Papers by Keyword: FEM Analysis

Abstract: Composite materials are mostly used in applications where stiffness-to-weight or strength-to-weight ratios are critical. For example, there can be produced a large number of acceptable designs that support a specific loading condition by varying fibre orientation in each ply, or in a certain number of plies. Due to ease of construction, structural elements, such as box structures, are widely used as a load bearing member in the fields of civil, mechanical and aeronautical engineering. The paper presents an analysis of finite element stability of a thin-walled structure which can be used in civil constructions. The structure is made of FRP composite material. The structure is stiffened with ribs which are made of the same composite, steel and aluminum. The critical buckling pressure was determined for this structure. The advantage of using FRP and sandwich composite, compared to conventional materials as steel or aluminum, consists in high strength to weight ratios, high corrosion resistance, lightweight and excellent fatigue performance. A neural network model was created and used for the prediction of stability behavior of the analyzed elements.

Abstract: The stability of the tunnel portal section under poor terrain and geological condition has always been the focus of construction safety. The stability problem has become more complex for the erosion accumulation area under the valley. In this paper, firstly the stability of the tunnel portal is classified. Combined with engineering cases, the FEM numerical method is used to simulate the supporting structure and construction process of the tunnel. Based on the distribution of the plastic zone and displacement of surrounding rock, the mechanism of the instability of the tunnel portal is analyzed. Through the optimized construction scheme that arranges pile foundation in tunnel arch foundation, the bearing capacity of foundation has been greatly improved, which has effectively prevented the instability of surrounding rock caused by the slope deformation and foundation settlement. The conclusions that have been drawn in this paper can be used for reference for related projects.

Abstract: The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

Abstract: Feasibility analysis of replacing split Hopkinson bars test by Charpy impact test for determination of Johnson-Cook’s material model parameters. The results show that the Charpy impact test may, due to the strain rates achieved, successfully replace the mentioned experimental test. Moreover the results shows that some further studies should be conducted to improve efficiency of the proposed method.

Abstract: The paper presents the results of milling tests of aluminum alloy with a sintered carbide tool. For selected sets of cutting data, the thin wall deformation of the workpieces was analyzed. Theoretical calculations were compared with the experimental measurements, using the high speed camera and FEM analysis.

Abstract: To generate a virtual human hip is a main goal for our research team. Also, starting from the normal virtual hip joint and using the important orthopedics information was defined the affected hip joint. All these models were generated in a 3D virtual environment starting with CT scanning images. Using an original method all the scanned CT images were re-defined and re-drawn and transferred to the 3D software. The resulted curves were used to generate the bones and the virtual complex system of both hip joints. With motion and geometric constrains the bio-mechanical assemblies were defined, starting from anatomical information. The normal hip joint and the model of the affected hip were defined and exported to ANSYS, software based on Finite element analysis.

Abstract: The works [1, 2] present the values of the force and moment of friction needed to disassemble the axisymmetric connection with oval and three-angular shape of cross-section of the shaft. These works additionally show the variable values of the Mises stresses and contact pressures. This paper presents research which is a continuation of the research program on the evaluation of the influence of cross-section deviations, radial deviations, and their compilations on the value of the contact area in the connection. The limited contact area has a decisive impact on functional and operational parameters of the connection. Point contact between the shaft and the hole is the reason of the reduction of load transmission. The paper concerns the connection between the shaft with four-angular shape of cross-section with the deviation T_w = 13 μm and the hub with the nominal roudness. The authors have proved the occurrence of variable values of the force and moment of friction during disassembling of the connection. The authors have also showed the occurrence of variable values of the reduced stresses and contact pressures.

Abstract: The article describes design of a drive module of a modular mobile chassis. This chassis was developed at the Department of Robotics, Faculty of Mechanical Engineering, VŠB-Technical University of Ostrava, as a part of the student grant competition “Research and development of modular robotic systems.” The article describes variants and the final mechanical construction of the drive module and also the structural analysis of this module according to the possible positioning in the whole modular system. The obtained results and possible ways of additional future development and modifications of the module are summarized in the conclusion.

Abstract: The paper is thematically connected with paper making machines. This type of the machine is equipped with a head which has a flexible slice lip for skimming the pulp applied to produce the paper. The definition of geometric features of the slice lip is a key issue. The slice lip should be made of material which is resistant to external factors, and designers want to obtain a high flexibility of this element. It is possible to get a high flexibility by forming a proper shape of the slice lip. The paper presents the proposal of dimensionless geometric indicators which combine basic geometric parameters of the slice lip. These indicators are the following: indicator of the cross-section, indicator of the length and indicator of the length of the transverse notch. FEM strength analyses were done – the aim of these analyses was the determination of the stress state and maximum deflection of the slice lip. The authors have analysed the slice lip with holes for mounting the actuators and the slice lip and with transverse notches for increasing its flexibility. The results were presented in the form of graphs.

Abstract: The article presents the stages of creating a virtual laboratory stand for performing the cycle of tests of the system response to dynamic excitation. To create the virtual laboratory stand was used the PLM Siemens NX 8.5 software. It was shown the method of realization the dynamic analysis in the Motion Simulation module, which result was the characteristic (form) of the system excitation. Then, on the virtual laboratory stand, was conducted the analysis of vibration of the investigated system realized in the Advanced Simulation module. For calculations was used the “Response Simulation” solver, which allows analyzing the system responses to dynamic excitations. Next the results were compared with vibrations measurements made on the real laboratory stand. This lets to verify and adjust the created FEM model.