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Background: Short carbon fibre reinforced epoxy composites have many advantages such as high strength-to-weight ratio, corrosion resistance, low cost, short fabrication time and easy manufacturing. Researches on the mechanical performance of the composites are mainly carried out by means of experimental techniques and numerical calculation. Objective: The study aims to report the latest progress in the studies of mechanical properties of short carbon fibre reinforced epoxy composites. Methods: Based on recently published patents and journal papers, the experimental studies of short carbon fibre reinforced epoxy composites are reviewed and the effects of short carbon fibre on the mechanical properties of the composites are discussed. Numerical studies using representative volume element in simulating macroscopic mechanical properties of the short fibre reinforced composites are also reviewed. Finally, future research of short carbon fibre reinforced epoxy composites is proposed. Results: Experimental techniques, experimental results and numerical simulating methods are discussed. Conclusion: Mechanical properties of epoxy can be improved by adding short carbon fibres. Fiber surface treatment and matrix modification are effective in enhancing interfacial adhesion between fiber and matrix, and as a result, better mechanical performance is achieved. Compared to the studies on equivalent mechanical properties of the composites, researches on the micro-mechanism of interaction between fiber and matrix are still in infancy due to the complexity of both the internal structure and reinforcing mechanism.

Coiled tubing (CT) is a joint-less long oil pipe that is wound around a reel and can be run and pulled continuously. Due to the particularity of the operating process, low-cycle fatigue (LCF) failure of the CT constitutes the main production cost. Aiming at the characteristics of small diameter and thin wall of CT, a single-edge-notched (SEN) arc specimen was designed and machined. LCF tests were conducted with force-controlled mode. Cyclic softening of the CT steel was presented and crack growing rates were measured. Meanwhile, finite element simulation was carried out to obtain the relationships among J-integral, crack size and load. Based on the experimental and numerical results, the speed of the LCF crack growth of the CT steel is expressed as an explicit function of the J-integral. It provides a basis for predicting the LCF life of the CT under working conditions from the perspective of crack propagation.

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