سيستم هاي مختلف ساختماني موزه همگي نمودي از موضوعات و زمينه هاي نظري و عملي پروژه هستند. سيستم گرمايش و سرمايش، سيستم كف تابشي خواهد بود كه در آن از فشردگي خاك و خنكي آب براي تنظيم درجه حرارت ساختمان استفاده مي شود.
فايل مورد نظر پاورپوينت بوده و داراي 11 اسلايد ميباشد.
نام پروژه:مرسدس بنز
مقاله جوشكاري با عنوان : Ultrasonic spot welded AZ31 magnesium alloy: Microstructure, texture, and lap shear strength
V.K. Patel, S.D. Bhole n, D.L. Chen
چكيده:
The structural application of ultra-lightweight magnesium alloys inevitably involves welding and
joining. A solid-state welding – ultrasonic spot welding (USW) – was conducted on AZ31B-H24 Mg
alloy sheet by varying a key parameter of welding energy in this study, aiming to identify the changes
in the microstructure, crystallographic texture, and lap shear tensile strength. The grain size was
observed to increase with increasing welding energy. Crystallographic texture determined via X-ray
diffraction showed a significant change that corresponded well to the change in the deformation and
recrystallization mechanisms of the Mg alloy. The lap shear strength first increased with increasing
energy input, reached the maximum value at a welding energy of 2000 J, then decreased. The welds
generally fractured along the joint interface when the welding energy was lower than 2000 J, while
fracture occurred at the periphery of the joint (button pull-out) for the samples made with an energy
input of higher than 2000 J.
سال ساخت 1987
ناپرويل (ايلي نويز)
زيربنا 44000فوت مربع
طراح پروژه peter Exley
فايل مورد نظر پاورپوينت بوده و داراي 20 اسلايد ميباشد.
انرژي ها به دو نوع تقسيم ميشوند:
-تجديد پذير:جايگزين ميشوند و فاني نيستند
-تجديد ناپذير:زوال پذيرند و منابعشان محدود است
فايل مورد نظر پاورپوينت بوده وداراي 72 اسلايد ميباشد.
مقاله جوشكاري با عنوان : Characterization of microstructure and deformation behaviour of resistance spot welded AZ31 magnesium alloy
N. Kishore Babua,∗, S. Brauserb, M. Rethmeierb,c, C.E. Crossd
چكيده :
Resistance spot welds were prepared on 3 mm thick sheets of continuous cast and rolled AZ31 magnesium
alloy. The microstructure and composition analysis of weld nugget, heat affected zone (HAZ)
and base metal were examined using optical and scanning electron microscopy (HR-SEM and EDS/X).
The resistance spot welded magnesium alloy joints consist mainly of weld nugget and HAZ. The nugget
contains two different structures, i.e. the cellular-dendritic structure at the edge of the nugget and the
equiaxed dendritic structure in the centre of the nugget. The structure transition is attributed to the
changes of solidification conditions. In the HAZ, grain boundary melting occurred and grain boundaries
became coarse. It has been shown that hardness reduction in the weld nugget and HAZ compared with
base metal is evident due to dendritic microstructure and grain growth, respectively. The results showed
that spot welded joints have failed in interfacial mode under torsion and tensile–shear loading conditions.
Digital image correlation during tensile–shear testing showed that low surface strains occur in the
interfacial failure mode, because fracture and deformation happened primarily in the nugget area.
مقاله جوشكاري با عنوان : Effect of electromagnetic stirring on the microstructures and mechanical properties of magnesium alloy resistance spot weld
Q. Yao, Z. Luo ⇑, Y. Li, F.Y. Yan, R. Duan
چكيده :
This paper investigates the effect of electromagnetic stirring (EMS) on the nugget formation, microstructure,
and mechanical properties of magnesium alloy resistance spot weld (RSW). The EMS was induced by
an external magnetic field (EMF), which produced by a pair of permanent magnets. The results showed
that the EMS drove the molten metal in the nugget to flow clockwise and generated a centrifugal movement,
which brought high temperature molten metal from the center of the growing nugget to its edge.
Compared with the traditional magnesium alloy RSW, the weld under the EMS effect (EMS-RSW) exhibited
larger weld diameter, higher tensile shear force and energy absorption, and finer equiaxed crystal
and columnar crystal. The EMS-RSW had a higher hardness ratio of fusion zone to pullout failure location,
which indicated that the EMS-RSW was more sensitivity to experience pullout failure. Finally, an empirical
failure load formula for magnesium alloy resistance spot weld was developed.
مقاله جوشكاري با عنوان : Effects of welding parameters on the characteristics of magnesium alloy joint welded by resistance spot welding with cover plates
Hongxin Shi a,b,*, Ranfeng Qiu a, Jinhong Zhu a, Keke Zhang a, Hua Yu a, Gaojian Ding
چكيده :
Magnesium alloy AZ31B sheets were welded using the technique of resistance spot welding with cover
plates. The effects of welding parameters on the characteristics of the joint were investigated. The joint
with larger nugget and higher tensile shear load was obtained under relatively low welding current condition.
Enhancing electrode force and extending down-sloping time are effective for inhibiting pores formation
and increasing the tensile shear strength of the joint under corresponding welding conditions.
The results reveal that the technique is feasible to weld magnesium alloy.
مقاله جوشكاري با عنوان : Electrical contact resistance effect on resistance spot welding
P.S. Wei a,., T.H. Wub
چكيده :
The effects of local electrical contact resistance on transport variables, cooling rate, solute distribution,
and nugget shape after solidification responsible for microstructure of the fusion zone during resistance
spot welding are realistically and systematically investigated. The model accounts for electromagnetic
force, heat generation and contact resistances at the faying surface and electrode–workpiece interfaces
and bulk resistance in workpieces. Contact resistances are composed of film and constriction resistances,
as functions of hardness, temperature, electrode force and surface condition. The computed results show
that the bulk dynamic electrical resistance cannot reliably reflect transport processes and nugget shape,
unless the local constriction resistance and electric current density are known. Regardless of high film
resistance, nugget growth and transport processes are independent of film resistance due to delayed
response time of local electric current in the early stage. A decrease in constriction resistance, however,
delays nugget formation, enhances convection and solute mixing, and changes circulation direction of the
stronger convection cell during cooling period.
مقاله جوشكاري با عنوان :
Effects of Welding Parameters and Surface Pretreatments on Resistance
Spot Welding of AZ31B Mg Alloy
Shiquan Zhou1, Lei Liu2,3, Jae Pil Jung4,*, Mok-Young Lee5, and Y. Norman Zhou3
چكيده :
The resistance spot weldability of AZ31B magnesium alloy using AC (alternating current) was investigated
in this paper. The surfaces of sheet coupons were prepared by acetone cleaning (as-received) and some coupons
were also cleaned with chromic acid (H2Cr2O7) after acetone cleaning (acid-cleaned). The surfaces of the
as-received AZ31B sheets consisted of MgO, Mg(OH)2, and MgCO3. The extent and thickness of the surface
oxide/reaction layer of the sheets varied according to the fabrication process of the sheets, and resulted in
different contact resistance. Effects of welding current and weld time were investigated while the electrode
force was kept constant. The results indicated that the as-received sheets produced expulsion both at the
faying surface and at the work piece/electrode interface due to high contact resistance. Diluted chromic acid
cleaning reduced contact resistance and produced good weld quality. Increasing the welding current and weld
time enhanced not only the nugget size and joint strength, but also increased indentation on the weld surfaces.
A weld lobe was established considering the minimum joint strength, weld expulsion, and surface indentation
based on a relevant American Welding Society Standard.
تعداد صفحات : 411
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