Section Modulus calculation and optimization

Section modulus calculation and optimization of hood

In this segment we are going to calculate and try to optimize the section modulus of the hood for better bending strength of the hood.

First of all, lets look at how the Section moment of inertia can be achieved for a 3D drawing in NX.

First, Create a Datum plane on the along the Y axis at the midpoint of the hood.

Then Create an intersection curve on the same and select the inner as well as outer hood.

Now unhide all solid bodies project the intersection curve into a sketch and Find the section inertia in command search.

Perform the analysis.

We will get the section moment of inertia analysis.

Consider the min value as we want to test the hood for failure.

The first time, Moment of inertia calculated was a as followed,

Now we need to optimize this such that we get a higher value for moment of inertia.

What we can do is we can offset the Inner hood by 1 mm and increase the area and see the results.

After 1mm offset, the results were as follows -

Minimum moment of inertia increased by a value of 0.12 while the section modulus increased by a value of 290mm3.

Hence, the Section modulus was optimized to a better value.

As Bending moment is directly proportional to Section Modulus and section modulus is directly proportion to Moment of inertia, an increase in moment of inertia will cause an increase in the bending moment of the component and hence increase the strength of the hood.

Refer to the following table to note the changes made which caused an increase in the moment of inertia and hence section modulus.

Conclusion

1. In the first case, we got a value of 3175.327mm3 as the section modulus.
2. Increase in the offset between inner and outer hood caused and in increase in Y as well as the section modulus value increased to about 3464.38mm3
3. Hence, the Section modulus and hence the Bending moment was optimized.