scholarly journals Evaluation of the durability of composite tidal turbine blades

2013 ◽  
Vol 371 (1985) ◽  
pp. 20120187 ◽  
Author(s):  
Peter Davies ◽  
Grégory Germain ◽  
Benoît Gaurier ◽  
Amélie Boisseau ◽  
Dominique Perreux
Keyword(s):  
Sea Water ◽  
Numerical Models ◽  
Turbine Blades ◽  
Cost Effective ◽  
Optimized Design ◽  
Tidal Turbines ◽  
Natural Choice ◽  
Tidal Turbine ◽  
Few Data

The long-term reliability of tidal turbines is critical if these structures are to be cost effective. Optimized design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades, but there are few data available to predict material behaviour under coupled environmental and cycling loading. The present study addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale, static and cyclic tests have been performed, both in air and in sea water. The influence of ageing in sea water on fatigue performance is then quantified, and much lower fatigue lives are measured after ageing. At a higher level, flume tank tests have been performed on three-blade tidal turbines. Strain gauging of blades has provided data to compare with numerical models.

scholarly journals Rotor Loading Characteristics of a Full-Scale Tidal Turbine

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1035 ◽  
Author(s):  
Magnus Harrold ◽  
Pablo Ouro
Keyword(s):  
Turbulent Flows ◽  
Mechanical Loading ◽  
Full Scale ◽  
Design Stage ◽  
Flow Profile ◽  
Expected Return ◽  
Tidal Turbines ◽  
Theoretical Predictions ◽  
Tidal Turbine

Tidal turbines are subject to highly dynamic mechanical loading through operation in some of the most energetic waters. If these loads cannot be accurately quantified at the design stage, turbine developers run the risk of a major failure, or must choose to conservatively over-engineer the device at additional cost. Both of these scenarios have consequences on the expected return from the project. Despite an extensive amount of research on the mechanical loading of model scale tidal turbines, very little is known from full-scale devices operating in real sea conditions. This paper addresses this by reporting on the rotor loads measured on a 400 kW tidal turbine. The results obtained during ebb tidal conditions were found to agree well with theoretical predictions of rotor loading, but the measurements during flood were lower than expected. This is believed to be due to a disturbance in the approaching flood flow created by the turbine frame geometry, and, to a lesser extent, the non-typical vertical flow profile during this tidal phase. These findings outline the necessity to quantify the characteristics of the turbulent flows at sea sites during the entire tidal cycle to ensure the long-term integrity of the deployed tidal turbines.

scholarly journals Influence of Seawater Ageing on Fracture of Carbon Fiber Reinforced Epoxy Composites for Ocean Engineering

Oceans ◽  
2020 ◽  
Vol 1 (4) ◽  
pp. 198-214
Author(s):  
Antoine Le Guen-Geffroy ◽  
Peter Davies ◽  
Pierre-Yves Le Gac ◽  
Bertrand Habert
Keyword(s):  
Carbon Fiber ◽  
Material Selection ◽  
Turbine Blades ◽  
Base Material ◽  
Fiber Reinforced ◽  
Ocean Engineering ◽  
Worst Case ◽  
Tidal Turbine ◽  
Carbon Fiber Reinforced ◽  
Few Data

Carbon fiber reinforced composite materials are finding new applications in highly loaded marine structures such as tidal turbine blades and marine propellers. Such applications require long-term damage resistance while being subjected to continuous seawater immersion. However, few data exist on which to base material selection and design. This paper provides a set of results from interlaminar fracture tests on specimens before and after seawater ageing. The focus is on delamination as this is the main failure mechanism for laminated composites under out-of-plane loading. Results show that there are two contributions to changes in fracture toughness during an accelerated wet ageing program: effects due to water and effects due to physical ageing. These are identified and it is shown that this composite retains over 70% of its initial fracture properties even for the worst case examined.

Durability of Polymers and Composites: The Key to Reliable Marine Renewable Energy Production

2018 ◽  
Author(s):  
Peter Davies ◽  
Pierre-Yves Le Gac ◽  
Maelenn Le Gall ◽  
Mael Arhant ◽  
Corentin Humeau
Keyword(s):  
Renewable Energy ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Synthetic Fiber ◽  
Marine Renewable Energy ◽  
Tidal Turbines ◽  
Marine Energy ◽  
Influence Of Water ◽  
Tidal Turbine ◽  
Significant Cost Reduction

Recovery of marine energy is progressing from the prototype stage to arrays, and all of the systems currently being developed include critical elements manufactured from polymers and composites. Structural MRE (Marine Renewable Energy) components range from composite turbine blades, for floating wind and tidal turbines, to polymer fiber ropes for wave, tidal and floating wind mooring systems. Elastomeric components are also widely used for sealing and protection. In all cases it is essential to understand how seawater diffuses into these polymers and how it affects mechanical properties; this allows appropriate safety factors to be applied without excessive over-conservative design, and can result in significant cost reduction. This paper will present a methodology for evaluating the long term behavior of such components based on accelerated testing. Three examples will be shown to illustrate the approach; tidal turbine blade composites, synthetic fiber rope moorings, and rubber components. In each case the seawater diffusion kinetics will be described first, then the influence of water on mechanical behavior will be quantified for the particular loadings of interest, and finally results from fully coupled fatigue tests in seawater will be discussed.

scholarly journals Applying a simple model for estimating the likelihood of collision of marine mammals with tidal turbines

