13:40
Thermal Methods 2
Chair: Mário A.P. Vaz
13:40
20 mins
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CRACK GROWTH MONITORING OF STAINLESS STEELS BY MEANS THERMOELASTIC STRESS ANALYSIS
Umberto Galietti, Davide Palumbo, Francesco Ancona, Rosa De Finis
Abstract: In this work, Thermoelastic Stress Analysis (TSA) was used to monitoring fatigue crack growth during fracture mechanics tests on various stainless steel. TSA technique was proposed in order to evaluate automatically and in continuous way the crack position and to reduce the test time.
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14:00
20 mins
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THERMO MACHANICAL BEHAVIOUR OF FRESH ZIRCALOY-4 UNDER LOCA CONDITIONS
Damien Campello, Nicolas Tardif, Marie Christine Baietto, Michel Coret, Jean Desquines, Julien Réthoré, Anne Maynadier
Abstract: During a Loss of Coolant Accident in a Pressurized Water Reactor, a break on the reactor primary circuit leads to the quick water depressurization from 155 to almost 1 bar. The fast temperature increase of the fuel cladding from 320°C to 1200°C induces filling gas pressure increase. Thus the pressure difference between the inner and outer tube surfaces grows leading to important hoop stresses. Simultaneously, steam environment affects the creep behaviour of the cladding by oxidation and hydriding. Hydriding has several noticeable effects [1] on the creep behaviour of Zircaloy-4, creep rate decrease, embrittlement and shift of phase transition temperatures (α→ α + β, α + β → β) towards lower temperature.
A custom experimental setup is used to study the macroscopic secondary creep behaviour of as received and hydrided zircaloy-4 (cladding material) under a representative thermo-mechanical loading. The experimental matrix focuses on the following ranges, temperature between 700°C and 800°C (the phase transformation temperature of the as-fabricated material is 820°C), hoop stress in a range of 20 - 75 MPa and hydrogen content between 0 and 750 ppm. Experimental setup, post-treatment and preliminary results are here presented on as received zircaloy-4.
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14:20
20 mins
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HYBRID STEREO-DIC USING INFRARED AND VISIBLE CAMERAS
Ali Charbal, John-Eric Dufour, François Hild, Martin Poncelet, Ludovic Vincent, Stéphane Roux
Abstract: 3D kinematic fields are measured using an original stereovision system composed of an Infrared (IR) and visible cameras. Matching both imaging systems is proposed via Stereo-Digital Image Correlation. The stereo system is calibrated by using a NURBS representation of the calibration target. The transformation matrices are determined by an Integrated-DIC approach and Stereo-DIC is performed once the matrices are calibrated to measure 3D displacements. Amplitudes varying from 0 to 30 µm are well captured for any direction, i.e. in plane or out of plane motions.
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14:40
20 mins
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LOCAL INVESTIGATIONS OF THE THERMOMECHANICAL BEHAVIOR OF A COARSE-GRAINED ALUMINUM MULTICRYSTAL USING CONSTRAINED DIC AND IRT METHODS
Li Li, Jean-Michel Muracciole, Laurent Waltz, Laurent Sabatier, Bertrand Wattrisse
Abstract: With the intention of achieving grain scale energy balances at finite strain, a mechanical test on a coarse-grained aluminium is presented in this paper using two complementary imaging techniques (visible and infrared). Specific image processing methods (Constrained DIC and Constrained IRT) are applied to investigate the thermomechanical behavior at the microstructural scale. In the long term, the ultimate goal is to provide energy balance during mechanically-loaded test at the granular scale in order to propose thermomechanically consistent constitutive modelling of crystalline plasticity.
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15:00
20 mins
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DAMAGE INVESTIGATION IN COMPOSITE MATERIALS BY MEANS OF NEW THERMAL DATA PROCESSING PROCEDURES
Umberto Galietti, Davide Palumbo
Abstract: In this work, thermal methods were used to investigate composite materials in order to assess damages that could compromise the mechanical strength of the material. In particular, various specimens and components were tested adopting different thermographic techniques such as Lock-in thermography and Pulsed thermography and new algorithms were proposed in order to reduce the testing and the processing data time.
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