Fibre fracture fatigue

Hearle, J. W. S. Buckley, C. P. Lomas, B. Fracture, fatigue and wear of man-made fibers. Presented at the Int. Man-made Fibre Conf., Dombirn, Austria, June 1979. 

Fibre Textile Fracture Fatigue Tensile Bending Twisting Abrasion... 

Fracture Fatigue Defects Cracks Cotton Wool Melt-spun synthetics Solution-spun fibres... 

J. W.S.Hearle, B.Lamos, and W.D.Cooke, Fibre Failure and Wear of Materials on Atlas of Fracture, Fatigue and Durability, Elhs Harword Limited, England, 44, 1989. 

Fracture process in multidirectional composite laminates subjected to in-plane static or fatigue tensile loading involves sequential accumulation of damage in the form of matrix cracks that appear parallel to the fibres in the off-axis plies, edge delamination and local delamination long before catastrophic failure. These resin dominated failure modes significantly reduce the laminate stiffness and are detrimental to its strength. 

Brunner AJ, Terrasi GP, Cartie DDR. Fatigue testing of Z-pin reinforced carbon-fibre laminates. In Proceedings 12th international conference on fracture ICF-12, paper no. 01199 2009. pp. 1-8. 

Glass fibres exhibit time-dependent fracture under a static load, which is referred to as static fatigue [36]. Since there is no time dependence of strength in a vacuum, it is considered that water is involved in the reduction in strength. Thus, a stress corrosion mechanism in condensed water is inferred. The chemical reactions associated with this process are given in Figure 12.17. 

Schulte [46,47] has demonstrated how different organic solvents, such as hydraulic fluid encountered in the aerospace stmctures, lead to a reduction in the secant modulus of 45° glass fibre laminate under flexural fatigue and the number of cycles to failure. The matrix in this case was a polyether imide (PEI) which is plasticised by ingress of the fluid. A reduction in the matrix modulus means that the shear strength of the matrix will also be reduced with the consequence that the failure mechanism in flexure will change from matrix-fracture to delamination. 

High performance polyethylene fibres such as Dyneema (a reinforcing polyethylene fibre from DSM) show a pronounced time-dependent behaviour under static loading conditions. An increase in strain rate and/or decrease in temperature results in an increase in fibre modulus and strength, but a decrease in work of fracture [33]. It is also known that creep can be observed even in unidirectional PE-fibre reinforced laminates. How far this specific behaviour influences the fatigue behaviour is of great interest and has to be investigated in order to find the appropriate applications for PE-composites. 

As an initially translucent FRP specimen fails in fatigue, it gradually becomes opaque. When the opacity first occurs, it does so only when the specimen is stressed, but after further stress cycles it becomes progressively permanent and more intense. At final separation of matrix laminates in axial loading, the fracture surface is normal to the loading direction and fibrous in appearance, the resin matrix often being reduced to a white powder. The initial (non-permanent) opacity is caused by debonding of fibres transverse to the load direction, which later cause matrix cracks and permanent opacity in the specimen. 

Miyajima T, Sakai M, Fibre pullout and fracture energy of C-fibre/C-matrix composites, Bradt RC, Hasselman DPH, Munz D, Sakai M, Ya Shevchenko V, Fracture Mechanics of Ceramics 9, Composites, R-Curve Behavior and Fatigue, Japan Fine Ceramics Center, Proc 5th Int Symp, Nagoya, Jul 15-17 1991, Plenum, 83-95, 1992. 

Gilchrist MD, Curley L, Manufacturing and ultimate mechanical performance of carbon fibre reinforced epoxy composite suspension push rods for a Formula 1 racing car. Fatigue Fracture of Engineering Materials <6 Structures, 22(1), 25-32, 1999. 

Savastano H Jr, Santos SF, Radonjic M, Soboyejo WO et al (2009) Fracture and fatigue of natural fibre-reinforced cementitious composites. Cement Concr Compos 31 232-243 79. Rahman WA, Tin SL, Razak RA et al (2008) Injection moulding simulation analysis of natural fibre composite window frame. J Mater Process Technol 197 22-30 Toledo FRD, Andrade SF, Fairbaim EMR, Melo FA et al (2009) Durability of compression molded sisal fibre reinforced mortar laminates. Construct Build Mater 23 2409-2420 Pillai MS (2006) Applications of natural coir fibre, proceedings, natural fibres vision 2020, New Delhi 8-9th December... 

Fi. 10. (a.b) Polye.sler fibres after a single bend, (c-e) Flex fatigue in polyester kink-band fracture, (f) Flex fatigue shear splitting in nylon, (g) Flex fatigue shear splitting in polyester. For further explanation. 

Konopasek, L. and Hearle, J.W.S. (1977) The tensile fatigue behaviour of para-oriented aramid fibres and their fracture morphology. J. Appl. Polym. Sci., 21 2791-2815. 

Silva, E.J., Thaumaturgo, C., 2002. Fibre reinforcement and fracture response in geopolymeric mortars. Fatigue and Fracture of Engineering Material and Structures, 26, pp. 167-172. 

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