A self-healing smart syntactic foam under multiple impacts

Li, Guoqiang; John, Manu

doi:10.1016/j.compscitech.2008.09.009

Cited by 178 publications

(127 citation statements)

References 32 publications

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“…The key for the success of this self-healing scheme is that the volume of the SMP matrix must be reduced during programming and external confinement must be provided during shape recovery (Li & Uppu 2010). It has been proved that volume reduction can be realized through compression programming (Li & Nettles 2010;Li & Uppu 2010) and external confinement can be provided through architectural design of composite structures such as grid-stiffened SMP-cored sandwich (John & Li 2010), three-dimensional woven-fabric-reinforced SMP composite (Nji & Li 2010b), or even the sandwich skin (Li & John 2008). In order to speed up the programming process, cold-compression programming of thermoset SMP has also been proposed, tested and modelled (Li & Xu 2011).…”

Section: Introductionmentioning

confidence: 99%

A viscoplastic theory of shape memory polymer fibres with application to self-healing materials

Shojaei

2012

Proc. R. Soc. A.

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103

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The difficulty in healing structural damage is that most existing schemes need external help to bring the fractured surfaces in contact before healing can occur. To facilitate the existing schemes to heal macroscopic cracks, we envision that the cracked surfaces can be brought in contact through constrained shape recovery of a shape memory polymer (SMP) fibre-reinforced grid skeleton that is embedded in thermoset polymer matrix, similar to stitch a cut in the human skin by suture. In this study, we show that polyurethane SMP fibres can be hardened through cyclic cold-drawing programming, which makes them suitable for reinforcement and healing in thermoset polymer composites. We characterized the microstructure of the SMP fibres, which provides fundamental understanding of the effect of programming on the degree of crystallinity and molecular orientation. Then, a micromechanical multiscale viscoplastic theory is developed to predict the thermomechanical behaviours of the SMP fibres, including the cyclic hardening and stress recovery responses. The proposed theory takes into account the stress-induced crystallization process and the evolution of the morphological texture based on the applied stresses. The cyclic loading and the thermomechanical responses of the SMP fibres confirm the capabilities of the proposed model in capturing these phenomena.

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Section: Introductionmentioning

confidence: 99%

A viscoplastic theory of shape memory polymer fibres with application to self-healing materials

Shojaei

2012

Proc. R. Soc. A.

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103

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“…The first shape memory foam was proposed by Tey et al 10 , using SMP core material in a open cell structure. Typical constituent solids for SMFs are epoxy 11,12 , polyurethane 13 and vinyl copolymer-based polymers 14 . SMF have a very low density, are highly compressible and possess a significant shape recovery ratio that is very desirable for various applications, specifically in aerospace and automotive industries 12,15 .…”

Section: Introductionmentioning

confidence: 99%

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

Boba

Bianchi

McCombe

et al. 2016

ACS Appl. Mater. Interfaces

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We describe a new class of negative Poisson's ratio (NPR) open cell PU-PE foams produced by blocking the shape memory effect in the polymer. Contrary to classical NPR open cell thermoset and thermoplastic foams that return to their auxetic phase after reheating (and therefore limit their use in technological applications), this new class of cellular solids has a permanent negative Poisson's ratio behavior, generated through multiple shape memory (mSM) treatments that lead to a fixity of the topology of the cell foam. The mSM-NPR foams have Poisson's ratio values similar to the auxetic foams prior their return to the conventional phase, but compressive stress-strain curves similar to the ones of conventional foams. The results show that by manipulating the shape memory effect in polymer microstructures it is possible to obtain new classes of materials with unusual deformation mechanisms.2

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“…In these types of systems, the damage and the healing processes occur separately, where just one of these processes is active. These systems may use thermoplastic particles (TPs; Zako & Takano 1999), thermally reversible covalent bonds (Liu & Chen 2007;Plaisted & Nemat-Nasser 2007), confined shape recovery of shape memory polymers (SMPs; Li & John 2008) or biomimic two-step close-then-heal (CTH) mechanisms to molecularly heal structural length-scale damages (Li & Nettles 2010;Li & Uppu 2010;Nji & Li 2010;Xu & Li 2010).…”

Section: Introductionmentioning

confidence: 99%

A theory of anisotropic healing and damage mechanics of materials

Voyiadjis

Shojaei

et al. 2011

Proc. R. Soc. A.

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Self-healing smart materials have emerged into the research arena and have been deployed in industrial and biomedical applications, in which the modelling techniques and predicting schemes are crucial for designers to optimize these smart materials. In practice, plastic deformation is coupled with damage and healing in these systems, which necessitates a coupled formulation for characterization. The thermodynamics of inelastic deformation, damage and healing processes are incorporated here to establish the coupled constitutive equations for healing materials. This thermodynamic consistent formulation provides the designers with the ability to predict the irregular inelastic deformation of glassy polymers and damage and healing patterns for a highly anisotropic self-healing system. Moreover, the lack of a physically consistent method to measure and calibrate the healing process in the literature is addressed here. Within the continuum damage mechanics (CDM) framework, the physics of damage and healing processes is used to introduce the healing effect into the CDM concept and a set of two new anisotropic damage-healing variables are derived. These novel damage-healing variables together with the proposed thermodynamic consistent coupled theory constitute a well-structured method for accurately predicting the degradation and healing mechanisms in material systems. The inelastic and damage response for a shape memory polymer-based self-healing system is captured herein. While the healing experimental results are limited in the literature, the proposed theory provides the mathematical competency to capture the most nonlinear responses.

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A self-healing smart syntactic foam under multiple impacts

Cited by 178 publications

References 32 publications

A viscoplastic theory of shape memory polymer fibres with application to self-healing materials

A viscoplastic theory of shape memory polymer fibres with application to self-healing materials

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

A theory of anisotropic healing and damage mechanics of materials

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