the partners

• Denmark
  • University of Denmark, DTU
  • DHI Water & Environment
  • Aalborg University
• Germany
  • ISET
  • University of Hannover
  • University of Kassel
  • University of Magdeburg
  • Carl von Ossietzky University of Oldenburg
  • University of Stuttgart
• Greece
  • University of Patras
  • CRES
  • National Technical University of Athens
• Netherlands
  • Delft University of Technology
  • ECN
• Norway
  • SINTEF, IFE and NTNU - Centre for Renewable Energy (SFFE)
• Spain
  • CENER
  • Instituto de Investigación de Energías Renovables (IIER)
  • Universidad Carlos III de Madrid (UC3M)
  • Universidad Politécnica de Madrid
  • Universidad Pública de Navarra
• United Kingdom
  • CREST
  • Durham University
  • Imperial College London
  • Manchester Metropolitan University
  • STFC Rutherford Appleton Laboratory
  • University of Manchester
  • The ICC at the University of Strathclyde
  • University of Surrey
  • Queen Mary

University of Patras

Contact University of Patras Applied Mechanics Laboratory, Dept. Mechanical Engineering and Aeronautics GR-265 00 Patras GREECE phone: +30 2610 996191 e-mail: saravanos@mech.upatras.gr web: www.mead.upatras.gr

Applied Mechanics Laboratory, Dept. Mechanical Engineering and Aeronautics of the University of Patras (AML/UP) is in operation since 1980 and deals mainly with the general field of materials & structures, giving emphasis in the science, technology and the applications of composite materials. Since 1990 AML/UP has systematically accumulated experience in wind energy technologies related to design, manufacturing, testing and certification of rotor blades. AML is associated with industry through consultancies, by participating in the technical committees of several corporations and in numerous national and EC-funded research projects.
After 1990, AML has been involved in private, national or EU R&D projects involving Greek industries and public organizations, aiming at the design and manufacturing of composite rotor blades or assessment of their structural integrity. AML/UP as a part of an educational institute provides courses about mechanics of composites, non-destructive testing techniques, structural mechanics, finite element and boundary element methods, structural dynamics, boundary elements in graduate and postgraduate level.

Research groups involved

Applied Mechanics Laboratory/UP consists of four University Professors, three Postdoctoral fellows and 20 PhD students. Their activities cover the following major research areas:

• Structural analysis of composite structures, Mechanics of composites, Smart materials/structures
• Development of novel analytical and numerical tools for design of composites (FEM, BEM, etc)
• Condition monitoring, NDT, Adaptive structures
• Nanomaterials and Nanocomposites

Research Focus

Application focus of the AML/UP expands in the following areas:

• Structural Analysis & Finite Element Methods for Composites and Structures
• Damped structural dynamics models of large wind-turbine blades including material and structural damping
• Structural Damping (Passive & Active Vibration Control). Development of Specialty Composite Finite Elements with Damping Capabilities
• Smart Materials and Structures. Mechanics for Composite Materials & Structures with Embedded Actuators and Sensors. Active Shape Control
• Anisotropic Material Property Characterization
• Structural Design, Optimisation and Dynamics of Composite Wind-Turbine Rotor Blades of current designs
• SHM and NDE Self-Detecting Smart Structure
• Fatigue Failure Prediction of Multidirectional Laminates under Combined Stress State and Variable Amplitude Loading
• Probabilistic Methods in the Design of Composite Structures
• Fatigue Characterization of Composite Materials using Conventional and Non-Destructive Testing
• Development of Numerical Tools (FEM and BEM)
• Vibration Testing

