Subspace-based damage detection on steel frame structure under changing excitation

International audienceDamage detection can be performed by detecting changes in the modal parameters between a reference state and the current (possibly damaged) state of a structure from measured output-only vibration data. Alternatively, a subspace-based damage detection test has been proposed and applied successfully, where changes in the modal parameters are detected, but the estimation of the modal parameters themselves is avoided. Like this, the test can run in an automated way directly on the vibration measurements. However, it was assumed that the unmeasured ambient excitation properties during measurements of the structure in the reference and possibly damaged condition stay constant, which is hardly satisfied by any application. A new version of the test has been derived recently that is robust to such changes in the ambient excitation. In this paper, the robust test is recalled and its performance is evaluated both on numerical simulations and a real application, where a steel frame structure is artificially damaged in the lab

Conception d'un banc de mesure des propriétés de films viscoélastiques

L'objectif du banc d'essai étudié ici est de déterminer expérimenta lement le module de cisaillement complexe de films viscoélastiques. De tels films sont utilisés dans des tôles sandwich où le glissement différentiel de parements raides permet une dissipation importante d'énergie. L'avantage principal du banc réalisé est de pouvoir travailler sur des échantillons de tôles standard et à terme de permettre l'étude de la précontrainte. L'étude montre le principe fonctionnel du banc, analyse ses limitations par calcul éléments finis et donne les résultats de la première validation expérimentale

Amélioration de méthodes de modification structurale par utilisation de techniques d'expansion et de réduction d'interface : applications

Une méthode proposant d'estimer de l'effet de modifications structurales distribuées est proposée ici. Une évolution des formulations classiques permettant de prendre en compte la non coïncidence des points de mesure et des points de couplage est présentée. La mise en œuvre de la méthodologie à un exemple académique et un cas d'application industriel permet de mettre en lumière les avantages de la méthodologie exposée

Model reduction applied to multi-stage assemblies of bladed

disk

Uncertainties propagation through robust reduced model

International audienceDesigning large-scale systems in which parametric uncertainties and localized nonlinearities are incorporated requires the implementation of bothuncertainty propagation and robust model condensation methods. In this context, we propose to propagate uncertainties through a model, which combines the statistical Latin Hypercube Sampling (LHS) technique and a robust condensation method. The latter is based on the enrichment of a truncated eigenvectors bases using static residuals taking into account parametric uncertainty and localized nonlinearity effects. The efficiency, in terms of accuracy and time consuming, of the proposed method is evaluated on the nonlinear time response of a 2D framestructure