Study On Crashworthiness Of High-speed Catamaran

Against the background of frequent collision accidents on catamaran passenger ferries,it is necessary to conduct collision performance research and structural optimization on this type of ship to improve its crashworthiness.In this thesis,a typical high-speed catamaran structure is modeled as a prototype,and the finite element numerical simulation method is used to study the bow collision performance of the catamaran and make structural optimization,in order to improve the collision resistance of the ship type and reduce casualties and property losses in collision accidents.The research results can fill the gaps in the research on collision performance of catamarans,and provide a reference for further research in the field of collision of catamarans in the future.The main research content of this article is as follows:(1)Summary of nonlinear finite element theory and key technologies for simulation of ship collisions.This thesis systematically elaborates on the basic theory of finite element method involved in numerical simulation of ship collisions,including nonlinear finite element problems,nonlinear finite element control equations,and explicit finite element solution methods.Introduced the key technologies of ship collision simulation in finite element simulation software,including numerical simulation calculation methods for ship collision,time step control,hourglass control,contact algorithm,friction algorithm,material constitutive model,etc.(2)Study on dynamic response and crashworthiness of high-speed catamaran in collision.Taking the high-speed catamaran passenger ferry as the prototype,the finite element simulation model of side collision between catamaran and large ship is established.Using the nonlinear finite element software ANSYS/LS DYNA,the dynamic process of catamaran impacting the side of a large ship at different speeds and angles is numerically simulated.The collision damage forms and damage characteristics of catamaran bow and connecting bridge structure are mainly studied,and the dynamic response characteristics of catamaran under different impact speeds and impact angles are obtained.Due to the particularity of catamaran structure,the structural response and damage mechanism of catamaran are different under different impact angles.(3)Optimization design of crashworthiness of high-speed catamaran.The crashworthiness of catamaran is optimized from the aspects of structural improvement and hull material improvement of catamaran.Design the structural crashworthiness of the bow and the entire ship through structural design and new material design,and compare the numerical simulation results before and after optimization to demonstrate the effectiveness of the optimization plan in improving crashworthiness.The results show that the crashworthiness of the catamaran with improved structure and materials is significantly improved compared with the original scheme.(4)Based on rigid body dynamics,the rotation of catamaran in oblique collision is studied.Taking the oblique collision between a catamaran and another large ship as the prototype,based on the theory of rigid body dynamics,this thesis studies the rotation of a catamaran in collision,and proposes an approximate calculation model for the closing speed of a piece of the catamaran on the side that is not directly impacted to the large tonnage ship during the "secondary collision",which provides a theoretical basis for the study of the "secondary collision".The proposed calculation model was validated through finite element numerical simulation to ensure its reliability.