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.

FOR IMMEDIATE RELEASE:

Brentwood, TN (September 4, 2024) – VEXTEC Corporation was selected by Bechtel Plant Machinery, Inc. (BPMI) to provide its VPS-MICRO Software for virtual testing and prediction of fatigue performance of metallic components, supporting the U.S. Navy. Software training for BPMI personnel has recently been completed, and BPMI’s initial focus will be to use the software to better understand component fatigue related to U.S. Navy mechanical components.

VPS-MICRO gives engineering teams and technical directors quantitative information to make quick decisions on component fatigue reliability and durability, by supplementing physical testing and providing increased confidence in accelerated qualification of parts. The software is compatible with nearly any material processing condition for metallic structural components: forging, casting, weldments, additive manufacturing (AM), surface treatments, etc. Clients have used the software to accelerate the push of AM into standard production and to identify causes of component fatigue failure.

VPS-MICRO, developed with the help of the U.S. government’s Small Business Innovation Research (SBIR) Program, addresses a gap in the existing capabilities of computer-aided design (CAD), finite element analysis (FEA) and physical material testing. VEXTEC’s technology effectively integrates these disciplines with probabilistic modeling into a single computational framework that accounts for material and processing variabilities.

“We are pleased BPMI has purchased a subscription of VPS-MICRO to add to its engineering toolbox,” said Bob Tryon, CEO and President of VEXTEC. “The virtual testing capabilities of our software can augment physical testing, reducing costly iterative testing loops and other resource burdens related to certification protocols. We are committed to fully supporting BPMI in its implementation and use of VPS-MICRO.”

About VEXTEC
Since 2000, VEXTEC Corporation has provided predictive analytics prognostics and life extension capabilities for hundreds of applications and products. VEXTEC’s clients include leading multinationals in the aerospace, automotive, electronics, heavy industry and medical device manufacturing sectors, as well as many federal government agencies. VEXTEC has seven U.S. patents related to its software technology. For more information on VEXTEC and VPS-MICRO software, visit vextec.com.

About Bechtel Plant Machinery, Inc.
Bechtel Plant Machinery, Inc. (BPMI) provides the U.S. Naval Nuclear Propulsion Program high quality nuclear power plant components for submarines and aircraft carriers. For more information, visit www.bpmionline.com.

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.

FOR IMMEDIATE RELEASE:

Brentwood, TN, October 10, 2022 – VEXTEC Corporation was awarded a sole source contract from the U.S. Navy to expand its Corrosion Cracking Maintenance Prediction Software (CCMPS). CCMPS is used by the Navy to predict the future maintenance needs for aluminum (5000 series) ship structures.

The U.S. Navy is tasked with extending the lifetime of certain naval vessels by 5-10 years at full mission capability, however, they have been challenged by stress corrosion cracking of their aluminum ship structures which impacts maintenance schedules. That’s where CCMPS comes into play. The Navy uses CCMPS to simulate inspection schedules of their aluminum fleet resulting in a “Time-to-Repair” prediction. This software capability gives the Navy a way to turn actual data in to actionable data which they can use to improve maintenance planning schedules.

Under this contract, VEXTEC will add new capabilities and technology to the software enabling the Navy to continue using CCMPS for years to come. “In the current CCMPS scheme, each ship location of the fleet is simulated individually and the next doesn’t begin until the prior has finished,” said, Dr. Animesh Dey, VEXTEC’s Chief Product Development Officer, “VEXTEC will be implementing a multi-threading method in the software; this will allow multiple locations to be simulated in tandem and compiled at the end once all ship locations of the digital fleet have completed the simulation.” These upgrades will reduce the overall time it takes to run a model benefiting the Navy’s condition-based maintenance needs which is essential to their overall mission.

About VEXTEC:

VEXTEC Corporation works with both federal & commercial clients across many industries to provide fatigue prediction software based on ICME (Integrated Computational Materials Engineering) to predict product durability. This unique software, VPS-MICRO, 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 has seven US patents related to its technology. For more information on VEXTEC and VPS-MICRO software, visit: http://vextec.com.

