Section Modulus calculation and optimization

SECTION MODULUS

Section modulus is defined as the ratio of area moment of inertia to the distance from the neutral axis to the extreme outer fiber.It is directly proportional to the moment of inertia, and which determines the strength of the body, section modulus increases,the strength of body increases.

section modulus S=I/Y

S= Section modulus

I= moment of inertia

Y= distance of extreme fibre from the neutral axis or intersection axis of the body.

unit is mm*4

so we can step to the challange,

we need to find the section modulus of hood design that i prepared before.

so open the hood design and we need to make a neutral axis of hood or intersecting axis.

so first create a datum plane at center and which should be planar to the intersecting axis and which is perpendicular to the viewing direction (from front)

so hide all the sketches,datums,assembly, and create a datum plane by the reference as centre curve of hood,by %cuve to 50%.

and after datum plane is created, we need a intersection curve through this datum plane, so create an intersecting curve from curves-curve intersect by selecting both outer panel face and inner panel face.

hence the datum and intersecting curve has formed,hide all the parts of hood for proper sketch view.

then the view is like this,

this intesecting has to go for the section inertia analysis so this should be sketched in a closed sketch.

so create a new sketch part and project this intersecting curve to new sketch part using 'project curves'.after in sketch part, join the curve to a closed structure by using 'spline studio' . trim the unwanted extended lines.

hence the curve is closed and it is ready to analyse the 'section inertia analysis' from analysis tool, by selectiong the entire curve and the corresponding plane.

hence the analysis result is shown below,

so from this analysis we got the values as shown.

we should concentrate on th minimum moment of inertia and improve its value to increase the strength of material and also the section modulus.

so from the first analysis,we god the result,

max moment of inertia =9.0454 mm*4

min moment of inertia =2.7248 mm*4

so we can find out the section modulus of thif section ,

section modulus ,S=I/Y

I=2.7248 mm*4

Y=879.4 mm(measured)

S=0.003097

So we found the section modulus of the hood asembly.

so after we should try to increase the section modulus of this same hood by changing some parameters.

so in this case we are trying to offset the inner panel depth by a 0.5mm downward hence the bending stress reduced and moment of inertia will increases slightly and hence section modulus of the new section also increases. it offer a good strength.

for that, we are offsetting the intersecting curve by 0.5mm and finish the sketch.so offset is done.

next we need to find the section modulus of th particular curve,for that curveshould be a closed curve.

for that we create a new sketch and project the expossed curve part to this new created sketch.and connect yhe lines if ther any gaps. and finish sketch.

this is the newly offseted curve,

so we can find 'section inertia analysis' of this curve. and we got a improved values for the moment of inertia and hence section modulus.

the analysis result is shown in below.

hence we can see that the values got improved slightly. this makes the section modulus a improvement as well.so it will improve the stenght of the hood.

and from this values we can calculate the section modulus by the equation S=I/Y

Section modulus, S=I/Y

I=2.7643 mm*4

Y= 879.4 mm

S=0.003143

So we can see the change in the values of section modulus of the hood when we changed its dimentions ,so we can improve the strenth of that hood by keeping maximum section modulus.

CONCLUTION

so we have calculated the section modulus of the hood for two different values of moment of inertia. and we increased the section modulus of hood when compared to the first hood model is that we offsetd the inne panel to 0.5mm outward. we can chnage this by different other methods also.