On high-speed turning of a third-generation gamma titanium aluminide

Gamma titanium aluminides are heat-resistant intermetallic alloys predestined to be employed in components suffering from high mechanical stresses and thermal loads. These materials are regarded as difficult to cut, so this makes process adaptation essential in order to obtain high-quality and defect-free surfaces suitable for aerospace and automotive parts. In this paper, an innovative approach for longitudinal external high-speed turning of a third-generation Ti-45Al-8Nb- 0.2C-0.2B gamma titanium aluminide is presented. The experimental campaign has been executed with different process parameters, tool geometries and lubrication conditions. The results are discussed in terms of surface roughness/integrity, chip morphology, cutting forces and tool wear. Experimental evidence showed that, due to the high cutting speed, the high temperatures reached in the shear zone improve chip formation, so a crack-free surface can be obtained. Furthermore, the use of a cryogenic lubrication system has been identified in order to reduce the huge tool wear, which represents the main drawback when machining gamma titanium aluminides under the chosen process condition

High performance cutting of gamma titanium aluminides: Influence of lubricoolant strategy on tool wear and surface integrity

Heat resistant gammatitaniumaluminidesareintermetallicalloysplannedtobewidelyusedinhigh- performanceaircraftengineswithinthenextfewyears.Thisapplicationfieldisascribedtothe exceptionalmaterialproperties,especiallythelowdensityandauniquestrength-to-weightratiofor titanium-basedalloys,goodoxidationbehaviourandthermalstability,limitedductilityandfracture toughnessbelowbrittle-to-ductiletransition,andgoodcreepresistance. The demandingmachinabilityofgammatitaniumaluminidescanbetracedbacktothesedesirable materialproperties.Consequently,cuttingprocessadaptationisessentialtoobtaincomponents suitabletosatisfystrongregulationsregardingsurfaceintegrity,withoutneglectinganeconomical production.Previousresearchactivitiesconfirmedthatthermalmaterialsofteningduringcuttingdue to thehighspeedmachiningisakeytoreachhighqualitysurfaces,buttoolwearwasidentifiedasthe limitingfactor. The relativelyhighcuttingspeedresultsinhightemperaturesintheshearzoneandthelowthermal conductivityofthe g-TiAl workpiecematerialleadstoanextremethermaltoolload.Furthermore,in combinationwiththeformationofsaw-toothchipsandthediscontinuousflowofthechipalongthe rake face,adhesiveweariscaused. The influenceofconventionalfloodcoolingandhighpressurelubricoolantsupply(wetconditions), cryogeniccoolingwithliquidnitrogen,andminimumquantitylubrication(MQL)wereinvestigatedin longitudinalexternalturningoperations.Toolwear,cuttingforces,chipmorphologyandsurface roughnesswereevaluated.Surfaceintegritywasanalysedintermsofmachinedsurfacedefectsand sub-surfacealterations. The investigationsindicatethatcryogeniccoolingisthemostpromisinglubricationstrategy, meaningthatthethermodynamicalimpactoftheexpandingliquidnitrogenapplieddirectlyclose to thecuttingzonesuccessfullycounteractthehugethermalloadonthetoolcuttingedges,providing potentiallyenormousbenefitsintermsoftoolwearreductionandconsequentsurfacequality improvemen

Avaliação do polidimetilsiloxano e graxa à base de silicone para selagem em motores elétricos à prova de explosão

