The Naval Architects: April 2020
A common criticism of the maritime industry is that it lags behind other industries when it comes to workflows and upgrading to new technologies. It’s a problem compounded by the many different CAD tools in use, which have to be carefully, but laboriously, converted before a design’s safety can be properly assessed for finite element (FE) analysis.
So a tool that can automate that process and take a model from almost any CAD system and simplify the meshing process has an invaluable role to play. That was certainly the view of class society DNV GL, which in February announced it was entering a strategic partnership with MSC Software to connect workflows using its Sesam structural and hydrodynamic analysis software with those of MSC Apex. The partnership will see DNV GL sell MSC Apex as a tool for translating from CAD to CAE.
First launched nearly six years ago, MSC Apex has evolved considerably, according to Stefan Tynelius, Apex business development specialist at MSC Software. “The first release of MSC Apex focused on the CAD-to-Mesh process based on its strong geometry and meshing tools. Over the years we have built out MSC Apex to a full-blown pre and post processor, with its own built-in solver, while continuously strengthening the geometry and meshing tools.”
Tynelius, naturally, thinks there are a number of things that make MSC Apex unique, but draws particular attention to the thought and energy that went into developing a tool that is both intuitive and easy to learn. “In fact we’ve received several awards for the MSC Apex GUI [graphical user interface] and its ease of use.”
Because Apex can import most CAD formats it removes the need to invest in additional translators. Another innovation is its Python based scripting, which makes it possible to automate and speed up workflows.
“Whatever new functionality we implement, we set a goal to ourselves to make the workflow 10 times more efficient than how it is done traditionally. This shows particularly well in our geometry tools and methods, which is often the key driver for new users,” says Tynelius.
Although MSC Apex is only just starting to make inroads into maritime, it represents a small but growing sector that builds upon its larger uptake by the aerospace industry. “Interestingly enough, a ship and an aero structure, for instance a fuselage or wing, are designed and analysed with very similar methods. Both structures need to be stiff yet weight efficient and, in addition, its panels need to resist buckling under pressure.”
Starting with an existing 3D CAD, which are often both large and very detailed, the geometry tools allow the user to idealise a detailed CAD to the right level, conforming with the strict modelling guidelines prescribed by classification rules.
As such, it dovetails with the functionality of DNV GL’s Sesam platform. “Sesam is used to show compliance of the structure with the design rules, in this case particularly the Common Structural Rules for Bulk Carriers and Oil Tankers, DNV GL Ship 1A and Offshore rules. Based on FE structural analysis, the design is evaluated with regards to buckling, yield and design,” explains Ole-Jan Nekstad, Sesam product director at DNV GL.
“MSC Apex is a very powerful tool with great opportunities for automating and scripting the preprocessing of the CAD assembly, running in batch,” he notes, adding that the two companies already have a long-term relationship through their collaboration in the development of the Sesam Patran-Pre software for geometry and FE modelling.
“The first workflow we are targeting [under the new partnership] is the model generation and meshing phase, where the FE model is built and attributed (with material, beam property and thickness data) before applying the ship-specific loading in the Seasam/Nauticus Hull tools for further analysis and code check,” says Tynelius.
