Research On Design And Fatigue Reliability For AUV Underwater Storage Cabin

With the rapid development of marine science,underwater equipment has been paid more and more attention by countries all over the world.Autonomous underwater vehicle(AUV),as a flexible and highly intelligent underwater operation equipment,plays an important role in the exploration and development of marine resources.However,the energy which AUV can carry is limited,resulting in a small operating range.Usually,the AUV needs to be recovered from the water surface again,and the next operation can only be carried out after the energy replenishment and information exchange are completed.This method reduces the working efficiency of AUV,and there are still problems such as poor safety and high cost of AUV water surface recycling and deployment.If the AUV completes the above process in the underwater storage compartment,the work efficiency of the AUV can be greatly improved.Common underwater storage compartments are generally open storage,and AUVs are in direct contact with the marine environment.This storage method has higher requirements on the design of charging schemes and information exchange schemes,and the marine environment is more complex.AUVs are stored in this way for a long time,it may be damage to the AUV hull.In this paper,the following research work is carried out to solve the above problems.According to the working requirements of the AUV underwater storage cabin,the cabin structure,cabin door opening and closing mechanism,cabin door locking mechanism,cabin door and end cover structure,cabin door pressing mechanism and cabin door sealing structure of the AUV underwater storage cabin in this paper were presented.The scheme demonstration and design were carried out,and the strength simulation and sealing simulation of the related structures were carried out.This paper also designed the filling and draining circuit and the air pressure circuit to realize the dry storage of AUV under water.In order to ensure the structural stability of the AUV underwater storage cabin,this paper studied the effects of different forms of frames and different ribbing methods on the stability of the cabin.At the same time,this paper proposed a non-uniform rib method with non-equal spacing and non-uniform stiffness.Compared with the traditional non-uniform rib method,this method improved the stability of the cabin more obviously.In order to ensure the service life of the AUV underwater storage cabin,this paper studied the low-cycle fatigue life of the AUV underwater storage cabin.The crack initiation life and crack propagation life of the AUV underwater storage cabin were calculated by the modified local stress method and Paris theory,and the finite element simulation was carried out with fatigue analysis software.And this paper studies the effects of material properties,cabin geometry and initial crack parameters on the low-cycle fatigue life of the AUV underwater storage cabin.In order to ensure that the AUV underwater storage cabin can work safely and reliably,this paper studied the reliability of the AUV underwater storage cabin based on the fatigue failure mode and stability failure mode.In view of the fatigue failure and stability failure of the cabin,this paper used the Monte Carlo method and the first order second moment method to analyzed and calculated the reliability of the AUV underwater storage cabin,and studied the effect of random variables on the reliability of the AUV underwater storage cabin.