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Objective time derivative defined as covariant deriative
Fiala, Zdeněk
A geometrically based approach, definining the time derivative as a covariant derivative in an appropriate nonlinear space - the infinite dimensional Riemannian manifold of deformation tensors, will be employed, and, via coordinate approach, the covariant derivative and its corresponding time derivative of an arbotrary tensor field will be explicitly expressed.
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Contact pressure between head and helmet loaded by external forces
Micka, Michal ; Jírová, Jitka
The simple test of the bike helmet loaded by statical forces on the top of the head is simulated using program ANSYS. The standardized model for laboratory tests of helmets is used as the model of the head. The goal of the project is to obtain details about contact forces or stresses between the cranium and the helmets, which will be used for future development of safety helmets or by modelling of a hurt of the head at accident.
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Evaluation of accuracy of steel plate girder initial imperfections measurement carried out by means of fringe projection method
Valach, Jaroslav
The method of fringe projection and its application to investigation of steel plate girders subjected to repeated loading is described in this contribution. The well known fact of decisive role of production-based girders imperfections on the girders period of service emphasizes the need of a reliable measurement method of the imperfections. The optical method described in this paper is based on determination of out-of-plane deviations by means of analysis of geometrical relations in the image of projected fringe pattern on the girder surface. The advantage of the method is its simplicity, scalable sensitivity and absence of any constrains regarding the size of the studied object. The results obtained using the method are compared to that attained by the existing method and their accuracy and time consumption is considered. Finally, applicability of the proposed method in other fields is discussed.
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