1,721,098 research outputs found
Development and stress behaviour of an innovative refrigerated container with PCM for fresh and frozen goods
No full textPurpose - The major objectives of this study are the engineering development and the structural analysis with finite element method (FEM) of a refrigerated container having a passive equipment and a remote control system to carry both fresh (+4°C÷±1°C) and frozen (-18°C ÷-20°C) goods. The purpose of this paper is to offer some solutions to the many disadvantages of using phase change material (PCM) to refrigerate the insulated container for transporting both fresh and frozen goods. Design/methodology/approach - In order to transport both fresh products (+4°C÷±1°C) and frozen products (-18°C ÷-20°C), the PCM elements are filled with one eutectic liquid only, so as to avoid problems related to filling and emptying the eutectic plates, and to plate corrosion. Moreover, specially shaped air ducts and a cool flow control system are designed to maintain a uniform circulation of cool air and constant humidity values. All the structures of the container are correctly designed by means of FEM calculations to assure that all the structural, safety standards parameters are satisfied. Findings - An innovative refrigerated container with PCM and a remote control system used to transport both fresh (+4°C÷±1°C) and frozen (-18°C ÷-20°C) products, in which it is possible to maintain the temperature values for almost seven days, has been considered here. Many disadvantages due to the use of PCM have been eliminated. It is possible to maintain a uniform circulation cool air and humidity values within the design parameters by means of fans; moreover, this container is light and environmentally friendly. All structures of the container are designed using FEM. Originality/value - This paper presents a refrigerated container with passive equipment and a remote control system to carry both fresh (+4°C÷±1°C) and frozen (-18°C ÷-20°C) goods in which it is possible to maintain the temperature values necessary for almost seven days. The container is equipped with a remote control system powered by photovoltaic panels which works in real time, is capable of giving information about the environmental parameters set in it and monitors the state of products by means of a network of sensors. Furthermore, the remote control system can send information about the position of the container to a remote control centre. The relevant structural conditions are numerically (FEM) evaluated and reported
DBEM and FEM analysis on non-linear multiple crack propagation in an aeronautic doubler-skin assembly
No full textThe performance of a riveted patch repair, applied on a cracked panel, is simulated by using both a commercially available Boundary Element code (BEASY) and a Finite Element code (ANSYS). A two-dimensional stress analysis on a single-sided repaired configuration is performed by both methodologies; consequently, the occurrence of out-of-plane bending and its effect on the through-thickness SIF (Stress Intensity Factor) variation is neglected. The connection between the two layers (patch and panel) is realised by 32 rivets, with through-cracks initiated on the most loaded holes. Special elements are used to model the crack: discontinuous elements in the DBEM (Dual Boundary Element Method) approach or quarter point elements in the FEM (Finite Element Method) approach. Different loading configurations are considered depending on the presence of a biaxial or uniaxial remote load and the non linear hole/rivet contact is simulated by gap elements. The most stressed skin holes are highlighted, and the effect of a through crack from such holes is analysed in terms of SIFs and stress redistribution. The accuracy in SIFs assessment by DBEM and FEM and the respective computational and pre-processing efforts are determined. Such a two-dimensional analysis allows us a straightforward pre-processing phase, and very short run times are needed. A peculiar arrangement of the pin configuration in the DBEM analysis allows us to take into account the real in-plane plate stiffness and the transversal pin stiffness, even in a 2D analysis (this is straightforward by using FEM)
Numerical simulation of a rolling process
No full textSilesian University of Technology, Gliwice, POLAN
Finite element analysis of residual stresses on butt welded joints
No full textLocalized heating during welding, followed by rapid cooling, usually generates residual stresses in the weld and in the base metal. Residual stresses in welding processes give significant problems in the accurate manufacture of structures because those stresses heavily induce the formation of cracks in the fusion zone in high strength steels. Therefore, estimating the magnitude and distribution of welding residual stresses and characterizing the effects of certain welding conditions on the residual stresses are deemed necessary. In this work, residual stresses and distortions on butt welded joints are numerically evaluated by means of finite element method. The FE analysis allows to highlight and evaluate the stress field and his gradient around the fusion zone of welded joints, higher than any other located in the surrounding area. Temperature-dependent material properties, welding velocity, external mechanism constraints, technique of 'element birth and death' and latent heat of fusion are also taken into account. Some numerical results are compared with experimental data showing a very good correlation
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