Modelling of health monitoring signals and detection areas for aerospace structures

Structural health monitoring (SHM) systems are increasingly being considered for implementation in aerospace structures. As the application of SHM systems increase, it will be important to define standardized procedures to test durability, reliability, and longevity of the systems. The work presented in this paper is some preliminary work on the integrity of Piezoelectric sensors itself when used to monitor the strains in structures. This study involved the measurements of pertinent electrical properties of these sensors over 100,000 cycles of fatigue loading. Marked changes in the capacitance and inductance of these sensors highlighted deleterious structural changes in the sensor itself without any discernible change in the structure it is supposed to monitor. This might have significant implications in the reliability assessment of sensory data from SHM systems.

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Correlating Shear Slip and Contact Pressure for Health Monitoring of Bolted Joints in Aerospace Structures

ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 2 ◽

10.1115/smasis2010-3885 ◽

2010 ◽

Cited By ~ 1

Author(s):

Mohammad Jalalpour ◽

Mahmoud Reda Taha ◽

Eric Austin

Keyword(s):

Contact Pressure ◽

Health Monitoring ◽

Continuous Monitoring ◽

Structural Integrity ◽

Bolted Joints ◽

Bolted Connection ◽

Aerospace Structures ◽

Ultrasonic Methods ◽

Shear Slip ◽

Critical Components

Bolted joints are critical components in aerospace structures. Checking the integrity of these connections, although time consuming, is a necessary step before launching aerospace vehicles and satellites. Recent advances in structural health monitoring (SHM) suggest the possible use of SHM technologies to assess the integrity of these joints. Moreover, there exists a need for continuous monitoring of aerospace structures after launching. This continuous monitoring requires relating damage features that can be extracted using sensing techniques (e.g. ultrasonic methods) to physical quantities representing the structural integrity of bolted joints typically related to contact pressure. This paper describes an experimental effort to correlate shear slip measurements of a bolted connection to contact pressure. The contact pressure map (spatial distribution of contact pressure) is calibrated to the torque applied to the bolted connection. Loading and unloading experiments on the joint allowed separating elastic and shear slip displacements. Shear slip is then correlated to contact pressure maps. Further efforts are underway to connect these measures to SHM metrics.

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