Press Release: Concept Laser, Honeywell, and PADT Build Largest Additive Manufacturing Center in Southwest at Arizona State University

PADT-Press-Release-IconOn January 18th, ASU will officially Launch their Manufacturing Research and Innovation Hub, the Largest Additive Manufacturing  research and teaching center in the Southwestern US.  PADT is proud to have partnered with ASU as well as with Concept Laser and Honeywell to get this important piece of the local manufacturing ecosystem started and to keep it growing.

Located on the Polytechnic School at ASU in Mesa, Arizona, this facility is amazing.  And you can see it for yourself, the public is invited to the launch on January 18th, 2017 at 9:00 am.  ASU Polytechnic Dean Kyle Squires and the Director Ann McKenna will be speaking as will our very own Rey Chu, John Murray from Concept Laser, and Don Godfrey from Honeywell.  Tours will follow. Learn more and register for this free event that will bring together the local 3D Printing community here.

You can also learn more by reading the official press release from Concept Laser that outlines what the center does and the partnerships that make it possible:

Press Release:

Concept Laser, Honeywell, and PADT Build Largest Additive Manufacturing Center in Southwest at Arizona State University

GRAPEVINE, Texas, January 11, 2017 – The Polytechnic School at Arizona State University (ASU) offers the only manufacturing engineering undergraduate degree in Arizona; it is also one of only 22 ABET accredited manufacturing engineering programs in the United States. By forming a partnership with Concept Laser, Honeywell Aerospace, and PADT, Inc. the largest additive manufacturing research facility in the Southwest is now on the Polytechnic campus. The 15,000 square foot center holds over $2 million of plastic, polymer, and 3D metal printing equipment.

The lab has a Concept Laser M2 cusing and Mlab cusing machine which are dedicated to 3D metal printing, also known as metal additive manufacturing. Unlike conventional metal fabrication techniques, additive manufacturing produces fully-dense metal parts by melting layer upon layer of ultra-fine metal powder. The Polytechnic School is using the machines for a wide range of research and development activities including materials development and prototyping complex mechanical and energy systems.

Supporting quotes:

Don Godfrey, Engineering Fellow at Honeywell: “Honeywell is thrilled to be participating in the opening of the new additive manufacturing laboratory at the Arizona State University Polytechnic campus.  For many years, we have worked with ASU seniors on their capstone projects with three of these projects this school year additive manufacturing focused. In addition to our own additive manufacturing operations, we have provided mentorship to students in the program and assisted in the procurement of one machine for the schools’ new lab.  We look forward to growing our relationships with the university in developing brilliant minds to tackle and overcome industry challenges associated with aviation and additive manufacturing.”

John Murray, President and CEO of US-based subsidiary Concept Laser Inc: “Changing the future of metal additive manufacturing begins with educated teachers and curious students. The educational leadership that the ASU Polytechnic School provides to the Southwest region and the industry will certainly be impactful. Concept Laser is proud to be a partner in this initiative.”

Rey Chu, Principal, Manufacturing Technologies at PADT, Inc: This partnership is the next and obvious step in the progression of additive manufacturing in the Southwest.  With Concept Laser’s outstanding technology, Honeywell’s leadership in applying additive manufacturing to practical Aerospace needs, PADT’s extensive network of customers and industry experience, and ASU’s proven ability to educate and work with industry, the effort will establish a strong foundation for the entire regional ecosystem.

Ann McKenna, Director of ASU’s Polytechnic School: “Partnering with these industry leaders provides us the capability to do additional research and enhance our education programs. With so few of these types of centers, this makes ASU more attractive among academic partners, federal agencies and corporations to advance additive manufacturing.

The ASU Polytechnic School will be hosting an open house to celebrate the launch of their Manufacturing Research and Innovation Hub on January 18, 2017 at 9am. There will be guided tours showcasing student projects. Honeywell, Concept Laser, and PADT will be in attendance. Please register your attendance at  www.mrihlaunch.eventbrite.com.

