Design And Verification Of The Bend Restrictor's Bending Stiffness Of Flexible Pipe And Cable

The bend restrictor is a common accessory which is installed outside the flexible pipe and cable to protect them from bending failure by adding extra stiffness,so bending stiffness is the core design index of the bend restrictor.With the accelerating development of offshore resources,the demand for flexible pipe and cable,the key equipment of offshore resources development,is increasing,and the design efficiency of bend restrictor is increasingly unable to meet the engineering requirements.In order to solve this efficiency challenge,it is necessary to study the bending stiffness of the bend restrictor from three aspects of structural stiffness analysis theory,design process and verification method.Based on Euler-Bernoulli beam theory,the overall pure bending beam model of bending stiffness of the bend restrictor is established.Then,the plate bending theory and Hertz contact theory are used to establish the bending model of the local locked structure.Finally,the two are combined to obtain the bend restrictor theoretical model of the bending stiffness.The bending stiffness theoretical model of the bending device,through the theoretical model,it is possible to intuitively understand the effect mechanism of each parameter on the bending stiffness of the bending device.The theoretical model is further used to obtain its semi-empirical solution form,and based on an example of a bend restrictor,finite element is used to verify the rationality of the assumptions in the theoretical model of the bending stiffness of the bend restrictor.It can be seen from the analysis results that the maximum relative error between the semi-empirical solution and the finite element analysis is only4.05%,and the calculation efficiency is more than 120 times that of the latter,which fully verifies the accuracy and efficiency of the semi-empirical solution of the established bending stiffness theoretical model.Based on the theoretical model,explore the influence trend of the four parameters of male end height,female end thickness,effective section length,and material elastic modulus on the bending stiffness of the bend restrictor,and then use the orthogonal experimental analysis method based on finite element to carry out quantitative analysis To be supplemented and verified.Then,according to the geometric relationship of the bend restrictor and the influence of the main parameters on the bending stiffness,the design process of the bending stiffness of the high-efficiency bend restrictor with more detailed design steps and more reasonable design sequence is given.Finally,based on the cantilever beam stiffness test method in the structural mechanics experiment,a simple and efficient cantilever beam structure bend restrictor experimental verification method that only needs to measure the structure deflection and concentrated force is proposed.Using this method to test three sets of bend restrictor s with different mating surface positions,the maximum relative error is 2.42%;and because the position of the mating surface of the bend restrictor is random in practical applications,the assembly direction of the mating surfaces of the two half-bodies can be ignored when engineering calculations or experimental verification of the bending stiffness of the bend restrictor.Then,the maximum value of the average relative error of each group of experimental results,the finite element numerical analysis results and the theoretical semi-empirical solution results is2.32%,and the maximum value of the maximum relative error of each group of experiments is 3.80%,which further proves The accuracy of the two analytical methods.