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico, de Ciências Exatas e Educação. Engenharia de MateriaisCada vez mais exigências têm sido observadas no que diz respeito aos procedimentos e normas para uso de motores elétricos em atmosferas explosivas. Deste modo, são exigidos diversos ensaios aplicados às atmosferas explosivas, assim, o número de estudos reportando arranjos, flanges e invólucros de artefatos expostos a estas circunstâncias tem aumentado. Por conseguinte, os invólucros internos dos motores elétricos à prova de explosão são projetados com características de resfriamento das passagens de chama, o qual é um procedimento muito conhecido e especificado na norma IEC 60079-1. Porém, o estudo da pressão da explosão não é um assunto totalmente elucidado, em que grandes volumes internos e geometria diversas podem causar o aumento da pressão da explosão, causando o estrangulamento das passagens de chama. Buscando contornar essa situação, neste trabalho foi realizado um estudo para aprimorar os invólucros dos motores elétricos à prova de explosão com o preenchimento do polidimetilsiloxano vulcanizável em temperatura ambiente ou uma graxa à base de silicone para selagem da caixa de ligação. Foi avaliado os comportamentos dos materiais propostos, com o intuito de reduzir a pressão de explosão da substância inflamável. Dentro desse contexto, foram selecionados dois elastômeros diferentes (silicones de cura em temperatura ambiente com catalisadores diferentes) e uma graxa de silicone, de modo a avaliar os seus comportamentos em ensaios aplicáveis aos motores elétricos para uso em atmosferas explosivas. Inicialmente, foram realizados análises comparativas entre os materiais e posteriormente avaliados os desempenhos elétricos e térmicos (resistência de isolamento, índice de polarização, e ensaio de envelhecimento), mediante a ensaios aplicáveis aos motores elétricos à prova de explosão. De acordo com os resultados obtidos, a graxa à base de silicone apresentou melhores resultados elétricos, tornando-a aplicável para executar o preenchimento de regiões de invólucros com a função de selagem da passagem da chama, nos motores elétricos com risco de acúmulo de mistura de gás explosivo.More requirements have been observed regarding procedures and standards for the use of electric motors in explosive atmospheres. Thus, several tests applied to explosive atmospheres are required, thus, the number of studies reporting arrangements, flanges and casings of artifacts exposed to these circumstances has increased. Therefore, the internal casings of the explosion-proof electric motors are designed with cooling characteristics of the flame passages, which is a well-known procedure and specified in the IEC 60079-1 standard. However, the study of explosion pressure is not a fully elucidated subject, in which large internal volumes and diverse geometry can cause the explosion pressure to increase, causing strangulation of the flame passages. In order to get around this situation, a study was carried out in this work to improve the casings of explosion-proof electric motors with the filling of vulcanizable polydimethylsiloxane at room temperature or a silicone-based grease for sealing the connection box. The behavior of the proposed materials was evaluated in order to reduce the explosion pressure of the flammable substance. Within this context, two different elastomers (curing silicones at room temperature with different catalysts) and a silicone grease were selected in order to evaluate their behavior in tests applicable to electric motors for use in explosive atmospheres. Initially, comparative analyzes were performed between the materials and subsequently evaluated the electrical and thermal performances (insulation resistance, polarization index, and aging test), by means of tests applicable to explosion-proof electric motors. According to the results obtained, the silicone-based grease showed better electrical results, making it applicable to fill regions of envelopes with the function of sealing the flame passage, in electric motors with risk of accumulation of mixture of explosive gas

Bio-Inspired Protective Skin Mechanism with an Exhaustive Arrangement of Tiny Rigid Bodies

The 11th International Symposium on Adaptive Motion of Animals and Machines. Kobe University, Japan. 2023-06-06/09. Adaptive Motion of Animals and Machines Organizing Committee.Poster Session P6

キャラクターの企画制作による産学連携の試み―クリアソン新宿との連携事例―

「クリアソン新宿キャラクター化プロジェクト」とは、東京都新宿区をホームタウンとして活動するサッカーチームであるクリアソン新宿と宝塚大学東京メディア芸術学部（以下、本学と記す）による産学連携プロジェクトである。本学とクリアソン新宿は2021年４月21日より包括連携協定を結んでおり、その取り組みの一環として発足した。 　本プロジェクトはチームの普及啓発及びファン層の拡大を目的としている。その方法として、本学の教育研究分野であるメディアデザイン・キャラクターデザインの経験を活かし、選手及び監督の２次元キャラクター化を提案。これまでに国立競技場ブース出展やグッズ展開を行ってきた。今回は、2021年12月から現在までにクリアソン新宿と本学学生・教職員の共同作業により行われてきた本プロジェクトの活動内容及び２次元キャラクター制作過程を連携事例として報告する。The Criacao Shinjuku Characterization Project is an industry-academia collaboration between Criacao Shinjuku, a football club based in Shinjuku, Tokyo, and Takarazuka University’s School of Media Art in Tokyo (SMAT). SMAT and Criacao Shinjuku signed a partnership agreement on 21 April 2021, after which the project was launched. 　The project is designed to promote the club’s brand awareness and attract more fans. To that end, SMAT proposed creating 2D characters representing the club’s players and coach, drawing on the school’s education and research expertise in media and character design. Activities in the project so far include setting up a booth with merchandise at an exhibition in the Japan National Stadium. This report presents, as a partnership case study, the project activities that Criacao Shinjuku and SMAT’s students and faculty have undertaken since December 2021, as well as the process by which the 2D characters were created.departmental bulletin pape

Arctic weather in 2012 summer and influences on Arctic Environment

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議