Search results for "FRICTION"
showing 10 items of 352 documents
Material flow analysis in dissimilar friction stir welding of AA2024 and Ti6Al4V butt joints
2016
The complex material flow occurring during the weld of dissimilar AA2024 to Ti6Al4V butt and lap joints was highlighted through a dedicated numerical model able to take into account the effects of the different materials as well as the phase transformation of the used titanium alloy.
A novel linear friction welding based approach for sheet-bulk joining
2019
In the last decades, the development of new, flexible manufacturing processes caused the increase of the demands for highly customized complex functional parts in many industrial fields. The peculiar design of these components often overcome conventional sheet metal and bulk metal forming processes capabilities. In order to face this issue, new hybrid techniques, capable of exploit key advantages of different processes, have to be developed. In this paper, a novel approach based on the Linear Friction Welding process is proposed to obtain sheet-bulk joints. The feasibility of the technique on high specific strength alloys is investigated through an experimental campaign.In the last decades,…
Modeling of the plastic characteristics of AA6082 for the friction stir welding process
2015
Focus of this paper is to model the plastic forming behavior of AA6082, in order to develop the numerical FE analysis of the friction stir welding processes and the simulation of subsequent forming processes. During the friction stir welding process, the temperatures reached can range up to 500 °C and have a fundamental role for the correct performance of the process, so the material data has to show a temperature dependency. Because of the tool rotation a strain rate sensitivity of the material has to be respected as well. In this context, the general material characteristics of AA6082 were first identified for different stress states. For the uniaxial state the standard PuD-Al used in the…
Force measurements and tip shape approximation with the atomic force microscope
2011
The Atomic Force Microscope (AFM) is an instrument with huge impact on modern research in the nanosciences and in nanotechnology. In AFM, a tip which is sharp on a scale of nanometers or tens of nanometers, is scanning along the surface which is imaged. A few among the large numbers of factors that potentially affect the interaction between the tip and the surface were studied in the experimental work that form this Thesis. Friction and elasticity measurements with AFM and the approximation of the tip shape are discussed. Also the contribution of the imaging environment is studied. A commercial AFM was modified into a so called environmental-AFM (env- AFM) , where the imaging conditions, su…
Using a neural network for qualitative and quantitative predictions of weld integrity in solid bonding dominated processes
2014
Solid-state bonding occurs in several manufacturing processes, as Friction Stir Welding, Porthole Die Extrusion and Roll Bonding. Proper conditions of pressure, temperature, strain and strain rate are needed in order to get effective bonding in the final component. In the paper, a neural network is set up, trained and used to predict the bonding occurrence starting from the results of specific numerical models developed for each process. The Plata-Piwnik criterion was used in order to define a quantitative parameter taking into account the effectiveness of the bonding. Excellent predictive capability of the network is obtained for each process.
Analytical bonding criteria for joint integrity prediction in friction stir welding of aluminum alloys
2014
Abstract In this study, two bonding criteria, previously used for porthole die extrusion, are applied to FSW starting from the local value of the main field variables calculated through a specifically developed 3D numerical model of the process. Their applicability and effectiveness have been assessed through an experimental and numerical campaign carried out with the main process parameters varying in a wide range. The pressure–time–flow criterion was demonstrated to be better suited for FSW processes when large welding speed is used.
Solid State Joining of Thin Hybrid Sandwiches Made of Steel and Polymer: a Feasibility Study
2020
Abstract The growing demand for more environmentally friendly vehicles has led to an increased use of light materials in the transportation industry with the aim to reduce structural weight, fuel consumption, and gas emissions, thereby boosting cost-effectiveness and recyclable properties. Complex multi-material steel-based components would allow to improve mechanical properties and minimize weight even further. In particular, new sandwich materials made by steel outer skins and a polymeric internal layer seems very promising for obtaining mechanical performance and lightness at the same time. Unfortunately, traditional welding techniques, like arc welding, laser welding, and resistance spo…
Optimisation of photoluminescent painting treatments on different surface layers
2016
Improving drivers visibility in night time conditions is vital. Night-time visibility represents one of the most important features of road safety. Within such context, the use of photoluminescent road markings could represent an enhancement with regard to road safety. Consequently, the objective of the investigation here described was confined into the analysis of photoluminescent paints by referring to dense-graded and open-graded friction courses. Measurements, based on photometry technique, were carried out in the laboratory. Cores extracted from the surface layer of known pavements were used. Transitory effects (charge and discharge) and decay phenomena were investigated and modelled a…
Numerical and Experimental Study of Friction Loss in Hydrostatic Motor
2012
Published version of an article in the journal: Modeling, Identification and Control. Also available from the publisher at: http://dx.doi.org/10.4173/mic.2012.3.2 Open access This paper presents a numerical and experimental study of the losses in a hydrostatic motor principle. The motor is designed so that the structural deflections and lubricating regimes between moving surfaces and, subsequently, the leakage and friction losses, can be controlled during operation. This is done by means of additional pressure volumes that influence the stator deflection. These pressures are referred to as compensation pressures and the main emphasis is on friction or torque loss modeling of the motor as a …