Inherently adaptive polymer nanocomposites

et al. 2016

Smart Mater. Struct.

Abstract. Intrinsic and extrinsic self-healing approaches through which materials can be healed generally suffer from several problems. One key problem is that to ensure effective healing and to minimise the propagation of a fault, the healing rate needs to be matched to the damage rate. This requirement is usually not met with passive approaches. An alternative to passive healing is active self-healing, whereby the healing mechanism and in particular the healing rate, is controlled in the face of uncertainty and varying conditions. Active self-healing takes advantage of sensing and added external energy to achieve a desired healing rate. To demonstrate active self-healing, an electrochemical material based on the principles of piezoelectricity and electrolysis is modelled and adaptive feedback control is implemented. The adaptive feedback control compensates for the insufficient piezo-induced voltage and guarantees a response that meets the desired healing rate. Importantly, fault propagation can be eliminated or minimised by attaining a match between the healing and damage rate quicker than can be achieved with the equivalent passive system. The desired healing rate is a function of the fault propagation and is assumed known in this paper, but can be estimated in practice through established prognostic techniques.

Section: Resultsmentioning

confidence: 99%

Section: Case Ii: Piezo-electrolytic Process Regulated By a Feedback mentioning

confidence: 99%

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Using feedback control to actively regulate the healing rate of a self-healing process subjected to low cycle dynamic stress

et al. 2016

Smart Mater. Struct.

“…Previous experimental work has shown that the macro properties of interest are recovered by the self-healing process adopted here. 34,35 However, details on how and to what extent the original macro material properties can be recovered for different host structures, would require further experimental investigation with the potential self-healing processes. Complete recovery of the macro material properties is assumed here, since the actual recovered values are not known and its adoption does not affect the investigation of the general concept, which is the main focus in this work.…”

Section: Integration Of System Model and Control With Fddmentioning

confidence: 99%

“…To achieve a sh (t h )=a est (t f ),( 51)m u s t hold. The fault monitoring index in (35) is redefined as (52) during self-healing. The second row of (46)i sa l s or e s e t to zero.…”

Section: Integration Of System Model and Control With Fddmentioning

confidence: 99%

A material system with integrated fault diagnosis and feedback controlled self‐healing

Adaptive Control & Signal

et al. 2022

Two significant drawbacks of current self-healing materials are that they are:(1) Passive and as such do not guarantee a match between the healing and damage rate; (2) Not monitored during and after healing, so that the performance of the healed material is not known without retrospective offline testing. As a consequence their application is currently limited in some sectors, such as the aerospace sector where high performance needs to be guaranteed within strict guidelines. This article proposes the first active self-healing material that integrates with control and fault diagnosis to provide a system with a desired healing response. A fault diagnosis algorithm using supervised regression is used to estimate the measure of damage. Then based on this estimate, adaptive feedback control is used to ensure a match between the healing response and the damage rate, while taking into account the nonlinear system dynamics and uncertainty.The system is demonstrated in simulation using a self-healing material based on piezoelectricity and electrolysis. This shows the ability of the integrated subsystems to tackle these two significant drawbacks of most current self-healing systems and will benefit applications with strict performance requirements, or systems operating under harsh conditions or that are remotely accessed.

Integrated Sensing, Monitoring and Healing of Composite Systems

7th Forum on New Materials - Part E

et al. 2016

The ability of a material to recover its nominal properties through self-healing is gaininginterest in the research community. However, current approaches remain predominantly passive incounteracting the effect of damage. As a result, healing only begins when the material has occurreddamage and typically there is a mismatch between the healing and damage rate. For applications suchas aircraft, where there is a thin line between functionality and non-functionality, these limitations maybe inherently restrictive. A self-healing system that combines a prognosis unit to predict and estimatethe failure rate and an active self-healing system that matches the healing rate to the estimated failurerate using a feedback loop, has the potential to overcome these limitations. In this paper we proposesuch a system and present results for its application to composite materials.