Section Modulus calculation and optimization
Section Modulus Calculation and Optimization
Section modulus
Section modulus is a geometric property for a given cross-section used in the design of beams or any component with flexural properties. Other geometric properties used in the design include an area for tension and shear, the radius of gyration for compression, and moment of inertia and polar moment of inertia for stiffness.
Types
- Elastic section modulus
- Plastic section modulus
Formulas
Elastic Section modulus
S = I/y
S - Elastic modulus
I - Area moment of inertia
Y - Distance between the center axis and the endpoint of the component.
Plastic Section modulus
Zp = AcYc + AtYt
Z – Plastic modulus.
Ac or At – Areas of cross-sections.
Yc or Yt – Distance from the local centroids of the two areas.
For calculating Section modulus for my hood design, I will be using the Elastic section modulus formulae because it is the general formula for all section modulus calculations.
Section Modulus calculation of the Hood Design:
Case 1: Initial Hood Design.
Area Moment of Inertia: I(min)
MOI(min): 0.000133354 mm^4
Distance Y: 485.0970mm
so, S=I/Y
S= 0.000133354 mm^4/485.0970mm
S=2.749017206867905e-7 mm^3
Case 2: Optimized Hood Design.
Area Moment of Inertia: I(min)
MOI(min): 0.000162443 mm^4
Changes made: I increased the distance between the outer hood panel & the inner hood panel 0.5 mm.
Distance Y: 485.0970mm
so, S=I/Y
S= 0.000162443 mm^4/485.0970mm
S= 3.348670472091149e-7 mm^3
Different Sections and the values:
Distance=300
Section=4
Distance=500
Section=2
CONCLUSION:
Different sections, as shown above, were tried in order to achieve a higher moment of inertia. It is observed that increasing the gap between the inner and outer panels has resulted in decreasing bending moments. No significant change in section modulus is observed just by increasing the gap between the panels. On the contrary, if we tend to add more geometric features to the master section resulted in a drastic increase in section modulus. Hence it is best to add more geometric features to the master section to improve the stiffness of a section. However, this could result in an increase in manufacturing cost.