NICOP - Fatigue Life of Post-Buckled Composite Structures
Abstract
The main objective of the proposed research is to develop a high-fidelity analysis methodology topredict the propagation of fatigue" damage in post-buckled laminated composite structures. Indeed,thin stiffened composite structures, typical of the aircraft wings a""nd fuselages, have the ability tosustain loads that far exceed buckling. However, this capacity is not usually exploited due to the"uncertainties associated with fatigue and damage tolerance. Difficulties in determining the durabilityand damage tolerance of post#NAME?"ts interaction with several damagemodes.For studying delamination progression under fatigue loading, a model based on Linear Elast""icFracture Mechanics, which correlates fatigue crack growth rate with energy release rate and moderatio,will be combined with cohe""sive elements, which set up damage evolution as a function of thenumber of cycles. In particular, a cohesive constitutive damage mo""del will be developed to take intoaccount the evolution of the damage variable, as a function of the cyclic loading that will be de"rivedfrom a fatigue crack growth rate given by the Paris Law. The damage model will take into account thenumber of cycles as well" as other loading variables, such as the load ratio, the energy release rate andthe fracture mode-ratio. The model will account for"" all loading ranges, from the threshold for nogrowth to unstable tearing.The delamination progression under fatigue loading will b""e at first developed for simple structuresthat present linear responses, and then will be extended for studying post-buckled struct"ures thatinclude nonlinear geometric responses. The interaction between the nonlinear post-buckled responseand the fatigue damage" progression will be investigated and taken into account.The methodology will be explored and implemented, keeping always in mind t"he need of amethodology that is sufficiently tractable for large structures and does not require the use of anymodel-specific adjustment parameters. It will be validated through carefully conducted tests with acomplete set of measurements.The proposed project also has a broader impact resulting in (1) the availability of modeling methodsfor computational mechanics of composite structures; (2) a better knowledge of composite materialsbehavior directly applicable to several and different engineering applications; and" (3) the exposure ofbachelor, Master and PhD engineering students to mechanically-rich problems of compositestructures, through nu"merical and experimental research.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 03, 2017
- Source ID
- N629091712129
Entities
People
- Chiara Bisagni
Organizations
- Delft University of Technology
- Office of Naval Research
- United States Navy