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”

Simulation Software to Solve Certification Challenges in Additive Manufacturing

In an article published for Aviation Week’s MRO-Network.com, author Lindsay Bjerregaard, discusses VEXTEC’s VPS-MICRO® simulation software and how it promises to reduce product development time and cost through optimization of design and manufacturing processes. Click here to read the full article.

• Microstructure : In its most basic sense, a material’s microstructure is the DNA that describes how the material will behave. VPS-MICRO’s mechanistic modeling approach accounts for the variability in key microstructural parameters. This makes it ideally-suited for the AM process, where microstructure is heavily dependent upon the printer machine’s parameter settings (scan speed, layer thickness, laser power, hatch spacing, etc.).

• Residual Stresses : Depending on their post-build processes, AM-built components can exhibit significant and complex residual stresses. This is due to the directionality of the layer-by-layer printing, and the subsequent cooling/solidification kinematics. VPS-MICRO can explicitly incorporate residual stress profiles in its computational framework, allowing for accurate definitions of localized stress states.

• Surface Roughness : Part of the attractiveness of AM is that the part can be built in its near-net shape, so little or no machining is necessary. An as-manufactured AM surface is rough by nature, and this roughness takes the form of a microstructurally-thin layer of stress concentration at all points along the surface (analogous to a surface after having experienced corrosion). Recent enhancements to VPS-MICRO provide modeling of these variations in stress concentration along a part’s surface.

VPS-MICRO for Certification of Structural Aerospace Components Built by AM

VEXTEC is collaborating with Oak Ridge National Laboratory (ORNL) on a NAVAIR-funded project to develop a computational material engineering software tool. The goal is to decrease the time and money needed to certify an AM-built structural component exposed to fatigue loading. Certification is an important obstacle to overcome, for widespread adoption of AM technology to occur in any industry. VEXTEC’s VPS-MICRO software tool for AM uses all available data and information to develop the material models. These models are computational and physics-based, and can predict other materials and microstructures to extrapolate outside of the test database. The material models are probabilistic, to predict the tails of the distributions that actually govern minimum properties. The models can be updated as more data and knowledge become available.

The computational tool integrates AM process information, material properties, computational models and microstructural damage tolerance simulations into the design and material certification process. VEXTEC’s toolbox of previously-developed software modules assesses the durability of parts processed by traditional methods of casting, forging, rolling, machining and welding. Additional modules have been more-recently developed to determine the durability of sophisticated methods such as powder metallurgy, single-crystal fabrication, and additive methods like Electron Beam Melting (EBM). In this project, the VEXTEC/ORNL team is using the tools to simulate the static and cyclic strength tests that are needed to certify EBM-produced titanium alloy Ti-6Al-4V. The program demonstrates a proof of concept capability: evaluating the variabilities in processing, geometry (surface finish) and microstructure, and their contributions to the uncertainty in durability.

VPS-MICRO to Predict AM Processing Variabilities

VEXTEC recently contributed to an Air Force research program on Selective Laser Melting (SLM) of the nickel superalloy Mondaloy, a desirable rocket engine material due to its tolerance of high-pressure gaseous oxygen. The research team, which included Aerojet Rocketdyne as the prime contractor, was tasked with creating models that link the variation in AM processing conditions to the microstructure of the resultant material. An extensive design of experiments matrix was conducted, to study the process sensitivity for off-nominal AM machine settings. A multitude of AM Mondaloy engine nozzles was built, each one having a different amount of defective material (representing different off-nominal machine parameter combinations).

VEXTEC was tasked with simulating failures from monotonic loading, and used these simulations in the static strength certification. Aerojet had performed a large number of microstructural observations of the various processing conditions. These data provided the inputs to VEXTEC’s VPS-MICRO simulations, to predict the probability of failure for the various microstructural conditions. It was only after the simulations were run, that Aerojet conducted the physical cyclic proof and bust tests of the nozzles. The failing burst pressure and the nozzle burst locations were accurately predicted by VPS-MICRO.

The future is bright for additive manufacturing, as well as for predictive durability modeling of additively manufactured components!

VEXTEC and AM: Built Together