2018 ◽  
Vol 1 (1 (Aug)) ◽  
pp. 27-33 ◽  
Author(s):  
A. E. Copping ◽  
M. E. Grear
Keyword(s):  
Simple Model ◽  
Potential Risk ◽  
Real World ◽  
Marine Mammals ◽  
Turbine Blades ◽  
Collision Risk ◽  
Risk Models ◽  
Collision Model ◽  
Tidal Turbines ◽  
Tidal Turbine

As tidal turbine deployments continue at test sites and in commercial areas, the potential risk for injury or death of marine mammals from colliding with rotating turbine blades continues to confound efficient consenting (permitting) of devices. Direct observation of collisions is technically very challenging and costly. Estimates of collision risk to date have been derived from complex collision risk models that depend on estimates of the number of marine mammals found in the area. Using a simple collision model, the risk of collision was examined at three real-world sites, each of which featured an indigenous marine mammal. Two different turbine designs were examined at each site to extend the range of the estimates. The results of the model runs allow for comparison of risk at a range of tidal sites for a variety of the marine mammals thought to be at potential risk.

scholarly journals Influence of Material and Effects of Tidal Turbine Blade: A Review

2021 ◽  
Vol 9 (VI) ◽  
pp. 753-756
Author(s):  
Aayushi Suryawanshi
Keyword(s):  
Essential Role ◽  
Turbine Blades ◽  
Electrical Energy ◽  
The Past ◽  
Tidal Turbines ◽  
Alternative Materials ◽  
Tidal Turbine ◽  
Overall Performance ◽  
Marine Currents ◽  
Tidal Turbine Blades

In the past few years, tidal turbines have been developed to exploit the kinetic energy of seawater currents to generate electrical energy. The blade is the greater essential part of the tidal mills. It is designed in line with hydrodynamic science so that you can seize the most power from marine currents and supposed to face up to the environment marine conditions for long intervals. The cloth choice of the tidal turbine blades in the sort of extreme surroundings performs a essential role inside the efficiency of the tidal turbine. This paper discusses vital factors that affect the overall performance and the sturdiness of the tidal modern turbine together with cavitation, biofouling and corrosion. This paper intends to offer a quick evaluation of the characteristics of available materials for tidal modern turbine blades. Apart from the traditional substances, new alternative materials undertaken are discussed.

Physical and Psychological Benefits of Written Emotional Expression

2015 ◽  
Vol 20 (4) ◽  
pp. 242-251 ◽  
Author(s):  
Éva Kállay
Keyword(s):  
Mental Health ◽  
Expressive Writing ◽  
Mental Health Problems ◽  
Cost Effective ◽  
Health Problems ◽  
Future Research ◽  
Psychological Benefits ◽  
Cost Effective Treatment ◽  
Meta Analyses

Abstract. The last several decades have witnessed a substantial increase in the number of individuals suffering from both diagnosable and subsyndromal mental health problems. Consequently, the development of cost-effective treatment methods, accessible to large populations suffering from different forms of mental health problems, became imperative. A very promising intervention is the method of expressive writing (EW), which may be used in both clinically diagnosable cases and subthreshold symptomatology. This method, in which people express their feelings and thoughts related to stressful situations in writing, has been found to improve participants’ long-term psychological, physiological, behavioral, and social functioning. Based on a thorough analysis and synthesis of the published literature (also including most recent meta-analyses), the present paper presents the expressive writing method, its short- and long-term, intra-and interpersonal effects, different situations and conditions in which it has been proven to be effective, the most important mechanisms implied in the process of recovery, advantages, disadvantages, and possible pitfalls of the method, as well as variants of the original technique and future research directions.

Antithrombotic Therapy for DVT/PE

1997 ◽  
Vol 17 (03) ◽  
pp. 161-162
Author(s):  
Thomas Hyers
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Oral Anticoagulants ◽  
Cost Effective ◽  
Therapeutic Agents ◽  
Great Promise ◽  
Term Therapy ◽  
Low Molecular Weight ◽  
Long Term Therapy

SummaryProblems with unfractionated heparin as an antithrombotic have led to the development of new therapeutic agents. Of these, low molecular weight heparin shows great promise and has led to out-patient therapy of DVT/PE in selected patients. Oral anticoagulants remain the choice for long-term therapy. More cost-effective ways to give oral anticoagulants are needed.

Strategic planning in grassland farming: Principles andapplications

1997 ◽  
pp. 191-197
Author(s):  
W.J. Parker ◽  
N.M. Shadbolt ◽  
D.I. Gray
Keyword(s):  
Strategic Planning ◽  
Performance Indicators ◽  
Cost Effective ◽  
Key Performance Indicators ◽  
Strategic Plans ◽  
Effective Manner ◽  
Farm Business ◽  
Pastoral Farming ◽  
Financial Environment

Three levels of planning can be distinguished in grassland farming: strategic, tactical and operational. The purpose of strategic planning is to achieve a sustainable long-term fit of the farm business with its physical, social and financial environment. In pastoral farming, this essentially means developing plans that maximise and best match pasture growth with animal demand, while generating sufficient income to maintain or enhance farm resources and improvements, and attain personal and financial goals. Strategic plans relate to the whole farm business and are focused on the means to achieve future needs. They should be routinely (at least annually) reviewed and monitored for effectiveness through key performance indicators (e.g., Economic Farm Surplus) that enable progress toward goals to be measured in a timely and cost-effective manner. Failure to link strategy with control is likely to result in unfulfilled plans. Keywords: management, performance

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