Auto­mated Solid Gen­er­a­tion for Struc­tural Analysis at MTU Friedrichshafen

Some time ago, our customer MTU Friedrichshafen (the core entity of Rolls-Royce Power-Systems) approached us with a very inter­est­ing request. They design large tur­bocharg­ers for diesel engines, and they use CAESES® for the design of volutes and other engine com­po­nents. Some of their impeller designs were created by applying NUMECA software. In NUMECA Auto­blade, such a model can then be exported using an ASCII format (*.vda), which basi­cally contains point data for the merid­ional hub and shroud contours and the blade geometry. What they needed now was a very quick, single-click solution to create a solid body from this ASCII file, in order to conduct struc­tural analysis for the impeller. The status quo had been that they already tried to semi-automate this process in a tra­di­tional CAD software. However, this step-by-step approach took them roughly 30 minutes for each design. The goal was to take this ASCII file and offer a fast and robust one-click solution in CAESES® to generate a solid body from this point data. The fol­low­ing screen­shot shows a typical vda-file, which was our starting point:

In general, a CAESES® user can define custom methods and func­tions, to read in and to parse files. For this purpose, so-called feature def­i­n­i­tions are used. Basi­cally, this is some kind of intu­itive script­ing envi­ron­ment where all CAESES® commands are avail­able. We created a feature that opens the ASCII file, reads in the data and creates curves and surfaces from it. Here is a code snippet of this feature definition:

Feature def­i­n­i­tion to read in and parse the ASCII file[/caption] The only input for this feature is the ASCII file, which is set in the user inter­face of CAESES®. By clicking on the ​“import” button in the next step, the entire data gets loaded into CAESES®. Here is a screen­shot of the user interface:

The first version of this feature code was ready in about an hour, and we were able to visu­al­ize the impeller data. This is shown in the next screen­shot. In a second iter­a­tion, we further fine-tuned this setup by setting specific colors, and we imple­mented an auto­matic split­ting of the leading edge region (to identify the leading edge location).

Imported impeller data based on the ASCII file content[/caption] In prepa­ra­tion of the upcoming solid model, we addi­tion­ally created surfaces for the hub and shroud, as well as some kind of trailing edge that can be cut-off later on. This geometry can be simply written into the same feature def­i­n­i­tion by adding the cor­re­spond­ing creation commands. As a result, this geometry gets also auto­mat­i­cally gen­er­ated when clicking the ​“import” button.

Addi­tional surfaces that are used for creation of a solid body[/caption] The final step was to create the solid body for which we used a so-called BRep object in CAESES®. This object takes surfaces or solid bodies, and applies a set of oper­a­tions such as Boolean oper­a­tions, inter­sec­tions and fillet gen­er­a­tion. We added the blade as well as the hub and shroud surfaces, and applied several oper­a­tions. Here is a screen­shot of the BRep interface:

The result of these oper­a­tions is shown in the fol­low­ing picture — it is the geometry that is used for struc­tural analysis. We colored all the surface patches dif­fer­ently, which is then auto­mat­i­cally detected and used in the external sim­u­la­tion software.

For the MTU engi­neers, this is now a single-click solution which saves them quite a lot of time. They simply choose a vda-file, click the ​“import” button and wait for a couple of seconds. That’s it. Finally, we imple­mented addi­tional controls that are not covered in the ASCII file, such as the bottom plate thick­ness and shape, as well as the shaft diameter. For us, this was a very inter­est­ing and untyp­i­cal CAESES® task – thanks to MTU for allowing us to publish this work.

“This amazing CAESES® setup saves us a tremen­dous amount of time, as well as tedious manual work! Thanks a lot to the guys of FRIEND­SHIP SYSTEMS.” — Friedrich Fröhlig, Tur­bocharg­ing and Fluid Systems, MTU Friedrichshafen (Rolls-Royce Power-Systems)

More Infor­ma­tion

Check out the quick guide about geometry script­ing. The use of features where the entire command set of CAESES® is avail­able gives you a powerful envi­ron­ment for custom tasks. Inter­ested in what else you can do with CAESES®? Then check out the product pages or drop us a line if you have questions.