Facilities & Characteristics

Mechanical testing of materials	Hydraulic Universal Testing Machine Instron 8872 (25 kN) for tensile, compression and fatigue testing Hydraulic Universal Denison-Mayes Testing Machines (100 kN) for tensile, compression and fatigue testing, equipped with oven for working from sub-ambient temperature to 5000 C Hydraulic Universal Testing Machine Instron (250 kN) for tensile, compression and fatigue testing equipped with video-extensometer 2 Quasi-Static Universal Testing Frames 25 kN 2 Electromechanical Universal Testing Machines Scheunk, (Maximum capacity 100kN and 25 kN), equipped with an induction heating oven for high temperature testing in air. Both may perform low cycle fatigue tests Dynamic and Thermal Analysis DuPont 2000 Equipment with 9900 Programmer Low velocity impact machine. Ballistic-Impact testing equipment Impact Pendulum (Sharpy & Izold Impact)
Data acquisition systems	Various multi-channel High-Speed Data Acquisition Devices Multi-channel high-speed dynamic data acquisition and spectral analyser Dynamic acceleration, strain, force and temperature measurements
Non-destructive testing	Equipment and system for in-situ SHM-NDE using active piezoelectric sensors NDT Equipment (pulse generator, resonant and broadband piezoelectric transducers, angle beam sensors, pre-amplifiers) USIP 11 Krautkraemer pulse generator and C-scan peripherals with bath size 1200x1000 mm for Ultrasonic Testing Ultrasonic System dedicated to the characterization of the stiffness matrix of anisotropic materials and the anisotropic damage developed under thermo-mechanical fatigue conditions. The necessary software (developed in-house) is included 6-channel SPARTAN 2000 (PAC) for Acoustic Emission 4-channel MISTRAS (PAC) for Transient Acoustic Emission Analysis 2-channel MISTRAS custom boards (PAC) for High-Frequency AE Analysis
Fabrication	RTM unit (1- and 2-component resins) Torrus Mill for dispersion of nanoparticles in polymer resins Laboratory platens press 300x300mm, hydraulic force 300kN,Max. temperature 4000 0C Hand Lay-up and Spray-up systems with vacuum bagging for the manufacturing of composite components Vacuum casting device for the manufacturing of working prototype components. Vacuum forming system Access to autoclave system for the manufacturing of composite components Full access to a Rapid Prototyping set-up consisting of SLA, LOM and Z-Print systems
Fractographic analysis	Nikon Thermo-camera system Nikon-Optiphot 66 Microscope equipped with CCD and video recorder
Conditioning chambers	Conditioning chamber for humidity and temperature control Conditioning chamber for bellow zero temperatures
Software	Nastran/Patran, ANSYS, ALGOR and LS-DYNA3D Finite Element codes Franc 2-D and 3-D for Fracture Analysis Several in house developed codes for advanced FEM, BEM and Statistical Pattern Recognition.

R&D Programme

The research group of AML/UP dealing with rotor blade structures has a long-term research plan on different aspects of composite materials applications for wind energy industry, aiming to achieve the following in the next 4 years period:

	Damped structural dynamics models for large wind-turbine composite blades. Inclusion of nonlinear structural effects.
	Optimized design procedures using advanced FE modeling techniques to improve rotor reliability. This includes the efficient 3D anisotropic material strength & stiffness experimental characterization, the introduction of structural damping tensor as a design parameter and the development of 3D fatigue life and residual strength computational procedures.
	Detailed 3D stress analyses (analytical & numerical) of structural joints such as T-bolts for very thick (>30 mm) composites and development of efficient life prediction procedures, including stochastic modeling of material property and loading.
	Development of damage tolerant design techniques for composites used in the wind-turbine industry introducing the use of NDI methodologies for assessment of blade structural integrity and composite repair efficiency in specific life intervals.
	Development of real-time data processing methodologies and NDT monitoring procedures including in-situ piezoelectric actuators and sensors for active damping control and assessment of blade dynamic response.

Advanced research techniques

AML/UP, produces advanced techniques that concern mechanics of composite materials, design with composites and smart materials.

• Composite Damping Mechanics, which include integrated damping models (micromechanics, ply, laminate) for polymer matrix composite laminates and layerwise models for laminates with constrained damping layers and sandwiched foam cores. Multi-Damped Composite Laminates with Shunted Piezoelectrics.
• Detecting Damage in Composite Laminates Using in-situ Piezo-Actuators & Sensors. Combined analytical and experimental work aims to study the effects of damage on the vibrational response and guided wave propagation in composite laminates with embedded piezoelectric sensors and actuators. The ultimate objective is the development of novel smart material and structural systems with damage self-detecting and self-monitoring capabilities.
• Composite Damping Characterization & Measurement of Damping Coefficients. A unique testing system is available for measuring Damping Coefficients and Elastic Constants of a composite material. There is also capability for characterizing the dependence of damping and elastic coefficients on frequency and temperature.
• In-house developed and commercial computational tools for advanced 3D stress analyses of thick composite structures (FEM, BEM), stochastic and reliability analyses
• In-house developed pattern recognition codes based on either conventional algorithms or neural networks for classification problems of data emanating from NDT measurements
• 3D experimental characterization of damage accumulation in thick composite samples using through-transmission ultrasonic testing and dedicated, in-house developed, S/W
• Acousto-Ultrasonic and AE NDT methods to assess structural integrity of new or repaired blade structures
• Characterization of composite damping properties and measurement of structural damping, Passive & Active vibration control