1,721,184 research outputs found
Trattamenti e Finiture
No full textOgni prodotto deve ricevere il suo corretto trattamento e la sua adeguata fi nitura per essere
poi immesso sul mercato. Le aziende che lavorano in questo particolare settore affi dano il
loro aggiornamento tecnico e professionale a «Trattamenti e Finiture», rivista specializzata
che informa e aggiorna su quanto le moderne tecnologie possono off rire per i trattamenti
superfi ciali e massivi, galvanica, lavaggio e verniciatura industriale.
I lettori sono ricercatori, ingegneri e tecnici in ambito: Industrie galvaniche, industrie che fanno trattamenti; termici e superfi ciali in genere, industrie di verniciatura; industrie che fanno lavaggi industriali
MODELLAZIONE NUMERICA DI ARTICOLAZIONI CEDEVOLI PER DITA DI MANI ROBOTICHE
No full textAbstract
In the present work, the flexural stiffness of a close-wound cylindrical spring for a novel joint of
robotic hands is developed by means of the finite element (FE) method. In the first step, the FE model
of the spring has been generated and verificated to guarantee its numerical accuracy. Experimental
measurements and theoretical results on close-wound springs in the same geometrical configurations
here analysed were used as benchmark to compare predictions of the developed FE models. A good
agreement was found in terms of stiffness (Nmm/rad) between numerical versus experimental and
theoretical analysis at the same rotation (90°) with a root mean square error respectively of 11% and
8%
Numerical and Experimental Investigation of Aluminum/CFRP Hybrid Tubes with Rubber-like Interlayer
No full textIn the automotive, aerospace, printing, and sports industries, the development of hybrid CFRP-metal components is becoming increasingly important and used. The coupling of metal with CFRP, in axial symmetric components, results in reduced production costs and an increase in mechanical properties such as bending, torsional stiffness, mass reduction, and critical speed, when compared to the single material-built ones. The challenge for engineers is to design hybrid co-cured tubes with external metal layers, which avoid possible detachments and delaminations due to the mismatching coefficients of thermal expansion of the two materials. In this work, residual thermal stresses and strain have been studied with numerical models based on Finite Element Method (FEM) and compared with experimental tests. The FEM model allowed for the investigation of the influence of length, diameters, thickness and interface layer material on residual thermal stress peaks near the free edges zone. To reduce the risk of premature failure,the interleaving of a rubber-like layer is proposed and experimentally validated
Damage assessment based on general signal correlation : Application for delamination diagnosis in composite structures
No full textThis work presents a Vibration-Based Structural Health Monitoring (VSHM) technique which is developed and applied for delamination assessment in composite laminate structures. It suggests the mutual information as a measure for nonlinear signal cross correlation. The mutual information between two signals measured on a vibrating structure is suggested as a damage metric and its application for the purposes of damage assessment is discussed and compared to the application of the traditional linear signal cross-correlation. The cross correlation is capable to detect linear dependence between two signals and thus can be used for diagnosing damage on linearly vibrating structures. On the other hand the mutual information is a nonlinear metric, and it is shown that it can detect linear as well as nonlinear signal dependence and thus it is particularly appropriate for structures with nonlinear dynamic behaviour and for composite structures as such. The application of the mutual information as a damage metric is demonstrated and discussed first for the case of a simple 2 DOF system with a nonlinear stiffness. Eventually the application of the suggested damage metric is developed and demonstrated for the purposes of delamination diagnosis in a composite laminate beam
Morphology, thermal, mechanical properties and ageing of nylon 6,6/graphene nanofibers as Nano2 materials
Full text linkNylon 6,6 nanofibers loaded with different Graphene (G) amounts were successfully produced with stable process and good fiber quality, using an optimized solvent system suitable both for electrospinning and for G-suspension. G addition is found to significantly affect diameter but not thermal behaviour. A new phenomenological model is proposed for the interpretation of mechanical behaviour of nanofibrous mat, trying to take into account the nanofibrous morphology. The model highlights a G contribution to mechanical properties that mainly affects the initial steps of deformation where fibers stretch, slide, twist and re-orient. Finally, the nanofibers were analysed after 20 months ageing, showing no significant alteration with respect to the pristine ones, thus the lack of detrimental ageing-effects due to G addition
Numerical analysis of frictional contact in the presence of a surface crack in a functionally graded coating substrate system
