Simulation technologies, such as computer-aided design (CAD) or finite element analysis (FEA), allow aerospace engineers to visualize complex part geometries, understand how parts respond to applied loads (structural analysis), and optimize tooling resources. Digital twins allow machine- asset monitoring and supply chain management. These technologies reduce costs by pulling critical product decisions further upstream where processes and simulations are less expensive than physical prototyping and testing physical prototyping and testing.

Similar benefits extend to testing, where technology increases the efficiency of quality assurance processes. Real-time data acquisition and processing, digital repositories for customer specifications, and collaborative workflow tools accelerate product rollouts.

Virtual testing – using computational modeling and simulation to improve designs and material properties – exposes a design to real-world loading and material properties to identify undesirable results before they happen. Virtual testing also optimizes maintenance, improving sustainment costs and reducing warranty risk – results American Airlines discovered firsthand.

Case study

In 2007, the Federal Aviation Administration (FAA) mandated American Airlines to cold start auxiliary power units (APUs) for each of its Boeing 777 aircraft once per quarter. Increased testing led to three to four APU removals each year, which were expensive, left aircraft out of service, and produced an unpleasant cabin odor upon failure. Bearing failures were to blame, but American Airlines couldn’t pinpoint the source of the problem: Was it the material, design, lubricant, or operating protocol?

To find the answer, materials engineering software company Vextec performed virtual tests analyzing a new APU bearing as well as a bearing broken by operating. The team also evaluated general operating condition notes provided by American Airlines. Vextec’s simulations studied sensitivities related to normal versus cold start, load and design, and lubrication. The studies showed the bearing design was appropriate, but the way the cold starts were performed caused the failures – and the lubrication needed to be changed.

After receiving FAA approval of this solution, American Airlines introduced new lubricant and cold start protocols in August 2011. Since then, the carrier has experienced no APU failures and saved up to $4 million annually. That improvement came while avoiding exorbitant physical testing costs and time commitments for bearings. Plus, American Airlines didn’t have to redesign the bearing, which simulation testing showed would lead to more failures.

Industry 4.0 and AM

Virtual testing is one of many technologies transforming aerospace manufacturing as part of Industry 4.0. Additive manufacturing (AM) plays a bigger role in that transformation by presenting a fundamentally different way to build aircraft.

As AM becomes more capable in production of flight-critical metallic parts, it will impact original equipment manufacturers (OEMs) and maintenance, repair, and overhaul (MRO) operators. Better control of production volume and just-in-time manufacturing should lower costs for OEMs. Producing replacement legacy parts that would otherwise be difficult to source will be a key revenue generator for MRO.

Closely tied to making AM able to produce critical parts is effectively certifying AM-built parts for use. Since AM processes have shown to be more variable than conventional processes such as casting and forging, typical quality assurance/quality control sampling techniques (for example, testing only a small number of produced parts) are difficult to implement. Virtual testing using a computational simulation of product performance can increase confidence in AM for critical uses without the need to test each AM-built part – similar to what American Airlines did with its APU bearing.

Implementing technology

Steps to technology adoption include:

Optimize product lifecycle management (PLM). PLM extends from early design phases through user performance. Technologies that can address multiple areas of PLM at once – such as simulation software – optimize PLM with the largest repository of data possible to create a feedback loop throughout the life cycle.

Leverage third parties. Software subscriptions often include technical and product support, adding value when integrating the technology into an established PLM workflow. Subscriptions are also more affordable and flexible than purchasing software outright.

Think holistically. AM, known mostly for rapid prototyping, can handle production in some instances. Explore how new technologies fit holistically into the PLM to identify areas it can (or can’t) apply.

Aerospace manufacturers must see technology for what it truly is: the future of the industry. For all the advancements and improvements made in recent decades, they pale in comparison to what will be possible, and, in many cases, what’s already possible for those who embrace the opportunities.

Vextec Corp.

About the author: Dr. Robert Tryon is the co-founder and CTO of Vextec, a software and engineering services company specializing in predictive analytics, prognostics, and life extension for automotive, aerospace, industrial, and medical device products. He can be reached at rtryon@vextec.com or 615.372.0299.

