AFRL and its primary collaborators (ARCTOS, The Barnes Global Advisors) have identified the main challenges in Q&C being:

1. effective/efficient non-destructive inspection techniques;
2. how to handle as-printed surfaces and articulate their debit to performance; and
3. lack of harmony in current Q&C approaches (multiple standards including AWS D20.1, NASA-STD-6033, AMS 7032, AMS 7003, EZ-SB-19-01).

The group has determined that adopting validated defect- and microstructure-inclusive modeling is the path forward to reduce the testing burden. They will explore the benefits of available modeling tools by comparing a “full testing” example to a “reduced testing” example that includes modeling, and demonstrating equivalent confidence between the two approaches. The proposed “reduced testing” example would take advantage of specimen-level testing (which is less expensive and time-consuming) to collect microstructure and defect data to inform the models. These models would then be used to predict equivalent initial damage size (EIDS) distributions and performance for a fully sized and geometrically complex part. Limited physical testing of parts would be used to validate the model-assisted analyses.

VEXTEC’s approach of model-assisted AM qualification aligns seamlessly with AFRL’s objective. Our VPS-MICRO® Software integrates materials science principles with standard structural engineering tools such as finite element analysis to model fatigue performance at the microstructural level, where damage actually occurs. Our tool has been used by both the Department of Defense as well as the private sector to predict the risk of cyclic fatigue failure of AM parts based on location-specific microstructure, defects, residual stress and surface roughness. Last month, VEXTEC was invited to participate in a QUASAR Program Update at AFRL offices in Dayton, Ohio. VEXTEC’s digital tools were highlighted as a means to integrate AM as-printed surface features.

AFRL QUASAR Program

VEXTEC looks forward to continuing our long-standing collaboration efforts with AFRL, and advocating for materials-based computational tools that lower barriers to AM adoption in the aerospace industry.

• integration of many conventional components into a single AM build;
• complex shapes and orientations;
• product volume control (short runs for sustainment vs. longer runs for new production); and
• limited post-build machining.

AM can bring 30-60% cost savings on complex, high-value parts in the aerospace industry. The limited post-build machining aspect is particularly attractive, in that it can eliminate many steps between production and end-use. As much as 20% of a part’s cost can be incurred during post-build machining to remove surface roughness effects. Another major potential for savings is reducing part count in complex assemblies, which creates internal and other hard-to-access surfaces that cannot be machined. Therefore, it is advantageous to computationally predict the impact of an AM as-printed surface (APS) on fatigue performance for metal parts. This can be done using our VPS-MICRO predictive software, by differentiating the APS from the machined surface in terms of stress and material properties.

While VPS-MICRO does not explicitly perform AM process modeling, it can model the effects on fatigue performance that result from a wide range of manufacturing processes such as surface roughness, residual stress, and heat treatment layers (carburizing, nitriding, etc.). The roughness due to APS typically comes from features like raised bumps due to AM powder unmelt, as well as extensive crevices (which likely exist along microstructural grain boundaries). These features can be effectively evaluated and measured using microscopy and/or serial sectioning.

After measuring these APS features, a 3D spatially varying probabilistic structural finite element analysis (FEA) can then be used to statistically model the stress effects from the features – some act as stress concentrations of undulating peaks and valleys, others act as sharp crack-like stress intensities. These can be represented by stress gradients which act on different size scales (micro-gradients and macro-gradients). It is the interactions between the stress concentrations and the stress intensities that contribute to fatigue crack nucleation and small flaw growth at the rough surface. These gradients from the FEA are direct inputs into VPS-MICRO.

Other contributing factors to fatigue of APS parts are found in the microstructure of the APS material itself. There can be material properties in the surface layer that are not found in the material’s core: voids of different sizes and shapes, depleted amounts of precipitates like carbides, etc. The core microstructure will be similar to the material of a smooth specimen (the APS being machined away). These layer differences can cause variations in local strength properties. While collecting the surface layer microstructural properties can be challenging, there are microcopy techniques available to assist. VPS-MICRO allows for input of multiple material layers, to effectively model these microstructural gradients.

