514 research outputs found
Structural and kinematic synthesis of overconstrained mechanisms
Thesis (Doctoral)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 133-140)Text in English; Abstract: Turkish and Englishxiii, 140 leavesInvestigation on overconstrained mechanisms needs attention especially in the structural synthesis. Knowing overconstrained conditions and including them in the design process will help creating manipulators with less degree of freedom (DoF) and more rigidity. Also this knowledge of overconstrained conditions will clarify concept of mobility of the parallel manipulators. Another subject, kinematic synthesis of overconstrained mechanisms, is important because it will allow describing a function, path, or motion with less DoF less number of joints. The aim of this thesis is to describe a generalized approach for structural synthesis and creation of new overconstrained manipulators and to describe a potentially generalizable approach for function and motion generation synthesis of overconstrained mechanism. Moreover, screw theory is investigated as a mathematical base for defining kinematics of overconstrained mechanisms. Also, overconstrained mechanisms are investigated and generation of new mechanisms is introduced with examples. Some mathematical models for the subspace geometries are given. A method for defining overconstrained simple structural groups is introduced and extended to design of manipulators with examples and solid drawings. Linear approximation and least squares approximation methods are used for the function generation and motion generation of overconstrained 6R mechanisms. A gap of describing overconstrained manipulators is filled in the area of structural synthesis. A general methodology is described for structural synthesis, mobility and motion calculations of overconstrained manipulators using simple structural groups. A potentially generalizable method for the kinematic synthesis of overconstrained manipulators is described both for function and motion generation
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
Dynamic response of Unreinforced Masonry Buildings with Flexible Diaphrams
The overall objective of the research was to provide recommendations for the evaluation and
rehabilitation of unreinforced masonry buildings. An experimental study was done to investigate nonlinear
dynamic response of two-story building systems with flexible floor diaphragms. Two reduced-scale test structures
were subjected to a series of simulated earthquake motions on the University of Illinois shaking table. The
experimental parameters were the relative lateral strengths of the two parallel shear walls and the aspect ratios
of piers between window and door openings. The accuracy of several computational methods were examined by
contrasting estimates with measured response. These methods included procedures that are prescribed in building
code requirements for new construction and guidelines for rehabilitation of existing buildings, as well as more
complex finite element and dynamic analysis methods. A nonlinear dynamic analysis model was developed to
estimate large-amplitude displacements.
This report includes descriptions of the experimental and analytical investigations, and provides a number
of recommendations for evaluation and rehabilitation of unreinforced masonry buildings.National Center for Earthquake Engineering Research Grants 92-3110, 93-3112, and 94-311
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