Abstract

A flexible pipe consists of several layers which have various materials and different functions. For a new design of flexible pipe, the structural response on external loads will vary depending on the characteristics of each layer. In order to compute the behavior of flexible pipe, a cross-section analysis is required. Theoretical, numerical, and experimental approaches can be used.

The prototype test is most reliable way to find the characteristics and strength of flexible pipe, and it is mandatorily required in most of applications. From experiments, failure mechanism and utilization of stress in each layer against tensile loads can be evaluated. However, it is limited in the number of tests due to the cost and the capacity of instrument.

The theoretical and numerical methods are efficient to the new flexible pipe design, and many previous researchers demonstrated that those give reliable solutions.

In order for prediction of the ultimate tensile strength, the non-linear material property of all layers should be considered. However, application of the non-linear material to the theoretical analysis of flexible pipe can rarely be found.

In this paper, a theoretical model using an equivalent orthotropic shell is developed considering the non-linear material of tensile armour in order for the assessment of the ultimate tensile strength of flexible pipe. Comparatively, FE models are also developed considering all contacts between layers and nonlinear materials for each layer. The 2.5? ID flexible pipe provided in the previous research is used for both models. From the comparative study, both results show good agreements with respect to the elongation and equivalent stresses depending on the tension. Similar ultimate tensile strengths of the flexible pipe are obtained.

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