Computer Aided Design of an Admission Valve with Autodesk Inventor

The paper presents the steps for 3D computer aided design (CAD) of an admission valve made by Autodesk Inventor

The Geometry Optimisation of a Triple Branch Pipe Using Finite Element Method

The paper presents the geometrical optimization of a triple branch pipesubmitted to an internal pressure. The goal of the optimization was todetermine the optimum thickness of piping and branch pipe ribs, in thecondition of reaching admissible values of the stress and displacement.The resistance calculus was realized with Cosmos DesignStar softwareand the geometry was modeled with Microstation Modeler software

Determine the Correlation between Wicked Gates Angles and Servomotors Strokes for Asymmetric Hydrofoil

The paper describe the results obtained from theoretical calculus of the kinematics of the wicked gates for the correlation: ao=f(α); aor=ao/Do(α); S=f(α) and propose analytical formulas for ao=f(α) correlation, applicable to 16, 24 wicked gates blade number and asymmetrical hydrofoils; also, numerical results compared with graphical values are presented

Cavitation Erosion Tests Performed by Indirect Vibratory Method on Stainless Steel Welded Samples with Hardened Surface

The paper presents the results of cavitation erosion tests performed on two types of samples. The materials of the samples are frequently used for manufacturing and repairs of the hydro turbines components submitted to cavitation. The first sample was made by welding of an austenitic stainless steel on austenito-feritic base material. The second sample was made similarly with the first but with a martensitic base material. After the welding processes, on both samples was applied a hardening treatment by surface peening. The cavitation erosion tests were performed on vibratory equipment using the indirect method with stationary specimen. The results show a good cavitation erosion resistance on both samples

Study on the effect of the friction coefficient on the response of structures isolated with friction pendulums

The paper presents a study regarding the effect of the friction coefficient on the behavior of structures isolated by friction pendulums. A laboratory-scale structure and its model created in SolidWorks are employed in the research. The excitation, ensured by a shaking table, follows a displacement after sinusoidal and complex rules. The study revealed the frequency at which the chosen friction pendulum assures efficient isolation is higher then 3 Hz irrespective to the friction coefficient. Experimental results coincide with those obtained from simulations

Numerical study on complex shaped cracks in cantilever beams concerning frequency and stiffness changes

The paper presents a mathematical relation to express the effects of a T-shaped crack on beam-like structures. The study is performed by using the finite element method (FEM) and contrived analytical formulas for proving the existing correlation between deflection, strain energy, and natural frequency changes. The damaged beam static and dynamic behaviors are analyzed by means of the FEM. The frequency shift for the first mode of vibration derived directly was compared with the frequency alteration calculated involving the change in the beam deflection for several scenarios of the T-shaped crack. The frequency shift is derived using the relations between deflection and natural frequency. As the final step in the research, we compared the outcomes for the same crack with the results achieved from a beam suffering a loss of stiffness

A versatile algorithm for estimating natural frequencies with high accuracy

Detection of damage requires an accurate estimation of the natural frequencies of the monitored structure. This paper introduces an algorithm implemented in Python which improves the frequency readability by increasing the number of spectral lines without requiring a signal extension in the time domain. We achieve this by overlapping several spectra calculated from the acquired signal repeatedly shortened. In this way, the overlapped spectrum gets an increased number of spectral lines. The dense mesh of spectral lines permits us to obtain a fine frequency resolution without being necessary an extension of the signal in the time domain. The high density of the spectral lines ensures a sufficient number of points on the main lobes that permits performing an efficient quadratic polynomial interpolation to find the maximizer. It represents the amplitude of the real frequency and is typically located on an inter-line position, thus cannot be found by standard frequency estimation. We implemented the algorithm in Python and tested it successfully for generated signals, containing one or more harmonics, with known frequencies

Thermal Calculation of the Reduction Gear 2XAB/StCu110So as Part of Hybrid Locomotive’s LHy-M Mechanical Transmission

The purpose of this work is to present the reduction gear’s efficiency, reduction gear that is load part of hybrid locomotive’s mechanical transmission. The purpose of the calculation is to determine the overall efficiency of the reduction gear to determine its operating temperature

Optimizing the Geometry of a LHy-M Hybrid Locomotive’s Chassis by Resistance Calculations

Starting from the initial geometry of the LDH 1250 CP locomotive chassis, the work aimed to optimize the geometry in the sense of maximum stresses reduction by geometric changes and the reinforcement of the structure. The optimization resulted from the need to transform the LDH 1250 Hydraulic Diesel Locomotive into the LHy-M Hybrid Locomotive, encompassing hybrid technology, powerful automation elements, as well as ergonomic redundant components that can complement and assimilate the extensive features of the old components of the rolling stoc

A procedure for an accurate estimation of the natural frequencies of structures

The paper presents a procedure to precisely estimate the natural frequencies of structures. It implies the acoustic excitation of the structure and the evaluation of the frequencies from the response signals, involving an advanced method developed by the authors. The study is performed on a cantilever beam. To demonstrate the efficiency of the contrived procedure, the values of the frequencies by applying this procedure are compared whit those obtained by standard frequency estimation made for the response to an impulsive excitation