检索结果-南通市图书馆

Mechanical properties of 2024-T4 aluminium alloy joints in ultrasonic vibration enhanced friction stir welding

在线全文

学校读者我要写书评

暂无评论

China Welding 2013年第4期22卷 8-13页

作者：刘小超武传松 michael rethmeier Andreas Pittner Key Lab for Liquid-Solid Structure Evolution and Materials Processing ( Ministry of Education) andInstitute for Materials Joining Shandong University Jinan 250061. China Federal Institute forMaterials Research and Testing Berlin 12205 Germany

Ultrasonic vibration enhanced friction stir welding （UVeFSW） is a recent modification of conventional friction stir welding （FSW）, which transmits ultrasonic vibration directly into the localized area of the workpiece near and ahead of the rotating tool. In this study, a high strength aluminium alloy （2024-T4） was welded by this process and conventional FSW, respectively. Then tensile tests, microhardness tests and fracture surface analysis were performed successively on the welding samples. The tests results reveal that ultrasonic vibration can improve the tensile strength and the elongation of welded joints. The microhardness of the stir zone also increases.

关键词： ultrasonic vibration friction stir welding mechanical properties

Simulation of welding

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2011年第2期5卷 77-78页

作者： Chuan-Song WU michael rethmeier Christopher SCHWENK Institute of Materials Joining Shandong University Jinan China Federal Institute for Materials Research and Testing （BAM） Berlin Germany

Welding has become the most important materials processing technology in manufacturing, and has critical effects on the quality, reliability and life of products as well as production cost, efficiency and response speed to market. As various kinds of high performance metallic materials are widely used in engineering, there are more demands in manufacturing industry for advanced welding technology.

关键词： manufacturing theory-experiment-production Science Promotion

Simulation of an Inductive Weld Pool Support for Deep Penetration Laser Beam Welding of Metal Parts

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第S1期19卷 114-117页

作者： BACHMANN Marcel AVILOV Vjaceslav GUMENYUK Andrey rethmeier michael BAM Federal Institute for Materials Research and Testing Unter den Eichen 87Berlin 12205Germany

A three-dimensional laminar steady state numerical model was used to investigate the influence of an alternating current(ac)magnetic field during single pass high power laser beam keyhole welding of 20 mm thick *** three-dimensional heat transfer,fluid dynamics and electromagnetic field equations were solved with the commercial finite element package COMSOL *** physical effects of the process were taken into account:Thermo-capillary(Marangoni)convection at the upper and lower weld pool surfaces,natural convection due to the gravity influence and the latent heat of solid-liquid phase *** were conducted for several magnetic field strengths and it was found that the gravity drop-out associated with welding of thick plates due to the hydrostatic pressure can be prevented by the application of an ac magnetic field below the weld specimen of around 70 mT(rms)at an oscillation frequency of 450 *** inductive support system allows for single-pass laser beam welding of thick aluminum *** flow pattern in the molten zone and the temperature distributions are significantly changed by the application of the electromagnetic forces in the weld pool.

关键词： electromagnetic weld pool support laser beam welding Lorentz force Marangoni stresses natural convection

Fluid Flow Simulation of the Influence of a Steady Magnetic Field on the Weld Pool Dynamics in Deep Penetration Laser Beam Welding of Aluminum

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第S1期19卷 467-470页

作者： BACHMANN Marcel AVILOV Vjaceslav GUMENYUK Andrey rethmeier michael BAM Federal Institute for Materials Research and Testing Berlin 12205Germany

A multi-physics numerical model was developed to investigate the influence of a steady magnetic field during partial penetration keyhole laser beam welding of an aluminum plate in fiat ***-dimensional heat transfer, fluid dynamics including phase transition and electromagnetic field partial differential equations were solved with the finite element differential equation solver COMSOL *** magnetic field was aligned perpendicularly to the welding *** main objective of these simulations was to estimate the critical value of the magnetic field needed to suppress convective flows in the weld pool during high-power(up to 20 kW)laser beam welding of aluminum alloys with up to 20 mm deep weld *** reveals that steady magnetic fields with corresponding Hartmann numbers Ha2-104 based on the half-width of the weld pool can effectively suppress convective flows in the weld ***,the typically occurring wineglass-shape of the weld cross section caused by thermo-capillary flow is weakened.

关键词： laser beam welding Lorentz force Marangoni stresses natural convection Hartmann effect

在线全文

学校读者我要写书评

暂无评论

镍基超级合金的电子束焊接

现代制造 2023年第10期 34-35页

作者： Julius Raute Max Biegler michael rethmeier 不详

增材制造技术是制造和修复高强度材料复杂零部件的理想工艺技术,但缺少避免热裂纹的焊接工艺方案,而电子束焊接技术可以改变这种局面。在包括镍基耐高温合金在内的高强度材料零件生产中,尤其是在结构复杂零件的生产中,增材制造技术有着... 详细信息

