GIORGOBIANI, I. Optimální modelování nýtového spoje pomocí metody konečných prvků [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2020.

Posudek vedoucího

Bartoněk, Jaroslav

Diploma thesis presents the research of means to represent rivets in a finite element model of aerospace metal structure. First part of the thesis provides general information about rivets, their use and comparison to other fasteners. It also includes description of finite elements which are later used for calculation, short overview of their properties and important differences. Second part is focused on calculation of rivets loading by various means and their comparison. Three typical rivet joint types are selected for a detailed analysis. Third part contains data from static tests of these joints - description, drawings, results and evaluation. As for the content, the thesis is logically structured, information can be found where a reader expects. All analytical calculations are written with numerical inputs which simplifies their understanding. Graphic representation of results are moreless clear and useful to compare results of analyses. Also, the documentation of tests is complete. There are some remarks on the finite element calculation. The nonlinear static solution is in this case useless (moreover, parameters are missing), it is possible to obtain correct results with using linear solution. The evaluation of results is limited to the three samples with a simple shape and rivet pattern. It would be good to take into account that real structures are usually more complicated. During the whole academic year student was showing his active approach. Despite objective difficulties which occurred few months before the deadline, he was progressing regularly in his work. Regarding also the other aspects of the thesis, I propose the classification Very good.

Posudek oponenta

Katrňák, Tomáš

The diploma thesis is focused on a research of the appropriate modelling of rivet joints with the use of MSC. Patran/Nastran software. The general overview of metal fastener joints, analytic design methods, rivet joints and failure types are described in introduction chapters. The essential parts of the thesis are finite element analyses of models and evaluations of load distributions in rivet joints. Characteristics of suitable elements for the rivet representation and multi-point connection elements are presented in chapter 4. A brief research of recommended rivet FE substitutions from scientific articles should have been done. Student used CBEAM and CBUSH elements and designed three typical specimens with rivet joints in serial, parallel and eccentric configurations. Finite element models with rivet holes, without rivet holes, with RBE2, RBE3 and node to node connections were used for FE simulations. All of these combinations defined the large amount of FE models. The results of analytic approach were compared with the results of FE analyses. According to these proper graphical comparisons the most appropriate rivet joint representations were selected. Student made and evaluated also the experimental static tests of three typical specimens with blind rivet joints. The correct thicknesses of joined metal sheets were used for providing of the rivet shear failure. Tests were properly documented and the detail evaluation of tests is in chapter 6. The final comparison of analytic, FEM and test results is missing. The evaluation of the total load capacity of the rivet joints should be the next step. Student focused analyses on the load distribution among rivets more than the strength analyses. The thesis is well structured and provides useful and practical information for understanding of load distributions. Therefore, I recommend it for the final defense.

eVSKP id 125203