סמינר מחלקה עם המסטרנט ניצן בריסקין
בנושא: מודלי נזק התעייפות מבוססי-מיקרומכניקה עבור חומרים מרוכבים שכבתיים.
School of Mechanical Engineering Seminar
Wednesday, December 29, 2021, at 14.00
Wolfson Building of Mechanical Engineering, Room 206
Micromechanics-based Fatigue Damage Modeling of Laminated Composite Structures
Nitsan Briskin
M.Sc. student of Prof. Rami Haj-Ali
The increased demand for new advanced composites in aerospace, automotive, civil, and military applications necessitate a predictive fatigue failure framework of composite materials and structures for wide range of multi-axial loadings. While fatigue theories are relatively well-established for homogenous-isotropic materials, most are unsuited for composites. Furthermore, fatigue failure in composites is often associated with several interacting damage modes.
Fatigue experiments can get highly resource-demanding, as a single specimen may need to be tested for up to several weeks. Moreover, a wide experimental effort is needed to enclose the possible different material systems and their constituents, such as fibers, matrices, and lamination stacking sequences. A robust fatigue model is needed in order to deal with these challenges.
This study is aimed to develop a predictive model for fatigue-life, residual stiffness, and residual strength of composite materials and structures, such as plates and shells for aircraft components and other applications. In this research, a homogenized model of the composite material is generated using the Generalized Method of Cells (GMC) for computationally efficient micromechanics-based calculations. A new fatigue model is integrated with GMC by utilizing the Kinetic Theory of Fracture (KTF). The GMC-KTF developed code is integrated within the Abaqus commercial-based FEA. The fatigue cyclic damage modeling is achieved by using a loading history as an input to the FEA-GMC-KTF framework in order to estimate the service-life, residual stiffness, and strength of composite structural components.
The second part of this study is to apply the FEA-GMC-KTF framwork for the post-impact fatigue damage of composites. Towards that goal, low-velocity impact (LVI) analysis was performed for composite plates. The proposed fatigue framework predictions agree with the degradation in stiffness with cycles for notched multidirectional laminates. Progressive damage contours can capture the general characteristics of the experimentally observed damage patterns. Finally, preliminary simulations for post-fatigue strength are in good agreement with the limited avilable experimental data.
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