The previously mentioned APS features can then be overlaid onto a standard VPS-MICRO analysis of a smooth, machined specimen. The resulting simulations provide quantitative information about how much fatigue debit there would be if the APS layer was not machined away. This type of computational analysis can help to avoid the “build-test-fail-repeat” iterative cycle that expends valuable resources during certification of an AM as-printed component.

VEXTEC is honored to present at this year’s ASTM International Conference on Advanced Manufacturing (ICAM 2023), held October 30 – November 3 2023 in Washington D.C. VEXTEC’s CTO Dr. Bob Tryon is speaking on “Computational Fatigue Models to Assist in Risk-Based Certification of Additively Manufactured Metallic Parts” on November 1 at 4:00pm ET.

The presentation focuses on physics-based models to provide predictive analytics for certification in Additive Manufacturing (AM). The models integrate computational material engineering to simulate the costliest aspects of AM certification testing, reducing test repeats and significantly lowering the cost of certification. Statistical distributions of properties including microstructure, voids and surface roughness are used in the modeling, as well as structural finite element analysis and Monte Carlo techniques to simulate fatigue of a large population of components with complex loading. Simulated fatigue results are compared to laboratory fatigue testing data, and a standard work protocol is created for AM replacement of an aircraft engine throttle linkage component, and AM repair of foreign object damage to an aircraft engine airfoil.

More information on ASTM ICAM 2023: https://amcoe.org/event/icam2023/

More information on VEXTEC’s VPS-MICRO® commercial software for AM fatigue performance prediction: https://vextec.com/additive-manufacturing/

VEXTEC is honored to be part of this year’s JANNAF Liquid Propulsion Subcommittee (LPS) Advanced Materials Panel (AMP) Additive Manufacturing for Propulsion Applications Technical Interchange Meeting (TIM) in Huntsville, AL. VEXTEC (supported by Aerojet Rocketdyne) presented results from a recent SBIR program that developed an additive manufacturing certification framework for Air Force applications, with the objective of accelerating the qualification and adoption process for new additive manufactured materials, augmenting the traditional verification process with a model-informed software tool called VPS-MICRO^®.   The purpose of the JANNAF (Joint Army, Navy, NASA Air Force) is to promote and facilitate exchange of technical and programmatic information among the Military Departments, Defense Agencies,

NASA, U.S. industry and academia; to establish standards; to effect coordination and avoid unnecessary duplication of basic research, applied research, advanced technology development, advanced component development and prototypes, and system development and demonstration programs in the areas of missile, gun, and space propulsion and energetics; to accomplish problem solving in areas of joint interest; and to support collaboration to maintain and strengthen the domestic rocket propulsion industrial base.

The VEXTEC developed software, VPS-MICRO, is an Integrated Computational Material Engineering (ICME) based tool that predicts the risk of cyclic fatigue failure of an additive manufactured metal part based on the location specific microstructure, defects, residual stress and surface roughness. Using the software eliminates unsuccessful design options early in the design processes. Also, the software greatly reduces the test cost and time needed to determine the statistical confidence in the certified lifetime instead of having to acquire a large population of fatigue tests needed to do the same.

Brentwood, TN, October 10, 2022 – The United States Air Force Rapid Sustainment Office (USAF RSO) has signed-on for a yearlong Phase III program with VEXTEC Corporation. The Phase III program will deploy VEXTEC’s VPS-MICRO computational predictive software to USAF engineering teams at the forefront of metal additive manufacturing (AM) for critical sustainment activities.

