Multi-fidelity fluid–structure interaction analysis of a membrane blade concept in non-rotating, uniform flow condition

In order to study the aerodynamic performance of a semi-flexible membrane blade, fluid–structure interaction simulations have been performed for a non-rotating blade under steady inflow condition. The studied concept blade has a length of about 5 m. It consists of a rigid mast at the leading edge, ribs along the blade, tensioned edge cables at the trailing edge and membranes forming the upper and lower surface of the blade. Equilibrium shape of membrane structures in the absence of external loading depends on the location of the supports and the prestresses in the membranes and the supporting edge cables. Form-finding analysis is used to find the equilibrium shape. The exact form of a membrane structure for the service conditions depends on the internal forces and also on the external loads, which in turn depend on the actual shape. As a result, two-way coupled fluid–structure interaction (FSI) analysis is necessary to study this class of structures. The fluid problem has been modelled using two different approaches, which are the vortex panel method and the numerical solution of the Navier–Stokes equations. Nonlinear analysis of the structural problem is performed using the finite-element method. The goal of the current study is twofold: first, to make a comparison between the converged FSI results obtained from the two different methods to solve the fluid problem. This investigation is a prerequisite for the development of an efficient and accurate multi-fidelity simulation concept for different design stages of the flexible blade. The second goal is to study the aerodynamic performance of the membrane blade in terms of lift and drag coefficient as well as lift-to-drag ratio and to compare them with those of the equivalent conventional rigid blade. The blade configuration from the NASA-Ames Phase VI rotor is taken as the baseline rigid-blade configuration. The studied membrane blade shows a higher lift curve slope and higher lift-to-drag ratio compared with the rigid blade

Particle-structure interaction using cad-based boundary descriptions and isogeometric B-REP analysis (IBRA)

The procedure and the properties with the use of NURBS-described CAD models in particle-structure interaction are presented within this contribution. This implies the needed entities of those models and the description of trimmed multipatches to discretize analysis suitable numerical models. Finally, the properties will be shown with some test cases in comparison to analytical benchmarks and simulations with FEM as boundary description

Coupling the Discrete Element Method with the Finite Element Method to Simulate Rockfall Impact Experiments

To numerically simulate rockfall impact on flexible protection structures two different numerical methods are coupled within the open-source multi-physics code KRATOS. The impacting object is modeled with the help of a cluster of spherical discrete elements and its movement and contact forces are simulated using the Discrete Element Method (DEM). To realize a partitioned coupling simulation the contact forces are subsequently transferred to the light-weight protection structure which is analyzed and simulated using the Finite Element Method (FEM). To allow a stable simulation even in the case of large contact forces and/or large time steps a strong coupling GaussSeidel algorithm is presented. Subsequently the applicability of the method is shown by calculating experiments and finally the inclusion of digital terrain data is demonstrated

Concept and realization of the coupling software empire in multiphysics co-simulation

The purpose of the software EMPIRE is to perform n-code co-simulation for solving multiphysics problems. EMPIRE provides a flexible way for constructing vari- ous co-simulation environments by introducing the concepts of connection and filter. It also provides data operations useful for general co-simulation including mapping between non-matching grids, extrapolation in time and relaxation in iterative coupling. The con- cepts and ingredients of EMPIRE are presented in this paper. Finally, the software is demonstrated by two FSI simulations

World Congresses of Structural and Multidisciplinary Optimization

The goal of robust design optimization is to improve the quality of a product or process by minimizing the deteriorating e#ects of variable or uncertain parameters. This robustness can be achieved by di#erent approaches using formulations of statistical decision theory which all require many function evaluations throughout the optimization. In cases where no closed-form descriptions of the objective are available and pointwise solutions are expensive to evaluate, metamodelling techniques based on design of experiments are used to replace the actual numerical analysis codes. In this paper we present a well-suited update criterion for global approximation models which have a local measure for the model variance to find a robust optimal design up to the desired precision both in the objective and the robustness