Integrated Computational Materials Design software simulates complex materials testing

The first century of humans in flight – both above the clouds and in outer space – was supported by a largely analog approach to materials engineering. Progress through the years was steady as technology advanced to continually stretch our understanding of what was possible.

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Now, a digital transformation of materials has drastically changed the industry, and the evolution continues today. Trial-and-error experimentation is becoming a thing of the past, as more errors can be sussed out long before any test flight can take place.

One of the tools leading the revolution is QuesTek’s ICMD^® (Integrated Computational Materials Design) software. Its impact on aerospace materials, manufacturing, and design is already evident. Timeframes for the creation, testing, and certification of novel materials can be cut in half, removing years of experimentation and millions of dollars from the equation.

But ICMD also helps push technology further, solving existing problems that currently constrain the limits of what humans can do and where we can go. ICMD uses computational physics-based modeling and powerful toolkits to enable materials design, accelerated qualification and certification, informatics and analytics, and simulation. This approach simulates complex systems of testing materials for different performance attributes.

Whether creating new materials or improving the properties of existing ones, there are four main pillars of QuesTek’s ICMD capabilities.

Alloy design
Alloy design brings completely novel materials to industry. To unlock greater performance, aerospace manufacturers need access to materials with properties that haven't existed before. By using ICMD, they can design, develop, qualify, and deploy novel materials in critical flight components.

It starts with a list of target properties of the material that they want to achieve. For example, existing materials for fuel pump components and housings for space launch vehicles subjected to high-pressure oxygen may have good burn resistance. But that burn resistance decreases with the alloying additions needed for strength, corrosion resistance, and oxidation resistance.

Commercially available alloys are lower in strength and don’t have significant burn resistance. ICMD can identify potential metallurgical concepts that might lead toward achieving the goal.

Through integrated computational materials engineering (ICME) – which is the linking of a material’s processing, microstructure, properties, and performance by bridging information from two or more validated models or simulation codes – promising compositions are calculated, prototyped, tested, and demonstrated to be heading in the proper direction of the improvement needed.

The modeling is also applied to scaling up the material to production scale, at which point the aerospace manufacturer takes over and, after several years of testing and qualification, the product takes flight.

QuesTek is the project principal investigator for an ARPA-E program with collaborators Pratt and Whitney, NASA and the University of Minnesota. The program is focused on the development of next-generation turbine-blade materials for jet engines. Aerospace turbine blades are made from nickel superalloys, and have been for many years. But there’s an industry need for a blade that could run hotter to make it more fuel efficient.

The goal is to increase the operating temperature of a jet engine by 200°C. The process includes switching to a niobium-based material instead of nickel. QuesTek is using its ICMD software to design a series of niobium alloys that achieve tailored properties within the component at the center and at the edge of the turbine blade.

In another example, Boeing and QuesTek collaborated in an America Makes program to 3D-print two widely different materials together for a component with one material on one portion and a second material on another portion. QuesTek was charged with developing the precise composition gradients to successful printing.

QuesTek used ICMD to model the phases that would form upon printing for the gradient material and recommend compositional modifications and post-printing heat treatment parameters to insure a smooth transit from one type of alloy to another. As one example of the key modeling metrics, one potential negative result that can be identified ahead of time is the likelihood of forming undesirable, brittle intermetallic phases during solidification, high-temperature exposure, or heat treatment.

Calculations assess printability, the freezing range, and cracking susceptibility of the material. Without using ICMD it’s a slow process which, if you were to try to do experimentally, would be almost impossible because of the nearly infinite combinations.

Material qualification
Material qualification as a term is self-explanatory – it’s the process of qualifying a material for a new application. Digital tools such as ICMD save development time and qualification cost by applying modeling to predict properties and quantify the uncertainty in those predictions.

QuesTek uses a method called Accelerated Insertion of Materials (AIM), developed initially under a DARPA-funded initiative, where the modeling capability within that framework allows for applying a limited data set to calibrate models and predict properties across a wider range of production lots with high fidelity.

That enables the use of modeling to determine if the process and material specifications are appropriate to achieve the desired properties. The savings lie in the ability to guide changes to certain specifications at an early stage of data development to ensure avoiding a costly and exhaustive effort of material production and testing only to fall short of intended goals.

