Strength analysis of composite cables

Felipe Ferreira Luz,Carlos Alberto Cimini Jr,Sandro Campos Amico,Eduardo Antonio Wink De Menezes,Laís Vasconcelos Da Silva

doi:10.1590/1679-78254177

Abstract

Abstract Carbon Fiber Reinforced Polymer (CFRP) cables, due to their outstanding performance in terms of specific stiffness and strength, are usually found in civil construction applications and, more recently, in the Oil & Gas sector. However, experimental data and theoretical solutions for these cables are very limited. On the contrary, several theoretical and numerical approaches are available for isotropic cables (metallic wire ropes), some of them with severe simplifications, nonetheless showing good agreement with experimental data. In this study, experimental tensile results for 1×7 CRFP cables were compared to a simplified analytical model (assumed transversally isotropic) and to a 3D finite element model incorporating the experimental uncertainty in important input parameters: longitudinal elastic modulus, Poisson’s ratio, static friction coefficient and ultimate tensile strain. The average experimental breaking load of the cable was 190.25 kN (coefficient of variation of 1.74%) and the agreement with the numerical model predictions were good, with an average-value deviation of –1.15%, which is lower than the experimental variations. The simplified analytical model yielded a discrepancy above 10%, indicating that it needs further refinement although much less time consuming than the numerical model. These conclusions were corroborated by statistical analyses (i.e. Kruskal–Wallis and Mann-Whitney).

Highlights

Carbon Fiber Reinforced Polymer (CFRP) cables present high stiffness-to-weight and strength-to-weight ratios, damping capabilities and high resistance to environmental degradation (Adanur et al, 2015), being natural candidates for harsh environments such as offshore applications
These results for longitudinal elastic modulus, Poisson’s ratio and ultimate tensile strain for the single rod are in agreement with others studies using similar rods for cable structures (Adanur et al, 2015; Meier, 2012; Cai and Aref, 2015; Wang and Wu, 2010; Schmidt et al, 2010)
Experimental tensile testing was conducted in 1×7 CFRP cable specimens resulting in average breaking load of 190.25 kN

Summary

Introduction

Carbon Fiber Reinforced Polymer (CFRP) cables present high stiffness-to-weight and strength-to-weight ratios, damping capabilities and high resistance to environmental degradation (Adanur et al, 2015), being natural candidates for harsh environments such as offshore applications. While the cost of composite materials is generally greater than that of traditional structural materials, their extended life leads to reduced long-term costs (Fabbrocino et al, 2016). Other benefits include low energy consumption during manufacturing, construction and execution processes (Dhand et al, 2015; Son et al, 2013; Wang and Wang, 2015). CFRP cables are traditionally manufactured by pultrusion using epoxy resin, allowing the use of long fibers and high fiber volume fraction. According to Meier (2012), Meier et al (1982), Meier (1992) and Rohleder et al (2008), in order to encourage the use of composite cables in structural applications, it is necessary to fully study and understand their behavior, which could be translated as evaluating analytical solutions, constructing numerical models and executing experimental tests. There is very limited experimental data in the literature for these cables and theoretical solutions still require further development

Methods

Results

Conclusion