Applied Mechanics and Materials Vols. 809-810

Abstract: Understanding fire behaviour indicators is very important, especially taking into account their integration in the primary fire evaluation process as part of the dynamic and continuous evaluation of risks to which people are exposed to. Construction fires are always characterised by certain critical behaviour factors such as smoke, air currents, heat and flames. Classical training methods for firefighters are practical exercises that are expensive and risky. The aim of the present article is to briefly present a new training method consisting of a dynamic 3D system based on immersive virtual reality. This paper presents results based on the characteristics and thermal values of the flashover in a case study. The phenomenon are simulated by using the Fire Dynamics Simulator, a computer program developed on a complex mathematical apparatus that can generate multiple output data (indicators such as temperatures, gas concentrations, speeds etc.). Results are validated by experimental tests in a testing metal facility from the Police Academy “A. I. Cuza”, Bucharest. The 3D graphic results offered by the simulation highlights the conditions and parameters to which the firefighters involved in putting-out a fire, in the presented training scenario, would be exposed.

Abstract: Welding and heat treatment are a modern, high efficient production technologies. During last few years requirements for quality of the welded joints have been constantly increasing in all production areas. Unfortunately, this approach increases the cost of production due to demand of intense experimental or prototype work prior the use of technology to make a final product. Preliminary experiments have to take into account proper chose of welding technology, materials, welding parameters, clamping and final optimization the welding conditions. All of these activities can be supported or even replaced by numerical simulations based on finite elements method. Tremendous advance in field of numerical simulation, facilitates very high correlation of simulation and experimental results bringing this new approach to common use. This paper highlight to usefulness of numerical simulation in heat treatment of bulk materials in various production stages. It was shown that it is possible to predict formation of metallurgical phases, hardness distribution, strains and stresses during and after quenching process. Simulations of different heating conditions and cooling media makes it possible to simulate processes such as heating, quenching, carburizing and nitriding.

Abstract: This paper emphasizes the benefits of part-model editing process that does not depend on hystory-based modelling system. The use of synchronous technology in mechanical engineering applications allows the NC programmer to efficiently generate the NC program regardless the source of 3D model. The programming and machining process can be more efficient if the intuitive geometric changes on 3D model are allowed. Synchronous technology makes possible NC programmer’s intervention over 3D model geometry, without breaking the rules defined in CAD. Synchronous technology works with both, native and non-native models and it is available in NX and Solid Edge. With synchronous technology, the changes are performed with or without regard to the history of the model.

Abstract: In the paper an application of the particle swarm optimizer (PSO) with cloning improvement to optimization problems is presented. Reinfored structures considered in this work are dynamically loaded and analyzed by the coupled boundary and finite element method (BEM/FEM). The method is applied to optimize location of stiffeners in plates using criteria depended on displacements or stresses. Numerical examples demonstrate that the combination of the PSO with the BEM/FEM is an effective technique for solving computer aided optimal design problems, both with respect to accuracy and computational resources.

Abstract: The applications areas of the multipoint forming technology are very large, due to its flexibility, one of them being medicine, with the field of cranioplasty. For reconstruction of a skull part, a deformed sheet metal part made from titanium alloy could be used. The paper investigates virtual steps in obtaining the sheet metal part for this scope. First the part skull is measured and using reverse engineering is recreated. Then using an original algorithm and a program, the geometry of the mutipoint die is obtained. A FEM analysis is made for the study of the titanium sheet metal behaviour in multipoint forming. The virtual part quality is evaluated in terms of springback and stresses state variation. The results are important for the real implementation of this technology in manufacturing cranial prostheses.

Abstract: Development of advanced engineering environment software allows changing the design process of complex technical means. This situation correlates with the increasing process of new product elaboration what results from the dynamically changing demand on a new market offer. It is important to elaborate the methodology of a designing process that improves and enriches the design process in an advanced engineering design. One of the most serious challenges is to elaborate the optimization methodology for the designing process of complex technical means. It should include both the requirements resulting from different social aspects of a technical mean existence and from different phases of its life cycle. The paper presents the integrative approach to the design process. It includes different types of design requirements integrating them in a design process. It allows obtaining optimized constructional solution. The method is illustrated using such advanced engineering environment like Siemens NX 8.5 software. It is also proposed the conception of object analysis that adding the design process.

Abstract: This paper presents a methodology that makes possible the recapture of manufacturing features of using a DXF file. The methodology is illustrated on a prismatic part. CAD/CAPP integration is achieved by Feature Recognizer Interface. Each CAD system has its own database stucture that offers geometric information regarding the parts, hence, the interpretation and change of these are impossible to be done. The methodology presented in this paper shows how geometric model provides the manufacturing information with the help of DXF file.

Abstract: As ergonomics has become an integral part of the design process, digital human modeling is a rapidly emerging area that links computer-aided engineering design, human factors engineering and applied ergonomics. This paper briefly presents some of the basic principles of user-centered design and their relationship to ergonomics, together with the application of digital human modeling (DHM) in the design process of an assistive walking aid for elderly users with low mobility, considering the assessment of risk and comfort of the system. The use of DHM in order to improve certain features of a system or product is not a new concept, various types of digital human models being used for over 35 years. Using the Human Builder module in CATIA V5 two human models are generated with the help of anthropometric data collected from a group of >65 years old participants living in assistive care centers. The models are further employed in testing the safety and comfort level of the walking aid currently used by the participants, resulting the need of immediate changes in the device.

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.

Abstract: Problems of design similarity identification and elements grouping play a key factor in the development of design standardization and the group technology methods. Design similarity identification methods are most often based on a comparison of codes ascribed to products design. Basically the code makes a quantitative product description including different product features. Whereas a qualitative description has constituted rather supplement of a quantitative description. The most important issue in a process of design similarity identification is a method of a product design description. This description is usually made with use of special codes composed of alphanumeric characters. The coding process allows reducing the number of data which are being processed during design similarity evaluation, but on the other hand in some cases it could cause information loss. Taking into account above there is still a need of working out of a new method of a product design description which will be able to reduce these negative features of coding techniques. In the paper a novel approach for a product design description is presented. It is proposed to apply a hybrid method for a design representation purpose. This method uses a combination of code chains for a product longitudinal cross-section representation and a spatial matrix for transvers sections. As a result of the conducted research a new method of a product design description was worked out. This method is especially suggested for application in automatic design feature recognition systems (AFR systems) in which a design feature database (DFD) is present.