Finite element modeling and experimental validation of conventional and high speed shear testing in Pb-free environment

2008 ◽  
Author(s):  
Abhinav Ajmera ◽  
S. Manian Ramkumar ◽  
Ti Lin Liu
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
High Speed ◽  
Experimental Validation ◽  
Shear Testing ◽  
Element Modeling ◽  
Free Environment

Rotordynamics of a Highly Flexible Hub for Inside-Out Ceramic Turbine Application: Finite Element Modeling and Experimental Validation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Céderick Landry ◽  
Patrick K. Dubois ◽  
Jean-Sébastien Plante ◽  
François Charron ◽  
Mathieu Picard
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
High Speed ◽  
Radial Displacement ◽  
Experimental Validation ◽  
Angular Position ◽  
Relative Displacement ◽  
Element Modeling ◽  
Induced Stress ◽  
Inside Out

The inside-out ceramic turbine (ICT) is a promising concept to increase turbine inlet temperatures in microturbines by integrating individual monolithic ceramic. This architecture uses a carbon–polymer composite rim to support the blades mainly in compression. High tangential velocities lead to elevated radial displacement of the rim, and therefore, the rotor hub needs to have sufficient compliance to follow this radial displacement. However, the rotordynamics of a flexible hub is not widely understood. This paper presents the rotordynamic analysis of a highly flexible hub for an ICT architecture. Finite element modeling (FEM) is used to design a simplified turbine prototype that maximizes the hub flexibility to explore the limits of the concept. The rotordynamics behavior of the highly flexible hub is measured by spinning a 171-mm diameter prototype up to 49 krpm. This paper highlights three principal challenges of this particular rotordynamics. First, critical speeds mode shape becomes highly coupled with bearings displacement, shaft bending, and hub deformation. At high-speed, the hub deforms out of phase with the shaft, which can cause high stresses in the hub. Second, the angular position between unbalance masses of the flexible hub and the composite rim changes the unbalance response significantly. Finally, vibration causes high stresses in the hub, due to the relative displacement between the composite rim and the shaft, which could lead to failure of the hub. Nevertheless, the rotordynamics of an ICT configuration is manageable as long as the vibration-induced stress in the hub is kept under its limit.

Friction Induced Vibration in Windscreen Wiper Contacts

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tom Reddyhoff ◽  
Oana Dobre ◽  
Julian Le Rouzic ◽  
Nicolaas-Alexander Gotzen ◽  
Hilde Parton ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
High Speed ◽  
Contact Angles ◽  
Element Modeling ◽  
Friction Measurements ◽  
Mixed Lubrication Regime ◽  
Bending Modes ◽  
Intermediate Surface ◽  
Friction Induced Vibration

This research is aimed at understanding the mechanisms that give rise to friction induced noise in automotive windscreen wipers, with a focus on frequencies between 500 and 3500 Hz. To study this phenomenon, experimental friction, sound, and high-speed video measurements are combined with finite element modeling of a rubber wiper/glass contact. In agreement with previous research, simultaneous sound and friction measurements showed that wiper noise in this frequency range results from the negative damping effect caused by the dependence of friction on speed in the mixed lubrication regime. Furthermore, during sliding, the friction induced noise recorded by the microphone occurred in one of two frequency ranges (close to 1000 Hz and between 2000 and 2500 Hz). These coincided closely with the eigen-frequencies of first two bending modes, predicted by finite element modeling. Experimental observations also showed the wiper to be oscillating backward and forward without any torsional motion and that the thickness of the glass had no effect on the emitted noise. These observations highlight how friction induced noise—although caused by conditions within contact—has characteristics that are determined by the structure of the excited component. A number of additional findings are made. Most importantly, both experiment and finite element modeling showed that the presence of water in contact with the wiper modulates the frequency and amplitude of the emitted noise by effectively adding mass to the vibrating system. While this is occurring, Faraday-like standing waves are observed in the water. In addition to this, friction induced vibration is shown only to occur for glass surfaces with intermediate surface energies, which is possibly due to high contact angles preventing water reaching the contact. Based on the understanding gained, a number of suggestions are made regarding means of reducing windscreen wiper noise.

scholarly journals Finite element modeling of high-speed milling 7050-T7451 alloys

2020 ◽  
Vol 43 ◽  
pp. 471-478
Author(s):  
Xianghui Huang ◽  
Jinyang Xu ◽  
Ming Chen ◽  
Fei Ren
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
High Speed ◽  
High Speed Milling ◽  
Element Modeling
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