Applied Mechanics and Materials Vol. 657

Abstract: All students in mechanical engineering courses receive training in using at least one parametric and associative 3D modeler. From the point of view of the logic behind the geometric design, a very important issue is how to parameterize the model, or put in other words, how to achieve the right balance between dimensions, as independent parameters, formulas (linking dimensions) and geometric constraints (parallel, concentric, horizontal etc.). We arrive following this logic to the notion of degrees of freedom of the model, as expressing the number of dimensions still free for a dynamic edit. The papers aim is to provide a case study capable to assist students in understanding how a good model could be built. The case study will be integrated in an on-line course, offered by our university as an expression of its commitment in developing e-learning applications [.The paper proposes a slightly different approach, compared with the ones presented in [2, 3, . While in the mentioned sources a graph approach is considered, our paper proposes a matrix oriented analysis, coupled with a live analysis of the model behavior. The paper also proposes different other models as good examples to be used in the teaching process.

Abstract: In this paper, we present a graphical method, developed in CATIA environment, based on the method of substituting circles family and dedicated to profile pinion cutters for generating interior surfaces. Hereby, the family of substituting circles associated to the worked piece (the profile to be generated) is determined at the same time to the curve transposed, in the rolling motion, to the tool centrod. After finding the position of the contact points between the generated profile and the family circles, we can determine, in the transposed family, the locus of the points from the reciprocal enwrapping profile the pinion cutter profile. The paper also includes a method application for generating a hole with square transversal section, and a comparison between the profiling results when using the graphical method, versus an analytical method. The results prove the coincidence between the two profiles determined as above, on one hand, and both rapidity and precision of the graphical method, on the other hand.

Abstract: In the present study the authors propose an experimental framework in order to perform FEA analyses upon a 3D model of a connecting rod. The study presents some of the technical issues that have been overcome by choosing the right software tools and the differences in terms of results that they may produce, it shows the setup used in the analyses including its constraints and loads, the proposed algorithm that imposed the number of analyses as well as their type, and the way the analyses were conducted in order for the results to validate or invalidate a optimized model. Because the connecting rod's 3D model presents a high level of complexity in terms of the number of free forms surfaces contained within the geometry, the authors propose a procedure by which they divide the geometry in areas of interest and in doing so can determine the most critical and the most affected areas under a given load for each FEA analysis. This procedure allows a virtual perspective of the modality through which the considered part gets affected and behaves under a given load in terms of distribution of stress and deformation, results that are consistent with its overall behavior.

Abstract: This paper presents a method for designing of an engine group for motorsport automotive using the concept from the core to the periphery of the assembly. The core engine solution is an engine block with non-removable cylinder casing, 10 cylinders in V-normal at 72°, double overhead camshaft (DOHC) distribution solution. This powertrain solution is cooled with liquid in a pressurized cooling system. The method used is based in the first step on the modeling of the crankshaft assembly followed by, in the second step, the modeling the peripheral parts-engine assembly. In order to achieve the digital prototype of the engine group is used the CAD/CAM/CAE system named CATIA V5.

Abstract: This paper presents a method of finite element modelling used for the impact analysis of a composite panel. In this research, the composite panel consists of an oxygen mask locking panel of an aircraft. This panel is loaded with one concentrated abuse loading and three uniform distributed abuse loading cases and the stress variation within the composite panel for each load case is determined. In order to assess the impact analysis on the oxygen mask panel of the aircraft, a finite element model is created using Patran as the main application for pre/post-processing and Nastran as the main processor. The paper also presents a comparison between results obtained using the same finite element modelling of the composite panel CAD model of the panel with four load cases with different material types. The results are used to determine the most capable material stresswise.

