Search results for "Friction"
showing 10 items of 352 documents
Friction Stir Spot Welding of AA6082-T6: influence of the most relevant process parameters and comparison with classic mechanical fastening techniques
2007
The results of an experimental study on friction stir spot welding (FSSW) of AA6082-T6 are reported. In particular, process mechanics is highlighted and joint strength is considered in relation to varying the most relevant process parameters. Furthermore, the results obtained are compared with those derived from the application of traditional mechanical fastening techniques such as clinching and riveting. In this way the effectiveness of FSSW is highlighted.
Are there any differences in various polyaxial locking systems? A mechanical study of different locking screws in multidirectional angular stable dis…
2012
Numerous angular stable plates for the distal radius exist, and technically based comparisons of the polyaxial locking interfaces are lacking. The aim of this mechanical study was to investigate three different locking interfaces of angular stable volar plates by cantilever bending: VA-LCP Two-Column Distal Radius Plates 2.4 mm (Synthes® GmbH, Oberdorf, Switzerland), IXOS® P4 (Martin, Tuttlingen, Germany) and VariAX™ (Stryker®, Duisburg, Germany). We assessed the strength of 0°, 5°, 10° and 15° screw locking angles and tested the bending strength from 10° to 5° angles by cyclic loading until breakage. The final setup repeated the above assessments by inclusion of four locking screws. The si…
Seismic Performance of Earthquake-Resilient RC Frames Made with HSTC Beams and Friction Damper Devices
2021
Seismic behavior of RC frames with hybrid steel-trussed concrete beams is affected by panel zone damage due to a large amount of longitudinal reinforcement. Here the seismic efficiency of innovative frames characterized by friction damper devices (FDDs) at beam-to-column connections is compared against traditional frame. Three configurations are investigated: FDDs alone; FDDs with column-to-foundation connections having preloaded threaded bars and disk springs; FDDs with self-centering friction devices. Non-linear analyses show that FDDs alone prevent plastic hinge formation at beam ends and beam–column joint damage. FDDs with self-centering friction devices effectively limit both peak and …
Conditions for static friction between flat crystalline surfaces
2000
The conditions for the presence of static friction between two atomically smooth crystalline surfaces are investigated. Commensurate and incommensurate walls are studied. While two commensurate walls always pin at zero lateral force and positive pressures, incommensurate walls only pin if mobile atoms are present in the interface between the surfaces or if the solids are particularly soft. Surprisingly, static friction can be observed between rigid surfaces, either commensurate or incommensurate, that are separated by a freely diffusing fluid layer.
A novel approach to enhance mechanical properties during recycling of aluminum alloy scrap through friction stir consolidation
2021
Solid state recycling (SSR) is a new approach for making metals recycling more efficient with respect to remelting-based approaches. Friction stir consolidation (FSC) is a new solid-state process that is employed to recycle metallic scraps. Until now, a single-step FSC process was applied to recycled metal chips. During the single-step approach, critical processes parameters, especially processing time and rotational speed, are considered vital to control the quality and mechanical properties of the billet. However, the effectiveness of process parameters is highly restricted by challenging masses of recycling chips and machine competency. The present study first highlights the issues of th…
Preparation and characterization of brass-based coatings
2018
Cold Spray (CS) has been widely investigated owing to its high deposition efficiency and retention of the properties of starting materials. Thus, this process has shown obvious advantages over the fabrication of different copper-based deposits and its alloys over other techniques, such as electroplating, Laser Cladding or thermal spraying. As one of the main copper alloys, brass is implanted in the fields of architecture or industry. Nevertheless, nowadays it is clear that there is very little work on brass coatings, and they were mainly made by electroplating and any other deposition methods, which has severely limits their uses in many applications.This study was applied to develop the br…
Analisi numerico-sperimentale per la determinazione delle tensioni residue in un giunto saldato
2013
La durata di un componente dipende dall’interazione tra le caratteristiche meccaniche del materiale con cui è costruito e gli sforzi a cui esso è sottoposto. Per la determinazione dello stato tensionale agente, oltre agli sforzi dovuti ai carichi imposti durante l’esercizio, è necessario conoscere accuratamente gli stati tensionali residui derivanti dal processo di produzione. Generalmente, le tensioni residue sono indesiderate poiché possono essere di entità elevata e tale da ridurre la resistenza complessiva del componente meccanico. Un aspetto particolarmente insidioso delle tensioni residue è che la loro presenza viene generalmente riconosciuta solo dopo il verificarsi di un malfunziona…
A theoretically-based overland flow resistance law for upland grassland habitats
2022
Abstract Sediments conveyed from interrill areas to rills are transported by a thin flow (overland flow) and the knowledge of overland flow resistance is useful to evaluate overland flow velocity and sediment transport capacity. The aim of this paper was to verify the applicability of a theoretical overland flow resistance law, based on a power-velocity distribution, using field measurements for four upland grassland types used in different management strategies (Hay Meadows, Low-density Grazing, Rushes and Rank Grassland). Particular attention was deserved to the effects of vegetation growth cycles on the surface roughness and the corresponding reduction of overland flow velocity. The rela…
A Cohesive-frictional interface model subjected to mixed complex loading paths
2017
The paper presents a cohesive-frictional interface model based on surface damage mechanics. The proposed model is developed under the assumption that the fracture energies in mode I and in mode II are different values, as shown by several experimental evidences. At difference with the most spread available interface models, only one isotropic interface internalvariable is adopted for the constitutive model. The interface constitutive model is developed in a Thermodynamic consistent framework with an Helmholtz free energy potential and the fulfillment of the thermodynamic principles is obtained enforcing the Clausius-Duhem inequality. The damage/friction activation functions and dissipative …
Innovative user defined density profile approach to fsw of aluminium foam
2007
Metallic foams are one of the most exciting materials in the world of mechanical industry due to their reduced mass and the good mechanical, thermal and acoustic characteristics. Consequently, their application, is increasing day by day even with the important drawbacks that reduce their suitability and diffusion such as high manufacturing cost and difficulty in processing. An innovative approach is outlined in this paper that enables the production of complex shapes taking advantage of deformation processing and friction stir welding (FSW). The aim is to create customized tailored manufactured parts. The cellular construction of foams makes this approach rather challenging as the cell wall…