Use Of Nonlinear Materials Research Articles

Numerical modeling of a mooring line system for an offshore floating wind turbine in Vietnamese sea conditions using nonlinear materials

The offshore renewable energy industry has been developing farms of floating offshore wind turbines in water depths up to 100 m. In Vietnam, floating offshore wind turbines have been developed to increase the production of clean and sustainable energy. The mooring system, which is used to keep the turbine stable and ensure the safety and economic efficiency of wind power production, is an important part of a floating offshore wind turbine. Appropriate selection of the mooring type and mooring line material can reduce the risks arising from the motion of wind turbines. Different types of mooring line material have been simulated and compared in order to determine the optimal type with the minimum motion risk for a floating wind turbine. This study focused on numerical modeling of semi-taut mooring systems using nonlinear materials for a semi-submersible wind turbine. Several modeling approaches common to current practice were applied. Hydrodynamic analysis was performed to investigate the motion of the response amplitude operators of the floating wind turbine. Dynamic analysis of mooring systems was performed using a time domain to obtain the tension responses of mooring lines under the ultimate limit states and fatigue limit states in Vietnamese sea conditions. The results showed that the use of nonlinear materials (polyester and/or nylon) for mooring systems can minimize the movement of the turbine and save costs. The use of synthetic fibers can reduce the maximum tension in mooring lines and the length of mooring lines. However, synthetic fiber ropes showed highly nonlinear load elongation properties, which were difficult to simulate using numerical software. The comparison of the characteristics of polyester and nylon mooring lines showed that the maximum and mean tensions of the nylon line were less than those of the polyester line. In addition, the un-stretched length of the polyester line was greater than that of the nylon line under the same mean tension load. Therefore, nylon material is recommended for the mooring lines of a floating offshore wind turbine.

Effect of Spoke Design and Material Nonlinearity on Non-Pneumatic Tire Stiffness and Durability Performance

Non-pneumatic tire has been widely used due to their advantages of no run-flat, no need of air maintenance, low rolling resistance, and improvement of passengers comfort due to its better shock absorption. It has variety of application in the military vehicle, earthmovers, lunar rover, stair climbing vehicles etc. Recently UPTIS (Unique Puncture-Proof Tire System) non pneumatic tire has been introduced for passenger vehicles. In this study three different design configuration Tweel, Honeycomb and newly developed UPTIS have been compared. Effect of Polyurethane (PU) material nonlinearity have also been introduced by applying 5 different nonlinear PU material property in the spokes. The combined analysis of the PU material nonlinearity and spoke design configuration on the overall tire stiffness and spoke damage prediction is analysed using 3-Dimensional FEM simulations performed in ANSYS 16.0. It has been observed that Mooney Rivlin 5-parameter model is best to capture all 5 studied PU materials the nonlinearity. Effect of material nonlinearity on various spoke designs have been studied. The best combination of spoke design and the use of nonlinear material have been suggested in terms of riding comfort, tire stiffness and durability performance.

Unidirectional Wave Propagation in Low-Symmetric Colloidal Photonic-Crystal Heterostructures.

We show theoretically that photonic crystals consisting of colloidal spheres exhibit unidirectional wave propagation and one-way frequency band gaps without breaking time-reversal symmetry via, e.g., the application of an external magnetic field or the use of nonlinear materials. Namely, photonic crystals with low symmetry such as the monoclinic crystal type considered here as well as with unit cells formed by the heterostructure of different photonic crystals show significant unidirectional electromagnetic response. In particular, we show that the use of scatterers with low refractive-index contrast favors the formation of unidirectional frequency gaps which is the optimal route for achieving unidirectional wave propagation.

Implementation of 1-Bit Random Access Memory Cell in All-Optical Domain with Non-linear Material

This paper demonstrates an all-optical 1-bit Random Access Memory (RAM) with massive use of nonlinear material. All-optical switching mechanism is exploiting here to realize the all-optical 1-bit RAM. The all-optical switch by a composite slab of linear medium (LM) and non-linear medium (NLM) is the building block of our proposed 1-bit RAM circuit. An all-optical clocked D flip flop is the main storing element of the RAM. These circuits are simple and all-optical in nature. It can also gear up to the highest capability of optical performance in high-speed all-optical data storing, comput- ing and communicating system.

Nonlinear Behavior of Single Piles in Jacket Type Offshore Platforms Using Incremental Dynamic Analysis

The operation for offshore oil has become an important issue in the recent years. Offshore platforms are some of those structures which are built to withstand environmental and accidental loads during oil exploitation operation. One of the most usual types of these platforms is the Jacket Type Offshore Platform (JTOP) which can be divided into three important parts, which are Deck, Jacket and piles. In order to increase the safety, particular attention should be paid to earthquake excitations which are directly applied to the piles of these structures. Nonlinearity in piles and buckling of the struts are important issues which have to be considered by the designers of offshore platforms. The case of nonlinearity in piles and failure capture in these members has not effectively been covered by researchers. Incremental Dynamic Analysis (IDA) is a powerful tool to assess the capacity of a structure upon seismic loads. In this paper incremental dynamic analysis has been implemented on single piles considering soil-pile interactions and free field site response. The use of nonlinear materials and lateral load resisting elements in the incremental dynamic analysis done in this paper has made it possible to get promising insights for incorporation of appropriate limit states and applications of performance based engineering. Special Engineering Demand Parameters (EDP) and Intensity Measures (IM) have been introduced for the single pile dynamic analysis in jacket type offshore platforms.

New method of all-optical data comparison with nonlinear material using 1's complement method

In high-speed computation, optics has established itself as a successful candidate. Many proposals have already been adopted for performing arithmetic, algebraic, and logic operations using light as the information carrier. We propose a new method of optical data comparison with the proper use of nonlinear material applying the 1's compliment method. The binary optical data are manipulated here properly to achieve the required result.

All-optical implementation of ASCII by use of nonlinear material for optical encoding of necessary symbols

We propose a simple all-optical technique for digital encoding of ASCII. The method accommodates a digital encoding system by using the optical tree architecture and a nonlinear-material-based optical switching operation.

Preparation and properties of electroluminescent phosphors for display devices

Electroluminescent phosphors for use in some electronic display devices should have brightness-voltage characteristics differing from those used in light sources, for example. The various factors of phosphor preparation and of cell construction which affect these characteristics have been studied. Special phosphor powders with unusually high or unusually low values of (a quantity related to the change in output as the applied voltage is varied) have been developed and their performance described. It has also been shown that thin phosphor films afford extremely high values of discrimination ratio, particularly if operated on dc. The use of nonlinear materials (especially zinc oxide) as auxiliary layers to increase the discrimination ratio obtained with a given phosphor has been studied.