About Concept Laser  

Concept Laser GmbH is one of the world’s leading providers of machine and plant technology for the 3D printing of metal components. Founded by Frank Herzog in 2000, the patented LaserCUSING® process – powder-bed-based laser melting of metals – opens up new freedom to configuring components and also permits the tool-free, economic fabrication of highly complex parts in fairly small batch sizes.

Concept Laser serves various industries, ranging from medical, dental, aerospace, toolmaking and mold construction, automotive and jewelry. Concept Laser machines are compatible with a diverse set of powder materials, such as stainless steel and hot-work steels, aluminum and titanium alloys, as well as precious metals for jewelry and dental applications.

Concept Laser Inc. is headquartered in Grapevine, Texas and is a US-based wholly owned subsidiary of Concept Laser GmbH. For more information, visit our website at www.conceptlaserinc.com

LaserCUSING® is a registered trademark of Concept Laser.

About Phoenix Analysis and Design Technologies

Phoenix Analysis and Design Technologies, Inc. (PADT) is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and 3D Printing solutions. PADT’s worldwide reputation for technical excellence and experienced staff is based on its proven record of building long term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work.” With over 80 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, and from offices in Torrance, California, Littleton, Colorado, Albuquerque, New Mexico, and Murray, Utah, as well as through staff members located around the country. More information on PADT can be found at www.PADTINC.com.

 About Arizona State University

The Ira A. Fulton Schools of Engineering at Arizona State University include nearly 19,000 students and more than 300 faculty members who conduct nearly $100 million in research, spanning a broad range of engineering, construction and technology fields. Across the six schools contained within the Fulton Schools, 24 undergraduate and 32 graduate programs are offered on ASU’s Tempe and Polytechnic campuses and online. The schools’ educational programs emphasize problem solving, entrepreneurship, multidisciplinary interactions, social context and connections. Arizona State University includes more than 80,000 students and 1,600 tenured or tenure-track faculty on multiple campuses in metropolitan Phoenix as well as online. For more information, please visit www.asu.edu or asuonline.asu.edu.

Press contact:
Joyce Yeung, Director of Marketing
Concept Laser
Phone: (817) 328-6500
E-mail: j.yeung@conceptlaserinc.com

PADT Contact
Eric Miller
PADT, Inc.
Principal & Co-Owner
480.813.4884
eric.miller@padtinc.com

ANSYS Startup Program: The Significance of Simulation – Webinar


Phoenix Analysis & Design Technologies Presents:

ANSYS Startup Program: The Significance of Simulation 


Do you work for a startup of know someone who does?

PADT would like to invite you to attend our upcoming webinar in support of the ANSYS Startup Program.

Click Here to register for this webinar

Wednesday January 25th, from 12 pm – 1 pm MST

Join us as our own Co-Owner and Principal Eric Miller discusses how simulation software is helping new entrepreneurs and startup companies alike to shorten their time to market and reduce their manufacturing costs.

While many startups tend to avoid using simulation due to cost or a lack of accessibility, this is a key aspect of the modern manufacturing process and should not be ignored.

As a partner in the Startup Program, you will gain instant access to ANSYS solutions so you can start building virtual prototypes of your new products. These virtual prototypes can be modified and tested with simulation hundreds of times in the same time it would take to build and test one physical prototype – saving you time and money as you work to perfect your product design. The partnership gives you access to the full portfolio of multiphysics simulation bundles, including the Structural and Fluids bundle and the Electromagnetics bundle.

Click Here to register for this webinar

Christmas Left-Right Gift Exchange Story: Western

For our Christmas parties at PADT we generally have over 40 employees so a traditional secret Santa gift exchange takes to long. So a couple of years ago we downloaded a right-left gift exchange story from the internet and it was a big hit. We ran out of stories on the internet, so we started writing our own, usually in some sort of over-the-top style.  This year, 2016, many of us had become addicted to West World, so a good old fashioned Western seemed appropriate.

Everyone gets their gift and forms a big circle in the middle of the room.  Someone with a strong voice reads the story and every time the world LEFT is read, everyone passes the package they have to the left. Every time the world RIGHT is read, everyone passes the package they have to their right.  You should pause a bit at each LEFT/RIGHT to give people a chance to pass.

