METASTABLE SANDWICH COMPOSITES FOR IMPACT AND FATIGUE DAMAGE TOLERANCE IN EXTREME CONDITIONS
Abstract
Research Problem: The primary objective of this research is to develop novel metastable sandwichcomposites and elucidate their damage tolerance and durability under extreme conditions, including,dynamic impact, fatigue loading and environmental conditions like, moisture, salt corrosion andvarying temperatures. ~Metastable~ materials are metamaterials that have multiple stableconfigurations with snap through response due to inherent architecture that can be tailored to achieveunconventional response to external stimulus.Approach: Several fundamental hypotheses will be tested that will significantly advance ourknowledge of polymer sandwich composites for minimizing the adverse effects of the abovementionedcombined loading conditions with the objective of achieving higher durability and damagetolerance. This will be achieved through cross-pollinating concepts from novel materials(metamaterials and syntactic foams for core), manufacturing processes (polymer additivemanufacturing for enabling multistable metamaterials), chemical processes (co-curing of polymers foradhesion between the facings and core), and advanced computational methods (phase field fracturemodeling and machine learning for damage and failure analyses). This research is split into 4 thrustareas: I. Mechanics driven hybrid inner/outer composite facing design, II. Additively manufacturemetastable syntactic cellular foam core, III. Seamless integration of composite facings and foam coreand IV. Assessment of structural integrity and fatigue life.Outcomes: Main outcomes are: Experimentally validated machine learned multi-physics and phasefield fracture modeling framework that elucidates the initiation and evolution of damage due to seawater exposure and varying temperatures in FRPC facings. Identified key underlying mechanisms ofstrengthening and toughening of hierarchical cellular metastable syntactic foams through combinedexperimental and computational approach. Established the importance of co-cured facing/metastablecore interface for achieving higher bond strength and toughness, along with an experimentallyvalidated computational model for optimizing the cure parameters. Determined the extent of impactdamage, compression after impact strengths, failure mechanisms and fatigue life of metastablesandwich composites under combined effects of mechanical loading and environmental effects, anddeveloped multi-dimensional maps that can potentially assist engineers with the design process ofstructural components.Impact: The proposed metastable sandwich composites have the potential to revolutionize the designand fabrication of naval structures by harnessing their unconventional properties manifested due tointernal architecture. Their response under static, fatigue and dynamic loading, as well as failuremechanisms in extreme conditions are critical for designing composite structures. Although themodeling approaches, fabrication technologies and testing procedures proposed here are in view ofmetastable sandwich composites, the thermo-chemo-mechanical behavior of a wide range of compositematerials can be determined using the established methodologies. This has the potential to directlysupport component design using lightweight composites for defense applications and contributing tothe priority of ONR towards improving the life cycle, durability, affordability and reliability for futureand legacy Navy systems and platforms. For the judicious selection of materials for naval applicationsin extreme environments, it is critical to establish longevity and structural integrity of lightweightmaterial systems and suggest appropriate improvements in the design process, which is the mainobjective of this research.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 24, 2019
- Source ID
- N000141912206
Entities
People
- Pavana Prabhakar
Organizations
- Office of Naval Research
- United States Navy
- University of Wisconsin System