1,721,010 research outputs found
Superficial Stress Reduction By Laser Annealing: Preliminary Study
No full textMost of the manufacturing processes introduce a locked-in stress state in the material that can have strong effect on the lifetime of the component. The presence of residual stress must be conveniently taken into account during the design process and minimized when possible. Thermal processing of the component is also possible in order to relax residual stress. If a proper thermal cycle is designed for the specific material it can be possible to reduce and even eliminate the state of stress. In this paper we explored an alternative approach to obtain stress relaxation based upon the focusing on the surface of an Al 5068 aluminium alloy of a high power diode laser (HPDL) source. In this way it is possible to obtain a localized effect of stress relaxation limited to the neighbourhood of the area irradiated by the laser beam. Final results, however, depend upon several factors, such as the adopted wavelength, the reflectivity of the material at that specific wavelength, the power of the HPDL source, the mode distribution and the duration of the irradiation. In this work temperature field distributions are calculated for the case of interaction with a point source, a Gaussian source and a double-Gaussian source. For these two, in particular, the influence of the HPDL power was studied. Results obtained by the double-Gaussian distribution analysis were used to set the proper experimental parameter for the experimental study. Finally, repeated annealing cycles were performed and the sample and the obtained stress reduction was evaluated by X-Ray diffraction
Espi analysis of thermo-mechanical behavior of electronic components
No full textThermo-mechanical aspects must be conveniently taken into account when designing electronic components and devices. Reliability issues can in fact arise due to stress induced by thermal field acting on materials with different coefficients of thermal expansion. In this paper an optical system based upon Phase Shifting Electronic Speckle Interferometry (PS-ESPI) was developed; it allows analyzing the in-plane displacement map experienced by the tested component during its working operation as a consequence of the Joule’s effect. The adoption of an optical technique allowed to get the measurement without contact with the component that is to say without altering the capability of thermal dissipation of the component. The system was demonstrated to be effective in analyzing asymmetries in the displacements along the component and in evaluating how different kinds of constraints can drastically affect the thermo-mechanical behavior of a given component. Furthermore the system was used to compare the thermo-mechanical response of the same component in presence or in absence of a critical defect. It was verified the ability of the set up designed to detect the very different thermomechanical response of a damaged electronic component with respect to an undamaged one
Analisi Delle Forme D’onda Associate Ad Emissioni Acustiche In Provini In CFRP Sottoposti A Test Di Delaminazione Modo I
No full textStudio dell’insorgenza di fenomeni corrosivi in campioni di bronzo mediante tecnica di proiezione di frange,
No full textMechanics and Analysis of Advanced Materials and Structures
No full textModern technological development has made the designing and characterization of materials sophisticated [...
Strain Field Analysis in Electronic Components by ESPI: Bad Thermal Contact and Damage Evaluation
No full textDesigning electronic components and devices is a complex task that must include also considerations about thermo-mechanical behavior of the component itself. This aspect, in fact, can affect the reliability of the device as a consequence of the thermal stresses that are introduced in the component while it is working. Stress concentration can arise, in fact, due to different thermal expansion coefficients of the materials involved. Determining the thermo-mechanical response by numerically methods is not simple and not always possible so that experimental methods are preferable. In this paper, specifically, the electronic speckle pattern interferometry technique was adopted to measure full-field strain of the component during exercise. By using an optical technique it is possible to get information about the behavior of the component without being in contact with the component itself so that the dissipation coefficient is not altered. The system was able to detect gradients of deformation in the component itself connected to the different distribution of internal current in the component. Moreover, it was observed, that the presence of bad thermal contact between the package and the heat sink can be revealed because it results in a different thermos-mechanical behavior of the component. Finally, a critical defect was introduced in the component and it was observed the way the presence of damage affects the in-plane displacement of the component. Very huge differences were observed leading to the consideration that this kind of approach could be conveniently adopted also as a damage detection tool
Assessment of tensile behaviour of plain weave fabric CFRP composites using acoustic emission technique and deep learning
No full textThe applications of Carbon Fibre Reinforced Plastic (CFRP) composites in aerospace applications have increased exponentially in the last decade. CFRP composites are now replacing conventional materials used in high temperature applications. Different types and strategies of reinforcements are used in these composites to improve their applicability to high temperature applications. One of the reinforcement strategies that has been used frequently in the recent years is the plain weave fabric configuration of reinforcing fibres in polymer matrix. A comprehensive damage assessment is essential to evaluate the characteristics of these composites at elevated temperatures. The Acoustic Emission (AE) signals generated during the damage evolution stages are used for studying the damage evolution stages when the plain weave fabric composites are tested at temperatures close to their glass transition state. A new information-theoretic parameter, Lempel-Ziv (LZ) complexity and the deep learning neural network is used for understanding the damage evolution stages. Furthermore, the neural network is used for validating the utilization of LZ complexity as a potential AE parameter for damage classification applications. The results are promising with the damage classification strategy using LZ complexity exhibits an accuracy of 85.1% which is validated through the neural network
L’effetto della temperatura della camera di stampa sulle tensioni residue sui componenti stampati FDM
No full textDesigning a Deep Neural Network for an Acousto-Ultrasonic Investigation on the Corrosion behaviour of CORTEN Steel
No full textDesign and Development of a Dual Chambered Interactive Juice Packaging for Children
No full textJuice packaging design as a marketing strategy to children is becoming highly sophisticated, increasingly well-funded, and takes place within the environment of other kinds of child-targeted marketing. The joint decision-making process by both parents and children who are the consumers of these products are often influenced by nutritional concerns and price sensitivity for parents while children aim to fulfill spontaneous desires resulting from factors such as visual elements, package image, cartoon characters, colors etc. Even with varieties of innovative juice packaging plaguing our markets today, issues such as little or no user experience, indecisive nature of kids picking just one flavor, and poor shelf life of packaging materials where tiny bit of oxygen penetration results in mold growth and unsustainability are yet to be fully addressed. This paper proposes a juice packaging design solution that adopts polyethylene furanoate material for prolonged shelf life and reduced carbon footprint selected through relative performance index of key features, a dual chambered body design to accommodate both lead and fringe users indecisive nature, a pressure induced closing diaphragm beneath the bottle cap and an interactive labeling for improved user experience in an environmentally responsible way still relatively cheaper compared to current market competitions
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