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Effects of bending moments and pretightening forces on the flexural stiffness of contact interfaces in rod-fastened rotors / Jin, Gao in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 10 (Octobre 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 10 (Octobre 2012) . - 08 p. Titre : Effects of bending moments and pretightening forces on the flexural stiffness of contact interfaces in rod-fastened rotors Type de document : texte imprimé Auteurs : Jin, Gao, Auteur ; Qi Yuan, Auteur ; Li Pu, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : gas turbines Langues : Anglais (eng) Mots-clés : rod-fastened  rotor  (RFR);  stiffness;  rotor  dynamic  performance  analysis Résumé : The rod-fastened rotor (RFR) is comprised of a series of discs clamped together by a central tie rod or several tie rods on the pitch circle diameter. The equivalent flexural stiffness of contact interfaces Kc in the RFR is the key concern for accurate rotor dynamic performance analysis. Each contact interface was modeled as a bending spring with a stiffness of Kc and a hinge in this study. The contact states of the contact interfaces, which depend on the pretightening forces and bending moments (static), have effects on Kc. The approach to calculating Kc in two contact states is presented. The first contact state is that the whole zone of the contact interface is in contact; Kc is determined by the contact layer, which consists of asperities of the contact surfaces. Hertz contact theory and the Greenwood and Williamson (GW) statistical model are used to calculate the equivalent flexural stiffness of the contact layer Kcc. The second contact state is that some zones of the contact interface are separated (when the bending moment is relatively large); the equivalent flexural stiffness of the rotor segment Ksf (not including Kcc) decreases, as the material in the separated zone has no contribution to the bending load-carrying capacity of the rotor. The strain energy, which is calculated by the finite element method (FEM), is used to determine Ksf. The stiffness Ksf is equivalent to the series stiffness of the discs of the rotor segment with flexural stiffness of Kd and a spring with bending stiffness of Kcf in the location of the contact interface, so Kc is equal to the series stiffness of Kcc and Kcf in the second contact state. The results of a simplified RFR indicate that, for a fixed pretightening force, Kcc decreases with bending moments in the first contact state, whereas increases with bending moments in the second contact state. In addition, Kcf and Kc decrease abruptly with the increase of bending moments in the second contact state when the rotor is subjected to a relatively large pretightening force. Finally, the multipoint exciting method was used to measure the modal parameters of the experimental RFR. It is found that the experimental modal frequencies decrease as the pretightening force decreases. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000010 [...] [article] Effects of bending moments and pretightening forces on the flexural stiffness of contact interfaces in rod-fastened rotors [texte imprimé] / Jin, Gao, Auteur ; Qi Yuan, Auteur ; Li Pu, Auteur . - 2012 . - 08 p. gas turbines Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 10 (Octobre 2012) . - 08 p. Mots-clés : rod-fastened  rotor  (RFR);  stiffness;  rotor  dynamic  performance  analysis Résumé : The rod-fastened rotor (RFR) is comprised of a series of discs clamped together by a central tie rod or several tie rods on the pitch circle diameter. The equivalent flexural stiffness of contact interfaces Kc in the RFR is the key concern for accurate rotor dynamic performance analysis. Each contact interface was modeled as a bending spring with a stiffness of Kc and a hinge in this study. The contact states of the contact interfaces, which depend on the pretightening forces and bending moments (static), have effects on Kc. The approach to calculating Kc in two contact states is presented. The first contact state is that the whole zone of the contact interface is in contact; Kc is determined by the contact layer, which consists of asperities of the contact surfaces. Hertz contact theory and the Greenwood and Williamson (GW) statistical model are used to calculate the equivalent flexural stiffness of the contact layer Kcc. The second contact state is that some zones of the contact interface are separated (when the bending moment is relatively large); the equivalent flexural stiffness of the rotor segment Ksf (not including Kcc) decreases, as the material in the separated zone has no contribution to the bending load-carrying capacity of the rotor. The strain energy, which is calculated by the finite element method (FEM), is used to determine Ksf. The stiffness Ksf is equivalent to the series stiffness of the discs of the rotor segment with flexural stiffness of Kd and a spring with bending stiffness of Kcf in the location of the contact interface, so Kc is equal to the series stiffness of Kcc and Kcf in the second contact state. The results of a simplified RFR indicate that, for a fixed pretightening force, Kcc decreases with bending moments in the first contact state, whereas increases with bending moments in the second contact state. In addition, Kcf and Kc decrease abruptly with the increase of bending moments in the second contact state when the rotor is subjected to a relatively large pretightening force. Finally, the multipoint exciting method was used to measure the modal parameters of the experimental RFR. It is found that the experimental modal frequencies decrease as the pretightening force decreases. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000010 [...]

Solidification of MSWI ash at low temperature of 100 °C / Chengchong Shan in Industrial & engineering chemistry research, Vol. 51 N° 28 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9540-9545 Titre : Solidification of MSWI ash at low temperature of 100 °C Type de document : texte imprimé Auteurs : Chengchong Shan, Auteur ; Zhenzi Jing, Auteur ; Li Pu, Auteur Année de publication : 2012 Article en page(s) : pp. 9540-9545 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Low  temperature  Ash  Solidification Résumé : Municipal solid waste incineration (MSWI) bottom ash could be solidified with fly ash addition at 100 °C, and the flexural strength of solidified specimens reached almost 20 MPa. The strength development was found to be due mainly to C-S―H gel formation. Leaching tests were conducted to determine the amount of heavy metals dissolved from the solidified specimens, and the results showed that, under the hydrothermal conditions of this study, the leaching of heavy metals was very low. As such, it is possible to solidify MSWI ash by 100% (80% bottom ash + 20% fly ash) in a continuous production process with a low cost. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163290 [article] Solidification of MSWI ash at low temperature of 100 °C [texte imprimé] / Chengchong Shan, Auteur ; Zhenzi Jing, Auteur ; Li Pu, Auteur . - 2012 . - pp. 9540-9545. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9540-9545 Mots-clés : Low  temperature  Ash  Solidification Résumé : Municipal solid waste incineration (MSWI) bottom ash could be solidified with fly ash addition at 100 °C, and the flexural strength of solidified specimens reached almost 20 MPa. The strength development was found to be due mainly to C-S―H gel formation. Leaching tests were conducted to determine the amount of heavy metals dissolved from the solidified specimens, and the results showed that, under the hydrothermal conditions of this study, the leaching of heavy metals was very low. As such, it is possible to solidify MSWI ash by 100% (80% bottom ash + 20% fly ash) in a continuous production process with a low cost. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163290