VEXTEC’s successful SBIR Phase II AM program with RSO, born out of an open call Pitch Day solicitation, catalyzed USAF interest in predicting risk of fatigue failure of AM metal parts. A demonstration project at the close of Phase II was coordinated between VEXTEC and Air Force Life Cycle Management Center – Propulsion Directorate (AFLCMC/LP) at Tinker Air Force Base. VPS-MICRO was able to provide quantitative predictive capabilities, that gave engineers and managers actionable information before any AM parts were even built.

“The Air Force wants to develop more digital tools to be able to take full advantage of the potential AM can provide,” stated Dr. Bob Tryon, VEXTEC Chief Technology Officer. “This Phase III program is structured such that, not only will VPS-MICRO be delivered to engineers who specialize in risk assessment, but standard work protocols will effectively integrate this technology into the teams’ workflows at Tinker. This will give the Air Force additional resource support to additively manufacture their own metal parts.”

The ultimate goal of the Phase III is to highlight how digital predictive tools can complement existing testing schemes, to accelerate risk prediction and alternative material qualification for new and legacy components that utilize AM.

About VEXTEC:

VEXTEC Corporation is the home of VPS-MICRO®, a unique microstructural fatigue durability prediction software based on ICME (Integrated Computational Materials Engineering). This technology fills a gap in the existing capabilities provided by CAD/CAM, FEA, statistical modeling, and physical material and component testing, by effectively integrating them into a single computational processing framework. Since 2000, VEXTEC has provided predictive analytics prognostics and life extension capabilities for hundreds of different products. VEXTEC’s clients include leading multinationals in the aerospace, automotive, electronics, energy, heavy industry and medical device manufacturing sectors, as well as many federal government agencies. VEXTEC has seven US patents related to its technology. For more information on VEXTEC and VPS-MICRO software, visit: http://vextec.com.

The work emphasized the fact that metal additive manufacturing techniques produce material microstructures that have such wide variation in properties that they cannot be appropriately modeled by deterministic approaches. Instead, they must be represented probabilistically in order to effectively characterize the nature of AM-processed materials. VPS-MICRO accounts for this variability using probabilistic material models and computationally-efficient simulation.

For more information on these presentations and published proceedings, see the links below:

Aircraft Structural Integrity Program (ASIP) Conference, Dec. 2021: “Fatigue Analysis of Laser Powder Bed Fusion (LPBF) Ti-6Al-4V”

American Institute of Aeronautics and Astronautics (AIAA) Science and Technology Forum and Exposition (SciTech), Jan. 2022: “Fatigue Analysis of Additive Manufacturing Materials with Microstructural Properties”

The award came on the heels of VEXTEC’s successful completion of a SBIR Phase II program which continued to mature our VPS-MICRO predictive durability software. The TEO Pitch Day award has been put to good use, as we have been expanding our software’s capabilities to meet AM Qualification and Certification needs for the Air Force and global OEMs.

Read the article as originally published on the Department of Defense Media Center’s website:

https://www.dvidshub.net/news/395814/vextec-uses-pitch-day-launch-into-additive-manufacturing-world

The significant upside offered by additive manufacturing in aerospace means that aircraft manufacturers will soon use it to build these components from the ground up. For one, 3D-printed parts weigh less thanks to opportunities to condense multiple parts into one composite object. Plus, a 3D-printed part can have a similar yield and ultimate strength as a conventionally produced part due to AM’s ability to work with high-performance materials like titanium efficiently. The applications are almost endless thanks to the rapid evolution of additive manufacturing technologies.

As that evolution continues, it promises to revolutionize how aerospace manufacturers operate. To get a sense of what the future holds, let’s consider one major advancement coming down the pipeline and the obstacles it still needs to clear.

3D Printing at Aerospace Scale

The size of 3D-printed parts is limited by the size of the printers themselves. Build chambers are growing steadily, which opens up the potential to print larger aircraft parts or to print more parts at the same time. Size and scale were among the biggest challenges facing additive manufacturing in aerospace, but they don’t appear insurmountable.

