Selection of Material and Shape
1
A few examples on the shape – performance relationship…
Whis glass is used to
consume a cold
beverage?
Heat Sink???
Torsion Box?
Can a sheet of paper carry load?
https://www.vectorstock.com/royalty-free-vector/white-sheet-of-paperbackground-vector-3726748
3
Macrostructure
– Efficiency
Makro Özellikler
Malzeme Özelliği Dışında Geometri
ile Mekanik
Dayanım
Kazandırma
Designer
vs.
Materials
Engineer
Makro Özellikler
alzeme Özelliği Dışında Geometri ile Mekanik Dayanım Kazandırma
Does the elastic modulus change
when a sheet of metal is folded?
http://www.snobarcolorbar.com/technical-data/
4
Structural sections
When materials are loaded in bending, in torsion, or are used as slender columns,
section shape becomes important
Shape = cross section formed to a
n
Tube
n
I-section
n
Hollow box
Simple shapes
Complex shapes (relatively higher efficiency)
5
Shape Factors
Normalized!
6
Shape Factors
7
Shape Factors
Mass distribution and stiffness.
8
Shape Factors
/ L3
Mass distribution and stiffness.
9
Shape Factors
/ L3
Mass distribution and stiffness.
https://en.wikipedia.org/wiki/Second_moment_of_area
10
Elastic Bending of Beams
11
Elastic Bending of Beams
12
Elastic Bending of Beams
DOES NOT DEPEND ON
SCALE!!!
BE CAREFUL ABOUT
SIMPLIFICATION!!!
13
BE CAREFUL ABOUT SIMPLIFICATION!!!
14
Solid equiaxed sections (circles, squares, hexagons, octagons) all have values very close
15
to 1 – for practical purposes, they can be set equal to 1.
16
Structural Elements
I - Beam
Why in I shape?
In which direction
should it be loaded?
17
Is stiffness always required?
18
Elastic Twisting of Shafts
19
Shape Factor for Elastic Twisting
20
What about failure?
21
22
Strength Efficiency
23
Section Modulus
24
Failure in Torsion
Torsional stress
T = Torque
rm = radial distance
J = Torsional moment of
area
Q = J/rm
25
Limits to Shape Efficiency
26
Limits to Shape Efficiency
27
Buckling
28
Limits to Shape Efficiency
Limits
29
Exploring Material Shape Combination
30
Exploring Material Shape Combination
31
Exploring Material Shape Combination
32
Exploring Material Shape Combination
33
Material Indices That Include Shape
34
Material Indices That Include Shape
35
Material Indices That Include Shape
36
Graphical Coselecting Using Indices
37
Architectured Materials:
Microscopic Shape
38
Architectured Materials:
Microscopic Shape
39
Architectured Materials:
Microscopic Shape
40
Architectured Materials:
Microscopic Shape
41