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Characterization of Machining-Induced Residual Stresses in Titanium-Based Alloys

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Characterization of Machining-Induced Residual Stresses in Titanium-Based Alloys/ Elias Abboud.
作者:	Abboud, Elias,
面頁冊數:	1 electronic resource (208 pages)
附註:	Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
Contained By:	Dissertations Abstracts International82-10B.
標題:	Metal fatigue. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28266399
ISBN:	9798708719362

Characterization of Machining-Induced Residual Stresses in Titanium-Based Alloys
Abboud, Elias,

Characterization of Machining-Induced Residual Stresses in Titanium-Based Alloys [electronic resource] /Elias Abboud. - 1 electronic resource (208 pages)

Source: Dissertations Abstracts International, Volume: 82-10, Section: B.

Machining-induced residual stresses (RS) have a major impact on the fatigue life of critical aero-engine parts subjected to dynamic loads in harsh environments. Their state and magnitude can be controlled by careful selection of cutting conditions. Tensile RS are extremely harmful as they accelerate crack nucleation and propagation, diminishing the resistance to fatigue failures. It is crucial to identify cutting parameters that promote desirable compressive RS in critical parts without compromising other aspects of surface integrity. Limited information is available in the open literature on machining-induced RS in Ti-alloys.In this research, an extensive experimental investigation is performed of the effect of cutting parameters on RS in two aerospace grade Ti-alloys, Ti-64 and Ti-6246, used for aeroengine fan and compressor parts. Cutting is performed at conditions relevant to industry. This is coupled with a comprehensive evaluation of surface integrity including RS, surface roughness, the near-surface microstructure, and hardness distribution. Based on x-ray diffraction measurements, empirical models are developed that offer fast and accurate predictions of surface RS. For the investigated finish turning regime, RS are compressive in nature. Due to a conflict between RS and surface finish, guidelines are established for the optimal selection of cutting parameters.Empirical models are non-generic, cannot be extrapolated, and cannot offer a physical interpretation of the phenomena that govern the cutting process. Available FE models for Tialloys mostly focus on chip formation and force prediction, and rarely extend to RS. In this work, a 2D FE model is constructed using DEFORM™ for the prediction of machininginduced RS in Ti-alloys, and is optimized for accuracy and computational efficiency. This is preceded by a numerical study on the relative contribution of thermal loads, mechanical loads, and phase transformations to the resultant stress state in commercially available materials. The FE model is firstly validated against experimental machining forces, cutting temperatures, and RS. It is then used as a virtual machining medium to gain insight into the effect of cutting parameters, tool edge preparation, flank wear, and chip segmentation on residual stress formation. FE predictions for Ti-6246 show that RS are highly sensitive to flank wear, which can cause a severe shift from the compressive to the tensile state. For the investigated cutting regime, residual stress prediction errors for Ti-64 are limited to ±10% provided that chip segmentation is modeled at relatively high cutting speeds.

English

ISBN: 9798708719362Subjects--Topical Terms:

