Variable-kinematics shell model: Application to delamination analysis Aewis Hii, Luiz Kawashita, Alberto Pirrera ACCIS CDT Conference 2019
2 Introduction Methodology: • Variable-kinematics models. • Variable-order cohesive segment method. Goals: • Reduce model size by selective refinements. • Minimal user inputs. Variable-kinematics shell model 16 th April 2019
3 Variable-kinematics shell model `Tune- able’ model kinematics In-plane order ( n ) … Through-thickness order ( m ) Based on the Unified Formulation. … Independently defined/refined in- … … plane and thickness Model order N,M kinematics. Variable-kinematics shell model 16 th April 2019
4 Analysis-specific model kinematics For iterative design analyses Parametric study for model kinematics • Model settings for 3D-FEM 𝜏 33 iterative analyses. 𝜏 12 𝜏 23 • Accurate stresses for higher-order variants. 3D Stresses Large deformation analysis 5 × 10 elements 10 × 20 elements 20 × 30 elements Modal analysis Stiffness analyses . . . In-plane displacement field . . . Through-thickness displacement field Variable-kinematics 3D stress analyses model Twisted composite shell with variable thickness Variable-kinematics shell model 16 th April 2019
5 Variable-order cohesive segment method Oscillation- free crack initiation and ‘partial cracking’ No pre-defined crack path Damaged state Elastic Kinematics blending/mapping Features: 𝐯 𝑞 = 𝐯 𝑢 • Complex crackfront geometry. 𝜖𝐯 𝑞 𝜖𝐲 ≠ 𝜖𝐯 𝑢 • Low model size due to adaptive refinement. 𝜖𝐲 • Large element size. 2 × N th order 2N th order N th order Variable-kinematics shell model 16 th April 2019
6 Application to delamination analysis Structural response Adaptive model for complex crackfront Model size comparison Model size Full model Force ‘Peeling’ of a laminate Adaptive model with pre-crack Full model Adaptive model Curved crack front with rectangle mesh Displacement Simulation time Relaxing mesh size requirements Elements are split Pure Mode I: `on-the- fly’ Double Cantilever Beam Regular elements 1 st order element Transition elements 3 rd order element Padding elements Experiment Delamination Analytical Variable-kinematics shell model 16 th April 2019
7 Acknowledgements The authors would like to acknowledge Rolls-Royce plc for their support of this research through the Composites University Technology Centre at the University of Bristol, UK Variable-kinematics shell model 16 th April 2019
Thank you! aewis.hii@bristol.ac.uk
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