That being said, printing on a bigger scale — in terms of size or speed — comes with its own issues. For instance, longer and thicker parts will cool at different rates, resulting in varying material microstructures from location to location. Manufacturers must account for this difference when attempting to certify a part for both ultimate strength (proof testing) and cyclic strength (fatigue testing).

Quality control and consistency are problematic in other ways, too. Multiple parts built within the same build cycle (e.g., nested parts) have complex interactions with the build chamber environment (e.g., gas flow, cooling rates, additional material deposition, etc.). This could create variability between these parts that would need to be quantified during certification.

It will take time before build chambers become massive and produce perfectly consistent parts, but it will be less time than many people expect. Boeing already uses a titanium structural component produced on an additive manufacturing platform, suggesting certain parts can already meet the industry’s exacting standards. And many more manufacturers will soon follow suit thanks to forthcoming technological breakthroughs.

Put yourself at the vanguard of the aerospace industry by exploring the right (and wrong) ways to implement additive manufacturing. Let VEXTEC be your guide.

BRENTWOOD, Tenn., April 28, 2020—VEXTEC^® Corporation in Nashville, TN, has been awarded a small business innovative research (SBIR) contract, supported by Aerojet Rocketdyne, to develop an additive manufacturing certification framework for Air Force applications, with the objective of accelerating the qualification and adoption process for new additive manufactured materials, augmenting the traditional verification process with a model-informed software tool called VPS-MICRO^®.

The VEXTEC developed software, VPS-MICRO, is an Integrated Computational Material Engineering (ICME) based tool that predicts the risk of cyclic fatigue failure of an additive manufactured metal part based on the location specific microstructure, defects, residual stress and surface roughness. Using the software eliminates unsuccessful design options early in the design processes. Also, the software greatly reduces the test cost and time needed to determine the statistical confidence in the certified lifetime instead of having to acquire a large population of fatigue tests needed to do the same.

“We are leveraging real word data we’ve collected like fatigue strength and microstructure to create a digital model that can be used to predict the critical fatigue failure points of a component and simulate how surface features affect overall component strength,” said Dan Matejczyk,  Materials and Process Engineer,  Aerojet Rocketdyne. “The goal is to have a mix of physical test data combined with virtual data to accelerate the qualification process. Aerojet Rocketdyne will provide years of historical test data and VEXTEC will provide the software modeling capability.”

Rapid and reliable part qualification is necessary for additive manufactured components to realize their potential benefits. However, variability in microstructure and surface features may be significant, and must be managed for assured reliability. This program’s certification framework, methods and tools will assure component performance and reliability while enabling additive manufacturing schedule and cost advantages.

Aerojet Rocketdyne, a leader in additive manufacturing for more than a decade, will support VEXTEC in incorporating the additive manufacturing certification with computational fatigue models into a standard work process.

Jeff Haynes, Additive Manufacturing Program Manager at Aerojet Rocketdyne, noted that “With regard to additive manufacturing, we need to answer questions like: Where does modeling fit into the certification process? What is the best mix of analysis and testing? What are viable near-term solutions and what are the long-term goals for computationally enhanced certification processes that will be useful in the broader aerospace industry to produce highly-reliable parts.”

VEXTEC’s SBIR technology transition plan (STTP) for its current Phase II work involves further maturing of its VPS-MICRO software to a higher Technology Readiness Level (TRL) through validation testing, and working with Aerojet Rocketdyne and the company’s DoD partners. This maturation beyond the Phase II level intends to focus on computational predictive modeling of additive manufactured parts in order to meet the Air Force’s needs in process development, vendor qualification/process control, and airworthiness certification.

“We feel that VEXTEC’s VPS-MICRO: additive manufacturing software can be an integral tool in this effort because it represents the integration of additive manufacturing process modeling with performance prediction to provide a better tool for certification. Having Aerojet Rocketdyne’s keen interest will assure the process will interface with the commercial engineering practice,” noted Dr. Bob Tryon, VEXTEC’s President and CTO.

