Study On The Method Of Ship And Platform 3D Parametric General Design

'General Design' is the determinants of ship and platform's performance, such as safety, functionality and economy etc. Currently, almost all of the ships and platforms are designed with traditional methods. Although traditional methods could ensure both functionality and safety of the products, problems exist such as lag in technology, low in efficiency etc. What's more, it is difficult to optimize the design scheme with traditional methods, which seriously affects both the cost and the operation economy of the ship and platform. Therefore, perfecting the design theory, improving the design method and increasing the design efficiency are of great importance to the engineering practice.The 3D parametric technology, which is widely used in the industrial design field, is able to improve the design efficiency and to raise the product quality significantly. However, there are very few applications of the parametric technology in ship and platform design field, and no systemic method has been proposed. The objective of this paper is to study how to apply the parametric technology in ship and platform design, and propose a systemic parametric design procedure. New methods based on 3D technology for the parametric design process are proposed to overcome the disadvantage of the traditional method. Those methods are as follows.A parametric hull surface design method is proposed, which expresses the hull with NURBS surface, and could accomplish the hull transform tasks with a uniform hull transformation function, such as global transformation, local transformation and UV degree transformation. The hull transformation function ensures that all design requirements are satisfied on the condition of hull surface fairness being unchanged. A 2D geometric constraint solving system is developed according to the characteristics of Theoretic Surface of Primary Structures (TSPS), which is able to complete parametric design of TSPS sketch. On the base of TSPS sketch, TSPS is created with 3D feature modeling.The floatation models and the tank models are expressed by two-layer parametric models, namely the outer model and the inner model. The outer model is consisted of TSPS, and the inner model is Boundary-Representation (BRep) solid model. The inner model is created automatically from the outer model. Hydrostatics and tank capacities are calculated based on the BRep model. A general stability calculation method base on BRep floatation model is presented, which calculates the righting lever with a direct iterative method. This method is applicable for both intact stability and damage stability calculation. The concept of stability surface is proposed as well as its creating method. The 3D stability of the platform is checked based on the stability surface.The structure model of ship and platform is created with parametric design method based on geometry constraint solving. A two-layer mesh generation method is developed, which is able to create the finite element model from complex parametric structure model for various finite element analysis. This mesh generator is very high efficient, and could generate fine mesh model with high quality. Two structure optimization methods, which are the shape optimization method and the plate thickness optimization method, are proposed based on the parametric finite element model. With these optimization methods, the structure strength is increased while the hull weight is reduced significantly.The ship and platform parametric design approach has the feature of dimension-driven, based on the unique database, feature modeling and top-down design procedure etc. The models created by this method are of great changeability and reusability, which make this method an excellent tool for variant design and series design. Softwares are developed in according with this method and were applied to the engineering practice, by which the engineering practicality of this method is proved.