You can find our older stories here

– Elf Family Christmas (2017)
– Western Christmas (2016)
– Star Wars Christmas (2015)
– Fairy Tail Christmas (2014)
– Science Fiction Christmas (2013)
– Romance Christmas (2012)
– Film Noir Christmas (2011)


Trixie and the Christmas Miracle

A train whistle echoed in the distance as US Marshal Dilan McRightland brought his horse Righty to a stop on the left side of the ridge. Down below, right in the middle of the valley was his destination, the place he had been headed right towards for three weeks. Wrightville Gulch. He’d seen a lot of dusty towns, not much more than a few buildings on the right and left side of a crooked street. Left to his own devices he would have left his job and gone right back to his family farm on left bank of Ohio river, right below Louisville Kentucky. But he had sworn an oath to uphold justice, to make sure that wrongs were righted, and that no criminal was left free to cause more harm. It was the right thing to do.
He dug his heals into Righty and they headed right down the trial, towards an encounter that would have been best left alone.

As he entered the town from the… south, he surveyed both sides of the street. On the right was a bank, livery stable, and what looked like a hotel that may not be where the ‘right type of people’ stay. The other side of the street held a saloon, blacksmith, general store, and a Chinese restaurant: Right and Wrong Noodles. Dilan assumed that the fugitive he was seeking was in the saloon. So he tied up Righty, using a left hitch not, and went right in the swinging doors.

It took a while for his eyesight to adjust to the dim interior. A long mahogany bar filled the wall. On the… other side, there was a stair case that led to rooms on the second floor. Right in the middle of the room stood a giant Christmas tree. That was right, Dilan thought, today was Christmas Eve. It has been a long time since he had enjoyed a right proper Christmas. He began to day dream about snowy Christmas mornings when a shout brought him right back to reality.

“Hey! You looking for me, stranger?” A man dressed in head to toe in black leather stood on the left side of the Christmas tree. “If you are Lefty Peterson, then yes.” Replied Dilan. “I’m US Marshal Dilan McRightland and I’ve traveled all the way to Wrightville Gulch, right here in the middle of no-where, to bring you to justice.”

The two men stared at each other across the room, their right hands hovering over their six shooters, which for now were left in their holsters. “I don’t think you have it right, Marshal. When I left the Stanton brothers for dead, right in the middle of Dodge City, I left that life behind me. I’m clean now, I’ve got a wife and kids. I started over. You know what I did was right, they deserved to die. So the right thing for you to do is get back on your horse and get right out of town.”

This left Marshall Dilan a bit baffled. What if Lefty was right? And then he stood up straight and looked Lefty in the eye. “The law is the law lefty, doesn’t matter if you think what you did was right, it is up to a jury to decide that.” Lefty looked right back, and snarled “The only way you are taking me back is as a corpse. If you don’t leave in a coffin yourself. Their right hands slowly moved to their guns.

Just when they were about to draw a girl dressed like a dancer the left bank of the Sein in Paris, dashed right between them. “Stop right now!” she shouted. “Gosh Nabit! It’s Christmas Eve. Have you any heart left, either of you?” She turned to Lefty “Lefty, darling, you don’t have to die. If you think what you did was… justified, go with the marshal, argue your case.” She spun to face Marshall McRightland “And you, you come riding in here on Christmas ever, where we was having ourselves a right nice party, and you threaten our friend Lefty, that just aint right either!”

Dilan stood. He could see the star on his chest reflected in the mirror behind the bar, and he could see the star right on top of the tree. And he looked right at the dancing girl, a small tear falling from her right eye. “Lefty” he said “you agree to let me handcuff you to that bar there, and we can have ourselves a right proper Christmas ever and morning. And then we ride out of here and you get your day in court. Does that sound…. All right?” Lefty thought for a minute, then responded “I right reckon that is the right thing to do. Right here and right now on Christmas eve, maybe some peace on earth is what we need.”

And so on that Christmas Eve in a dusty town right in the middle of no-where, a little Christmas spirit, and a fiery dancing girl named… Trixie, brought a little peace on earth and goodwill towards men to a place called Wrightville Gulch.

