Sandia Fracture Challenge – A Double Blind Benchmark Assessment of Failure Modeling Methodologies
Special Session Description:
Failure of structural metals is relevant to a wide range of engineering scenarios. Although computational methods are employed to anticipate the critical conditions of failure, generating predictions that have adequate confidence levels still pose significant difficulties to the simulation community. To elucidate the accuracy of these predictions, it is necessary to evaluate existing models in validation scenarios that approximate the conditions seen in practical applications. For this purpose, Sandia National Laboratories has organized a series of fracture challenges where participants are asked to predict quantities of interest (QoIs) in a given fracture scenario. The participants have never seen the challenge scenario previously, so the predictions are “blind” as is often the case in real engineering predictions. Moreover, while the scenarios are geometrically simple, they present mechanical complexities that are impossible to predict with intuition or simple calculations alone. After the blind predictions are reported, they are subsequently compared against experimental results to determine how closely they replicated the fracture behavior observed in the laboratory.
Since the first international challenge launched in year 2012, the Sandia Fracture Challenge (SFC) series has made significant impact in three aspects in computational mechanics and fracture modeling communities. Firstly, the Challenge is an assessment of state-of-the-art techniques to predict problems involving ductile fracture accurately. These methods cover many models and approaches pursued by academia and industry to deal with ductile fracture analysis. Secondly, the blind prediction environment offers individual participating team an environment of "true blindness" to evaluate the strengths and weaknesses of their methodology. This unique setup is a precious opportunity to refine their methods and tools. Thirdly, SFC has brought together a group of teams that have been actively working in the ductile fracture area for many years. Each team worked independently on the same fracture problem. The collective wisdom obtained by attacking a single specific task with a variety of strategies strengthens our understanding of ductile fracture. This Challenge process facilitates identifying current difficulties, acquiring experience to avoid certain pitfalls in future efforts, and fosters collaboration between universities, national laboratories, and industries around the world. It also contributes to a cumulative learning process.
At this special session the SFC project team and invited speakers will report the following SFC activities, share the lessons learned, and discuss the plan of future challenges.
Concept of SFC design and principles of managing the blind tests
Summary and lessons learned of SFC1, i.e. quasi-static fracture
Summary and lessons learned of SFC2, i.e. ductile failure at different loading rates
Summary and lessons learned of SFC3, i.e. fracture in additively manufactured material
Shear dominated ductile failure – an internal challenge at Sandia National Laboratories
Future direction of SFC
Brad L. Boyce, Ph.D.
Sandia National Laboratories, USA
Krishnaswamy Ravi-Chandar, Ph.D.
The University of Texas at Austin, USA