Author: Gary Whelan
Recently, I attended ICAF 2023 – the 38th Conference and 31st Symposium of the International Committee on Aeronautical Fatigue and Structural Integrity in Delft, The Netherlands. As a materials design engineer specializing in fatigue modeling, it was great to be surrounded by peers in this exciting field while visiting such a beautiful, vibrant location.
At the conference, I gave a talk that I co-authored with QuesTek founder Greg Olson and CTO Jiadong Gong titled “Using Digital Twins to Accelerate Qualification and Certification of Fatigue Critical Components.” I’ve included the complete abstract below, but before I dive into that, and would like to share some key takeaways from the general discussion at ICAF 2023.
The main challenges currently facing the international aerospace fatigue community include:
-Efficiently and reliably predicting fatigue life with modeling and simulation to reduce the cost and time required for testing in the qualification process.
-Sustainment of aging aircraft fleets that are nearing their originally prescribed end of life.
-Understanding the effects of hydrogen on degradation, fracture, and fatigue of metallic components as the aerospace community moves toward hydrogen as a more environmentally friendly alternative to hydrocarbon fuel sources.
QuesTek is uniquely positioned to lead solutions to all three of these challenges. We offer world-leading microstructure-sensitive fatigue modeling which combines extremely effectively with our accelerated insertion of materials (AIM) methodology to reduce testing and accelerate qualification and certification for fatigue-critical metallic components. Similarly, these tools can be applied toward sustainment to increase reliability of predicted remaining life and enhance inspections.
QuesTek has a long history of developing high-strength structural materials that are resistant to hydrogen effects using our hydrogen databases based on DFT and experimental results and our grain boundary embrittlement modeling approach. Additionally, we have experience modeling the effects of hydrogen on dislocation dynamics and in turn on crystal plasticity to model the effects of hydrogen on fracture and fatigue.
Another highlight of ICAF 2023 was seeing first-hand how rapidly the industry is moving toward advanced manufacturing techniques like additive manufacturing. QuesTek has a foothold as one of the technical leaders in understanding both material and process challenges in AM. There was also a lot of talk about sustainability and extending the life of existing aircrafts as well as designing the next generation to be more environmentally friendly (e.g., hydrogen-powered).
Between sessions, I was pleased to have the opportunity to speak with representatives from organizations such as Canada’s National Research Council, the FAA and AFRL. I am looking forward to applying insights from ICAF over the coming months, and hopefully my presentation was of value to attendees as well.
Using Digital Twins to Accelerate Qualification and Certification of Fatigue Critical Components
Gary F Whelan, Jiadong Gong, Greg B Olson
Fatigue of engineering alloys is a major challenge in aerospace applications. Developing and qualifying fatigue critical components for use in aerospace requires manufacturing and testing of a significant number of test coupons. This process is highly time consuming and expensive.
QuesTek’s ICMD® modeling software can provide reliable property predictions that can significantly lower the amount of testing required while still yielding a robust material property dataset. Utilizing integrated computational materials engineering methodologies, QuesTek has been developing microstructure sensitive fatigue models that can account for both intrinsic (e.g., grain size, grain morphology, phase fractions, crystallographic texture, etc.) and extrinsic (e.g., inclusions, surface roughness, porosity, etc.) features that drive fatigue life in engineering alloys.
QuesTek uses a fatigue modeling framework combing crystal plasticity finite element method to predict fatigue indicator parameters at the mesoscale, with microstructurally small crack propagation and physically long crack propagation algorithms, to predict the full fatigue life from incubation to ultimate fatigue failure in both high and low cycle fatigue. This approach depends on both microstructure characterization used to generate the inputs for a microstructure digital twin, as well as a select few experiments to calibrate the physics-based models.
By simulating the majority of loading scenarios of interest, testing can be targeted to just the most informative experiments during qualification. This approach offers three key benefits when compared with traditional design of experiment approaches; (1) decreased cost of qualification, (2) decreased time for qualification, and (3) improved mechanistic understanding of the key driving features for fatigue failure in a given alloy system, enabling optimization and improvements.
QuesTek has recently made major strides in improving this modeling approach by decreasing the computational cost of simulations, making the approach feasible on QuesTek’s cloud-based software, and by incorporating key microstructure features of interest for additively manufactured alloys such as anisotropic grain morphology/texture, porosity, and surface roughness. While this toolkit can be applied to traditionally manufactured alloys, it is particularly impactful for additively manufactured alloys due to their complex microstructures which result in difficult and expensive qualification processes when microstructure sensitive models are not utilized.