Phoenix Business Journal: ​Is acquiring disruptive innovation good for everyone?

It seems like the trend these days is for large companies to not do R&D in house. Instead the let StartUps develop innovation and then buy it when the market proves it out.  I had to ask myself “​Is acquiring disruptive innovation good for everyone?”  I don’t think it is and explain why in this week’s blog post.

Phoenix Business Journal: ​When did we start thinking amateurs were a good idea?

We have a problem. At some point it become not just OK, but prefered to count on amateurs to tackle difficult problems. In politics and in business it is a trend to go with people who have no background and no experience. Seeing the results, I a not a fan.  In “​When did we start thinking amateurs were a good idea?” I look at this disturbing reality, why it is a bad idea, and offer some suggestions on turning things around.

PADT Events – January 2017

Welcome to 2017. We are all very excited about what we have planned for events this year. As we travel around the country, and the world, we hope to have to chance to meet many of you who follow PADT. 2017 will look a lot like 2016 except that, based on your feedback, we will be trying more on-line webinars and events.  As always, contact us if you have any questions.


Launch of ASU Manufacturing Research and Innovation Hub

01/18/17
ASU Polytenic Campus
Mesa, AZ

PADT will be on-hand at ASU Polytechnic school for the launch of ASU’s new Manufacturing Research and Innovation Hub. Stop by to see their new facilities and meet the students and staff along with partners like PADT that helped make it happen.
Learn more

ANSYS Startup Program Webinar: The Significance of Simulation

01/25/17
Online

This seminar will discuss how ANSYS simulation software can be used by startups to shorten their time to market and reduce their manufacturing costs. We will discuss what simulation is and how to use it effectively, as well as go over the ANSYS Startup Program and how it gives early stage companies access to world class simulation.
Learn more

Invited Speaker at the 2017 Arizona Science Bowl (High School Event)

01/28/17
ASU West Campus
Glendale, AZ

PADT’s Dhruv Bhate, PhD will speak to students at the High School Science Bowl. This is a great event, and if you have never been, you should go. The level of technology and scientific rigour fo these Middle School and High School kids is amazing.
Learn more

Tesla Test Drive at PADT

01/30/16
PADT Tempe
Tempe, AZ

Yes, you read that right. We will be inviting customers to come to PADT and see how the simulation and 3D Printing technologin we sell, support, and use is applied to advanced automotive systems – Cool Cars! Tesla Motors has been kind enough to partner with us to allow a select few the oportunity to test drive a Tesla. Look for your invite via email and register quickly, space is limited.
Learn more

Metal AM Magazine Article: Modeling the Mechanical Behaviour of Additively Manufactured Cellular Structures

Fig 1. Metal AM Magazine Cover: Winter 2016 (Vol. 2, No. 4)

Metal AM Magazine publishes an article by PADT!

Our 10-page article on “Modeling the Mechanical Behavior of Cellular Structures for Additive Manufacturing” was published in the Winter 2016 edition of the Metal AM magazine. This article represents a high-level summary of the different challenges and approaches in addressing the modeling specific aspects of cellular structures, along with some discussion of the design, manufacturing and implementation aspects associated with AM.

Click HERE for link to the entire magazine, our article starts on page 51. Digital editions are free to download. Swing by PADT in the new year to pick up a hard copy or look for it at our table when you visit us at trade shows.

To stay in touch with the latest developments at the intersection of AM and Cellular Structures, connect with me on LinkedIn, where I typically post 1-2 blog posts every month on this, or related subjects in Additive Manufacturing.

Fig 2. Dimensional tolerances and how the influence models – one of the many concepts discussed in the article

The next webinar of the ANSYS Breakthrough Energy Innovation Campaign is now available!

 Register here to watch

Thermal Optimization for Energy Efficiency 

Nearly everything has an optimal operating temperature and thermal condition. Millions of dollars each year are spent generating and transporting thermal energy to achieve thermal goals. Thermal optimization not only improves the economy of transporting energy, maintaining building temperatures, manufacturing processes and products, it improves their efficiency as well. Engineers use simulation to reveal detailed pictures of thermal processes, providing a deep understanding of all aspects of thermal management.

