Micro-electro-mechanical-systems (MEMS) for assessing and monitoring civil infrastructures

“…The diversity of materials and manufacturing methods available in the MEMS fi eld allow designing novel sensor fusion opportunities to be manufactured on the same wafer. Discrete sensor elements (e.g., AE, accelerometer) on the same device can open tremendous opportunities in SHM of civil structures (e.g., Martinez et al , 2012;Saboonchi and Ozevin, 2013b). Additionally, accelerometers with six degrees of freedom can be allocated in a miniaturized package.…”

A Critical Comparison of Shape Sensing Algorithms: The Calibration Matrix Method versus iFEM

“…After the initial illumination-based methods, which were unsuitable for larger scale applications, various alternative methods were proposed: minimization of an objective function with regularization [ 9 , 15 , 16 ], statistical methods based on Bayesian theory [ 15 ], fitting to a polynomial [ 16 , 17 , 18 , 19 ], dynamic programming [ 20 ], modal transformation [ 21 ], and direct integration of multicore optical fibers [ 22 , 23 , 24 , 25 ]. Each of these methods has its own drawbacks: most require manual tuning to determine parameters such as regularization constants, polynomial order, and/or the number of modes.…”