Enabling quick, easy, reliable and efficient design iterations for custom bellow forming simulations

About the customer

Interlaken Technology Company (Interlaken), headquartered in Chaska, Minnesota, is an engineering firm specializing in systems and processes around material formability and hydroforming. Interlaken embraces virtual design validation, making extensive use of tools within the Simcenter™ software design and simulation platform to gain insight into part geometry, tooling surfaces and process development during forming.

Simcenter is part of the Siemens Xcelerator business platform of software, hardware and services.

Their challenge

Interlaken were awarded projects by aerospace original equipment manufacturers (OEMs) to develop processes and tooling for manufacturing bellows – accordion-like devices used often in rocket propulsion systems – from tubular stock. To ensure the production of high-quality bellows with minimal development costs and time, Interlaken needed to study the bellow forming process for various tool geometries, tool kinematics, process conditions and stock tube geometry and material. Doing this with physical prototypes would add several weeks to the development time and involve multiple iterations. To shorten this process and minimize physical prototyping, Interlaken sought leading computer-aided engineering (CAE) based simulation tools. Siemens was ready to help Interlaken meet their goals.

Figure 1. Interlaken’s bellows forming tool in Simcenter Hyperform.

Our solution

Together with Siemens, Interlaken set up a bellows forming process simulation comprising a multi-layered tube using Simcenter Hyperform software which is part of the mechanical solver package, Simcenter Radioss® software and Simcenter Hyperview™ software to visualize and analyze finite element analysis (FEA) results with a guided 3D workflow (figure 1). The goal of this analysis was to virtually validate the tooling design concepts in combination with process parameters that would produce bellows that met design tolerances after spring-back and were free from defects (like splits or wrinkles).

Interlaken was delighted with the Simcenter Hyperform virtual modeling capabilities, which showed the complex tool motion involved in the bellow manufacturing process (figure 2). With it, they achieved excellent correlation between physical tests and simulations when analyzing material deformation, thickness distribution, splits, forming pressure and spring-back after forming (figure 3).

Figure 2. Modeling of bellows forming process, complex tool kinematics and results in Simcenter.

Results

With confidence in the simulations from Siemens tools, the Interlaken team was able to iterate on several design concepts, optimize the forming process and compensate the tools for spring-back to manufacture high-quality parts – all while meeting design goals, minimizing costs and effort and speeding time to market.

“A key benefit of using Simcenter is the flexibility to create workflows that impact setup time for each simulation,” says Robb Bass, president of Interlaken. “After working with Siemens to develop the bellows setup workflow, Interlaken has seen a significant increase in simulation iterations.

“This has created a faster path to understanding the effects of adjustments made to tooling profiles or recipe variables. The team at Siemens and their tools have been a very valuable resource for us. “

Thanks to the open architecture and automation capabilities of Siemens tools, Interlaken could create a custom bellows forming tool. This sped the entire workflow from a day to few hours – even for bellows with more than 30 convolutes (a setup time reduction of 1,500 percent in the CAE process). Overall, Interlaken’s new bellow forming workflow helps engineers perform quick, easy, reliable and efficient design iterations for simulating bellow forming, increasing their competitiveness and propelling them into a simulation-driven mindset.

Figure 3. Comparison between simulation and production trials, showing individual ply deformation results in the bellows.