Design And Research On The Material And Connection Of The Bend Stiffener For Flexible Pipes And Cables

The bend stiffener,which is widely used in the field of marine engineering,has a good bending protection effect on the marine flexible pipes and cables.Previous work has a certain scale for the analysis and optimization of main structure of the bend stiffener,but the main structure's material design of the bend stiffener and geometric parameters design of the connection structure are not paid much attention.Optimized design for the main structure's material of the bend stiffener can reduce the volume of the bend stiffener and make it more economical.The study of the influence of bend stiffener's geometrical parameters of the connection structure on the performance of the bend stiffener can be used for the connection structure's design and analysis,and it can make the bend stiffener safer and more reliable in engineering applications.These studies are of great significance to the engineering application of the bend stiffener.In order to optimize the material of the bend stiffener,the enhancement effects of polypropylene,nylon,polyester and glass fiber on the mechanical properties of the polyurethane elastomer are compared.According to the test results,the long-fiber made of polyester is used as the reinforcing phase of the polyurethane elastomer,and the mechanical properties of the material of polyurethane reinforced by long-fiber made of polyester are studied.When the volume fraction of the long-fiber is 0.8%,it is found that the longitudinal elastic modulus can be increased by 26.8% by theory,numerical methods and tests.When the material is used in the bend stiffener,compared with the bend stiffener made of polyurethane elastomer,the volume of the polyester/polyurethane elastomer bend stiffener can be reduced by 6.5% under the same protective effect.The volume optimization of the bend stiffener can be realized.In order to improve the stiffness of the bend stiffener's material to a greater extent,on the basis of polyester reinforcement,chopped carbon fiber with a volume fraction of 0.3% is mixed into the matrix.It is found that the longitudinal elastic modulus of the carbon fiber/polyester hybrid reinforced polyurethane elastomer is 56.5% higher than the polyurethane elastomer by tests and numerical analysis.After applying this material to the bend stiffener,the bend stiffener made of composites can be reduced by 14.5% compared with the bend stiffener made of the polyurethane elastomer without reducing the performance of bending protection.The effect of volume's optimization of the bend stiffener is obvious.In order to analyze the connection structure of the bend stiffener,a finite element model of the bend stiffener including the connection structure is established.The finite element model is verified by the bending test.On this basis,the orthogonal text is designed to analyze the influence of five geometric parameters on the protection performance of the bend stiffener.The level of influence of the connection structure on the key performance indicators of the bend stiffener is obtained from the results of the orthogonal test,when the connection structure's geometrical parameters are changed.The finite element model and analysis method established in this paper have practical guiding significance for the design and analysis of the connection structure of the bend stiffener.