What is structural engineering?
Structural engineering lies at the very heart of every vessel. When a client comes to us for a design for a vessel with particular capabilities, it is the structural engineers who calculate the loads that the weight and layout of the vessel and its equipment will generate. They also determine the structure of the hull and internal reinforcement to create a safe and effective ship. In short, it must be strong and stiff enough to fulfill its function and be fully Class-compliant.
What our engineers say
Main construction plan
At C-Job, the starting point for our structural engineers on a new project is the general arrangement (GA) drawn up by their naval architect colleagues in the initial design phase, showing the dimensions and internal layout of the ship and where its equipment and machinery will be placed. With this global viewpoint, the structural team can start with the main construction plan starting with the main cross-section and establish the optimal spacing of the frames and proceed with the structural calculations to ensure that the vessel has all the strength it needs in the places that need it without being excessively heavy.
With the completion of the main construction plan for Class-approval package, the detail design can get underway. The engineering team produces a detailed construction plan into an as-built ready package that includes production information and cutting files for the shipyard.
Finite Element Analysis (FEA) is one of the most important tools in the structural engineer’s toolbox, validating as it does the construction geometry through the analysis of stress throughout the structure. To achieve this the geometry of the vessel is split into very small sections, each of which is then exposed to a range of forces under different simulated conditions and the results quantified. As a process, it involves repetition on a grand scale, making it ideal for automation. By using FEA, the process is fast, accurate, and, to the benefit of the client, cost-effective.
Another recent innovation at C-Job has been our work on vibration assessments, with the goal of identifying and preventing excess resonance. This can be damaging both to the vessel and the people on board it. Thanks to a holistic approach of simultaneously addressing the source, the pathway, and the receiver of the vibrations, a lasting solution can be designed and implemented. Vibration assessment, with FEA used for the more complex structures, now also forms part of the structural design process at C-Job, as does the related fatigue assessment. As fatigue can have a major impact on the lifespan of any vessel, the identification of stress cycles can be used to optimize the structural design and specification of the steel used in key places on board.
Specialized software tools
Specialized software tools available to the C-Job structural engineering team include 3D modeling, AutoCAD, and CADMatic. The ability to use software to automate the many calculations that structural engineers have to make regarding the large and complex structures that they are designing has transformed their work in recent decades. Automation speeds up what is a highly repetitive process and reduces the cost of doing so.
R&D: buckling tool
Another useful software tool, developed in-house by C-Job, is its buckling tool. This analyzes the proposed metallic structures and materials to be used in the build of the vessel to establish the points at which they will fail. One of the failure modes assessed is buckling. This was done in response to clients’ seeking certainty that their designs are compliant with the standards laid down by the classification societies at an early stage in the design development process.
Its strength is that it generates information about the stresses on each elementary plate panel and further calculates the buckling capacity of each of the panels, be they unstiffened or stiffened. With these results, a global, color-mapped 3D FEM model can then be created that identifies those areas more susceptible to buckling as well as areas that are actually underutilized. This enables the faster optimization of ship structures and the minimization of weight with all its resulting benefits without any compromise in the structural integrity.