Liftra Designs ‘Climbing Crane’ for Wind Turbine Installation 5X faster

Challenges

Traditional cranes are large and expensive, requiring a fleet of trucks to move the crane to the site and between installation areas on a wind farm. In designing a smaller “climbing” crane that would take up less ground space and require just one truck to move to the next installation site, Liftra engineers needed to be able to ensure that the tower elements would not be crushed by the applied climbing forces, including the load on the tower and flanges, and the gripping forces.

Engineering Solution

Liftra engineers ran finite element structural simulations both in Ansys Cloud and on their own workstations to perform static simulations of the loads involved when a crane is attached to and climbs up the long tower of a wind turbine as it is being assembled. They ran both linear material models and nonlinear material models for elastic/plastic analysis of the towers to determine whether the crane would cause any permanent deformation to the tower, and, if so, how much. 

The linear material model was run in Ansys Cloud on an HC Virtual Machine of Microsoft Azure featuring 44 Intel Xeon Platinum 8168 processor cores. This model includes 1.8 million nodes with many nonlinear contacts (more than 100 frictional contacts). Using Ansys Cloud, the simulation was completed in 1 hour versus 5 hours on company workstations — a speed-up of 5X.

Benefits

• Finite element simulations confirmed that the LT1500 crane climbing the tower would not cause any deformation of the wind turbine tower.
• Being able to set up these large models to run as a single simulation on Ansys Cloud made for a better and safer design. Instead of splitting the analysis up into multiple simulations and calculating the interface forces, Liftra engineers were able to do everything in the same simulation.
• The best simulation setup was a combination of Ansys Cloud, Ansys Elastic Licensing and Liftra’s own licenses. With design offices in Spain and in Denmark, it’s very useful to be able to borrow licenses and avoid waiting until someone finishes a simulation before starting something new.
• A cost analysis revealed many barriers to Liftra maintaining its own on-premises cluster. These included maintenance costs, paying employees to manage the cluster, and the need for extra licenses. Using Ansys Cloud is less expensive while delivering higher computing power; they can run many parallel jobs with almost unlimited power.