Aircraft and aerospace OEMs need to submit a package to the FAA or NASA to qualify new designs, components, and materials. The amount of testing is significant. But the FAA and NASA are both open to  receiving data packages or qualification packages with less testing, but with more backed-up computational predictions. While the FAA won’t accept a data package from a large aerospace OEM  with 15 data points and a bunch of ICME modeling, there are ways to accelerate the timeline.

The normal qualification process is extremely time-consuming, costly, and requires lots of material. The amount of processing and testing is extensive. With ICMD, there’s early confidence in the ability to achieve the properties needed for the design. The savings are extreme when a time span of 10 to 20 years can be knocked down to five.

NAVAIR Public Release #2014-712 Distribution Statement A - “Approved for public release, distribution is unlimited.”

A NIST-sponsored case study on Ferrium® M54 steel acceleration outlines how the qualification was employed and the reason why the timeline was able to be shortened. The predictions of the models – which sped up the process by eliminating multiple production-scale heats, heat treatments, and characterizations by modeling the exact heat treatment required – gave the Navy the confidence to start manufacturing test components before receiving aerospace certification for the material.

Optimizing existing processes
Optimizing existing processes for aerospace clients starts when they're either running into an issue with a process already in place or they want to improve it. ICMD models can be applied to process and production optimization. It can also help to eliminate steps and/or make steps more efficient.

Better properties are achieved by tweaking the process, like with Ferrium^® C64 steel, where its processing was optimized using ICMD to eliminate certain steps used in conventional gear production for aerospace.

Ferrium C64 had initially been developed by QuesTek under a Navy-funded program more than a decade ago. It boasts surface hardenability, core strength and toughness, high temperature stability, slower cooling rates for distortion mitigation, and streamlined processing.

C64 steel was designed specifically to withstand the kind of high temperatures that result from a gearbox drained of oil and greatly increase oil-out survivability. It uses a specific type of carbide that allows it to be tempered at an extremely high temperature, around 900°F. Many incumbent steels, on the other hand, are heat treated at much lower temperatures. Those steels fail in high temperatures because the strengthening particles start to coarsen and dissolve when the temperature exceeds that number.

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The optimization processes in developing C64 were achieved through QuesTek’s computational modeling approach. For example, with heat treatment optimization, modeling can efficiently help determine the right combination of time and temperature to achieve the desired properties.

Computational modeling also saves time and resources on challenges such as how to reduce distortion during the cooling process. How slowly can you cool a material without altering its microstructure in a way that compromises key properties? Design inputs like this help ensure that the material functions as intended.

Additive manufacturing
Additive manufacturing (AM) is a relatively new way of building parts and manufacturing components. Many industries are dedicating a lot of time and effort into iterative testing. QuesTek helps clients optimize that process using modeling instead of going through multiple trials, which costs time, money and creates significant material waste.

QuesTek’s ICMD software optimizes material compositions for the additive process and AM parameters to make crack-free, efficient builds and achieve target properties. It essentially helps replace design of experiments, iterative testing, and trial and error, and helps bring confidence to that process.

Norsk Titanium and QuesTek recently collaborated to advance the breakthrough use of nickel alloy Inconel Alloy 625 wire in directed energy deposition AM. This will provide manufacturers an alternative to casting for large aerospace and industrial components and allow them to bypass significant supply chain delays, while also leveraging the additive process for unique weight savings and performance improvements.

The collaboration will also accelerate the timeline for perfecting the heat treatment of nickel wire in AM. Using trial-and-error could require dozens of test cases, but QuesTek’s ICMD software narrows the number needed to just one or two for demonstration.

Another example is the development of new aluminum powders. The goal is to balance creating a material microstructure that isn’t prone to cracking when printed using an additive process while achieving strength levels of conventional casting or forging materials.

ICMD allows for the ability to model the formation of unique microstructural phases with very rapid cooling rates and enables the design of microstructures that harness these phases for enhanced strength while balancing crack-free printability. The formation of these novel phases is unique to the rapid cooling rates of AM, and ICMD allows for understanding what these phases are and how they can be leveraged.

There’s no modeling anywhere that can accurately predict the heights the aerospace industry will eventually reach. But with tools like ICMD digitally transforming the industry, creating materials that were once nonexistent and making us reconsider what is possible, the sky is most definitely not the limit.

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Jeff Grabowski is business development director and Kerem Taskin is a senior client solutions engineer at QuesTek Innovations. They can be reached at QuesTek.com