Join our experts for this Webinar to learn how you can capture thermal processes in powerful simulations, seamlessly identify multiphysics interactions that impact performance, and quickly achieve thermal optimization using integrated design optimization tools.
Register Here – or Click Here for more information on Thermal Optimization

This webinar is presented by Richard Mitchell and Xiao Hu

Richard Mitchell is the Lead Product Marketing Manager for Structures. He joined ANSYS in 2006 working in pre-sales and support roles. Before this Richard was an ANSYS user working for a high tech company in the UK. He worked as an analyst on space and vacuum tube technologies.

 

Xiao is a principal engineer at ANSYS Inc. Xiao has spent a combined 12 years of his career at ANSYS and Fluent corporation working with customers in the modeling and simulation of powertrain related applications. Xiao spent his earlier years with Fluent working on engine CFD applications.

Keep checking back to the Energy Innovation Homepage for more updates on upcoming segments, webinars, and other additional content.

Metal 3D Printing a Shift Knob

I have always had an issue with leaving well enough alone since the day I bought my Subaru. I have altered everything from the crank pulley to the exhaust, the wheels and tires to the steering wheel. I’ve even 3D printed parts for my roof rack to increase its functionality. One of the things that I have altered multiple times has been the shift knob. It’s something that I use every time and all the time when I am driving my car, as it is equipped with a good ol’ manual transmission, a feature that is unfortunately lost on most cars in this day and age.

prevknobs

I have had plastic shift knobs, a solid steel spherical shift knob, a black shift knob, a white shift knob, and of course some weird factory equipment shift knob that came with the car. What I have yet to have is a 3D printed shift knob. For this project, not any old plastic will do, so with the help of Concept Laser, I’m going straight for some glorious Remanium Star CL!

One of the great things about metal 3D printing is that during the design process, I was not bound by the traditional need for a staple of design engineering, Design For Manufacturing (DFM). The metal 3D printer uses a powder bed which is drawn over the build plate and then locally melted using high-energy fiber lasers. The build plate is then lowered, another layer of powder is drawn across the plate, and melted again. This process continues until the part is complete.

The design for the knob was based off my previously owned shift knobs, mainly the 50.8 mm diameter solid steel spherical knob. I then needed to decide how best to include features that would render traditional manufacturing techniques, especially for a one-off part, cost prohibitive, if not impossible.   I used ANSYS Spaceclaim Direct Modeler as my design software, as I have become very familiar with it using it daily for simulation geometry preparation and cleanup, but I digress, my initial concept can be seen below:2016-10-18_16-19-33

I was quickly informed that, while this design was possible, the amount of small features and overhangs would require support structure that would make post-processing the part very tedious. Armed with some additional pointers on creating self supporting parts that are better suited for metal 3D printing, I came up with a new concept.

2016-10-18_16-24-24

This design is much less complex, while still containing features that would be difficult to machine. However, with a material density of 0.0086 g/mm^3, I would be falling just short of total weight of 1 lb, my magic number. But what about really running away from DFM like it was the plague?

2016-10-18_16-23-31

There we go!!! Much better, this design iteration is spec’d to come out at 1.04 lbs, and with that, it was time to let the sparks fly!

img_7602

Here it is emerging as the metal powder that has not been melted during the process is brushed away.

untitled

The competed knob then underwent a bit of post processing and the final result is amazing! I haven’t been able to stop sharing images of it with friends and running it around the office to show my co-workers. However, one thing remains to make the knob functional… it must be tapped.

img_7762

In order to do this, we need a good way to hold the knob in a vise. Lucky for us here at PADT, we have the ability to quickly design and print these parts. I came up with a design that we made using our PolyJet machine so we could have multiple material durometers in a single part. The part you need below utilizes softer material around the knob to cradle it and distribute the load of the vise onto the spherical lattice surface of the knob.

img_7765img_7764

We quickly found out that the Remanium material was not able to be simply tapped. We attempted to bore the hole out in order to be able to press in an insert, and also found out the High Speed Steel (HSS) was not capable of machining the hole. Carbide however does the trick, and we bored the hole out in order to press in a brass insert, which was then tapped.

img_7873

Finally, the shift knob is completed and installed!

