Adaptive Neural Network Feedforward Control for Dynamically Substructured Systems

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Understanding friction induced damping in bolted assemblies through explicit transient simulation

The design of joints is seeing increased interest as one of the ways of controlling damping levels in lighter and more flexible aeronautic structures. Damping induced by joint dissipation has been studied for more than a decade, mostly experimentally due to the difficulty of simulating large structures with non-linearities. Experimentally fitted meta-models were thus used for damping estimation at design stage without a possible optimization. The aim of this paper is to demonstrate that damping estimation using local friction models is feasible and that it can be usable for design. The simulation methodology is based on an explicit Newmark time scheme with model reduction and numerical damping that can be compensated for the modes of interest. Practical simulation times counted in minutes are achieved for detailed models. The illustration on a lap-joint shows how simulations can be used to predict the amplitude dependence of modal damping, answer long standing questions such as “does the modeshape change?” or analyze the evolution of pressure fields during a cycle

Enhancing the collaboration of earthquake engineering research infrastructures

Towards stronger international collaboration of earthquake engineering research infrastructures International collaboration and mobility of researchers is a means for maximising the efficiency of use of research infrastructures. The European infrastructures are committed to widen joint research and access to their facilities. This is relevant to European framework for research and innovation, the single market and the competitiveness of the construction industry.JRC.G.4-European laboratory for structural assessmen

Recent Advances on Pseudodynamic Hybrid Simulation of Masonry Structures

Hybrid Simulation has been introduced to simulate the seismic response of civil structures. The hybrid model of the emulated system combines numerical and physical subdomains and its dynamic response to a realistic excitation is simulated using a numerical time-stepping response history analysis. In the current practice, lumped parameters structural topologies such as shear type frames or inverted pendulum characterize the physical subdomain and the design of the testing setup is straightforward. Although hybrid simulation has been extensively exploited for testing concrete and steel structures, in the authors' knowledge, there is still a paucity of scientific publications devoted to masonry applications. This is in contrast to the inherent uncertainty carried by masonry failure mechanisms, which hinders any attempt of implementing predictive numerical models. From this perspective, this paper summarizes our recent research achievements aimed at extending hybrid simulation to distributed parameter specimens, such as masonry walls, using the minimum number of actuators. The great potential of reduction bases in driving the substructuring process has been shown in a previous work and here is enhanced to floating physical subdomains

Identification of Blade-root Joint Dynamics in Turbine Disks

L'abstract è presente nell'allegato / the abstract is in the attachmen

Computational methods and software systems for dynamics and control of large space structures

Two key areas of crucial importance to the computer-based simulation of large space structures are discussed. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area involves massively parallel computers

Real-time hybrid testing in structural dynamics

Real-time hybrid testing is a method of simulating dynamic structural response by splitting the system being emulated into one or more physical test specimens of key parts, and a numerical model of the remainder. The simulation is achieved by passing data between the physical and numerical parts in real time as the test proceeds. The method has the potential to offer significant improvements in the realism of laboratory simulation of dynamic structural response. This paper gives an overview of the development of hybrid testing within the field of earthquake engineering, and discusses some of the main technical issues such as actuator delay compensation and fast numerical model solution. Some other applications and possible future developments are also briefly discussed

Substructurability:The effect of interface location on a real-time dynamic substructuring test

A full-scale experimental test for large and complex structures is not always achievable. This can be due to many reasons, the most prominent one being the size limitations of the test. Real-time dynamic substructuring is a hybrid testing method where part of the system is modelled numerically and the rest of the system is kept as the physical test specimen. The numerical–physical parts are connected via actuators and sensors and the interface is controlled by advanced algorithms to ensure that the tested structure replicates the emulated system with sufficient accuracy. The main challenge in such a test is to overcome the dynamic effects of the actuator and associated controller, that inevitably introduce delay into the substructured system which, in turn, can destabilize the experiment. To date, most research concentrates on developing control strategies for stable recreation of the full system when the interface location is given a priori. Therefore, substructurability is mostly studied in terms of control. Here, we consider the interface location as a parameter and study its effect on the stability of the system in the presence of delay due to actuator dynamics and define substructurability as the system’s tolerance to delay in terms of the different interface locations. It is shown that the interface location has a major effect on the tolerable delays in an experiment and, therefore, careful selection of it is necessary

Hybrid simulation techniques in the structural analysis and testing of architectural heritage

L'abstract è presente nell'allegato / the abstract is in the attachmen