增材制造技术是制造和修复高强度材料复杂零部件的理想工艺技术,但缺少避免热裂纹的焊接工艺方案,而电子束焊接技术可以改变这种局面。在包括镍基耐高温合金在内的高强度材料零件生产中,尤其是在结构复杂零件的生产中,增材制造技术有着非常强大的的应用潜力。然而在灵活的增材制造过程中,却缺少了这些零部件可靠的连接工艺技术。镍基合金零部件所面临的最大挑战是避免热裂。电子束焊接技术就是增材制造零部件可靠连接的解决方案。多年来,镍基合金已经在许多工业领域中得到了广泛的应用。

关键词：镍基合金电子束焊接高强度材料热裂纹增材制造零件生产连接工艺复杂零件

Fabrication of sub-20 nm MoS_(2) horizontal nanowire on silicon substrates by inclusion of precursors into polystyrene-bpolyethylene oxide nanopatterns: Detailed structural investigation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 2145-2153页

作者： Tandra Ghoshal michael A.Morris School of Chemistry AMBER and CRANNTrinity College DublinDublinIrelandD02 AK60

Herein,we demonstrate the fabrication of sub-20 nm MoS_(2) horizontal nanowire arrays on silicon substrates using a self-assembled block copolymer assisted in situ inclusion *** separated long-range ordered polystyrene-b-polyethylene oxide(PS-b-PEO)block copolymer(BCP)line-space nanopatterns were achieved through thermo-solvent *** patterns produced had long-range order and domain sizes>1μ*** BCP structures were lightly etched and modified by anhydrous ethanol to facilitate insertion of molybdenum precursor within the film maintaining the parent BCP *** ordered molybdenum oxide nanowire arrays were then fabricated by ultraviolet(UV)/ozone treatment at room *** oxides were converted to sulphides by thermal evaporation at different temperatures in Ar/H_(2) environment.X-ray photoelectron spectroscopy revealed the composition and phases of the molybdenum oxide and sulphide *** mapping was performed to investigate the interfaces between the oxide and sulphide nanowires with the substrate *** formation and stability of the sulphide nanowires were studied at different *** photoluminescence and Raman properties were studied at different formation temperatures to investigate defects and estimate the number of layers.

关键词： MoS_(2) block copolymer nanowires inclusion X-ray photoelectron spectroscopy(XPS) mapping photoluminescence

A GHz chirped amplitude-modulated laser for high-contrast plasma gratings

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2024年第1期12卷 74-83页

作者： michael Valdman Amir Hen Gilad Marcus Applied Physics Institute Hebrew University of JerusalemJerusalemIsrael

The generation and control of large amplitude plasma gratings and other plasma structures is of paramount importance for the realization of plasma photonics. Autoresonant excitation of such structures by means of chirped amplitude-modulated lasers has been recently discussed and analyzed theoretically. Here we discuss the parameter space for the realization of such a scheme and describe the laser system that was built towards this goal. We also expand our earlier theoretical study to account for the more realistic case of a moderately focused laser beam, instead of the simplified plane wave approximation.

关键词： amplitude modulation high-frequency modulation autoresonance ion acoustic wave

Neuronal trafficking as a key to functional recovery in immune-mediated neuropathies

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第11期19卷 2331-2332页

作者： Felix Kohle michael Schroeter Department of Neurology University of Cologne and University Hospital CologneCologneGermany

Immune-mediated neuropathies are rare diseases of the peripheral nervous system(PNS),substantially affecting patients’functionality and quality of *** are amenable to immunomodulatory treatments,which in many cases stabilize disease progression,but long-term deficits persist in many *** long-term deficits are particularly observed in monophasic autoimmune neuropathies like Guillain-Barrésyndrome and also in chronic variants,e.g.,chronic inflammatory demyelinating neuropathy(Fadia et al.,2019).

关键词： diseases autoimmune

Transcranial photobiomodulation for the brain: a wide range of clinical applications

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第3期19卷 483-484页

作者： michael R.Hamblin Laser Research Centre Faculty of Health ScienceUniversity of Johannesburg-Doornfontein CampusDoornfonteinSouth Africa

Photobiomodulation therapy(PBMT)is a rapidly growing approach to the healing,stimulation,protection,and regeneration of many human organs and tissue *** started in the 1960s as low-level laser therapy for wound healing,but since then the introduction of light-emitting diodes(LEDs)has dramatically increased the number of applications and reports of positive *** generally uses red(620-700 nm)and/or near-infrared(780-1270 nm)wavelengths of light at an intensity that causes no tissue heating,and its activity is based on well-established biological and cellular mechanisms(de Freitas and Hamblin,2016).While laser therapists continue to use various types of laser in their office practice,LEDs are ideally suited for home use devices because they are completely safe and without any known significant adverse *** the various body parts on which PBMT has been shown to exert beneficial effects,the brain stands out as perhaps the most promising *** has been shown to reduce neuroinflammation,while increasing mitochondrial function,oxygen consumption,and blood flow within the brain(Hamblin,2016).Moreover,PBMT can stimulate the processes of synaptogenesis,neurogenesis,and neuroplasticity thus helping the brain to heal itself.

关键词： healing stimulation wound