Real-Time Hybrid Model Testing of Moored Floating Structures Using Nonlinear Finite Element Simulations

2017 ◽  
pp. 79-92 ◽  
Author(s):  
Stefan A. Vilsen ◽  
Thomas Sauder ◽  
Asgeir J. Sørensen
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Hybrid Model ◽  
Model Testing ◽  
Finite Element Simulations ◽  
Nonlinear Finite Element ◽  
Floating Structures

A Compliant Transmission Mechanism With Intermittent Contacts for Cycle-Doubling

2006 ◽  
Vol 129 (1) ◽  
pp. 114-121 ◽  
Author(s):  
Nilesh D. Mankame ◽  
G. K. Ananthasuresh
Keyword(s):  
Finite Element ◽  
Conceptual Design ◽  
Finite Element Simulations ◽  
Nonlinear Finite Element ◽  
Transmission Mechanism ◽  
Input Frequency ◽  
Length Scales ◽  
Wide Range ◽  
Macro Scale ◽  
Functional Prototype

A novel compliant transmission mechanism that doubles the frequency of a cyclic input is presented in this paper. The compliant cycle-doubler is a contact-aided compliant mechanism that uses intermittent contact between itself and a rigid surface. The conceptual design for the cycle-doubler was obtained using topology optimization in our earlier work. In this paper, a detailed design procedure is presented for developing the topology solution into a functional prototype. The conceptual design obtained from the topology solution did not account for the effects of large displacements, friction, and manufacturing-induced features such as fillet radii. Detailed nonlinear finite element analyses and experimental results from quasi-static tests on a macro-scale prototype are used in this paper to understand the influence of the above factors and to guide the design of the functional prototype. Although the conceptual design is based on the assumption of quasi-static operation, the modified design is shown to work well in a dynamic setting for low operating frequencies via finite element simulations. The cycle-doubler design is a monolithic elastic body that can be manufactured from a variety of materials and over a range of length scales. This makes the design scalable and thus adaptable to a wide range of operating frequencies. Explicit dynamic nonlinear finite element simulations are used to verify the functionality of the design at two different length scales: macro (device footprint of a square of 170mm side) at an input frequency of 7.8Hz; and meso (device footprint of a square of 3.78mm side) at an input frequency of 1kHz.

Hybrid Model Tests for Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Maxime Thys ◽  
Alessandro Fontanella ◽  
Federico Taruffi ◽  
Marco Belloli ◽  
Petter Andreas Berthelsen
Keyword(s):  
Wind Tunnel ◽  
Real Time ◽  
Hybrid Model ◽  
Wind Turbines ◽  
Ocean Basin ◽  
Model Testing ◽  
Model Tests ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Abstract Model testing of offshore structures has been standard practice over the years and is often recommended in guidelines and required in certification rules. The standard objectives for model testing are final concept verification, where it is recommended to model the system as closely as possible, and numerical code calibration. Model testing of floating offshore wind turbines is complex due to the response depending on the aero-hydro-servo-elastic system, but also due to difficulties to perform model tests in a hydrodynamic facility with correctly scaled hydrodynamic, aerodynamic and inertial loads. The main limitations are due to the Froude-Reynolds scaling incompatibility, and the wind generation. An approach to solve these issues is by use of hybrid testing where the system is divided in a numerical and a physical substructure, interacting in real-time with each other. Depending on the objectives of the model tests, parts of a physical model of a FOWT can then be placed in a wind tunnel or an ocean basin, where the rest of the system is simulated. In the EU H2020 LIFES50+ project, hybrid model tests were performed in the wind tunnel at Politecnico di Milano, as well as in the ocean basin at SINTEF Ocean. The model tests in the wind tunnel were performed with a physical wind turbine positioned on top of a 6DOF position-controlled actuator, while the hydrodynamic loads and the motions of the support structure were simulated in real-time. For the tests in the ocean basin, a physical floater with tower subject to waves and current was used, while the simulated rotor loads were applied on the model by use of a force actuation system. The tests in both facilities are compared and recommendations on how to combine testing methodologies in an optimal way are discussed.

scholarly journals Method for Real-Time Hybrid Model Testing of ocean structures: Case study on horizontal mooring systems

2019 ◽  
Vol 172 ◽  
pp. 46-58 ◽  
Author(s):  
S.A. Vilsen ◽  
T. Sauder ◽  
A.J. Sørensen ◽  
M. Føre
Keyword(s):  
Real Time ◽  
Hybrid Model ◽  
Model Testing

Forming new steel-framed openings in load-bearing masonry walls: design methods and nonlinear finite element simulations

2019 ◽  
Vol 17 (5) ◽  
pp. 2647-2670 ◽  
Author(s):  
Lorenzo Billi ◽  
Francesco Laudicina ◽  
Luca Salvatori ◽  
Maurizio Orlando ◽  
Paolo Spinelli
Keyword(s):  
Finite Element ◽  
Design Methods ◽  
Finite Element Simulations ◽  
Nonlinear Finite Element ◽  
Masonry Walls ◽  
Load Bearing

Hybrid Modeling of Melt Pool Geometry in Additive Manufacturing Using Neural Networks

2021 ◽  
Author(s):  
Kevontrez Jones ◽  
Zhuo Yang ◽  
Ho Yeung ◽  
Paul Witherell ◽  
Yan Lu
Keyword(s):  
Neural Networks ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Real Time ◽  
Hybrid Model ◽  
Computational Models ◽  
Single Layer ◽  
Element Model ◽  
Additive Process ◽  
Melt Pool

Abstract Laser powder-bed fusion is an additive manufacturing (AM) process that offers exciting advantages for the fabrication of metallic parts compared to traditional techniques, such as the ability to create complex geometries with less material waste. However, the intricacy of the additive process and extreme cyclic heating and cooling leads to material defects and variations in mechanical properties; this often results in unpredictable and even inferior performance of additively manufactured materials. Key indicators for the potential performance of a fabricated part are the geometry and temperature of the melt pool during the building process, due to its impact upon the underlining microstructure. Computational models, such as those based on the finite element method, of the AM process can be used to elucidate and predict the effects of various process parameters on the melt pool, according to physical principles. However, these physics-based models tend to be too computationally expensive for real-time process control. Hence, in this work, a hybrid model utilizing neural networks is proposed and demonstrated to be an accurate and efficient alternative for predicting melt pool geometries in AM, which provides a unified description of the melting conditions. The results of both a physics-based finite element model and the hybrid model are compared to real-time experimental measurements of the melt pool during single-layer AM builds using various scanning strategies.

Sign in / Sign up

Export Citation Format

Share Document