Piezo-driven self-healing by electrochemical phenomena

Abstract

Self-healing structures mimic the ability of biological structures (e.g. bone) to redistribute their structural mass in response to dynamic service loads and damaging effects. The self-healing features yield enhanced levels of structural efficiency and safety in dynamic service environments. In this study, the piezoelectric effect was used to convert the dynamic mechanical energy applied to the structure into electrical energy that, in turn, was used to drive electrochemical selfhealing phenomena within a solid electrolyte. A theoretical framework was developed for self-healing materials, and experiments were conducted to verify the fundamental principles of the approach. The theoretical models confirmed that: (1) the piezoelectric effect can, within the geometric and mechanical constraints of actual structural systems, generate sufficient electric potential and charge (through harvesting the available mechanical energy) to enable electrochemical mass transport within a solid electrolyte; and (2) the redistribution of structural mass in dynamic service environments can occur within viable time frames. The fundamental principles of the new self-healing materials were validated through the demonstration of piezo-induced electrolytic phenomena in solid electrolytes and by verifying the gains in mechanical performance associated with such phenomena. KeywordsSelf-healing, piezoelectric effect, mechanical performance, solid electrolyte, electrolysis Bond, 2005) has increased the interest in this technique. Kersey et al. (2007) have reported two general categories of the self-healing techniques available for recovery of mechanical properties. Self-healing is noted to occur either through the creation of new chemical bonds within the material, for example, by in situ polymerization of monomers in cracks or by re-creation of the ruptured chemical bonds as demonstrated by Chen

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

“…The adaptive feedback controller was designed and implemented first on a newly developed model of an electrolytic system to regulate the process. The model is based on previous experimental work [6,38] which proposed an electromechanical material system, whose intrinsic self-healing mechanism is based on a piezo-electrolytic drive. This system suffers from an inherent non-linear deadzone which limits the performance of selfhealing.…”

“…This ensures reliability and improved recovery from the effect of damage. To demonstrate the effectiveness of the proposed approach to constant and varying perturbation, an electromechanical material that has previously been experimentally demonstated [6,38] has been modelled and simulated. This paper then shows how adaptive feedback control can compensate for the insufficient potential energy driving the self-healing and can guarantee a response that will match the effect of fault propagation in the simulated system.…”

“…Experiments have previously been carried out to show the potential of using an electromechanical material for self-healing [6,38]. Poly vinylidene fluoride-cohexafluropropylene (PVDF-HFP), zinc oxide and copper nanoparticles were mixed together to form a PVDF-HFP solid electrolyte.…”

Control of electro-chemical processes using energy harvesting materials and devices

“…Lang et al 87 demonstrated that HA is both piezoelectric and pyroelectric indicating potential for harvesting human motion and temperature changes; the reader is referred to a review on the topic by Baxter et al 88 A biomimetic approach was used by Soroushian et al who investigated self-healing structures that were able redistribute their structural mass in response to dynamic loads. 89 In their work the piezoelectric effect was used to convert dynamic mechanical energy applied to a structure into electrical energy that was able to drive an electro-chemical self-healing phenomena within a solid electrolyte. Zhang et al also used PVDF to use piezoelectric energy to indirectly power cathodic protection 38 and the output of the fabricated device was used to protect metal surfaces from the chemical corrosion, see Fig.…”

Inherently adaptive polymer nanocomposites

“…The self‐adaptation capabilities of biological materials such as bone provide the inspiration for development of synthetic materials with inherently adaptive capabilities . Bone uses a powerful control mechanism to reconfigure its structure to remove stress gradients generated after damaging effects for optimum performance.…”