This article presents an experimental investigation into the mode I delamination fatigue properties and fatigue crack healing mechanism of a self-healing carbon fibre–epoxy composite containing mendable thermoplastic stitches. Mode I interlaminar fatigue tests using double cantilever bending specimens show that through-the-thickness reinforcement of the composite with mendable poly(ethylene-co-(methacrylic acid)) stitches is highly effective in healing delamination cracks and restoring the fatigue properties. Aided by a pressure delivery mechanism unique to this type of mendable thermoplastic, the healing agent stored in an interconnected network of stitches is able to flow into narrow delamination cracks. The mode I interlaminar fatigue resistance as well as the fracture toughness of the composite was fully restored by poly(ethylene-co-(methacrylic acid)) stitches. Transverse tension tests were performed to determine the traction law of the healing agent, which controls the healing efficiency and interlaminar toughening mechanism under static and fatigue mode I interlaminar loading.
ArgüellesAViñaJCanteliAF. (2008) Interlaminar crack initiation and growth rate in a carbon-fibre epoxy composite under mode-I fatigue loading. Composites Science and Technology68: 2325–2331.
2.
CartiéDDRLaffailleJ-MPartridgeIK. (2009) Fatigue delamination behaviour of unidirectional carbon fibre/epoxy laminates reinforced by Z-Fiber® pinning. Engineering Fracture Mechanics76: 2834–2845.
3.
DransfieldKBaillieCMaiY-W (1994) Improving the delamination resistance of CFRP by stitching – a review. Composites Science and Technology50: 305–317.
4.
HargouKPingkarawatKMouritzAP. (2013) Ultrasonic activation of mendable polymer for self-healing carbon-epoxy laminates. Composites Part B: Engineering45: 1031–1039.
5.
HashemiSKinlochAJWilliamsJG (1990) The analysis of interlaminar fracture in uniaxial fibre-polymer composites. Proceedings of Royal Society of London A 427: 173–191.
6.
HojoMAndoTTanakaM. (2006) Modes I and II interlaminar fracture toughness and fatigue delamination of CF/epoxy laminates with self-same epoxy interleaf. International Journal of Fatigue28: 1154–1165.
7.
KnipprathCMcCombeGPTraskRS. (2011) Identification of effective healing locations for recovering compressive strength. Composites Science and Technology72: 752–759.
8.
MasakiHShojiroOGustafsonC-G. (1994) Effect of matrix resin on delamination fatigue crack growth in CFRP laminates. Engineering Fracture Mechanics49: 35–47.
9.
MeureSFurmanSKhorS (2010a) Poly(ethylene-co-(methacrylic acid)) healing agents for mendable carbon fiber laminates. Macromolecular Materials and Engineering295: 420–424.
10.
MeureSVarleyRJWuDY. (2012) Confirmation of the healing mechanism in a mendable EMAA–epoxy resin. European Polymer Journal48: 524–531.
MeureSWuDYFurmanSA (2010b) FTIR study of bonding between a thermoplastic healing agent and a mendable epoxy resin. Vibrational Spectroscopy52: 10–15.
13.
MouritzAP (2007) Review of z-pinned composite laminates. Composites Part A: Applied Science and Manufacturing38: 2383–2397.
14.
MouritzAPCoxBN (2000) A mechanistic approach to the properties of stitched laminates. Composites Part A: Applied Science and Manufacturing31: 1–27.
15.
MouritzAPCoxBN (2010) A mechanistic interpretation of the comparative in-plane mechanical properties of 3D woven, stitched, and pinned composites. Composites Part A: Applied Science and Manufacturing41: 709–728.
16.
MouritzAPBainiCHerszbergI (1999) Mode I interlaminar fracture toughness properties of advanced textile fibreglass composites. Composites Part A: Applied Science and Manufacturing30: 859–870.
17.
NguyenORepettoEAOrtizM. (2001) A cohesive model of fatigue crack growth. International Journal of Fracture110: 351–369.
18.
NorrisCJBondIPTraskRS (2011) Interactions between propagating cracks and bioinspired self-healing vascules embedded in glass fibre reinforced composites. Composites Science and Technology71: 847–853.
19.
PatelAJSottosNRWetzelED. (2010) Autonomic healing of low-velocity impact damage in fiber-reinforced composites. Composites Part A: Applied Science and Manufacturing41: 360–368.
20.
PingkarawatKBhatTCrazeDA. (2013a) Healing of carbon fibre-epoxy composite using thermoplastic additives. Polymer Chemistry4: 5007–5015.
21.
PingkarawatKWangCHVarleyRJ. (2012a) Self-healing of delamination cracks in mendable epoxy matrix laminates using poly(ethylene-co-(methacrylic acid)) thermoplastic. Composites Part A: Applied Science and Manufacturing43: 1301–1307.
22.
PingkarawatKWangCHVarleyRJ. (2012b) Self-healing of delamination fatigue cracks in carbon fibre-epoxy laminate using mendable thermoplastic. Journal of Materials Science47: 4449–4456.
23.
PingkarawatKWangCHVarleyRJ. (2013b) Effect of mendable polymer stitch density on the toughening and healing of delamination cracks in carbon-epoxy laminates. Composites Part A: Applied Science and Manufacturing50: 22–30.
24.
SjogrenAGreenhalghESAspLE (2001) Delamination growth and thresholds in a carbon/epoxy composite under fatigue loading. Journal of Composites, Technology & Research23: 55–68.
25.
SuKB (1989) Delamination resistance of stitched thermoplastic matrix composite laminates. In: NawazGM (ed.) Advances in Thermoplastic Matrix Composite Materials, ASTM STP 1044. Philadelphia, PA: American Society of Testing and Materials, pp. 270–300.
26.
TraskRSBondIP (2006) Biomimetic self-healing of advanced composite structures using hollow glass fibres. Smart Materials and Structures15: 704–710.
27.
TuronACostaJCamanhoPP. (2007) Simulation of delamination in composites under high-cycle fatigue. Composites Part A: Applied Science and Manufacturing38: 2270–2282.
28.
VarleyRJvan der ZwaagS (2008) Towards an understanding of thermally activated self-healing of an ionomer system during ballistic penetration. Acta Materialia56: 5737–5750.
29.
VarleyRJCrazeDAMouritzAP. (2013) Thermoplastic healing in epoxy networks: exploring performance and mechanism of alternative healing agent. Macromolecular Materials and Engineering. Epub ahead of print 18April. DOI: 10.1002/mame.201200394.
30.
WuDYMeureSSolomonD (2008) Self-healing polymeric materials: a review of recent developments. Progress in Polymer Science33: 479–522.
31.
YangTWangCHZhangJ. (2012) Toughening and self-healing of epoxy matrix laminates using mendable polymer stitching. Composites Science and Technology72: 1396–1401.
