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

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

This final report on computational methods and software systems for dynamics and control of large space structures covers progress to date, projected developments in the final months of the grant, and conclusions. Pertinent reports and papers that have not appeared in scientific journals (or have not yet appeared in final form) are enclosed. The grant has supported research in two key areas of crucial importance to the computer-based simulation of large space structure. 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, as reported here, involves massively parallel computers

A Substructuring Technique With Application to Spot Weld Placement Design

It is quite common in the industry to use various interface methods, such as welding, fasteners, bolts, adhesive bonding, etc., to join substructures together. The quality of the assembled structure is directly related to the type of the interface methods used in the manufacturing process. Thus, it is important to include the interface conditions as part of design variables in any design process. To this end, this work develops a reanalysis method that can efficiently analyze structures with variations on the interface conditions. This reanalysis method is based upon a new two-step substructuring technique. The first step performs substructural level analyses for each of the isolated substructures. Any commercially rated structural analysis code is allowed to be used in this step. The results of the first step are then used to form a reduced order matrix equation in terms of the interface reactions. Once the interface reactions are calculated, the displacements and stresses in each of the substructure can be conveniently calculated. In this proposed method, only the reduced order matrix equation in Step 2 is required to be resolved for structures with different interface conditions. The first pail of the work will discuss the derivation and implementation aspects of the substructuring technique. Later, the technique is used to support a simple genetic algorithm for placement design optimization of spot welds. Assessment of the proposed method via numerical study is summarized at the end of the dissertation

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Advanced interface modelling for 2D shell & 3D continuum problems

This work is motivated by the need for an efficient yet accurate approach for static and dynamic contact analysis of large-scale structures which can a) capture the optimum con- tact position with a moderate number of contact elements, and b) enable across-partition adaptive contact analysis within a parallel processing environment. In addressing these two issues, a novel adaptive node-to-surface contact approach is proposed to discretise the contact boundaries and to trace the evolution of contact locations. Contact search is a demanding process that can become quite complicated for certain types of problem. In this work, an efficient and robust contact search method is proposed, which can a) locally track the master facet of a given slave node despite the appearance of highly non-smooth contact surface, including surfaces with concave/convex regions or with distinct boundaries as well as reversible normals, and b) globally reallocate the master-slave contact pairs based on the penetration state without an expensive global search, providing an effective adaptive contact approach. A dual-interface-based domain decomposition method emphasising across-partition con- tact coupling is proposed. A pair of fully decomposed node-to-surface contact element are proposed to discretise the across-partition contact boundaries. The assumption of small incremental displacements is adopted, which a) avoids the excessive coupling between the decomposed master and slave, b) reduces significantly the communication overhead, and c) facilitates a flexible across-partition adaptive analysis. This strategy is found to provide good results for a sufficiently small time- or load-step, and it also facilitates mix-dimensional contact simulation. Another interest in current thesis is the inaccuracy in non-smooth plates modelled us- ing 2D displacement-based shell elements. In this work the dominant factor causing the inaccuracy is recognised as the incompatible tangential rotations on the two sides of the in- tersection. A 3-noded coupling element is introduced to impose a continuous constraint to couple the incompatible rotations. The significance of the discontinuity in the shell-based folded structure and the effectiveness of the coupling element is demonstrated through numerical studies comparing shell-based models to high fidelity solid-based models.Open Acces

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

An efficient solution procedure for elastohydrodynamic contact problems considering structural dynamics

This work presents an efficient solution procedure for the elastohydrodynamic (EHD) contact problem considering structural dynamics. The contact bodies are modeled using reduced finite element models. Singly diagonal implicit Runge-Kutta (SDIRK) methods are used for adaptive time integration. The structural model is coupled with the nonlinear Reynolds Equation using a monolithic coupling approach. Finally, a reduced order model of the complete nonlinear coupled problem is constructed