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.

For critical applications such as aerospace, naval, automotive and energy, performance continually drives the need to innovate. And whether it’s designing new components or sustaining legacy platforms, the engineering innovation “push” must be balanced against the “pull” of safe and reliable operation. This is where qualification standards and certification processes come into play. They help ensure new designs, material sources, and processing techniques produce consistently performing parts that meet minimum requirements.

The push/pull contrast is most evident in the “testing” phase of any certification process. The amount of physical testing involved in bringing a new product to market, qualifying a new manufacturing technique, or approving a new vendor can be immense. But it is done in order to mitigate the risk of the “new”. In particular – the world of additive manufacturing (AM) has been prone to extensive testing, because of the variability currently seen in the many manufacturing processes under the AM umbrella. The reality of all of this testing means long lead times and high development costs, with valuable resources taken up by going down blind alleys leading nowhere.

VEXTEC’s VPS-MICRO® software is a predictive tool based on Integrated Computational Materials Engineering (ICME). Our analytical software simulates metal fatigue at the microstructural level, and accounts for the material and processing variabilities seen in any type of manufacturing – including AM. With VPS-MICRO, you create and run virtual Design of Experiments (DOE) to hone in on appropriate material conditions that give high confidence for passing physical tests. Without changing the parameters of the certification process, the software efficiently simulates what will happen when a metallic component is tested in fatigue. This allows you to direct the physical testing to only acquire the data you need and nothing more, saving valuable time and money in the process.

The U.S. Department of Defense is investing big in AM, and has recently enlisted VEXTEC’s help to provide VPS-MICRO for Air Force use in this initiative. The U.S. Navy has also recently contracted with VEXTEC to expand the capabilities of our Corrosion Cracking Maintenance Prediction Software (CCMPS). This software aids in the condition-based testing and maintenance of stress corrosion cracking onboard naval vessels, with the goal of extending their service life by as much as a decade.

Find out how VEXTEC’s commercial VPS-MICRO software can help in your paradigm – to be able to test smarter, certify faster, and build better products. Click below to schedule an introductory call with our team today!

VEXTEC provides software and services to predict and improve product durability. Our VPS-MICRO software helps clients virtually qualify their metal components for fatigue durability. It is an Integrated Computational Materials Engineering (ICME) tool that simulates fatigue at the microstructural level, where there can be significant variability in additively manufactured (AM) metal parts. Without changing the required elements of the AM certification process, the technology can efficiently simulate what would happen if that part was tested in fatigue. This allows physical testing of the part only after there is high confidence it will pass the test, reducing costly repeats.

The details of an annual subscription for VPS-MICRO software license and support include:

•      Access to VEXTEC’s materials library & knowledge.

•      Complete user training for at least two users–training process will also validate the methodology on the client’s material/design, as training will result in a specific alloy addition to the client’s materials library and the ability for VEXTEC to address almost all potential use cases.

•      Option for floating license with multiple users.

•      VEXTEC ensures that our clients are fully supported in their use and implementation of VPS-MICRO.

Our standard annual software subscription service is priced at $80k. For a limited time, VEXTEC is offering this service at the discounted price of $60k to fellow America Makes members.

About America Makes

America Makes is the nation’s leading public-private partnership for AM technology and education. America Makes members from industry, academia, government, workforce and economic development organizations, work together to accelerate the adoption of AM and the nation’s global manufacturing competitiveness. Founded in 2012 as the Department of Defense’s national manufacturing innovation institute for AM and first of the Manufacturing USA network, America Makes is based in Youngstown, Ohio and managed by the not-for-profit National Center for Defense Manufacturing and Machining (NCDMM). Visit americamakes.us to learn more.

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”

Watch the webinar on the America Makes YouTube page

If the terms Metal Additive Manufacturing, AM, 3D Printing, ICME, Computational Fatigue Modeling resonate with you, we are interested in speaking with you.

Selected as America’s Most Promising Company by Forbes Magazine, VEXTEC is the developer and provider of VPS-MICRO® software as a SaaS model. We help our clients to save time and money by accelerating push for Additive Manufacturing (AM) into standard production & reducing physical testing burden for qualification of new materials/sources.  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.

If you are interested in joining a small business with a dedicated team that is at the cutting edge of computational material science developing software to revolutionize Metal AM, please apply.

Qualified candidates for the position will have the following requirements and skills:

• Engineering graduates that have a M.S. and Ph.D. in Engineering (Civil, Mechanical, BME, Material Science degrees are preferred).
• Aptitude and demonstrated ability to write engineering code in Fortran, Python, C# is very desirable.
• Experience in structural mechanics or fracture mechanics.
• Knowledge of probabilistic methods and statistics.
• Knowledge of finite element modeling and analysis. Deep familiarity and experience with commercial finite element software such as ANSYS, Abaqus, Nastran will be an asset.
• Self-motivated with the ability to pick up new analytical skills.

Employment with VEXTEC offers competitive salaries and a flexible work environment, as well as a comprehensive benefits package.

VEXTEC Corporation provides software, technical expertise and services in the areas of component, system, and fleet durability.  In collaboration with our client companies, we utilize VPS-MICRO to help make better products and resolve in-service durability and reliability issues.

To apply for a career at VEXTEC, please send your cover letter and resume to hr@vextec.com.