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 flexural members.It is also referred to as the polar modulus or the Torsional sectional modulus.Other geometric properties used in design include area for tension and shear,radius of gyration for compression, and moment of inertia and polar moment of inertia for stiffness.Any relationship between these properties is highly dependent onthe shape in question.Equations for the section moduli of common shapes are given below.There are two types of section moduli,the elastic section modulus and the plastic section modulus.
S=I/Y
Here,
S=Section modulus,
I=Moment of Inertia,
Y=Distance between nuetral axis and extreme end of the object.
It gives us an idea about how much load a given structure can take.Increase in section modulus increases the load bearing capacity of the object.The following calculations of centre of gravity,maximum and minimum moment of inertia,sectional length and sectional area of given model are performed using Section inertia analysis in NX CAD.
BEFORE OPTIMIZATION
For section modulus calculation we take the hood assembly which we designed and create an intersection curve.Those are hood assembly outer panel upper curve and inner panel lower curve.Project the intersection curve and close off any gaps.Then use the tool section inertia analysis to calculate the moment of inertia and then measure the distance from one end of the section to the other end and divide it by 2 to calculate Y.
From the section inertia analysis we get the above data,
I=5.664718028e+03[mm^4] =5664.718mm^4
Y=493.4151/2 =246.70mm
Therefore,
S=I/Y=5664.71/246.70=22.96mm^3
AFTER OPTIMIZATION
For optimizing the section,we offset the inner panel curve by 1mm.Then we close of the open boundaries and apply the section inertia analysis tool.The following data is we get in after section modulus optimization.
There are,
I=6.095869778e+03[mm^4]=6095.869mm^4
Y=493.4151/2 =246.70mm
Therefore,
S=I/Y=6095.869/246.70=24.709mm^3
CONCLUSION
By comparing the cases before and after optimization,where in the section modulus after optimization is greater than the one before optimization.when the area of cross is increases,the section modulus of the given body also increases.to improve the geometry of the carry more bending load,the section modulus can be improved by increasing the area moment of inertia of a given section.