L7 SCUT 2013 Sh Factors (2) 华南理工大学-材料选择.pptx

L7 SCUT 2013 Sh Factors (2) 华南理工大学-材料选择.pptxSCUT 2013 Lecture 7 (2/3) Shape Factors
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SCUT 2013 Materials Selection
Lecture 7: Materials and Shape (2/3) Materials for Efficient Structures
Textbook Chapters 9 & 10
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Materials and Shape: Lectures Outline
 We have seen (Lecture #6 (1/3)):
The shape factor.
Material Indices that include shape.
Graphical ways of dealing with shape.
Lecture #7, Today (2/3):
More graphical ways of dealing with shape.
Selecting structural sections.
Shape limits.
Lecture #8 Last one (3/3):
Case studies. Ultra efficient springs.
Microstructural shape factors (Timber). Foamed panels.
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A shaped beam of shape factor for elastic bending, e = 10, is 10 times stiffer than a solid square section beam of similar cross section area.
Quick review of Lecture 6
Shape factor for bending stiffness (Beams):
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A shaped beam of shape factor for bending strength, f = 10, is 10 times stronger than a solid square section beam of similar cross section area.
Lecture 6, Shape factor for bending strength (Beams)
Section modulus,
Z = I/ym
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Note that new material with
Shape on selection charts: stiff beams pp. 269/70
Density (Mg/m3)
Young’s modulus (GPa)
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Note that new material with
Shape on selection charts: strong beams pp. 269/70
Stength: Shift bubble by the square of the Shape Factor
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Limits to Shape Factors?
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There is an upper limit to Shape Factors for each material Table , p. 258
Empirical Maxima set by: (a) manufacturing constraints
(b) local buckling
Material Max e Max f
Steels 65 13
Aluminium alloys 44 10
GFRP and CFRP 39 9
Unreinforced polymers 12 5
Woods 8 3
Elastomers < 6 -
Other materials ..can calculate
Empirical Maxima
SCUT 2013 L