Fracture toughness of unidirectional fibre reinforced composites in MODE II

✍ Scribed by G.S. Giare

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 767 KB
• Volume: 20
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(84)90111-5

✦ Synopsis

A~~act-Expe~mental

investigations have been performed on unidirectional glass fibre reinforced/epoxy composites in Mode II (Forward shear) with the presence of crack parallel to the fibres direction through the use of end-cracked beam. A concentrated load at the Centre of the beam produced ending-indu~d shear deformation at the crack tip. Calibration factors for Mode II have been obtained. The stress-intensity factor at instability KiiRuNsj is obtained by experiments on a small end cracked beam through a compliance matching procedure. The crack growth resistance at instability and the corresponding critical strain energy release rate are independent of initial crack in the range of crack length investigated. In composite materials, Iibre-matrix interfacial shear stress play an important role in load transfer mechanism: hence Mode II study may be very useful to analyse the interfacial mechanisms and to understand the fracture behaviour of unidirectional fibre reinforced composites in Mode I when load is applied in the direction of the iibres. NOTATION a initial crack length a, instantaneous crack length (estimated) d depth of beam t width of beam V shear force at the section of the beam F shear force tangential to crack surface at neutral axis of beam E* effective modulus C compliance C, non-dimensional compliance curve KR crack growth resistance K RI,NSl crack growth resistance at instability or the fracture toughness.