Complete designs for moving structures and demanding tools, with code and certification requirements

For the welding of UHMWPE for a specific application, Huygens Engineers developed an assembly method and designed a mobile welder that involves very little labour. An extensive process was initiated for the preliminary design, and the strength distribution of the realised welds was carefully mapped.

Huygens Engineers designed a cutting machine for plastic modules. This machine uses various blades with very thin blades (with thicknesses of only 0.6 mm on average) in order to cut the plastic cleanly without material breakage. To prevent buckling of the thin steel, the blades are pre-stressed using a specialised holder. A very strong frame was required to position and clamp the blades. A pre-stress of 30 kN combined with a clamping tension of 300 kN causes the cutting force to reach an impressive 10 kN. The holder has five blades of various sizes, each with a different pre-stress. The blades are tightly prestressed and clamped using bolts. The prestressing tool is designed according to the poka-yoke principle: each part can only be inserted in one way, and all bolts can be tightened to the proper torque with a conventional torque wrench.

For the tidal turbines in the Afsluitdijk, Huygens Engineers designed a steel suspension structure. The construction could not be anchored in the existing, brick structure. We had to spread the forces to meet the local maximum pressure requirements of Rijkswaterstaat. As the turbines cause irregular loads, related to the rotational speed, their natural frequency plays an important part in the design of the frame. 

The client also wanted to investigate the damping phenomena caused by the water, for which they needed to be able to adjust the natural frequency of the suspension structure. We were able to vary the stiffness and therefore also the natural frequency thanks to a modular approach to the structure. Huygens Engineers carried out the entire project, from concept design to delivery. We converted the design into 2D working drawings, sought and instructed suppliers for the hydraulics of the construction and were involved in the production process and installation.

A mobile handling and maintenance access tool was sought for the tidal turbines at the Oosterschel-dekering. These are 15-tonne turbines suspended beneath a site road and must be accessible for periodic maintenance work. In extreme cases, the turbines also require transport to a workshop. The space between the concrete elements makes it possible to get next to the turbines via a metal structure from a concrete upper beam. However, this same tight space also imposes significant limitations on the maximum size of the metal beams of the mobile hoisting structure.

For this, Huygens Engineers created the concept and detailed design for a foldable tool that can reach, hoist and transport the turbines. This metal tool is compact enough to be transported by a single truck. As the local force on the concrete structures during the hoisting must remain within specific limits, the tool rests on the arm and suspension structure of the turbine on one side and on the upper side of the concrete structure on the other side. The turbine can be lifted using a winch and pulleys attached to an overhead beam of the tool. 

The structure was designed in compliance with the EN codes for cranes. All requirements for tension levels and safety factors were met. We validated the structure via FEM in various load scenarios to demonstrate that it meets safety requirements. In addition, after careful consideration for ease of use, we worked out the design into workshop drawings. The tool can be stored in the hall of the workshop.