It’s hard to believe that anything could have been done cheaply to save costs on the NASA space shuttle. Yet that appears to be exactly the case with the insulation problems that have been plaguing recent flights. On Friday, cracked insulation was found on all three of the fuel tanks scheduled for upcoming flights. And the cracks have probably been there a while.
Cracks are appearing in foam-covered cork insulation that is applied to aluminum alloy brackets. The brackets, which are 17 inches long and four inches wide when foamed, support the liquid oxygen feedline on the external fuel tank. The cork prevents ice from forming on the brackets. Super-cold fuel is inside the tank. Engineers are now finally developing a better solution—replacement of the aluminum alloy with titanium. For the next shuttle flight, the foam and high-density cork insulation will be removed and replaced with foam only. The titanium parts will be ready by spring.
Bad materials engineering has been one of the banes of the space shuttle program. And the problems have not exactly been rocket science. The most famous, or course, was the O-ring failure that led to the disintegration of the Challenger in 1986. It was well known that the fluoroelastomeric materials in the O-rings had extremely poor low-temperature capabilities. Once compressed, very cold O-rings take time to return to their normal shape. Temperatures were very cold the night before the Challenger launch, but temperatures at launch time were within allowable guidelines. Because of poor communications, the problems with the O-ring materials’ properties were not adequately known, and the launch proceeded. O-ring joints now have on-board heaters that are turned on when temperatures drop below 50F.
As the 3D printing and overall additive manufacturing ecosystem grows, standards and guidelines from standards bodies and government organizations are increasing. Multiple players with multiple needs are also driving the role of 3DP and AM as enabling technologies for distributed manufacturing.
A growing though not-so-obvious role for 3D printing, 4D printing, and overall additive manufacturing is their use in fabricating new materials and enabling new or improved manufacturing and assembly processes. Individual engineers, OEMs, university labs, and others are reinventing the technology to suit their own needs.
For vehicles to meet the 2025 Corporate Average Fuel Economy (CAFE) standards, three things must happen: customers must look beyond the data sheet and engage materials supplier earlier, and new integrated multi-materials are needed to make step-change improvements.
3D printing, 4D printing, and various types of additive manufacturing (AM) will get even bigger in 2015. We're not talking about consumer use, which gets most of the attention, but processes and technologies that will affect how design engineers design products and how manufacturing engineers make them. For now, the biggest industries are still aerospace and medical, while automotive and architecture continue to grow.
More and more -- that's what we'll see from plastics and composites in 2015, more types of plastics and more ways they can be used. Two of the fastest-growing uses will be automotive parts, plus medical implants and devices. New types of plastics will include biodegradable materials, plastics that can be easily recycled, and some that do both.
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