Section Modulus calculation and optimization

Section Modulus calculation and optimization:-

Introduction-

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. Section modulus is a direct measure of strength of any sectional area of an object about an reference axis. Equations for the section modulus of common shapes are given below-

S = I/y

S = Section Modulus

I = Moment of Inertia

y = distance between the neutral axis and the extreme end of the object

• Moment of inertia is nothing but offering resistance against of moment, bending or twisting. If we applied any external load on the body, how much resistance its offering to tend to deform.
• If we vary neutral axis towards positive or negative side the overall strength of the body will decrease, because when neutral axis line lies on the middle of the section only have higher strength at particular point. Here, y value was inversely proportional to section modulus.

Now i going to calculate the strength of an hood panel.

Moment of inertia was calculated by using NX-software as below-

Imax= 4.692614785x10^6 mm^4

Imin= 1.484323332x10^4 mm^4

Total length of 'Y' value was 880.374 mm

At neutral axis 'Y' value= Y/2= 880.374/2= 440.187 mm

1) Section modulus (S)= 4.692614785x10^6/440.187= 1.06605x10^4 mm^3

2) Section modulus (S)= 1.484323332x10^4/440.187= 0.0337x10^3 mm^3

Hence, strength of a hood varies from 0.0337x10^3 mm^3 to 1.06605x10^4 mm^3

Another option trail done by offsetting inner panel curve outside by 1mm, so that increase in cross sectional area, NX results shown below-

Imax= 4.706402091x10^6 mm^4

Imin= 1.555890504x10^4 mm^4

Total length of 'Y' value was 880.374 mm

At neutral axis 'Y' value= Y/2= 880.374/2= 440.187 mm

1) Section modulus (S)= 4.706402091x10^6/440.187= 1.06918x10^4 mm^3

2) Section modulus (S)= 1.555890504x10^4/440.187= 0.035x10^3 mm^3

Hence, strength of a hood varies from 0.035x10^3 mm^3 to 1.06918x10^4 mm^3

So Newton's 1st law also says that, if higher the mass, the force required to move the object is also high due to offering more resistance in order to move the object, this resistance we called it is a Moment of Inertia.

The strength of material also depends upon the composition of material, thickness & cross sectional area of an object.

Conclusion-

The strength of material is directly proportional to the moment of inertia, hence increase in sectional area there is have increase in overall mass of an object, hence have increase in strength.