2.1.1: Mechanical Engineering
- Page ID
- 113076
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In mechanical engineering, modular design is valuable for extending the lifespan and flexibility of a product. However, it does involve trade-offs. Joints between modules, such as nuts, bolts, and welds, can become weak points and may fail over time. Shear stress and normal stress can cause damage to these components, leading to potential failures. In well-designed modular devices, bolts and screws often become weak points. Fasteners such as bolts usually have well-documented material properties, which engineers need to take into account when designing (1).
Consequently, it is important to weigh the benefits and drawbacks of each module and their interface during the design process, as it is rare for a product to consist of only one component. In the following pages, you will find two compelling examples of modular design, although many more can be encountered in your daily life.
Practical Examples
International Space Station
The International Space Station (ISS) was launched in 1998 as a joint project between the United States and Russia. It began with the launch of the Russian Zarya module in November, followed by the United States' Unity Node 1 in December. Since then, the ISS has expanded significantly, now boasting the same square footage as a 6-bedroom house (13,696 cubic feet). (2)
Over the years, 15 different space agencies have joined the program, including the European Space Agency (ESA) and Japan’s Aerospace Exploration Agency (JAXA). These agencies have contributed several modules, such as the Kibo laboratory, the U.S. Lab module, the Columbus lab, and the Canadarm—a robotic arm provided by Canada that helps guide spacecraft and attach new modules. Since 2005, the ISS has also functioned as the United State's newest national laboratory, a status maintained largely through the ongoing contributions of international partners. (3)
The ISS's modular design has been central to its growth and international collaboration. By allowing new modules to be added over time, the station has evolved far beyond its original scope, enabling continuous contributions from various nations. This flexibility has been crucial in sustaining and advancing the project.
Like many other examples of modular design, the ISS still has its issues. Over time, it has developed leaks. Astronauts need oxygen to live, and it is leaking out of the Russian portion of the ISS at a joint between modules. (4) When implementing modular design, it is important to not only install all modules correctly but also ensure that they are all high-quality. Incorrect implementation of modular design may lead to structural problems and increased maintenance costs if it is not implemented well.
Figure 3.3.2.1 The International Space Station (ISS) is in low Earth orbit, showcasing its large solar arrays and modular structure, with Earth’s atmosphere visible below.
Cars
Cars are an excellent example of modular design. A vehicle’s components can be replaced or serviced by a mechanic decades after being built. Modular design simplifies car manufacturing by allowing key components to be designed and tested separately. For example, the engine can be developed independently of the transmission, and the chassis can be designed separately from the powertrain. By developing components separately, companies are able to pool resources into different divisions and decrease the costs of developing any individual component. (5)
Modularity has also facilitated the rapid development of automotive technology. Tesla, for instance, started by heavily modifying the chassis of a Lotus Elise to incorporate electric motors and batteries (6). Companies like Ultima (ultima website here) and Pagani can source transmissions from other manufacturers, such as Porsche, to build functioning cars without investing millions in developing their own transmissions. Similarly, Volkswagen standardizes parts across its entire fleet, including brands like Audi and Lamborghini, drastically simplifying manufacturing, logistics, and costs. (7) In this way, modular design serves as a catalyst for many of the positive advancements in vehicle design.
However, while modular design has spurred innovation in the automotive industry, it does have its challenges. If a part is defective, the vehicle must be serviced, adding to the cost and complexity of ownership. Quality control issues during manufacturing can also lead to frequent repairs, negating some of the benefits of modularity.
Figure 3.3.2.2 A yellow Lotus Elise sports car parked in a lot, highlighting its aerodynamic design and signature round headlights with other cars in the background.
References:
(1) Miller, D. Bolt Strength & Failure. How Strong Are Nuts and Bolts? Fine Power Tools. https://www.finepowertools.com/hand-...bolt-strength/.
(2) NASA. International Space Station Facts and Figures - NASA. Nasa. https://www.nasa.gov/international-s...s-and-figures/.
(3) ISS National Laboratory. History and Timeline of the ISS. ISS National Laboratory. https://www.issnationallab.org/about/iss-timeline/.
(4) Garcia, M. NASA Provides Update on International Space Station Operations. blogs.nasa.gov. https://blogs.nasa.gov/spacestation/...on-operations/.
(5) Editorial. Understanding Modular Vehicle Architecture: Revolutionizing Design - Automotive Quest. The Insurance Universe. https://automotivequest.com/modular-...Implementation (accessed 2024-10-27).
(6) John Webber. Just how similar are the Lotus Elise and Tesla Roadster? Grassrootsmotorsports.com. https://grassrootsmotorsports.com/ar...esla-roadster/.
(7) Marriage, O. Rear-drive battle: Lamborghini Huracán RWD vs Audi R8 RWS. Top Gear. https://www.topgear.com/car-news/big...vs-audi-r8-rws (accessed 2024-10-27).