Applied Mechanics and Materials Vols. 809-810

Abstract: In this paper, the 3D model of the centrifugal fan impeller will be obtained using CAD software (CATIA). The blade will be obtained with 4 design methods: constant blade width and variable blade angle; hyperbolic blade width and variable blade angle; hyperbolic blade width and constant blade angle; linear blade width and variable blade angle. A comparative analysis of the weight of the blade, as well as of the weight of the rotor composed by cascade of blades, front and rear shrouds will be presented. Two materials have been used for all the elements of the centrifugal fan impeller: steel and aluminium. For computational purposes the MATLAB programming language will be used. The centrifugal fan blade will be designed as untwisted geometry with =2 reference curves (one on the rear shroud and the other one on the front shroud) with different numbers of reference points ={5, 10, 20, 30, 40, 50}. After running the MATLAB script file, the coordinates of reference points of the blade will be obtained for all 4 blade design methods. The transfer of the reference points coordinates from MATLAB workspace to CATIA has been performed using the automatic surface generation method, via an EXCEL macro file. This is the recommended method especially for a big number of reference points.

Abstract: In this paper, the finite element analysis for stress/deformation/modes of vibration for the centrifugal fan impeller with constant thickness backward-curved blades using CATIA software will be presented. The principal steps of the finite element analysis procedure using CATIA/Generative Structural Analysis environment will be presented: creating the 3D model; configuring the mesh; applying the restraints; applying the loads; running the numerical static analysis and the numerical frequency analysis; interpreting the results and observing the modes of vibration correlating with the impeller mode shape. This procedure will be used for 4 different centrifugal fan impellers according with the 4 blade design methods and the results will be comparatively analyzed. For each design method, two materials will be used: steel with density of 7860 kg/m³ and aluminium with density of 2710 kg/m³. Two important results have been obtained after the structural analysis: under the working conditions considered for the analysis, all 4 blade design methods leads to impellers with very good mechanical behaviour; any frequency of the main modes of vibrations for all blade design methods and for both materials is not in phase with the impeller speed, thus the possibility of resonance being eliminated.

Abstract: Various architectures exposing certain phases of the design process have been developed. A closer analysis of the presented timelines is leading more to postpone the design solution rather than advancing it in the early phases. This paper advances a new architecture for the design process with the main emphasize on the product functional design, based on functional-constructive knowledge stored in databases, and on the principle of selecting design solutions in an incipient phase and developing them during the further design process stages.

Abstract: In order to obtain a better designing of the industrial products, various software can be used. Sometimes, such a software allows simulation and highlighting the behavior of the product during its use. It is important to know and select adequate software applicable in the engineer activity. The study of the accessible information showed that such a software is ANSYS. In this paper, a case study for some modalities of modern calculation by FEM method using ANSYS program is presented.

Abstract: A three-dimensional measurement system has been set up. The digital models have been obtained using a webcam and structured light. After this, a software for measuring the digital geometries has been applied. In order to validate the digital models, the workpiece has been measured in a Laboratory of Metrology by means of a Coordinate Measuring Machine. While digital models can be obtained from multiple scan system configurations, not all of them get the same degree of accuracy. After analyzing the results, it can be determined the best condition for obtaining the digital model so that discrepancies between measurements and corresponding digital model of the workpiece are minimized. Also, it has been estimated a value of measurement uncertainty for each of the models studied.

Abstract: Influence on the environment has caused and still causes today the destruction of terrain and buildings. It further analyzes the main forms of land and the effects of surface destruction. The state of tension and deformations of the massif is affected by underground mining. On the 23^rd of February of 2008, in Saarland, a vibration of 93.54 mm/s, which corresponds to a value of 4.0 on the Richter scale, was measured. Numerous resistance structures have suffered as a result of strong subsidence damage. Size and expansion of compact according to the characteristics of the mine is studied. Less well known are the effects of mining compaction on the behavior of a resistance structure. This study attempts to answer this question. The research method is the numerical simulation using the finite element method combined with in situ measurements of damage. Framework was charged as the usual load of a building norm. The corner to a 300 mm compacted statically indeterminate structure produces additional stresses and strains. Research results are comparisons between load cases with and without compaction and the calculated mechanical stress with rupture stress. As a result of the rupture is measured experimentally effective crack opening.

Abstract: This paper presents an applicative methodology of parametric computer aided design using the CATIA v5 software to model and assembly a modular fixture device. The device is then used in the orientation and clamping a part of type casing cover which has a face machined by milling. Having a constructive solution of the fixture device, the next step is to simulate a milling process through a FEM analysis to identify the working conditions: milling tool diameter, number of teeth, cutting forces, required power of the machine tool etc. Some parameters were chosen according to various tools manufacturers catalogues and the cutting force components were determined experimentally in laboratory conditions. The analysis results show that in the FEM simulated milling process, in all the fixture device parts, some tensions cause displacements that have an influence over the casing cover surface roughness.

Abstract: The heterogeneity and anisotropy of structural composites make the application of the standard mesh-based methods using the meshing of interfacial region between matrix and fibers a difficult task. The objective of this study is to present the EFG formulation for problems of composite micromechanics. It is expected that the tediousness and approximations involved in mesh generation, and hence inaccuracies in the results can be avoided using the new meshless techniques such as the Element Free Galerkin (EFG) method. The theoretical methodologies, computer implementations and practical application are carried out. Periodic boundary conditions of the unit cell under tensile load are set up. The method of Lagrange multipliers is introduced for the treatment of material discontinuity at the fiber-matrix interface in which both the displacement continuity and traction reciprocity are satisfied. The EFG method is formulated for the generalized plane strain problems. Examples are presented to illustrate the effectiveness of the proposed micromechanical model, and it is validated by comparing the results with available numerical solutions.

Abstract: In this paper, we comparatively present two heuristics search methods – Simulated Annealing and Weighted Sum Genetic Algorithm, in order to find optimal cutting parameters in turning operation. We consider five different constraints aiming to achieve minimum total cost of machining. We developed a customizable software application in Microsoft Visual Studio with C# source code, flexible and extensible that implements the optimization methods. The experiments are based on real data gathered from S.C. “Compa” S.A Sibiu, a company that manufactures automotive components and targets improving of product quality and reducing cost and production time. The obtained results show that, although the Weighted Sum Genetic Algorithm does not guarantee the optimality of finals solution despite of a high probability to be, it is superior to that provided by Simulated Annealing.

Abstract: The paper deals with an application of the artificial immune system (AIS) to the optimization of shape, topology and material properties of 3-D structures. Structures considered in this work are analyzed by the finite element method (FEM). Optimization criteria that are taken into account concern minimize mass and of elastic strain energy. Numerical examples demonstrate that the method based on soft computing is a very effective technique for solving computer aided optimal design.