Abstract: It is primary object of the present study to create a 3D model of the human ankle and an axis system that will show the position the tibia and the foot on a healthy subject. Regarding this scope of the study, the first step in obtaining the 3D model of the bones is scanning. The graphic modeling software used is Catia V5 R20. It is another object of the present study to create an axis system that will be very easy to maneuver and on which we can show different pathological situations, not only on a healthy subject, creating their assembly reference systems considering the mechanical and anatomical axes existing and creating prerequisites for the study of different possible pathological situations. For this scope, was used a triorthogonal axis system called skeleton that is defined as a system of axes Euler. This means that the angles can change the grid, in the desire to analyze different situations. In this study the focus is on the situation of varus equinus, in which the foot leg is not aligned with the tibia, as it is on a healthy subject. It was realized an important element: the incorporation of geometric and dimensional references. The last object in this study is to determine the status of CAE, in order to study the stress and the strain. Creating the CAD system is very important because it can be used to study the osteoarticular system, treatment strategies and related surgery.

Abstract: Many companies use Computer-Aided Design & Drafting (CADD) systems to create design drawings. Using CADD design as a replacement of the manual drafting method is only a fraction of its potential. The work that is done repeatedly can be in most cases performed automatically through customization. Customization of standard CAD packages can significantly increase productivity. The custom functions and programs can extend the capabilities of CAD packages to perform a wide range of drafting tasks. The paper discusses a customization strategy intended to facilitate completion of some repetitive drafting tasks in mechanical drafting process. One way to extend the capabilities of AutoCAD is by creating and using blocks. Blocks are useful for creating repeated content, such as standard components. The Dynamic Blocks feature enables user to modify blocks by adding parameters, actions, constraints that increase the versatility and power of the blocks. The paper presents two examples in creating and using dynamic blocks in order to save time and get maximum benefits of AutoCAD features. The first example shows a way to manage bolted joints drawing process by defining parameters and actions to the joint standard components. The second one presents a way to define and use a dynamic block with parametric design for radial ball bearings. The customization approach presented, developed for basic AutoCAD package, is intended for automating quite common tasks in mechanical design drafting. The major advantage of customization is the significant increase of drafting productivity.

Abstract: In this paper a new solution for design features identification is show. The proposed method is based on manual arbitral identification of the potential design features. Application of this method allows identifying a set of design features which can be used for a design modelling in CAD system. As a result of application of the proposed method a user is able to identify the set of design features. This set can be next applied in the process of design production preparation subsystem formation at the stage of design feature library creation.

Abstract: Element geometry can be restored with basic measurement techniques. However if the element geometry is too complex (free form surfaces), it is not possible to take all measurements in that way. Example presented in the paper is a drop forged element (car suspension link). In situation when spare element is out of reach (product withdraw from market, producer technological process tooling redesign), the element can be reproduced (singularly or in series, what depends on producer). Reconstructed element is slightly different from a master element (impossible existence of reliably identically designed and manufactured parts), because of measurement uncertainty. Another problem is that original element is usually worn out or during disassembly process can be damaged, so it has different geometry,(when worn out is not fitting to tolerances) than newly manufactured one. The practical approach for reverse engineering is based on: measurement uncertainty extrapolation, 3D part scanning, transformation of point cloud to solid model, composition examination of an alloy. The method is a complex solution that brings: geometrical description and material assignment and heat treatment. Important part of the method is typical measurement techniques. In cases when tolerances have to be preserved, additional tolerance assignment is needed according to linkage between redesigned part of element and parts of other elements in assembly. The insurance of measurement was checked according to typical tolerance of the drop forged element. The retrieved 3D model was compared with virtual mass to real master element mass. The technological tooling reconstructed prototype and element reconstructed prototype have been made. Finally the alloy material is assigned according to measurement result analysis (electron spectroscopy EDS). Proposed example shows many important clues that can be used in order to provide properly redesigned element.

Abstract: This paper refers to an elastic shaft coupling named Vulkan coupling, with its general behavior. Vulkan shaft couplings link two shafts in diesel-engine and electric drives. They are simple from the construction point of view, are easily mounted and dismounted. Parts and assembly modeling, preprocessing, processing and post processing can be performed using all leading CAD tools, like CATIA. The main goal of this work is to generate a finite element model for a Vulkan coupling, using FEM Solid (FMD). For the demonstration, a Vulkan coupling with a torque of 350 Nm has been chosen. At the end of the modeling with finite element, it results that, for intermediate coupling elements with mechanical material properties very different from those of steel components, MEF analysis with rubber parts only is to be preferred. The other components can be simulated using the virtual rigid elements.