A Synthesis Analysis Of Stability Of Structures Of Grillage And The Design Of Its Program System

The stability of a ship's structure is an important problem in the design of a ship's structure. The structure of grillage is the backbone of a ship's structures and its compressive ultimate strength is one of the main parts in the strength analysis of a ship's structures. So it's important to make a deep research into the compressive ultimate strength of the grillage structure.After summarizing the results of former researchers,some analyses are separately performed for all kinds of buckling modes of the grillage structure. In the analysis of the elastic local buckling strength of the plates in stiffened plates,an analytical expression is derived for calculating the local strength of a stiffened plate subjected to biaxial thrust considering plate/stiffener interaction and welding residual stresses and initial deflection. Then a series of buckling strength analyses are performed to investigate the combined effects on the elastic local buckling strength by using this method and some useful conclusions can be drawn.In the analysis of the elastic local buckling strength of the stiffener's web,the elastic critical stress is analytically derived by solving the characteristic value problem involving the governing differential equation under the corresponding loading and boundary conditions .In the analysis of the elastic tripping of the stiffener,the critical stress under this mode of failure is derived by using the energy method and the principle of least potential energy.In the analysis of the elastic overall buckling of stiffened plates,attention is focused on global buckling,and local buckling effects are neglected. By using a simplified direct energy approach together with Marguerre's plate theory and some appropriate hypothesis,a simple closed-form solution is found.In a summary,a simple method of determining the ultimate strength of ship deck structures under inplane compressive loads is developed by analyzing and discussing the modes of failure . Finally,a program system is developed in FORTRAN language by using this simplified method to analyse the stability of grillage structure of deck. In comparison with FEM method,this simplified method has engineering accuracy and can be used in the phase of design.