Applied Mechanics and Materials Vol. 816

Abstract: This article introduces evolutionary algorithms and their utilization in mechanical engineering. First part of this work describes evolutionary algorithms and their characteristica. The main body of evolutionary algorithms, the selection methods for parents and the types of reproduction are explained in the next part of this article. Termination conditions are also discussed. Finally, the application of evolutionary algorithms to a problem in mechanical engineering is described. Thereby, the material parameters for a Bodner-Partom model describing visco-elastoplastic material behavior are determined by fitting data from experiments on Aluminum test samples under tension load.

Abstract: Article deals with the possibilities of modelling and simulating in program Extend. It is a simple tool that allows you to model and carry out simulation of specified process to create a good precondition for decision-making. The development of simulation tools and their introduction into industrial practice is the now common practice, particularly in large enterprises. In these turbulent times it is only a matter of time before these virtual tools are commonly used in small businesses.

Abstract: The goal of the paper is to present the original discrete optimization approach of the structural mass minimization subjected to cumulative fatigue damage (or fatigue life). We’ll consider high-cycle multi-level fatigue, new discrete optimization algorithm and finite element analysis. The presented computational approach was implemented in MATLAB.

Abstract: This article monitors the influence of the number of individuals in generation, number of elite individuals and the time of algorithm run on the quality of results. Reasons for monitoring these influences and the process of calculation are explained in the first part. Basic vocabulary used in this work is described as next. The results of calculations are written down in tables and illustrated on figures. At the end of the article the most suitable parameters for next calculations using Bodner-Partom (B-P) model are summarized.

Abstract: Residual stress determination requirements of production and research users grow rapidly. Commercially available programs enable relatively quick residual stress evaluation with certain level of accuracy and with limited user access to used compliance matrices and calculations. However precise analyses require sensitive approach to compliance matrices determined for individual case e.g. for specific specimen dimensions. Therefore program tools for complex residual stress evaluation by Ring-Core method were developed using finite element analysis and Visual Basic scripts.

Abstract: The paper describes an experimental determination of kinematic quantities using high-speed digital image correlation system. It deals with the analysis of minimal sampling frequency needed for correctly performed high-speed correlation analysis. The authors also describe the influence of cameras sampling frequency on the quality of the obtained results. Mentioned analysis was performed using a rotational object. For the purposes of the results comparison the data obtained from correlation system in a form of displacements in three mutually perpendicular directions were processed in Matlab and in the paper are depicted in a form of graphical visualizations.

Abstract: This paper is focused on the detection of the level of destruction of a cylinder lock, opened using the Salinger-Grydilov (SG) method, and on measuring the resonance curve while striking a bump key as well as its influence on overcoming locks using SG method. It also presents an analysis and verification of the laboratory measurements of the level of destruction of a lock which was overcome using the SG method and its differentiation from a lock opened using the appropriate key. Further, attention is paid to measurements of the frequency of individual blows when using the SG method and its influence on overcoming cylinder locks.

Abstract: The paper deals with the estimation of modal parameters and its main purpose is to compare differences in the values of natural frequencies and damping ratios, which were estimated using three different extraction methods: Rational Fraction Polynomial method, Complex Mode Indicator Function and Polyreference Time Domain Technique. These methods are well suited to the more general application to multi-FRF data, both of the SIMO and the MIMO types. The object of measurement was a freely suspended steel rod of circular cross section. The responses of the analyzed structure were measured by accelerometer and laser vibrometer. The results of these measurements are also discussed in the paper.

Abstract: The main purpose of this paper is to made experimental stress analysis of flat specimen. Specimens were cycles with constant amplitude loaded in order to maintain adiabatic conditions. Whole loading process of specimens was recorded by infrared camera with high sensitivity. Subsequently values of stress were according to equations for thermoelastic analysis evaluated on the face of specimens. Evaluate values of stress are equal to the sum of the principal stresses thus it is the first stress invariant.

Abstract: In practice, the mobile machines, machinery and their parts are sources of vibrations which could shorten their technical working life. In every machine, a specific energy is converted into vibrations of the machinery or their individual components. The information about machinery is fundamental condition of its future running. The methods of vibration diagnostic could be useful for monitoring of device wear and determining of real state of machines.