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Image Correlation (image + correlation)
Selected AbstractsFULL-FIELD DYNAMIC DISPLACEMENT AND STRAIN MEASUREMENT-SPECIFIC EXAMPLES USING ADVANCED 3D IMAGE CORRELATIONEXPERIMENTAL TECHNIQUES, Issue 4 2003T. Schmidt First page of article [source] Fatigue damage analysis in a duplex stainless steel by digital image correlation techniqueFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2008A. EL BARTALI ABSTRACT Strain field measurements by digital image correlation today offer new possibilities for analysing the mechanical behaviour of materials in situ during mechanical tests. The originality of the present study is to use this technique on the micro-structural scale, in order to understand and to obtain quantitative values of the fatigue surface damage in a two-phased alloy. In this paper, low-cycle fatigue damage micromechanisms in an austenitic-ferritic stainless steel are studied. Surface damage is observed in real time, with an in situ microscopic device, during a low-cycle fatigue test performed at room temperature. Surface displacement and strain fields are calculated using digital image correlation from images taken during cycling. A detailed analysis of optical images and strain fields measured enables us to follow precisely the evolution of surface strain fields and the damage micromechanisms. Firstly, strain heterogeneities are observed in austenitic grains. Initially, the austenitic phase accommodates the cyclic plastic strain and is then followed by the ferritic phase. Microcrack initiation takes place at the ferrite/ferrite grain boundaries. Microcracks propagate to the neighbouring austenitic grains following the slip markings. Displacement and strain gradients indicate probable microcrack initiation sites. [source] Three-dimensional sonography in the prenatal diagnosis of aortic arch abnormalitiesJOURNAL OF CLINICAL ULTRASOUND, Issue 5 2009RDMS, Sifa Turan MD Abstract Purpose To assess the added value of 3-dimensional (3D) echocardiography with spatiotemporal image correlation (STIC) in the diagnosis of aortic arch abnormalities in fetuses with isolated abnormal upper thoracic 3-vessel view (3VV). Method A total of 3,420 women underwent a targeted anatomic survey at 18,22 weeks' gestation in a 1-year period. An isolated abnormal upper thoracic 3VV detected on 2-dimensional (2D) imaging was followed up by conventional 2D echocardiography and 3D fetal echocardiography with STIC. Offline reconstruction by a second operator blinded to the suspected diagnosis was performed. Neonatal echocardiography and MRI with 3D reconstruction were performed to verify the prenatal diagnosis. Result Of the 3,420 patients referred, 4 had an isolated abnormal 3VV (0.09%). A right-sided aortic arch (RAA, n = 3) and double aortic arch (DAA, n = 1) were suspected. In all aortic arch abnormalities, 3D fetal echocardiography and STIC correctly identified RAA with aberrant left subclavian artery in 3 cases and DAA in 1 case with a degree of definition that was equal to the confirmatory postnatal echocardiography and 3D MRI. Conclusion Although the 2D upper 3VV is a powerful screening tool for isolated aortic arch abnormalities, 3D fetal echocardiography with STIC allows an accurate prenatal characterization of the abnormality to a degree that is typically attainable only by post partum imaging. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2009 [source] Four-dimensional sonography with B-flow imaging and spatiotemporal image correlation for visualization of the fetal heartJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2008Toshiyuki Hata MD Abstract Purpose. To use B-flow imaging with 4-dimensional (4D) sonography and spatiotemporal image correlation (STIC) in the evaluation of normal fetal heart and congenital heart disease during pregnancy. Method. Volume data sets of the fetal heart were acquired with automated transverse and longitudinal sweeps of the anterior chest wall. We studied 13 normal fetuses and 2 fetuses with congenital heart disease (1 double-outlet right ventricle and 1 hypoplastic left heart syndrome) at gestation ages ranging from 13 to 39 weeks using transabdominal 4D B-flow sonography with STIC (4D BF-STIC). Results. 4D BF-STIC demonstrated dynamic angiographic features in both normal and abnormal fetal hearts. 4D BF-STIC images could not be obtained in 2 normal fetuses at 18.1 and 33.1 weeks because of the high fetal heart rate and inappropriate fetal position. In normal fetal heart, characteristic hemodynamic changes in both atria and ventricles were clearly demonstrated in systole and diastole. 4D BF-STIC also allowed visualization of the relationship, size, and course of the outflow tracts, thus helping the examiner to better understand the relationships between the vessels. In a case of hypoplastic left heart syndrome, dramatic hemodynamic changes including the right atrium, right ventricle, and pulmonary artery were evident. In a case of double-outlet right ventricle with ventricular septal defect, left-to-right shunt flow through a ventricular septal defect was clearly shown, as were great arteries originating in parallel from the right ventricle. Conclusion. 