Production Balance of Ship Erection

A network plan model of ship erection was established based on the network planning technology and the work-package breakdown system. The load-oriented production control method was introduced to build up a throughput diagram model thus it is possible to describe the ship erection process numerically. Based on the digitalized models some cases of production balance of ship erection were studied and three balance indexes were put forward, they are the load balance rate, the input manpower balance rate and the maximum gantry crane operating times. Such an analytic method based on the balance evaluation is the important foundation for digitization and intelligentization of shipyard production management.

Numerical Procedure for Static and Dynamic Analysis of Fluid-Conveying Submarine Pipeline Span on Linear Elastic Seabed

Based on the Hamilton principle,dynamic differential equation of the submarine pipeline span,under the interaction of internal flow and external environmental loads,is established. A constraint-equivalent method is used to deal with the boundary conditions of pipeline span on the linear elastic seabed. Effects of the internal flow velocity and seabed stiffness on the pipeline's lateral deformation and bending stress are studied by the static analysis,while the preliminary relationships between the internal flow velocity and the foundation stiffness to the natural frequency of pipeline span are investigated by the dynamic analysis. It is found that the lateral deformation increases with the increment of internal flow velocity,but decreases with the increment of seabed stiffness. The bending stress at the ends of span increases with the increment of internal fluid velocity and the seabed stiffness,however the stress at the middle of the span shows the converse tendency. Moreover,increasing the seabed stiffness or decreasing the internal flow velocity can lead to higher natural frequency. The dynamics response of midpoint of span at different foundations and internal fluid velocities are also given in this paper.

Energy Principle of Corrosion Environment Accelerating Crack Propagation During Anodic Dissolution Corrosion Fatigue

A general method to predict the crack propagation of anodic dissolution corrosion fatigue is developed in this paper. Crack propagation of corrosion fatigue is presented as the result of the synergistic interactions of mechanical and environmental factors, and corrosive environment accelerates crack propagation mainly in term of anodic dissolution. By studying the variation of mechanical energy and electrochemical energy of anodic dissolution during the crack propagation process, an explicit expression of crack propagation rate is derived by the conservation of energy. The comparisons with experimental data demonstrate the validity of the proposed model. Moreover, the applicable upper-limit crack length for steady crack propagation is determined and the crack propagation life is evaluated.