The 3D printing of metal parts has been advancing, in medical implants, aircraft components, and aircraft engines. Even complex lattice structures are not unusual, as Within has demonstrated in titanium implants. Now engineers at UK-based building design firm Arup have come up with a design method for 3D printing structural steel elements to be used in construction projects.
Interestingly, the curved lines of the first element, a steel node, resemble in a general way the "liquid lattice" structures Within designed for an automotive load-bearing engine block, using EOS's direct metal laser sintering (DMLS) process, as well as the turtle skeleton-inspired car body designed by the German firm EDAG Group. They are all beautiful art as well as elegant engineering design.
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Structural engineers at UK-based building design firm Arup have come up with a design method for 3D printing structural steel elements to be used in construction projects. The steel node shown here is the first component to be produced using the new method.
Also of interest is that Arup says it worked with both Within and CRDM, a 3D printing and prototyping service bureau acquired by 3D Systems that targets the aerospace, automotive, defense, consumer, and medical sectors for prototyping, pre-production, and full production parts. CRDM uses EOS DMLS machines and recently made several props and costumes for the Tom Cruise movie Edge of Tomorrow, including the stars' exoskeleton suits. EOS also collaborated with Arup during the beginning of the technology's development.
Arup's structural engineers say redesigning the steel node for a lightweight structure so it could be 3D printed resulted in a more efficient, individualized piece. Using 3D printing for making structural steel building elements will also reduce costs and cut waste. It will especially enable highly sophisticated, complex designs that don't have to be simplified later on during a project in order to cut costs.
The company's engineers have previously designed several lightweight, large, complex structures such as 470-meter-long pedestrian Kurilpa Bridge in Brisbane, Australia. That multi-mast cable-stay structure was designed using tensegrity principles, a term coined by Buckminster Fuller that combines "tension" and "structural integrity." The global distribution of force through a non-rigid structure, such as those found in natural forms like cells, gives maximum strength without adding weight, and minimizes the number of points of local weakness. NASA has used tensegrity principles to design its Super Ball Bots.
Arup says it's at the forefront of designing the complex geometry, tensegrity-based structures. The company has also designed bridges and structures based on unusual forms, such as the world's first curved double-helix bridge in Singapore, the improbable-looking China Central Television headquarters in Beijing, as well as high-rise buildings, airports, and hospitals.
These parts are very impressive, Ann. When the mechanical properties are finally revealed, I wonder how this will compare to commonly-used A36 structural steels in terms of tensile and flexural strength, as well as modulus of elasticity.
Are any standards for mechanical and structural integrity being set or sought for this 3D printing method? The possible shapes are certainly more complex than any that could be achieved via casting. But different printers have different resolution -- and different temperatures and print rates. How will such parts be certified?
Not just the properties, but the construction techniques? I can see the part pictured requiring several elements bolted or pinned to it (as this is described as a node). But how does this look for a construction comany that has to eventually build a structure with these parts? Erector set building with detailed instructions? Afterall, wouldn't want to mix up the nodes if they are uniquely engineered and printed for a specific load path.
Impressive indeed. Previously 'impossible' shapes could now become a reality.
Charles, I do agree with you, it would be interesting to compare the mechanical properties of these new materials with standard steel and confirm that these new properties are also consistent and repeatable for each 3D build batch.
I concurr with Charles, in that while the parts certainly look good the proof would be in actual test results, since these creations are intended to carry loads that are at least "sort of known." And if it is as good as predicted then it will indeed open up a new realm of ways to build stuff. At some point it will be cheaper to desgn and print instead of design and have fabricated. Production speed is definitely a limiting factor, though. Presently engine blocks are produced at one per minute, likewise completed engines. Doing that with 3D printing would be quite an achievement indeed. But for short runs of machinery this method may be a very economical option.
Frequently, I seem to be the annoying gadfly buzzing around and disturbing the otherwise pleasant conversation on 3D printing.
The issues with real-world application of these approaches in safety-critical applications depends on knowing the properties and behavior of the resulting material. That is very true and has been stated already. As engineers, we owe it to our clients or employers to consider what else might need investigation. Here I offer a few areas of concern:
1) What are the dynamic properties of these complex structures under time variant and multi-axis loads? Are there any unwanted resonances which could lead to premature or unexpected failure?
2) What are the failure modes for these parts in use? For better or worse, many existing, accepted designs have decades of in-use field data showing they are reliable and if they fail, how they do fail. This allows preventive maintenance and inspections, possibly installing monitoring, etc. How do we approach that with these new alternatives?
3) How do these strucutres differ in their response to environmental variation from proven designs? For example what is the thermal - dimensional behavior of the "node" shown in the article vs. the existing practices? Buildings, aircraft, bridges--many of the targeted end applications often operate over a very wide range of temperatures, humidity, shock, vibration, etc.
4) Related to (2) and (3) what are the new corrosion behaviors of metal parts made this way? Do they hold up better or worse? Does the apparently high surface area lead to faster growth of corrostion per unit mass of the part? Is that a concern?
5) The question of bolts was raised. I would ask a related question--how are the bolt locations chosen for such an asymmetric part, and do the loads on the different bolts vary by location? If so, how is this accounted for in the safety margins used in the design?
6) As noted already there is a high risk of improper installation. Using either the wrong customized part, or installing it wrong. This requires introduction of mistake proofing approaches into parts that in the past were "idiot proof". This is no small matter--on another UBM forum we discussed how a high percentage of advanced electrical systems may be installed wrong. Complexity creates high risk of this, and that risk must be mitigated.
7) Does the design with such parts make maintenance more or less difficult? That may not matter for buildings, but could matter for other applications. Most of the reports talk about all the benefits yet nothing about the negatives. There must be tradeoffs. As Heinlein coined in "The Moon is a Harsh Mistress": TANSTAFL ("There ain't no such thing as a free lunch").
"The 3D printing of metal parts has been advancing, in medical implants, aircraft components, and aircraft engines. Even complex lattice structures are not unusual, as within has demonstrated in titanium implants. Now engineers at UK-based building design firm Arup have come up with a design method for 3D printing structural steel elements to be used in construction projects."
Ann, I think in application level 3D printing is expanding to almost all areas ranging from aerospace to medical to common structures. Good, would you think it will help any advancement in construction segment?
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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