About Aerojet Rocketdyne:
Aerojet Rocketdyne, a subsidiary of Aerojet Rocketdyne Holdings, Inc. (NYSE:AJRD), is a world-recognized aerospace and defense leader that provides propulsion systems and energetics to the space, missile defense and strategic systems, and tactical systems areas, in support of domestic and international customers. For more information, visit www.Rocket.com and www.AerojetRocketdyne.com. Follow Aerojet Rocketdyne and CEO Eileen Drake on Twitter at @AerojetRdyne and @DrakeEileen.

About VEXTEC:

VEXTEC Corporation has a unique microstructural fatigue durability prediction software based on ICME (Integrated Computational Materials Engineering) to predict long-term product durability. This technology fills a gap in the existing capabilities provided by CAD/CAM, FEA, statistical modeling, and physical material and component testing, by effectively integrating them into a single computational processing framework. VEXTEC’s clients include leading multinationals in the aerospace, automotive, electronics, energy, heavy industry and medical device manufacturing sectors, as well as many federal government agencies. VEXTEC has also received several grants from the United States Department of Defense through its Small Business Innovative Research (SBIR/STTR) programs. VEXTEC has been granted seven patents related to its technology.

For more information, visit: https://vextec.com/

BRENTWOOD, Tenn., November 18, 2019 – VEXTEC was selected to be an awardee at the Air Force’s inaugural Technical Executive Officer Pitch Day, held near Wright-Patterson Air Force Base in Dayton, Ohio on November 15, 2019. This marked the second Pitch Day award that VEXTEC garnered in the same week; VEXTEC was also awarded a Pitch Day contract from the Air Force’s Rapid Sustainment Office for Additive Manufacturing on November 13, 2019.

VEXTEC’s pitch for enhancing computational methodologies for durability performance prediction of metallic components made by Additive Manufacturing (AM) was well-received by the Air Force’s representatives from Acquisition, Technology, Logistics, and the Air Force Research Laboratory (AFRL). VEXTEC’s Chief Technology Officer, Dr. Bob Tryon, and Chief Product Development Officer, Dr. Animesh Dey, were on-hand to make the pitch and receive the award.

VEXTEC accepting the Air Force Research Laboratory’s funding award at the inaugural Technical Executive Officer Pitch Day, on November 15 2019 in Dayton, Ohio. Pictured left to right are: Lt. General Duke Richardson (Military Deputy at the Office of the Assistant Secretary of the Air Force for Acquisition, Technology and Logistics), Dr. Animesh Dey (VEXTEC’s Chief of Product Development), Dr. Bob Tryon (VEXTEC’s Chief of Technology), and Maj. General William Cooley (Commander at the Air Force Research Laboratory) Photo credit: AFRL.

VEXTEC’s pitched SBIR technology transition plan (STTP) for its current Phase II work involves further maturing of its VPS-MICRO predictive durability software to a higher Technology Readiness Level (TRL) through validation testing, and working with industrial and DoD partners. This maturation beyond the Phase II level intends to focus on computational predictive modeling of AM parts, to meet the Air Force’s needs in process development, outside vendor qualification/process control, and airworthiness certification.

“The Air Force needs a path to efficiently certify AM products to realize maximum gains with regards to airworthiness, sustainment and fleet readiness objectives. We feel that VEXTEC’s VPS-MICRO:AM software can be an integral tool in this effort,” Dr. Tryon said.

In total, $14 million in total SBIR funding was awarded at the Pitch Day event, to small businesses from across the country specializing in many different areas. Lt. General Duke Richardson (of the Office of Air Force Acquisition, Technology and Logistics in Arlington, Virginia) closed the event with an enthusiastic statement to all of the awardees: “Today was fun! Tomorrow, let’s get after it. Give us even more than we’re expecting.” We intend to, sir!