Chuck, the mechanical properties of 3D printed metal parts used in end-production aerospace, medical and dental applications are the same as those they replace, otherwise they couldn't be used in those highly regulated industries. Same goes for that 3D-printed, load-bearing engine block we mention in this story, and the 3D-printed titanium bike parts in one of the links at the end of the blog.
Space-X Rocket Engines being built from it? That statement implies that it's used to build the whole thing. I'm sure that only a very select few parts are fabricated this way, not anywhere near the whole thing. It would be interesting to know exactly which parts.
"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?
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").
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.
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.
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.
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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