No full textIn this paper, the frictional two-dimensional contact in the presence of a surface crack in a functionally graded coating substrate system is studied for rigid circular and flat stamps. A computational method based on finite difference (FD) is developed to evaluate the contact stresses and also the fracture parameters, which are KI and KII due to mixed mode fracture. The FD method applied here, uses a mapping technique which enable the analysis to consider any geometry of the punch and the crack. The Coulomb's dry friction law is considered in the contact area. The advantage of this study, compared to the efforts done by other researchers, is the ability to analysis a system with any arbitrary material properties distribution. Here, the elastic material properties distribution is estimated by TTO model which takes into account the interaction between the constituting phases as well, and the Poisson's ratio is assumed to be constant. The effect of material nonhomogeneity, the interaction of the constituting phases, the thickness of the graded coating layer, the size of the punch and the coefficient of friction is studied. In a general case, the findings of this research show that increasing the size of the punch, the coefficient of friction and the thickness of the graded layer increase the contact force and hence the contact stress; however, the interaction of the constituting phases does not have any effects on the contact parameters. In frictionless contact, the stress intensity factor is negative. In addition, increasing the coefficient of friction increases KI but decreases KII. These results are valid for any materials properties distribution
Tissue Engineering for the Insertions of Tendons and Ligaments: An Overview of Electrospun Biomaterials and Structures
Full text linkThe musculoskeletal system is composed by hard and soft tissue. These tissues are characterized by a wide range of mechanical properties that cause a progressive transition from one to the other. These material gradients are mandatory to reduce stress concentrations at the junction site. Nature has answered to this topic developing optimized interfaces, which enable a physiological transmission of load in a wide area over the junction. The interfaces connecting tendons and ligaments to bones are called entheses, while the ones between tendons and muscles are named myotendinous junctions. Several injuries can affect muscles, bones, tendons, or ligaments, and they often occur at the junction sites. For this reason, the main aim of the innovative field of the interfacial tissue engineering is to produce scaffolds with biomaterial gradients and mechanical properties to guide the cell growth and differentiation. Among the several strategies explored to mimic these tissues, the electrospinning technique is one of the most promising, allowing to generate polymeric nanofibers similar to the musculoskeletal extracellular matrix. Thanks to its extreme versatility, electrospinning has allowed the production of sophisticated scaffolds suitable for the regeneration of both the entheses and the myotendinous junctions. The aim of this review is to analyze the most relevant studies that applied electrospinning to produce scaffolds for the regeneration of the enthesis and the myotendinous junction, giving a comprehensive overview on the progress made in the field, in particular focusing on the electrospinning strategies to produce these scaffolds and their mechanical, in vitro, and in vivo outcomes
Electrical Resistance Curing Method for Hybrid Metal-CFRP Tubes
No full textHybrid metal-Carbon Fiber Reinforced Polymers (CFRP) core tubes and rollers are becoming progressively important in the automotive, aerospace, and printing industry for the excellent performance/price ratio. The enhanced mechanical properties and favorable tribological performance of these tubes are provided by the coupling of metal with CFRP compared to tubes build from solely CFRP or metal. However, these kinds of tubes are very expensive and only the co-curing technique of metal and CFRP parts guarantees a reduction in production cost and the competitiveness of products. In this work, a simple outof-autoclave (OOA) electrical resistance co-curing method for hybrid metal-CFRP tubes, based on an analytical model, that exploits the Joule effects, is proposed and verified by experimental test and finite element analysis (FEA). This technique can also be used for other geometries and guarantees considerable energy savings
SUBSTRATE OF POLYMERIC MATERIAL AND METHOD OF CARRYING OUT THEREOF
No full textThe main object of the present invention is to propose a substrate for wound care that is economically cheap and that can be stored also at room temperature in ambient atmosphere conditions.
Another aim of the invention is to propose a substrate that can be applied to patients in non-sterile room and that doesn't need a broad-spectrum antibiotic treatment.
A further aim is to propose a substrate useful for the preparation of a medicament that can be applied directly on the damaged tissue, such medicament having better therapeutic and wound healing properties with respect to presently existing commercial products. The polymeric material substrate is an artificial support constituted by continuous polymer fibres, preferably characterized by a diameter value lower than 1 .micro. .tau. .
Such a substrate contains antimicrobial and/or helping tissue regeneration substances, selected among Hyperforin, Adhyperforin, I-3 Diapigenin, II-8 Diapigenin, Rutin, Quercetin, Hypericin, Azadirachtin .alpha.-.beta., Nimbin, Nimbidin, Salanin, Gallic Acid, Gedunin and their blends
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