Increasing the component’s fatigue life by a factor of four while reducing the seam weld’s length by 3.5 meters

Background information

In modern passenger transport systems, flawless operation, comfort and safety are key engineering criteria for design. To guarantee these key performance indicators (KPIs), demanding fatigue tests are performed to ensure a component’s performance and strength.

Today, advanced simulation methods can help to achieve an optimal design and ensure that components meet even the highest safety requirements. Doppelmayr Group (Doppelmayr), a manufacturer of ropeways and innovative transportation systems for ski areas and urban areas, used Siemens Digital Industries Software’s solutions to analyze and redesign a structural component.

Using Simcenter™ Inspire™ software, Doppelmayr built a design that passed the safety test, and optimized the gondola station to be lighter, safer and more durable than requested. This case study demonstrates how Siemens’ solutions and support enabled Doppelmayr to develop with confidence.

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

About the customer

Doppelmayr is an international manufacturer of ropeways and innovative transportation systems for ski areas, urban transport, amusement parks and material handling systems. Doppelmayr was founded in 1893. By merging with the Swiss Garaventa AG in 2002, the Doppelmayr Group is now one of the world’s leading ropeway manufacturers. As of 2020, the group has realized more than 15,100 installations in 96 countries worldwide.

Since 2017, it has used Siemens solutions like Simcenter Inspire for the topology optimization of its design parts to reduce material usage and product weight, and to increase durability. More recently, Doppelmayr started using Simcenter Simsolid™ software to explore its designs and create structurally efficient concepts for large models and complex assemblies.

Their challenge

The Doppelmayr engineers had the task of optimizing a bracket of a Doppelmayr lift station building. Since the seam weld of this bracket had failed a critical fatigue test, it was necessary to improve the design of the component for increased strength and fatigue life of the connection.

The main challenge for the new design was to pass the critical fatigue test. This procedure tests the bracket by considering the maximum forces that can occur during ropeway operation, while measuring defined parameters like vibration and material strain. To meet the high-safety standards of the gondola transport system (the construction must withstand 100 Mio load cycles), Doppelmayr engineers had to find a solution that would enable them to realize high-precision components while considering material usage and manufacturing, time and budget constraints.

From previous successful projects, the team has already gained a lot of experience with Siemens solutions. With Simcenter Inspire and the expertise of Siemens engineers, the Doppelmayr team was confident they would achieve a weight-reduced bracket with increased lifetime and endurance to pass the critical vibration test.

Doppelmayr was able to create an optimal design of a lift station building bracket using Simcenter Inspire.

Our solution

Using test parameters, Doppelmayr engineers were able to create a full-scale simulation scenario. In the first step of the optimization process, the engineers specified the requirements of the new bracket design and generated the computer-aided design (CAD) model. As the initial tests revealed overstressing in one part, the aim was to redesign for better stress distribution and relocate the stress concentration outside the weld seams.

The original CAD data was then imported to Simcenter Inspire and the team defined both the external and internal clearance, design space and manufacturing method. After two iterations in Simcenter Inspire, the engineers were able to find the optimal design. The final design solution was a welded insert with a flame-cut profile and weld preparations. This ensured that the stress remained outside the weld seams, creating a better stress distribution and an increased lifetime.

Siemens enabled the Doppelmayr engineers to develop a multistep process, accurately predict the critical area of the first design that had failed the test and find the proper design modifications. Thanks to using Simcenter Inspire, Doppelmayr was able to generate an optimal design in a reasonable amount of time that met performance targets and was lighter than the original.

Left: The design with the overloaded area at the weld seams.
Right: The optimized design with welded inserts using Inspire.

Results

Thanks to optimization using Simcenter Inspire, the engineers were able to increase the lifetime of the seam weld while reducing the length of each component’s weld seam by 3.5 meters. As a result, the component passed the vibration test and the component’s fatigue life was increased by factor four – from fatigue limit design to fatigue cut-off limit. In addition to meeting the safety targets, Doppelmayr also reduced manufacturing time and costs by approximately 10 percent for the new design. Long-term results also include reduced maintenance costs due to the increased lifetime of the bracket.

“Thanks to working with Siemens, we are now able to accurately match our components to stringent quality and safety requirements,” said Philipp Schneider, head of the structural calculation department of Doppelmayr. “The experience we have gained by working with Siemens engineers will help us to continuously provide our customers with safe and comfortable transport solutions.”