Want to learn more, check out the article in “Additive Manufacturing Media.”

 

Phoenix Business Journal: ​How far away are we from 3D Printing the androids on ‘Westworld?’

A bit of a twist for this weeks Phoenix Busines Journal blog post… “​How far away are we from 3D Printing the androids on ‘Westworld?‘”  In discussing this great new reboot of a classic, and yet another fantastic cautionary tale from Michael Crhichton, a couple people started wondering how far off the tech in the show is.  The answer, well you will have to read the article.

ANSYS Breakthrough Energy Innovation Campaign – Thermal Optimization

Information regarding the next topic in the Breakthrough Energy Innovation Campaign has been released, covering Thermal Optimization and how ANSYS simulation software can be used to help solve a variety of issues related to this topic, as well as capture all thermal processes.

Additional content regarding thermal optimization can be viewed and downloaded here.

This is the next topic of a campaign that covers five main topics:

  1. Advanced Electrification 
  2. Machine & Fuel Efficiency
  3. Thermal Optimization
  4. Effective Lightweighting
  5. Aerodynamic Design

Information on each topic will be released over the course of the next few months as the webinars take place.

Sign Up Now to receive updates regarding the campaign, including additional information on each subject, registration forms to each webinar and more.

We here at PADT can not wait to share this content with you, and we hope to hear from you soon.

Modeling 3D Printed Cellular Structures: Approaches

How can the mechanical behavior of cellular structures (honeycombs, foams and lattices) be modeled?

This is the second in a two-part post on the modeling aspects of 3D printed cellular structures. If you haven’t already, please read the first part here, where I detail the challenges associated with modeling 3D printed cellular structures.

The literature on the 3D printing of cellular structures is vast, and growing. While the majority of the focus in this field is on the design and process aspects, there is a significant body of work on characterizing behavior for the purposes of developing analytical material models. I have found that these approaches fall into 3 different categories depending on the level of discretization at which the property is modeled: at the level of each material point, or at the level of the connecting member or finally, at the level of the cell. At the end of this article I have compiled some of the best references I could find for each of the 3 broad approaches.

1. Continuum Modeling

The most straightforward approach is to use bulk material properties to represent what is happening to the material at the cellular level [1-4]. This approach does away with the need for any cellular level characterization and in so doing, we do not have to worry about size or contact effects described in the previous post that are artifacts of having to characterize behavior at the cellular level. However, the assumption that the connecting struts/walls in a cellular structure behave the same way the bulk material does can particularly be erroneous for AM processes that can introduce significant size specific behavior and large anisotropy. It is important to keep in mind that factors that may not be significant at a bulk level (such as surface roughness, local microstructure or dimensional tolerances) can be very significant when the connecting member is under 1 mm thick, as is often the case.

The level of error introduced by a continuum assumption is likely to vary by process: processes like Fused Deposition Modeling (FDM) are already strongly anisotropic with highly geometry-specific meso-structures and an assumption like this will generate large errors as shown in Figure 1. On the other hand, it is possible that better results may be had for powder based fusion processes used for metal alloys, especially when the connecting members are large enough and the key property being solved for is mechanical stiffness (as opposed to fracture toughness or fatigue life).

Fig 1. Load-displacement curves for ULTEM-9085 Honeycomb structures made with different FDM toolpath strategies

2. Cell Level Homogenization

The most common approach in the literature is the use of homogenization – representing the effective property of the cellular structure without regard to the cellular geometry itself. This approach has significantly lower computational expense associated with its implementation. Additionally, it is relatively straightforward to develop a model by fitting a power law to experimental data [5-8] as shown in the equation below, relating the effective modulus E* to the bulk material property Es and their respective densities (ρ and ρs), by solving for the constants C and n.

homogenizationeqn

While a homogenization approach is useful in generating comparative, qualitative data, it has some difficulties in being used as a reliable material model in analysis & simulation. This is first and foremost since the majority of the experiments do not consider size and contact effects. Secondly, even if these were considered, the homogenization of the cells only works for the specific cell in question (e.g. octet truss or hexagonal honeycomb) – so every new cell type needs to be re-characterized. Finally, the homogenization of these cells can lose insight into how structures behave in the transition region between different volume fractions, even if each cell type is calibrated at a range of volume fractions – this is likely to be exacerbated for failure modeling.

