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Metals in the 21st Century: Smarter, Lighter, Stronger

From inflatable steel to a microlattice lighter than air, metal innovations abound in manufacturing and design.

By Blaine Brownell

Metals Photo 1

Since the Industrial Revolution, materials such as iron and steel have been inextricably connected to images of hulking, and factories churning out parts elements for ships and skyscrapers. But these substances have evolved far beyond early manifestations. More than a century later, in 1960, architectural critic Reyner Banham wrote, "We have already entered the Second Machine Age, the age of domestic electronics and synthetic chemistry, and can look back on the First, the age of power from the mains and the reduction of machines to human scale, as a period of the past.” Now there is evidence that metal technology is undergoing yet another major shift-with profound consequences for future design and construction.

One transformation pertains to energy conservation. Steel is one of the most widely utilized and materials today, and its manufacturing represents about 12 percent of the world's energy consumption. One new method aimed at improving this situation originates from an unlikely source: Henry Bessemer, the British inventor of the process for mass-producing steel in the mid-19th century. Long before concerns about global warming arose, he realized there could be a much more efficient steel-making process than his original one, in which heavy ingots of steel required additional energy-consuming heating and forming.

In 1865, Bessemer patented an idea to cast steel directly into sheets between two water-cooled rollers. Unfortunately, the technique was too challenging to implement reliably at the time. Today, however, manufacturers like U.S.–wide Nucor are utilizing Bessemer's twin-roll process. Nucor's Castrip method can reduce the energy of liquid steel processing by up to 90 percent and reduce greenhouse gas emissions by up to 80 percent. Additionally, the Castrip process requires significantly less land area compared to conventional steel mills (50 acres versus 5,000 acres for an integrated steel mill). Now under license to large steelmakers such as China's Shagang, Castrip technology has the potential to improve the environmental performance of steel in fundamental ways.

Other manufacturing innovations concern lightweight fabrication. MX3D Metal, a process created by the eponymous Amsterdam-based company, combines a welding apparatus with an industrial robot to produce wire-frame constructions in mid-air. This system demonstrates that additive manufacturing can produce resourceful scaffold-based structures, as opposed to requiring many thick layers of material that other 3D printing methods necessitate. Since MX3D's invention in 2014, the company has continued its plans to construct the world's first 3D-printed bridge.

In another example, Polish designer Oskar Zieta has developed an inflatable steel of sorts for which thin sheets are welded at the edges and filled with air at high pressure. The technique enables the production of robust, biomorphic constructions that are incredibly lightweight while introducing a welcome element of unpredictability in the forms. "Normally, designers draw up a shape for a particular object and then attempt to adapt the technology to it," Zieta states in a promotional video. "In our case, we monitor the production process and the shape is the end result of this process."

Metals Photo 2

Due to the increased interest in lightweight components-particularly in the transportation industry due to concerns about energy consumption-robust frames are giving way to ultralight support systems. This phenomenon of dematerialization is illustrated best in examples such as the invention of nickel-phosphorous microlattice by HRL Laboratories, which is one of the lightest known materials. Composed of a multicellular structure reminiscent of a space frame, the substance exhibits a density of only 0.9 milligrams per cubic centimeter, which is lighter than air. Despite its ephemerality, the microlattice is stronger than conventional foam materials of the same density and can accept 50 percent strain before it deforms.

The microlattice approach, which replicates structural forms typically seen buildings and bridges in tiny materials, is evident in other recent inventions. For example, Charlottesville, Va.–based Cellular Materials International manufactures low density, high strength cellular-based materials with their MicroTruss bonding technique, an ultralight construction of various alloys for ballistic resistance and thermal management.

Metal applications are also becoming smart and responsive. Do|Su Studio Architecture in Rolling Hills, Calif. is known for its work with thermobimetals, which consist of two different alloys that expand at different rates. The firm's Exo installation is a thin-shell structure composed of interlocking thermobimetal strips. In addition to its novel form, Exo's ingenuity lies in its construction. The designers first heated the metal strips above their activation temperature of 350 F, holding them in their desired configuration while they cooled. Once below the activation point, the bimetal pieces locked together to create a unified assembly-essentially a pretensioned bow-beam-without requiring a single hardware connection.

Similarly, Rotterdam, Netherlands–based Studio Roosegaarde's Lotus installations are made of thin aluminum and Mylar smart foils. Constructed in dome and curved wall configurations, the surfaces respond to user proximity by opening their smart petals. These foils respond to the heat generated by interior lights that illuminate in the presence of visitors-enabling the wall to shift from closed to open states like a field of tropistic plants.

Collectively, do these advances in metal technology represent the beginning of another machine age? Perhaps not. Or perhaps we already occupy such an age, characterized by the production of materials with dramatic energy and land savings; the construction of ultralight, printed scaffolds and inflated shell structures; the fabrication of lighter-than-air alloys in the form of micro-scaled trusses; and the creation of shape-changing, thermally responsive material assemblies.

Although not all of these materials and processes are commonly used, glimpses of a future metal architecture composed of a diaphanous material filigree or continuously morphing surfaces already exist-as seen in Wolfgang Buttress' U.K. Pavilion for the 2015 World Expo in Milan or Do|Su's 2012 Bloom Pavilion in Los Angeles. Such forward-looking applications require architects to possess, in Banham's words, "the new mental equipment to handle their new environment."

Today, many assumptions we have made about steel and other materials are outdated. New advances in metal promise many untapped design opportunities that invite visionary architects to demonstrate their full potential.

This article was originally published in ARCHITECT in March 2017.

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