SECTION MODULUS CALCULATION

1 INTRODUCTION

SECTION MODULUS is the ratio of total moment resisted by the section to the stress in the extreme fiber. It gives an idea of how much load a structure can withstand if section modulus increases the moment of resistance increases, and hence its load-bearing capacity increases.

`S=I/y` (1)

S = section modulus, I = moment of inertia, y = distance between the neutral axis and end of the object.

2 PROCEDURE TO CALCULATE SECTION MODULUS

1. For the hood design, select the INTERSECTION CURVE command and take the cure in the o-y direction.
2. 
3. Edit the sketch and, using the PROJECT CURVE command, project the intersection curve onto the sketch plane.
4. Using the QUICK TRIM CURVE command, delete the inner curves of the outer and inner hood panel.
5. 
6. Connect the blank spaces between the outer and inner panels to form a closed curve.
7. In the analysis tab, select the SECTION INERTIA ANALYSIS command. The max. and min. MOI of the section is displayed.
8. 
9. In the sketch plane, select the two furthest points and draw the reference lines perpendicular to it. Using the RAPID DIMENSIONING command, find the dimension.
10. Half of the dimension is the ‘y.’
11. 
12. Calculate the section modulus using Eq. 1.
13. For the new section, offset the inner panel curve to 0.5 mm and follow the same procedure.
14. 

3 RESULTS AND DISCUSSION

Table 1: Section modulus calculation

Section	Imax (mm4)	Imin (mm4)	y (mm)	`S_max=I_max/y`(mm3)	`S_min=I_min/y`(mm3)
1	8.371761864×105	7.590243052×`10^3`	`488.3/2`= 244.15	3428.941	31.08844
2	8.349813354×105	7.82722995×`10^3`	244.15	3419.952	32.05910

From Table 1, it is observed that the section modulus of Section-2 is greater than the section modulus of section-1. So the section-2 is good as it has more section modulus and can withstand high stresses.

4 CONCLUSION

From the challenge, the calculation of section modulus for the different sections is studied using NX CAD. Tools like SECTION INERTIA is exposed.