3. Member Modeling

The third approach involves describing behavior not at each material point or at the level of the cell, but at a level in-between: the connecting member (also referred to as strut or beam). This approach has been used by researchers [9-11] including us at PADT [12] by invoking beam theory to first describe what is happening at the level of the member and then use that information to build up to the level of the cells.

membermodeling
Fig 2. Member modeling approach: represent cellular structure as a collection of members, use beam theory for example, to describe the member’s behavior through analytical equations. Note: the homogenization equations essentially derive from this approach.

This approach, while promising, is beset with some challenges as well: it requires experimental characterization at the cellular level, which brings in the previously mentioned challenges. Additionally, from a computational standpoint, the validation of these models typically requires a modeling of the full cellular geometry, which can be prohibitively expensive. Finally, the theory involved in representing member level detail is more complex, makes assumptions of its own (e.g. modeling the “fixed” ends) and it is not proven adequately at this point if this is justified by a significant improvement in the model’s predictability compared to the above two approaches. This approach does have one significant promise: if we are able to accurately describe behavior at the level of a member, it is a first step towards a truly shape and size independent model that can bridge with ease between say, an octet truss and an auxetic structure, or different sizes of cells, as well as the transitions between them – thus enabling true freedom to the designer and analyst. It is for this reason that we are focusing on this approach.

Conclusion

Continuum models are easy to implement and for relatively isotropic processes and materials such as metal fusion, may be a good approximation of stiffness and deformation behavior. We know through our own experience that these models perform very poorly when the process is anisotropic (such as FDM), even when the bulk constitutive model incorporates the anisotropy.

Homogenization at the level of the cell is an intuitive improvement and the experimental insights gained are invaluable – comparison between cell type performances, or dependencies on member thickness & cell size etc. are worthy data points. However, caution needs to be exercised when developing models from them for use in analysis (simulation), though the relative ease of their computational implementation is a very powerful argument for pursuing this line of work.

Finally, the member level approach, while beset with challenges of its own, is a promising direction forward since it attempts to address behavior at a level that incorporates process and geometric detail. The approach we have taken at PADT is in line with this approach, but specifically seeks to bridge the continuum and cell level models by using cellular structure response to extract a point-wise material property. Our preliminary work has shown promise for cells of similar sizes and ongoing work, funded by America Makes, is looking to expand this into a larger, non-empirical model that can span cell types. If this is an area of interest to you, please connect with me on LinkedIn for updates. If you have questions or comments, please email us at info@padtinc.com or drop me a message on LinkedIn.

References (by Approach)

Bulk Property Models

[1] C. Neff, N. Hopkinson, N.B. Crane, “Selective Laser Sintering of Diamond Lattice Structures: Experimental Results and FEA Model Comparison,” 2015 Solid Freeform Fabrication Symposium

[2] M. Jamshidinia, L. Wang, W. Tong, and R. Kovacevic. “The bio-compatible dental implant designed by using non-stochastic porosity produced by Electron Beam Melting®(EBM),” Journal of Materials Processing Technology214, no. 8 (2014): 1728-1739

[3] S. Park, D.W. Rosen, C.E. Duty, “Comparing Mechanical and Geometrical Properties of Lattice Structure Fabricated using Electron Beam Melting“, 2014 Solid Freeform Fabrication Symposium

[4] D.M. Correa, T. Klatt, S. Cortes, M. Haberman, D. Kovar, C. Seepersad, “Negative stiffness honeycombs for recoverable shock isolation,” Rapid Prototyping Journal, 2015, 21(2), pp.193-200.

