Ronald Krueger
Research Fellow,
National Institute of Aerospace
Wednesday, February 21, 2024 | Zoom Meeting Online6:00 to 7:00 pm Pacific
Face sheet/core disbonding poses a threat to the structural integrity of a sandwich component. In this presentation a methodology is provided to predict the onset and growth of face sheet/core disbonding in sandwich structures. The methodology is similar to the one used for delaminations in monolithic composite laminates where an assessment is typically made by measuring a critical strain energy release rate.
Two general steps are required to address the phenomenon associated with face sheet/core disbanding:
- First, a reliable means of characterizing face sheet/core disbonding has to be established. The Single Cantilever Beam (SCB) test has been identified as the most appropriate configuration to develop an ASTM standardized test method for a mode I dominated fracture toughness of sandwich constructions. Additionally, the development of a guide for mode I fatigue based on the static SCB test is proposed. Further, a Sandwich Mixed-Mode Bending (S-MMB) test for mixed-mode I/II fracture toughness of sandwich constructions based on the ASTM MMB test for laminates is suggested.
- Second, analysis methods are required to help assess the likelihood of a structure exhibiting critical disbonding. The Virtual Crack Closure Technique (VCCT) and the Crack Surface Displacement Extension (CSDE) methods have been used to calculate the total energy release rate along the disbond front based on the results obtained from high-fidelity finite element analysis of the disbonded sandwich panel.
An alternate approach uses cohesive elements at the interface to determine disbond growth. A rapid engineering analysis tool based on an energy-based Rayleigh-Ritz approach is also discussed. Join us at 6:00 pm PDT Thursday February 2nd to dig into this important topic!
About Our Presenter
Dr. Ronald Krueger is a Research Fellow at the National Institute of Aerospace (NIA), which he joined as a Senior Research Engineer in 2003. He is involved in the development of durability and damage tolerance analyses for composite and sandwich structures using finite element analysis and fracture mechanics.
Prior to joining NIA, he worked as a Staff Scientist at ICASE in the NASA Langley Research Center, following an NRC post-doctoral research position at NASA Langley Research Center.
He is an accomplished presenter and awarded author of 85 technical papers published in refereed journals and international conference proceedings. His work has been cited more than 4300 times in the open literature. He has received awards from a host of technical societies and organizations, including:
- ASTM, and its Committee D30 on Composite Materials
- American Society for Composites
- Australian Composite Structures Society
- NASA Langley Research Center
- National Institute of Aerospace
- The Composite Materials Handbook (CMH-17).
- Peninsula Engineers Council Engineer of the Year
- AIAA Hampton Roads Section Engineer of the Year
- AIAA Region I Engineer of the Year Honor Society Distinguished Member
- Co-chair of the Technical Conference on Composite Materials, 2006 & 2014
He is an AIAA Associate Fellow and a member of ASTM International and its Committee D-30 on Composite Materials, where he currently serves as chair. He is an active member of the American Society for Composites and The Composites Materials Handbook (CMH-17), where he currently serves as co-chair for the Disbonding and Delamination Task Group. He is an active member of the NAFEMS Composites Working Group, which he chaired from 2011 until 2021.
Dr. Krueger received his doctorate in Aerospace Engineering from the University of Stuttgart, Germany, where he worked as a research and teaching assistant at the Institute for Statics and Dynamics of Aerospace Structures.
Registration
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