Most studies on the natural course of coronary artery spasm in patients with normal or nearly normal coronary arteries are based on medium-term follow-up in small populations. The present series includes 277 successive patients with a median follow-up of 89 months (range: 1 to 198 months). There were 206 men and 71 women whose mean age was 53.6 +/- 9.3 years. They were all assessed with coronary arteriography which revealed no stenoses greater than 50%. Spasm was confirmed during the coronary arteriography in 157 patients (56.7%), by a positive provocation test following the arteriography in 113 patients (40.8%), and by an electrocardiogram which showed Prinzmetal's variant angina in seven patients (2.5%). The majority of patients, 264 (95.3%) were treated with calcium channel blockers. At the end of this study: 35 patients (12.6%) were lost to follow-up; 20 patients (7.2% died) including 10 (3.6%) from cardiac causes; 18 patients (6.5%) experienced myocardial infarction in 11 of whom repeat coronary arteriography consistently demonstrated one or more significant stenoses (greater than 70%); 109 patients (39%) had persistent angina, in 52 of whom the severity (more than one episode per month) warranted repeat coronary arteriography which detected significant stenosis in 19 cases; 95 patients (34.3%) were asymptomatic. Multivariate statistical analyses showed that only predictors of major coronary events (death, myocardial infarction or angina requiring repeat coronary arteriography) were systemic hypertension or the finding of minor parietal irregularities on the initial coronary arteriogram. Conclusion. Despite treatment with calcium channel blockers, persistent or recurrent episodes of angina are frequently observed whereas complications such as myocardial infarction or death are rare.

The virtual fields method has been developed for extracting constitutive parameters from full-field measurements provided by optical non-contact techniques for instance. It is based on the principle of virtual work written with some particular virtual fields. This paper can be regarded as a general review summarising some 15 years of developments of this method. The main aspects of the method are first recalled in the case of both linear and non-linear constitutive equations. They are then illustrated by some recent relevant examples. Some studies underway as well as relevant issues to be addressed in the near future are eventually discussed.

No abstract

This work presents a methodology for reconstructing full-field surface pressure information from deflectometry measurements on a thin plate using the Virtual Fields Method (VFM). Low-amplitude mean pressure distributions of the order of few O(100)Pa from an impinging air jet are investigated. These are commonly measured point-wise using arrays of pressure transducers, which require drilling holes into the specimen. In contrast, the approach presented here allows obtaining a large number of data points on the investigated specimen without impact on surface properties and flow. Deflectometry provides full-field deformation data on the specimen surface with remarkably high sensitivity. The VFM allows extracting information from the full-field data using the principle of virtual work. A finite element model is employed in combination with artificial grid deformation to assess the uncertainty of the pressure reconstructions. Both experimental and model data are presented and compared to show capabilities and restrictions of this method.

Rate-dependent behaviour characterization of metals at high strain rate remains challenging mainly because of the strong hypotheses when tests are processed with statically determinate approaches. As a non-standard methodology, Image-Based Inertial Impact (IBII) test has been proposed to take advantage of the dynamic Virtual Fields Method (VFM) which enables the identification of constitutive parameters with strain and acceleration fields. However, most of the test parameters (e.g. projectile velocity, specimen geometry) are not constrained. Therefore, an FE-based approach is addressed to optimize the identification over a wide range of strain and strain-rate, according to two design criteria: (1)-the characterized viscoplastic spectra (2)-the identifiability of the parameters. Whereas the first criterion is assessed by processing the FEA simulations, the second is rated extracting material parameters using synthetic images to input the VFM. Finally, uncertainties regarding the identification of material constants are quantified for each IBII test configuration and different camera performances.