4D BF-STIC provides a means of real-time 3-dimensional evaluation of fetal intracardiac and extracardiac hemodynamics in the second and third trimesters. This novel technique assists in the evaluation of fetal cardiac hemodynamics and may play an important role in future fetal cardiac research and in the evaluation of congenital heart disease in the fetus. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008. [source] 3-D DYNAMIC OPTICAL TECHNIQUES TO MODEL FOOD MECHANICAL DEFORMATIONJOURNAL OF TEXTURE STUDIES, Issue 4 2010MURIEL JACQUOT ABSTRACT Finding new instrumental rheological parameters that better describe sensory textures can improve correlation between rheological and sensory measurements of food. Two optical three-dimensional (3-D) techniques commonly used in mechanical engineering field were studied. These techniques have never been used in food science. Digital image correlation and Breuckmann scanning systems were successful to distinguish gelatin gels and soft cheeses varying in firmness and viscoelastic properties. These two systems were coupled with a universal testing machine to provide information regarding 3-D displacements and surface deformation of sample. Mathematical models were developed to determine surface displacement profiles of samples from their firmness and viscoelastic properties. Three parameters were obtained to describe surface displacement profiles linked to samples textural properties. These parameters may be useful to develop models predicting accurately food sensory texture from instrumental measurements. PRACTICAL APPLICATIONS Finding new instrumental rheological parameters that better describe sensory textures to improve correlation between rheological and sensory measurements of food. [source] Tools for multiaxial validation of behavior laws chosen for modeling hyper-elasticity of rubber-like materialsPOLYMER ENGINEERING & SCIENCE, Issue 2 2002L. Chevalier We present an experimental approach to discriminate hyper-elastic models describing the mechanical behavior of rubber-like materials. An evaluation of the displacement field obtained by digital image correlation allows us to evaluate the heterogeneous strain field observed during these tests. We focus on the particular case of hyper-elastic models to simulate the behavior of some rubber-like materials. Assuming incompressibility of the material, the hyper-elastic potential is determined from tension and compression tests. A biaxial loading condition is obtained in a multiaxial testing machine and model predictions are compared with experimental results. [source] Three and four dimensional ultrasound: a novel method for evaluating fetal cardiac anomaliesPRENATAL DIAGNOSIS, Issue 7 2009L. Gindes Abstract Objective To evaluate the role of various new models of 3- and 4-dimensional (3D and 4D) ultrasound (US) applications in prenatal assessment of fetal cardiac anomalies. Methods Volume data sets of 81 fetuses with fetal cardiac anomalies, as previously diagnosed by 2D US, were acquired by 3D and cine 4D using spatiotemporal image correlation (STIC) software. Various additional rendering tools were applied. Color, power, high definition Doppler and B-flow were added to the volumes acquired. A retrospective offline analysis of the cardiac defects was performed. Results The mean gestational age at diagnosis was 24 weeks (range 13,38); 128 anomalies were detected and were classified into the following categories: I, Situs anomalies in 8 cases; II, abnormal four-chamber view in 63 cases; III, outflows tract anomalies in 27 cases; IV, arches anomalies in 21 cases; and V, veins anomalies in 9 cases. Rendering tools differed in each groups of anomalies. Conclusions Fetal cardiac anomalies can be evaluated adequately by the information gained by 3D and 4D volumes obtained by STIC. Since no single module is sufficiently accurate for the diagnosis of all cardiac anomalies, each of the cardiac anomaly categories requires different and appropriate module of visualization. Copyright © 2009 John Wiley & Sons, Ltd. [source] Untersuchungen zum Einfluss von Temperatur und Holzfeuchte auf das Versagensverhalten von ausgewählten Klebstoffen bei ZugscherbeanspruchungBAUPHYSIK, Issue 5 2009Peter Niemz Prof. Dr.-Ing. habil. Feuchte; Versuche; moisture; experimental set-ups Abstract An drei verschiedenen Klebstoffen wurde der Einfluss von Temperatur und relativer Luftfeuchte auf die Scherfestigkeit im Zugscherversuch geprüft. Es wurden zwei handelsübliche Klebstoffe (PVAc, Harnstoffharz) und ein labortechnisch hergestellter 1KPUR bei erhöhter Temperatur und relativer Luftfeuchte geprüft. Ergänzend wurde mittels Video Image Correlation die Verzerrung im Bereich der Klebfuge ermittelt und daraus ein Schubmodul der Klebfuge berechnet. Studies on the influence of temperature and timber moisture on the failure behaviour of selected adhesives under tensile shear load. The influence of temperature and relative humidity on shear strength was tested in a tensile shear test with three different adhesives. Two standard adhesives (PVAc, urea resin) and a 1KPUR (one-component polyurethane adhesive) produced in the laboratory were tested at a high temperature along with relative humidity. In addition distortion around the glue joint was measured by means of video image correlation and a shear modulus of the glue joint calculated from this. [source] | |||||||||||||