Section Modulus calculation and optimization

Hi,

Here I am submitting the Section modulus calculations, Moment of Inertia & Optimizations done in the Hood design.

Section modulus:

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members.

It is the ratio of Moment of Inertia (I) of the beam cross-section about the neutral axis to the distance (y_max) of extreme end from the neutral axis.

Procedure followed for the sketch section creation:

• Initially, I had hidden the hinges & striker on the hood assembly.
• Then created a datum plane on the middle curve of the outer panel by using % arc length.
• Then created a section of inner panel & outer panel using ‘intersection curves’ along z-axis.
• I have created the section along z-axis instead of x-axis because ‘can calculate the section modulus on larger section & the frontal crash on the hood of a car is more frequently happened on most of the cars than side.
• Then I projected the 3d curve created on the datum plane (which used to create intersection curves) using ‘project curve’.
• Then I connected the outermost sketches of the inner & outer panels & trimmed the inner sketches.
• And for the cutouts made in the inner panel, I have used ‘studio splines’ to close the curves.
• Now, I got the complete section, I’m going to calculate section modulus of the hood.

Section modulus calculation – Case 1:

• First, I have gone into the tool ‘section inertia analysis’ & selected the entire sketch.
• Then I got the maximum & minimum Moment of Inertia values.

S = I/y

where,

S = Section Modulus

I = Moment of Inertia

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

S = I_max/y

= 4.710/439.32

S = 0.010 kgm².

S = I_min/y

= 1.156/439.32

S = 0.002 kgm².

Section modulus calculation – Case 2:

• Then, I have modified the inner panel sketch by deleting the cutout sketches made by studio splines.
• And created an emboss like sketch by offsetting the curve to 3.5mm.
• Then, I have gone into the tool ‘section inertia analysis’ & selected the entire sketch.
• Then I got the maximum & minimum Moment of Inertia values.

S = I/y

Where ,

S = Section Modulus

I = Moment of Inertia

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

S = I_max/y

= 8.824/439.32

S = 0.0200 kgm².

S = I_min/y

= 2.123/439.32

S = 0.00484 kgm².

Section modulus calculation – Case 3:

• Then, I have modified the inner panel sketch by deleting the cutout sketches made by studio splines.
• And created an emboss like sketch by creating a new sketch.
• And offsetting the inner panel sketch to 0.2mm.
• Then, I have gone into the tool ‘section inertia analysis’ & selected the entire sketch.
• Then I got the maximum & minimum Moment of Inertia values.

S = I/y

Where ,

S = Section Modulus

I = Moment of Inertia

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

S = I_max/y

= 8.859/439.32

S = 0.0201 kgm².

S = I_min/y

= 2.148/439.32

S = 0.00488 kgm².

Thus, submitted the section modulus calculation & optimization of the hood assembly.

Thanks,

Deepak kumar A S.