Study On The Topology Optimization Design Of Underwater Pressure Hull

As a innovative conceptual design tool, topology optimization method is adoptedbyengineeringdesignerstofndoptimalmateriallayoutundergivenobjectives(minimumcompliance) and constraints(volume of material or stress).In this work, the application of topology optimization to design of underwaterpressure structure is studied. With the innovation of advanced material, the optimalpressure structural forms under diferent work cases need further study. Convention-al optimization methods primarily concern the size optimization of stifener types andthickness or shape optimization under given topology. Conversely, topology optimiza-tion, which is a method to fnd optimal material distribution in design domain undergiven criteria,allows designers to obtain new layouts even those that cannot be predict-ed with experience.In topology optimization of underwater pressure structure, the pressure loadingsurface changes with intermediate topologies,thus leads to diference of loading con-dition and ultimate optimal results with prescribed loads. Therefore, identifcation ofloading surface in the optimization process becomes an important issue in solving thiskind of problem. Based on the fact that the intermediate layouts obtained by usingSIMP method can actually be regarded as grayscale images, the paper proposes a newimage segmentation techniques-based method to searching loading surface. The paperadopts the image boundary detection algorithm on the basis of level set method anddevelopts it to3D problems, which assures the topology optimization of3D pressur-ized structures. With the merits of level set method inherited, the presented methodbecomes more stable, more general and less dependable on experience of designers incontrast with conventional methods. Inthepracticaldesignofunderwaterpressurestucture,weneedtoconsiderfactorslike cost, material strength and reliability and so on. For the purpose of simplifcation,the paper mainly focuses on optimizing complicance of structure under given materialvolume. Since the structural hull of underwater pressure structure always stays identi-cal along axis, the plane stain assumption is frstly employed to study the problem withhydrostatic loads. The result obtained verifes the reasonability of cylindrical shell tobe pressure structure. With diferent displacement boundary conditions adopted, thepaperalsostudiespossiblepressurehullsusingaxisymmetricmodel. Theoptimizationresults demonstrate the method’s application value in design of multiple intersectingspherical hull. Finally, the paper studies3D solid model under hydrostatic pressureand obtains a spherical hull.The implementation of algorithm shows that the methodcan completely be utilized to fnd the optimal pressure hull under given design require-ments as long as appropriate boundary conditions are predefned. At the same time,reasonable calculated result futher cetifes the advantages of the proposed scheme intracking complicated loading surface.The topology optimization of2D continuum structure under local stress con-straints is investigated and the specifc details to implement are expatiated. Based onthe stability of the proposed loading surface searching scheme and its merit in dealingwithscatteredmaterialdistribution, thepaperalsostudiesthelightweightdesignofun-derwater pressure structure considering the strength of materials and obtains expectedresults.