Commercial building designs from today’s architectural engineering industry are growing ever taller and more elaborate. Currently the world’s tallest skyscraper is the Burj Khalifa in Dubai, UAE, standing at 828 meters (2,717 feet). This commanding height brings a unique set of engineering challenges, one being how to transport people efficiently from the ground floor to the top.
Most elevator systems raise and lower the elevator cabin by means of a motor-driven cable system installed at the top of the building. However, such systems generally afford a maximum ride length of 400 meters (1,312 feet)—just half the height of the Burj Khalifa, meaning passengers would have to board two, or possibly more, elevators to reach the top level.
ThyssenKrupp Elevator, a unit of ThyssenKrupp Corporation, is one of the world’s leading manufacturers of elevator systems, with annual sales of €6.4 billion and more than 50,000 employees at 900 locations. To meet the challenge of efficiently transporting occupants within the Burj Khalifa, the company’s design and engineering teams conceived and developed a novel design that uses electromagnetic drives attached to the frame of each elevator cabin for propulsion. This eliminates the need for roof-mounted cable systems and lets a single elevator traverse the Burj Khalifa’s full 800-meter height. In addition, it allows the elevator cage to move horizontally as well as vertically. But this new concept also brought new challenges, chief among them being that the cabin would not be able to carry as much passenger weight as a traditional elevator.
Working with Altair ProductDesign to lightweight the cabin design
To make the new cabin design as lightweight as possible in order to maximize loading capacity, ThyssenKrupp Elevator selected the Altair ProductDesign engineering services organization to explore methods and materials that could help minimize cabin weight, based on its recognized experience and expertise in removing mass from products in the automotive and aerospace industries.
ThyssenKrupp Elevator had developed two concept designs for how the electromagnetic drives would lift the cabin. The first was a “BackPack” concept that used an electromagnetic drive positioned on the rear of the cabin, lifting it by a support structure from underneath. The second was a “SideGuide” concept that used a frame built around the cabin with drives on the left and right sides to provide lift. ThyssenKrupp Elevator’s weight targets for both designs were extremely low compared with traditional cabin designs.
Using optimization technology to minimize weight
To achieve the required design targets, Altair ProductDesign developed a three-stage approach. In the first stage, the team performed a topology optimization study on the BackPack concept using OptiStruct, the design optimization solution within Altair’s HyperWorks suite of simulation tools. With the freedom to create a totally new design, the team specified the cabin’s physical “design space”—the areas of the structure where the software was free to remove material, and those where material had to remain as specified, such as the door guides.
Loading information—acceleration forces on the floor, occupants leaning on one of the walls, a person standing on top of the cabin, and the like—was gathered from ThyssenKrupp Elevator and entered into the software. OptiStruct then calculated the most efficient material layout for the cabin’s structure that would meet the design requirements. The results of the topology optimization study were then interpreted by Altair ProductDesign into a material layout that could be manufactured.
Exploring new material configurations
With the basic structure of the cabin defined, Altair ProductDesign moved to the second stage of the project, which was to investigate material thicknesses in search of further opportunities to minimize weight through use of different material configurations.
The walls of elevator cabins are usually made of metallic sheet panels, but Altair and ThyssenKrupp Elevator wanted to explore the lightweight potential of sandwich-panel structures wherein aluminum or plastic facing sheets are used with a foam core. Again using OptiStruct, the team performed a sizing optimization exercise wherein the technology explored the thicknesses of the wall facing sheets and foam core. Profile sections and sheet thicknesses were optimized at the same time to find the ideal layout for the various material combinations.
The third stage of the project involved exploring new materials. Altair ProductDesign has considerable experience working with carbon fiber in automotive and aerospace, where the material is gaining traction as a lighter-weight alternative to metals. To explore its potential for the walls of the new elevator cabin, the team developed an optimization study to find not only the ideal material thickness but also the ideal fiber ply shapes and lay-up orientation of each layer. The same process was applied to the SideGuide concept, with the aim of providing detailed results to ThyssenKrupp Elevator to inform its decision on which of the two systems to select for further development.
Achieving weight and performance targets
The weight reduction project delivered dramatic results. The concept optimization process on the BackPack structure, in combination with the sizing optimization of the sandwich panel walls, yielded a cabin that was 42% lighter than the target weight. If the walls were constructed from carbon fiber, it would be possible to go even further, down to 56% below target. The SideGuide concept also saw weight savings—16% lighter than target using traditional materials, with the potential to reach 33% under target using carbon fiber.
These weight savings gave ThyssenKrupp Elevator added confidence that its electromagnetic concept is a practical alternative to the traditional cable system. Motivated by the positive results from this project, the company is continuing development of its BackPack concept, and has now advanced this design for further testing and prototyping.
About Altair ProductDesign
Altair ProductDesign is staffed by an integrated team of 800+ people across more than 45 offices worldwide. “Together, we break the boundaries of engineering and design,” the business says. “From concept to execution, or at any stage of your product lifecycle, let Altair ProductDesign offer our expertise.”
- Product development—Design and analysis support from the component level up to complete product engineering at any stage of the lifecycle.
- Industrial design—End-to-end product development, strategy and design services, all under one roof.
- Workflow automation—Increasing engineering efficiency by creating customizable process flows that automate CAE tasks.
- Staffing services—Supplying engineering and IT resources onsite and offsite at all skill levels.