Original equipment manufacturer (OEM) performance targets for aluminum demand higher production speeds and lower costs. A manufacturing method promises to produce complex, high-strength aluminum pressings, potentially reducing material use and the mass of conventionally pressed aluminum structures.

Impression Technologies Ltd. (ITL) was formed in 2012 to bring to market the hot form quench (HFQ®) process developed within Imperial College, London, UK (see Figure 1). The process heats a shaped aluminum blank to its solutionizing temperature (500°C to 550°C) before pressing and rapidly cooling the workpiece while still in the tool. The now-formed part can be subjected to further treatment, ensuring the material reaches its full strength.

The technique

Aluminum HFQ structural components could reduce weight up to 20% compared with lower strength, cold-formed aluminum counterparts. In addition, the material’s increased formability at HFQ temperatures means parts can be deep drawn in a single operation, reducing the need for reinforcements. Removing the requirement for secondary forming operations also reduces tooling costs.

The essential features of the technique, says ITL’s Director of Innovations Dr. Alistair Foster, are that “it combines mechanical and heat treatment into a single forming operation.”

He explains this is achieved by raising the material’s temperature until it reaches the relevant solution heat treatment level. At that point, the alloying elements form a solution within the material and stay in solution after the in-tool quenching process initially provides a “W temper that will naturally age to a T4 condition, which can be artificially aged to an alternative temper, such as T6 condition” – the latter being the strongest possible state for the material.

The blank is held in situ to allow quenching of the formed part. Quenching the part in this way combined with optimized age hardening stabilizes the aluminum’s microstructure, delivering strength, formability, and productivity.

HFQ virtually eliminates springback – also known as elastic recovery – compared with cold-forming aluminum. John Sellors, director – applications engineering at ITL, says this has important implications for dimensional control during assembly operations and is something of interest to OEMs.

“With cold-formed, high-strength aluminum especially, springback can be a problem, but with HFQ, it’s reduced to nearly zero,” he states.

Innovation

Recently, ITL management announced the company’s collaboration in the Future Advanced Nacelle Technologies and Structural Integration Concepts (FANTASTIC) project led by Bombardier and supported by the UK Aerospace R&T program, a partnership between Aerospace Technology Institute (ATI) for Business, Energy, and Industrial Strategy (BEIS) and Innovate UK. The FANTASTIC project seeks to enable design and delivery of high-strength, high-accuracy, lightweight HFQ-formed components in aerospace-approved aluminum at lower cost than existing processes.

In a separate development, aluminum rolling and recycling company Novelis Inc. has agreed to partner with ITL to explore innovative ways to increase adoption of aluminum through the hot-forming process.

Currently, ITL has inquiries from several aerospace companies for applications such as seat components, wing ribs, wing flaps, engine inlet lip skins, and leading-edge slats.

Any shape or form

HFQ technology can solve many forming and assembly problems caused by cold forming and superplastic forming techniques. ITL offers aerospace component suppliers the opportunity to install HFQ manufacturing technology within their organizations by becoming a licensee, which gives access to support services to assist in designing and manufacturing HFQ technology components.

These services include:

• Design & simulation – ITL team assists companies to maximize cost-effective mass reduction of complex, high-strength HFQ aluminum panels
• Development – ITL team reduces the number of press tools required to produce a part, significantly lowering the required investment
• Prototyping – ITL’s facility carries out in-house production runs, supports HFQ technology customers
• Tooling – In-house prototype, production tooling try-out facility, with assistance from expert know-how team
• Training – Customized training courses covering each aspect of the product life cycle

ITL plans to continually develop HFQ technology to ensure the benefits of the technology are maximized for future use.

Impression Technologies Ltd.

What began as a prototyping concept, 3D printing has become an essential tool in aerospace and an important technology to scale production, develop fully functional parts, and lower part costs. This is especially critical for the U.S. Air Force (USAF), which is under constant pressure to accelerate aircraft repairs, reduce costs, and get aircraft back in the air quickly. Plus, for many aging aircraft, replacement parts are scarce, and it can be difficult to find manufacturers willing to resume production for parts that may not be reordered for many years.