1372747
Metal fatigue.
Subjects--Index Terms:

Machining

Characterization of Machining-Induced Residual Stresses in Titanium-Based Alloys
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500 $a Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
500 $a Advisors: Thomson, Vincent; Attia, Mahmoud Helmi.
502 $b Ph.D. $c McGill University (Canada) $d 2015.
520 # $a Machining-induced residual stresses (RS) have a major impact on the fatigue life of critical aero-engine parts subjected to dynamic loads in harsh environments. Their state and magnitude can be controlled by careful selection of cutting conditions. Tensile RS are extremely harmful as they accelerate crack nucleation and propagation, diminishing the resistance to fatigue failures. It is crucial to identify cutting parameters that promote desirable compressive RS in critical parts without compromising other aspects of surface integrity. Limited information is available in the open literature on machining-induced RS in Ti-alloys.In this research, an extensive experimental investigation is performed of the effect of cutting parameters on RS in two aerospace grade Ti-alloys, Ti-64 and Ti-6246, used for aeroengine fan and compressor parts. Cutting is performed at conditions relevant to industry. This is coupled with a comprehensive evaluation of surface integrity including RS, surface roughness, the near-surface microstructure, and hardness distribution. Based on x-ray diffraction measurements, empirical models are developed that offer fast and accurate predictions of surface RS. For the investigated finish turning regime, RS are compressive in nature. Due to a conflict between RS and surface finish, guidelines are established for the optimal selection of cutting parameters.Empirical models are non-generic, cannot be extrapolated, and cannot offer a physical interpretation of the phenomena that govern the cutting process. Available FE models for Tialloys mostly focus on chip formation and force prediction, and rarely extend to RS. In this work, a 2D FE model is constructed using DEFORM™ for the prediction of machininginduced RS in Ti-alloys, and is optimized for accuracy and computational efficiency. This is preceded by a numerical study on the relative contribution of thermal loads, mechanical loads, and phase transformations to the resultant stress state in commercially available materials. The FE model is firstly validated against experimental machining forces, cutting temperatures, and RS. It is then used as a virtual machining medium to gain insight into the effect of cutting parameters, tool edge preparation, flank wear, and chip segmentation on residual stress formation. FE predictions for Ti-6246 show that RS are highly sensitive to flank wear, which can cause a severe shift from the compressive to the tensile state. For the investigated cutting regime, residual stress prediction errors for Ti-64 are limited to ±10% provided that chip segmentation is modeled at relatively high cutting speeds.
520 3 $a Les contraintes résiduelles (CR) induites par l'usinage ont un impact majeur sur la résistance à la fatigue des composantes soumises aux charges dynamiques dans les environnements sévères. Leur état peut être contrôlé par la sélection soigneuse des conditions de coupe. Les CR en tension réduisent la résistance à la défaillance par fatigue. Par conséquent, l'identification des paramètres de coupe qui promeuvent des CR compressives, en évitant l'endommagement de l'intégrité de la surface, est extrêmement importante. Les études sur les CR produites par l'usinage des alliages de titane son très limitée.Dans ce travail, une enquête approfondie est effectuée sur les effets des paramètres de coupe sur les CR générées dans deux alliages de titane, Ti-64 et Ti-6246, utilisées dans les moteurs d'avions. L'usinage et réalisé à des conditions pertinentes pour l'industrie. Cela et suivi par une évaluation de l'intégrité de la surface incluant les CR, la rugosité, la microstructure, et les profils de dureté. Basé sur des mesures des CR par diffraction des rayons X, des modèles empiriques rapides et précis sont développés. Pour les conditions de tournages de finition enquêtées, les CR sont compressives. Du à un conflit entres les CR et la rugosité, des lignes directrices sont développées pour la sélection des paramètres de coupe.Les modèles empirique qui sont non-générique ne peuvent pas être extrapolés et ne peuvent pas offrir une interprétation des phénomène physiques. Les modèles d'élément finis disponibles pour les alliages de titane abordent rarement la formation des CR. Dans cette recherche, un modèle 2D d'élément finis est développé à travers DEFORM™ pour la prédiction des CR générées par l'usinage. Le modèle est optimiser pour l'efficacité et la précision. Cela est précédé par une étude numérique sur la contribution relatif des charges thermiques, charges mécaniques, et transformations de phases a l'état final des CR dans des nombreux matériaux. Le modèle est validé contre des mesurent de forces, température, et CR produites par l'usinage. Par la suite, le modèle est utilisé comme un milieu d'usinage virtuel pour l'analyse des effets des paramètres de coupe, l'usure, et la segmentation des copeaux sur l'évolution des CR. Les études numérique liées au Ti-6246 démontres que les CR sont très sensibles à l'usure qui peut promouvoir un changement d'état des CR de compression en tension. Pour les conditions de tournages de finition enquêtées, la marge d'erreur de prédiction des CR générées dans le Ti-64 est de ±10% en condition que la segmentation des copeaux est modélisé a des vitesses de coupe relativement élevées.
546 $a English
590 $a School code: 0781
650 # 4 $a Metal fatigue. $3 1372747
650 # 4 $a Residual stress. $3 1083680
650 # 4 $a Titanium alloys. $3 811066
650 # 4 $a Materials science. $3 557839
650 # 4 $a Manufacturing. $3 1295128
650 # 4 $a Engineering. $3 561152
653 # # $a Machining
653 # # $a Residual stresses
653 # # $a Titanium
653 # # $a Alloys
690 $a 0548
690 $a 0794
710 2 # $a McGill University (Canada). $3 845629
720 1 $a Thomson, Vincent $e degree supervisor.
720 1 $a Attia, Mahmoud Helmi $e degree supervisor.
773 0 # $t Dissertations Abstracts International $g 82-10B.
790 $a 0781
791 $a Ph.D.
792 $a 2015
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28266399