曝光臺 注意防騙 網曝天貓店富美金盛家居專營店坑蒙拐騙欺詐消費者

Part 1-2 Structural fire design
Part 1-3 Structures susceptible to
fatigue
Part 1-4 Cold-formed structural
sheeting
Part 1-5 Shell structures
Part 1-1 is used for all static
design and Part 1-3 for all
fatigue design shown in this
chapter.
A new European standard for the
execution of structural aluminium
is under development and is
soon ready for publication. It is
recommended to use relevant
parts of this standard for execution
of aluminium components
for use in commercial vehicles.
The name of this standard is:
EN 1090-3: Execution of steel
structures and aluminium structures
– Part 3: Technical requirements
for aluminium structures
2. Possibilities
with aluminium
The advantages of designing
with aluminium are:
• High strength-to-weight ratio
• Possibilities to create your own
cross-sections with the extrusion
technique
• Good corrosion resistance
• Long vehicle life
• Easy to work with
• Easy to repair
Especially for product design, the
use of tailor-made profiles is a
great advantage for aluminium
compared with other metals. In
profile design the material can be
placed where the effect of the
material is optimal regarding
resistance. Details can be made
in such a way that it will ease the
fabrication and assembling of
the components.
3. Symbols
Frequently used symbols are
defined in this section:
fo characteristic value of 0.2 %
proof strength
fu characteristic value of ultimate
tensile strength
fub characteristic ultimate tensile
strength of bolt
E modulus of elasticity
d bolt diameter
do hole diameter
t wall thickness
A cross section area
W section modulus
γM partial safety factor for resistance
(see the definitions in section
5.2), in EN 1999-1-1:
Subscript Ed is used for factored
load effects. It may be on axial
force (NEd), bending moment
(MEd), shear force (VEd), torsion
(TEd) and forces in connection
with bolted connections (Fv,Ed for
shear force and Ft,Ed for tension
force).
58
ALUMINIUM IN COMMERCIAL VEHICULES CHAPTER VI DESIGN AND CALCULATION 58 | 59
Both steel and aluminium are
metals with relatively high
strength. Both materials are
incombustible and will not contribute
to a fire. For structural
purposes the main differences
are:
Elasticity: The modulus of elasticity
(E-modulus) of aluminium is
1/3 of that of steel. This means
that an aluminium beam with
the same cross-section and the
same loads as a steel beam will
have a deflection 3 times that of
the steel beam.
Weight: The density of aluminium
is 1/3 of that of steel. This
means that a steel beam will
weigh 3 times more than an aluminium
beam with the same
cross-section.
Welding: When welding a hardened
aluminium alloy some of
the hardening effects will be lost.
The strength in the heat affected
zone (HAZ) will be reduced. This
reduction depends on the alloy,
temper, type of product and
welding procedure. Ordinary
steel has no strength reduction
after welding.
Thermal elongation: The coefficient
of thermal elongation of
aluminium is twice that of steel.
This means that an aluminium
member will get twice the thermal
elongation as a similar steel
member with the same temperature
difference. Since the elastic
modulus of aluminium is 1/3 of
steel, the stresses in an aluminium
member with fixation are 2/3 of
that in a similar steel member.
Most of the structural aluminium
alloys have relatively high
“strength-to-E modulus” ratio.
This effect is especially clear
when the aluminium alloy is
strain-hardened or heat-treated.
Structural aluminium alloys have
roughly twice the “strength-to-E
modulus” ratio than standard steel.
However, when compared with
high strength steels, structural
aluminium alloys have about the
same “strength-to-E modulus”
ratio. It should also be noted that
the elastic modulus of an alloy
mainly depends on its parent
metal. In other words, all aluminium
alloys have very similar Emodulus,
but this is also valid for
steel alloys. Consequently, the so
called “high strength steels”
don’t have better elastic properties
than mild steel.
Steel designers often use the
strength of the material as governing
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：航空資料25(15)