Computational Structural Dynamics Model Research Articles

The Sensitivity of 5MW Wind Turbine Blade Sections to the Existence of Damage

Due to the large size of offshore wind turbine blades (OWTBs) and the corrosive nature of salt water, OWTs need to be safer and more reliable that their onshore counterparts. To ensure blade reliability, an accurate and computationally efficient structural dynamic model is an essential ingredient. If damage occurs to the structure, the intrinsic properties will change, e.g., stiffness reduction. Therefore, the blade’s dynamic characteristics will differ from those of the intact ones. Hence, symptoms of the damage are reflected in the dynamic characteristics that can be extracted from the damaged blade. Thus, damage identification in OWTBs has become a significant research focus. In this study, modal model characteristics were used for developing an effective damage detection method for WTBs. The technique was used to identify the performance of the blade’s sections and discover the warning signs of damage. The method was based on a vibration-based technique. It was adopted by investigating the influence of reduced blade element rigidity and its effect on the other blade elements. A computational structural dynamics model using Rayleigh beam theory was employed to investigate the behaviour of each blade section. The National Renewable Energy Laboratory (NREL) 5MW blade benchmark was used to demonstrate the behaviour of different blade elements. Compared to previous studies in the literature, where only the simple structures were used, the present study offers a more comprehensive method to identify damage and determine the performance of complicated WTB sections. This technique can be implemented to identify the damage’s existence, and for diagnosis and decision support. The element most sensitive to damage was element number 14, which is NACA_64_618.

CFD-CSD method for coupled rotor-fuselage vibration analysis with free wake-panel coupled model

An efficient comprehensive vibration analysis method for a helicopter rotor–fuselage coupling system is presented. This loose computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling approach with a free wake–panel coupled model is used for system vibration response analysis. The CSD model of the helicopter consists of a fuselage model using a refined three dimensional (3 D) finite element model (FEM) and a rotor model consisting of nonlinear moderate deflection beam elements with 15 degrees of freedom. The unsteady Euler CFD solver is used for the flow field analysis of the entire vehicle. The induced inflow of the quasi-steady aerodynamic force is calculated with the free wake–panel coupled model, which is used to simulate rotor–fuselage aerodynamic interference. Using a full-scale helicopter as an example, the vibration responses of the typical fuselage position in hovering and level flights are analysed. When compared with the literature results and flight test data, the predictions of the proposed method are closer to the test data than those of the traditional method in hovering and low forward ratio flights, and the difference between the two methods is minimal in high forward ratio flight.

CFD-CSD coupled analysis of underwater propulsion using a biomimetic fin-and-joint system

The remarkable performance of various species of fish in propulsion and maneuvering has motivated the design and analysis of flexible, biomimetic underwater propulsors, which may be particularly suitable to small-scale, unmanned vehicles. In this work, we employ a novel fluid-structure coupled computational framework, referred to as FIVER (a FInite Volume method based on Exact Riemann solvers), to simulate the flapping motion of a fin-and-joint system, which mimics the caudal peduncle and caudal fin of fish, and serves as a simplified engineering model of tail-dominated fish propulsion. This problem is dominated by fluid-structure interaction, featuring a three-dimensional, unsteady fluid flow, large structural motion and deformation, and strong added-mass effect. To handle these challenges, we apply an embedded boundary method and a numerically-stable partitioned procedure to couple a hybrid finite volume – finite element computational fluid dynamics (CFD) solver and a nonlinear finite element computational structural dynamics (CSD) solver. First, we validate the CFD and CSD models using experimental data in fundamental vibration frequency, hydrodynamic forces, and structural displacement. Next, we investigate the fluid and structural dynamics, as well as the propulsive performance, focusing on the two-way fluid-structure coupling and the three-dimensional flow variation, which supplements the existing body of literature on biological and bio-inspired fluid dynamics. Further, by comparing a wide, trapezoidal fin and a narrow, forked fin, we investigate the various effects of fin geometry, and more generally, also demonstrate the use of observations and knowledge of biological diversity in the design of engineering systems.

Aeroelastic Analysis of a Hingeless Rotor Using a Dynamic Wake Model

Aeroelastic Analysis of a Hingeless Rotor Using a Dynamic Wake Model

Comparison between computational fluid dynamics, fluid–structure interaction and computational structural dynamics predictions of flow-induced wall mechanics in an anatomically realistic cerebral aneurysm model

Haemodynamically induced stress plays an important role in the progression and rupture of cerebral aneurysms. The current work describes computational fluid dynamics (CFD), fluid–structure interaction (FSI) and computational structural dynamics (CSD) simulations in an anatomically realistic model of a carotid artery with two saccular cerebral aneurysms in the ophthalmic region. The model was obtained from three-dimensional (3D) rotational angiographic imaging data. CFD and FSI were studied under a physiologically representative waveform of inflow. The arterial wall was assumed elastic or hyperelastic, as a 3D solid or as a shell depending on the type of modelling used. The flow was assumed to be laminar, non-Newtonian and incompressible. The CFD, FSI and CSD models were solved with the finite elements package ADINA. Predictions of velocity field and wall shear stress (WSS) on the aneurysms made using CFD and FSI were compared. The CSD model of the aneurysms using complete geometry was compared with isolated aneurysm models. Additionally, the effects of hypertensive pressure on CSD aneurysm models are also reported. The vortex structure, WSS, effective stress, strain and displacement of the aneurysm walls showed differences, depending on the type of modelling used.