Reliability Research And Structure Optimization Of Underwater Pile Gripper

As a kind of underwater special equipment,the underwater pile gripper plays an important role in the construction of the offshore platform.The underwater pile gripper is mostly used for the construction of the offshore platform of the jacket.The platform generally has four legs with one device installed on each leg.After the pipe pile is leveled,the underwater pile gripper clamped pipe piles in order to ensure that the horizontal and vertical position of the pipe piles are not changed.In China,there are not any underwater pile gripper products with independent property rights.This technology has long been monopolized by foreign countries,which hampers the development of offshore oil industry.The research subject of this paper is "Industrial Pile Grippers Industrialization Research".The project focuses on the reliability of underwater pile grippers.The purpose is to develop underwater pile gripper products with independent property rights and to promote Chinese offshore oil equipment related to the exploration,and the mining industry can be developed rapidly with the technology no longer controlled by others.The present research aims to reduce the costs of marine development.Based on the reliability of underwater pile gripper system,a study on the relationship between the reliability of underwater pile gripper system and component reliability is carried out.Meanwhile,the reliability value is used as an indicator to evaluate system reliability.In view of the requirements of relevant design specifications,the reliability of the preliminary design of the underwater pile gripper system does not meet them.Therefore,the reliability optimization design of some key parts of the underwater pile gripper is implemented.After optimization,the system reliability has been improved and the design meets the requirements.Experiments are performed on the testing machine of the underwater pile gripper developed by the optimized design data,which has verified the relevant performance.The components of the underwater pile gripper system are connected in series.Therefore,in order to study the reliability of the underwater pile gripper system,it is necessary to know the reliability of many components that make up the system.Most hydraulic components are selected only based on the pressure requirements.The reliability is available from the service data provided by the supplier.However,the reliability of the self-developed component-frame ring and the jaw-is unknown.Therefore,it is necessary to carry out reliability research on the frame ring and the jaws,from which the reliability of the system is finally obtainned.The factors affecting the reliability of components are environment,parameters and so on.Therefore,it is necessary to study the force in order to determine the reliability of the frame ring and the jaws.When the underwater pile gripper is working,the jaw is extended to clamp the pipe pile.By establishing a force model diagram,the friction relationship between the jaws and the pipe pile is determined,with the equivalent friction coefficient is 1.2.Then the force analysis of the frame ring is carried out to determine the optimal design result of the number of circumferential openings in the frame ring.The number of circumferential openings in the frame ring is that of hydraulic cylinders.According to the optimization results,it is known that 12 hydraulic cylinders are arranged circumferentially in the frame ring.When the underwater pile gripper is working,the environmental load is mainly the wave force load.Therefore,the wave force is calculated to determine the environmental load of the frame ring and the jaw.After the mechanical calculation is completed,the reliability calculation is performed on the underwater pile gripper.The reliability is calculated by the response surface method,and then the reliability calculation is conducted by the verification point method.When the reliability index of the frame ring and the jaw is obtained,the reliability of underwater pile gripper is calculated.Therefore,the reliability of the preliminary design system is 0.9813.It is found that the reliability of the underwater pile gripper system does not meet the engineering requirements.Therefore,reliability-based optimization of frame rings and jaws is required.Finally,the system reliability is 0.99877,which meets the requirements.The validity of the optimization results is verified by finite element analysis.To verify the accuracy and effectiveness of optimization design of the frame ring and jaw,the field experiment is carried out in this paper.The experiment is divided into the hydraulic cylinder pressure holding test,the jaw clamping capacity experiment and the frame ring carrying ability experiment.The frame ring and the jaws used in the experiment are all manufactured according to the design parameters before and after the optimization presented in the paper.The experimental process was certified by CCS.The experimental results show that the content of this paper is correct,and the performance of underwater gripper products meets the product requirements.