Vibration-based structural health monitoring through self-diagnosing structural components made of nano enriched composites

Project: Research

Description

The main goal of this proposal is to develop the foundations of dynamically self-sensing and self-diagnosing structures capable of measuring their vibrations and using them to diagnose their structural integrity . This will be achieved by using conductive or piezo-electric nano-inclusions and applying vibration-based monitoring and health assessment methods.
The idea of self-diagnosing structures opens the road towards autonomous structures, capable to not only self- diagnose their condition but eventually even take some repair steps. This is applicable for a wide variety of structures including aerospace, mechanical and civil engineering ones like e.g. aircrafts, turbine blades, buildings and bridges.
The idea of using nano-inclusions as sensors is based on the piezo-resistive and piezo-electric properties of some materials. The first relate the conductivity and the strain of the structure and hence its vibrations, while the latter convert the strain into voltage and vice versa and they are used for dynamic/vibration transducers. This proposal suggests to employ piezoresistive and/or piezo-electric nano-inclusions for measuring and assessment of the structural vibrations and use them to estimate the structural health. The rationale for using vibration-based structural health monitoring (VSHM) is two-fold: 1) there is a vast amount of research and more than 30 years experience in VSHM and 2) most structures are naturally subjected to some kind of vibrations which can come e.g. from the work of an engine or a motor, or from traffic and wind.
The suggested approach is based on a no-intervention principle, coupled with new integrated within the structure sensing technology. It proposes a unified approach comprising 1) a new self-sensing theory, coupled with 2) a vibration-based monitoring and diagnostic methodology for detecting anomalies in both short term (damage) and long term ( fatigue or wear) scale. A data-centred VSHM approach is suggested which deals with the extraction and handling of appropriate information obtained from the self-measured signals and with the derivation of data-driven models and damage detection and assessment methods.
This research will advance the concept of vibration-based structural health monitoring expanding it to self-health monitoring by applying piezo-resistive and piezo-electric nano inclusions. It will also promote our understanding for the dynamic properties and behaviour of piezo-resistive and piezo-electric materials and their influence on the global dynamic properties of the structure in which they are included. The suggested research will further the knowledge about the sensing properties and capabilities of the conductive and piezo-electric nano-inclusions in terms of sensitivity to different damage types and precision. This will be done employing a joint approach combining an experimental track coupled with modelling approach to achieve the envisaged knowledge and results. The proposed self-diagnosis methodology will bring the paradigm of monitoring and prognosis on a new level eliminating the need of external sensors and thus removing the error due to contact and improving the precision of the measurements. It will introduce the viability of in operation continuous monitoring through self-measurement thus reducing the need for additional maintenance and intervention and hence minimizing the risk of introducing faults associated with maintenance and inspection.

Key findings

This project will contribute to the understanding and the ability to predict the dynamic performance of materials enriched with nano -inclusions, which is one of the gaps in our knowledge. This is a crucial issue regarding the safety and the reliability of structures since most structures are subjected to vibrations during their operations and life time. We need to be able to predict this behaviour in order to properly design the structures so that are capable to perform their operations without posing threat to the people and the environment.
This proposal suggests the development of self-sensing and self –diagnosing structures which will advance the understanding and the applications in the area of measurement and sensing. The challenge in this research involves the inclusion of the sensing material within the structure so that it is able to assess its vibrations and from it make conclusions about its integrity and condition. This will improve the precision of the dynamic sensors eliminating issues related to their mass and contact with the structure, which otherwise affect the precision of such instruments significantly.
The simulation and the modelling of the behaviour of the structures enriched with nano-materials is one of the key aspects of this proposal. These are novel structural elements and materials and we need to be able to model and simulate their behaviour for the purposes of their proper design and exploitation. There are no current standards that can be used for the design of such structures so the development of some standards will follow from the development of models and modelling strategies to simulate their behaviour.
This proposal addresses the reliability of nano-enriched structures to ensure that they are able to maintain their operations safely and perform their functions without presenting any risk or danger to the people and the environment. This includes the estimation and the prognosis of possible damage and delamination or other failure modes in such structures so that when designing them one is able to guarantee that they will not fail and that their performance will not pose a threat to the people and the environment.
An important aspect of this proposal is that it will address one of the key gaps in our knowledge and understanding, the measurement of the state of a material during its operation. This is one of the main objectives of the current proposal. The inclusion of the sensor within the material and within the structure as a whole will provide the availability of monitoring around the clock while the structure is in operation. The in service monitoring will provide crucial information about the state of the material and the structure, but in the same time it will provide important data regarding the material and the structural behaviour during the operation.
Short titleself-diagnosing structural members
StatusFinished
Effective start/end date30/09/16 → 30/09/19