The main aims of the project were to explore the feasibility of, and propose a design for, a composite carabiner. The possibility of reducing the weight of a carabiner was defined as the major motivation. A set of detailed requirements for a carabiner have been defined based on international safety standards, geometrical criteria and environmental resistance criteria. Material and manufacturing options have been studied and related to the carabiner application. Low toughness was determined to be the major problem of composite materials for lightweight carabiner design. Literature research was used to find methods of improving composite toughness. Two design options were proposed and one of these designs was described in detail - this made use of an injection moulded, short carbon fibre/PEEK composite, specifically, Victrex 90HMF40. This material was noted for its high specific strength, other excellent mechanical properties, and its compatibility with injection moulding - which enables economical production. A CAD model and a rapid prototyped model of the proposed design were created.
A carabiner made from composite materials likely to be up to 40% lighter than a conventional aluminium carabiner. Producing a composite carabiner is likely to be more expensive than aluminium carabiner production - particularly if hand lay-up is used.
Limited testing and finite element analysis were carried out as part of the early stages of design optimisation. Further analysis and development is required before carabiner production can begin.
The author would like to thank Bill Belcourt, Corey LaForge, Brendan Perkins and Chris Grover of Black Diamond Equipment Ltd for generously providing technical information on their carabiners and testing methods.
Thanks to Malcolm Daly of Great Trango Holdings Inc for factual corrections.