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This paper compares two approaches to predict the overall mechanical properties of solids with irregularly shaped pores. The first approach involves direct finite element simulations of representative volume elements containing arrangements of irregularly shaped pores subjected to periodic boundary conditions. The second approach utilizes numerical results for individual defect shapes in a micromechanical scheme. Several realizations of parallel and randomly oriented distributions of defects are considered. It is determined that the Mori-Tanaka micromechanical scheme provides good correlation with the full field finite element simulations.

Many post-tensioned concrete bridges have been reported to have ruptured tendons due to corrosion [1] and the assessment of their residual structural capacity has to account for the possibility of re-anchorage of failed tendons. This paper presents an experimental programme to validate a numerical model developed by the authors for the re-anchorage of a ruptured tendon in post-tensioned concrete [2]. The experimental programme considered 33 post-tensioned concrete prisms, in which the rupture of tendon was simulated by releasing the tendon at one end. The full field displacement at concrete surface after release was measured using 3D Electronic Speckle Pattern Interferometry (ESPI). A wide range of parameters: tendon diameter, duct material, grout strength, concrete strength and shear reinforcement were investigated to validate the proposed model, which is found to be suitable for use in assessing post-tensioned concrete bridges with damaged tendons.

Measured data from operating systems are often acquired to predict structural health of a system. With only a few measurement sensors, very limited understanding of the system can be obtained. Utilizing some recent novel expansion results, full field information can be obtained to identify a more complete strain description for the system. Using these results in conjunction with an analytical prediction of the expected strains, comparisons and differences can be identified using time response data. The expected full field stress-strain from the analytical model is compared to the predicted full field dynamic stress strain from limited sets of measured locations due to either operating or imposed loading on the structure. Differences in strain distributions at many time increments can provide indications of regions of possible damage in the structure. The work presented in this paper identifies the methodology as well as some results to illustrate the usefulness of the approach.

International audience; This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed.

The paper is devoted to numerical modelling of R-curve behaviour in laminates with strong interfaces, in particular multilayers made of alumina (A) and zirconia (Z). Contrary to previous studies based upon the application of approximate weight function method originally developed for homogeneous specimens, a full field analysis by FE of a three-point bending test of a sandwich beam is attempted and compared with the results obtained by approximate weight function method. Also the crack penetration across the layer interfaces is discussed, particularly in the case of a weak singularity.

A full field phase detection system for surface plasmon resonance (SPR) bio-sensor is presented. The phase difference variation between s and p polarization resulting from the SPR was detected by the polarization interferometry. In the polarization interferometry, the light reflected from the SPR sensor was divided into four phase quardrature parts by polarization components. By means of an algorithm similar to phase shifting interferometry, the phase distribution of SPR bio-sensor was obtained. We have successfully detected the phase difference variation with 0.07º resolution within 1×1 mm2 full field range. The corresponding detection limit of the refractive index change is about 1×10-7.

In this paper, the modulation transfer function with aberration of a multichannel laser induced fluorescence analyzer is presented. Based on an f-theta lens, the confocal system was used both to transform the exciting laser and to collect the fluorescence emitted from sample. The total MTF is the combination of that of both systems. A simple method for the numerical calculation of that was also given. From the calculating result we could conclude that the aberration had poor impact on the MTF of a confocal multichannel fluorescence analyzer and the imaging performance was uniform in the full field.

Photoelasticity is one of the most widely used techniques for experimental stress and strain analysis. With the availability of low cost digital image processing systems, a separate branch of photoelasticity known as digital photoelasticity came into existence providing whole-field values of the isoclinics (θ) and isochromatics (N) in a true sense. Among the several methods available for data acquisition, phase shifting / polarization stepping techniques are most widely used for their simplicity and accuracy. In this paper a new digital photoelastic method based on phase shifting using monochromatic light source is presented. It provides full field values of θ and N. The arrangement is carefully chosen with the intention of reducing the influence of quarter wave mismatch error in the evaluation of θ and N. The methodology is validated for the benchmark problem of a disk under diametral compression.

A special speckle microinterferometer has been developed to test the mechanical properties of thin films electroplated on the single crystal silicon wafer. A piezo-actuated micro-loading unit is synchronized with the microinterfermeter to measure thin film deflection in bending with an accuracy of sub-micrometers. All of the film specimens were microfabricated to be the type of microbridge samples. They are made of Cu and NiFe, the sizes from 1102.9µm to 213.7µm long, 491.0µm to 9.7µm wide. The corresponding thicknesses are 9.4µm and 7.6µm, respectively. Deflections of the microbradge samples can be measured full-field and real-time by using the microinterferometer and no patterning or marking of the specimen surface is needed. The loading force is directly measured using a miniature load cell. The Young’s moduli are calculated for both material and sample size from the load-deflection curves. Test techniques, procedures and factors which affect on the deflection measurements are briefly presented along with detailed analyzes of the results.