Cell Homogenization Models

[5] C. Yan, L. Hao, A. Hussein, P. Young, and D. Raymont. “Advanced lightweight 316L stainless steel cellular lattice structures fabricated via selective laser melting,” Materials & Design 55 (2014): 533-541.

[6] S. Didam, B. Eidel, A. Ohrndorf, H.‐J. Christ. “Mechanical Analysis of Metallic SLM‐Lattices on Small Scales: Finite Element Simulations versus Experiments,” PAMM 15.1 (2015): 189-190.

[7] P. Zhang, J. Toman, Y. Yu, E. Biyikli, M. Kirca, M. Chmielus, and A.C. To. “Efficient design-optimization of variable-density hexagonal cellular structure by additive manufacturing: theory and validation,” Journal of Manufacturing Science and Engineering 137, no. 2 (2015): 021004.

[8] M. Mazur, M. Leary, S. Sun, M. Vcelka, D. Shidid, M. Brandt. “Deformation and failure behaviour of Ti-6Al-4V lattice structures manufactured by selective laser melting (SLM),” The International Journal of Advanced Manufacturing Technology 84.5 (2016): 1391-1411.

Beam Theory Models

[9] R. Gümrük, R.A.W. Mines, “Compressive behaviour of stainless steel micro-lattice structures,” International Journal of Mechanical Sciences 68 (2013): 125-139

[10] S. Ahmadi, G. Campoli, S. Amin Yavari, B. Sajadi, R. Wauthle, J. Schrooten, H. Weinans, A. Zadpoor, A. (2014), “Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells,” Journal of the Mechanical Behavior of Biomedical Materials, 34, 106-115.

[11] S. Zhang, S. Dilip, L. Yang, H. Miyanji, B. Stucker, “Property Evaluation of Metal Cellular Strut Structures via Powder Bed Fusion AM,” 2015 Solid Freeform Fabrication Symposium

[12] D. Bhate, J. Van Soest, J. Reeher, D. Patel, D. Gibson, J. Gerbasi, and M. Finfrock, “A Validated Methodology for Predicting the Mechanical Behavior of ULTEM-9085 Honeycomb Structures Manufactured by Fused Deposition Modeling,” Proceedings of the 26th Annual International Solid Freeform Fabrication, 2016, pp. 2095-2106

PADT Events – December 2016

PADT-Events-LogoWelcome to December! The holiday season is upon us as is the end of 2016.  It has certainly been an eventful year, although we don’t have a lot going on event wise this month, just two things.

We will take this oportunity to send a Happy Hollidays! to everyone and wishing all a very merry New Year!  Come back in January and we will have lots to share, it’s going to be a busy year.

As a reminder, PADT is closed the week of December 26-30, 2016.


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December 1: Phoenix, AZ
BioAccel Solutions Challenge for BioTech Startup in Arizona

This is a fantastic event that puts a nice cap to the year for Biotech startups in Arizona, and PADT is proud to be a sponsor.  We will be at the “Scorpion Pit” competition as well as the networking event after. See you there.

The full agenda and all the details for this event are here.


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December 6: Albuquerque, NM
Medical Device Product Development for Startups, The Bitter Pill

We will be in New Mexico for this lunch time event looking in to the harsh realities of doing a Medical Device startup.  All are welcome!  We hope this is the first of many regular seminars with the New Mexico Technology Council.

Get the details and register here.

 

​Phoenix Business Journal: The Arizona startup market needs bridge funding for growth

Just-Published-PBJ-1The state of Arizona has made some great strides in creating a vibrant and growing startup community. Only a few things are missing and the big one right now is that “The Arizona startup market needs bridge funding for growth” Check out the article to get my feelings on the topic, what our problems are and how we can fix them.

Phoenix Business Journal: Publishing your own book, technology makes it easy

Just-Published-PBJ-1A few years back PADT turned one of our training courses into a book, and even though it is about an obscure programming language for a software product that is only known to our industry, it has done well. In “Publishing your own book, technology makes it easy” I review how truly easy and affordable on-demand self publishing can be. You can see the book here “Introduction to the ANSYS Parametric Design Language – Second Edition

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