To address these challenges, the USAF has begun a multi-year collaborative contract with Texas-based Essentium to drive development and deployment of advanced additive manufacturing (AM) solutions for applications in tooling; ground support; maintenance, repair, and overhaul (MRO); and flight-certified parts for military aircraft and ground vehicles through the Air Force and the National Guard Bureau (NGB). Their big push is for sustainment and lifecycle management of aging aircraft.

Driving development

The Essentium-USAF project team will test and develop new materials and processes using the company’s high speed extrusion (HSE™) 3D printing platform, which prints parts 5x to 15x faster than competing systems.

“Essentium demonstrated it has the expertise and capabilities to create parts with consistent replication using the Essentium HSE 3D printing platform,” says Elisa Teipel, Ph.D., chief development officer and co-founder of Essentium. “We’ll work together to drive additive manufacturing technology forward and for faster aircraft repairs that massively reduce time to deliver parts to keep our war fighters ready.”

The platform allows for rapid part production at the point of use and decreases new material certification times. It has the size, speed, and capacity to operate at scale.

Additionally, a machine on the ground, at a base, or at a location that can print provides supply chain efficiencies for on-demand and expeditionary parts.

The HSE 3D printer’s open platform enables a larger variety of materials and there’s more room for development. It can make molds to create tools or quantities of end-use parts. Something new can be created each day, without the need for retooling.

A key component is the HSE Hozzle, a nozzle with an integrated heating and temperature sensing unit that can heat to 550°C in three seconds. It has a sapphire tip, allowing users to extrude high-performance materials. Leveraging these capabilities, the Essentium-USAF team is also focusing on two types of materials important for the industry – high-temperature and ground support materials. Materials must resist high temperatures and chemicals due to the different lubricants and additives used. Additionally, it’s imperative to have materials that are also anti-corrosive to avoid harm by the rigorous additives, fuels, and liquids used in production, Teipel explains.

For the Air Force, which is no longer relying solely on traditional supply chains, the HSE 3D printers also allow them to execute their forward way of thinking.

“That’s another key breakthrough,” Teipel adds. “It used to be that you could design things as an engineer, but you couldn’t manufacture. With additive, you can design things that you can print that you could have never made before.”

The platform also addresses the challenge of developing replacement parts.

According to Teipel, the USAF estimates nearly 10,000 replacement part requests are delayed each year. In some cases, they’re not able to get the original equipment manufacturers (OEMs) to make the part, or it’s no longer available. There are some critical pieces that cause aircraft to be grounded, therefore, airworthy parts, as well as those on the ground including jigs and fixtures, need to be tailored specifically. Additive is a transformative approach for these industry requirements, delivering improved performance for replacement parts and advancing ground tooling and technology.

Additive ecosystem

With AM technology, Essentium is focused on equipping the Air Force with tools for training so they can maximize use and deploy it to become a key component for their already well-established ecosystem. Accelerating the industrial scale of 3D printing will allow it to play a role in the supply chains and keep factory floors and USAF depots moving. Therefore, if a crisis occurs, or if there’s some type of supply shortage, having the machine in place will provide the necessary flexibility to meet demand.

“It’s really about getting this technology in the hands of men and women and making sure that they’re able to use it and design what they need for their world, what they need to keep us all safe, and design what they need to for everyday use,” Teipel says.

Teipel goes on to explain how additive is already being used in the Air Force, but the difference is that this is industrial additive. It’s additive at scale, not a trinket, prototyping, or one-off part; it’s actually a way to build up inventory.

“We’re a materials-first company, so we’re poised to continue to lead in that area and help understand all the different things you can do with this tool, depending on materials and the application,” Teipel says. “So, we’re really doing a deep dive into the applications and providing materials that can be used across the Air Force and the U.S Department of Defense.”

The project is also demonstrating how additive is transforming the Department of Defense, as well as the commercial side of aerospace. Teipel predicts that more industries, both public and private, will continue to partner to bring more AM into their ecosystem and advance production in newer ways.

Essentium Inc.

U.S. Air Force

About the author: Michelle Jacobson is the assistant editor of AM&D. She can be reached at mjacobson@gie.net or 216.393.0323.