Section Modulus calculation and optimization

SECTION MODULUS CALCULATION AND OPTIMIZATION

OBJECTIVE:

The main objective of this project is to learn the basic tools, commands, and the calculation and optimization of the Section Modulus of using Siemens NX CAD.

The objectives of this project are as follows:

•  To understand and learn the basic Graphical User Interface (GUI) of Siemens NX CAD
• To understand and learn the Calculation and Optimization of the Section Modulus of Hood Design Using Siemens NX CAD.

QUESTION

Use the Section from your Hood design and calculate the section modulus using the formula S = I/y

S = Section Modulus

I = Moment of Inertia

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

Come up with a new section that has improved the section modulus of the previous section and mention what change you made that has increased the strength.

What is Section Modulus?

•  The ratio of total moment resisted by the section to the stress in the extreme fiber.
• It gives us an idea about how much load the given structure can take.
•  if the section modulus increases the moment of resistance increases and hence its load-bearing capacity.

There are two types of section modulus:

  • Elastic section modulus(S).

  • Plastic section modulus(Z).

Significance of Section Modulus:

•   Section modulus is an important factor for designing beams and flexural members. The higher the section modulus, the higher will be the resistance to bending.
•   Easier to calculate strength and stresses in beams.
•   If two beams are made of the same material and the section modulus of two beams are being compared and vice versa, the beam with a larger section modulus will be tougher and more capable to withstand larger loads.

SECTION MODULUS CALCULATION AND OPTIMIZATION

To calculate section modulus the below section was considered which has be to parallel to x-coordinate. We Create an intersection Curve with the help of the plane consider both the Outer & Inner panels of the hood.

After the proper intersection curve has been made, We Use the Section Inertia Analysis tool and also show the distance from the neutral axis to the most extreme end.

1. Initial Hood section modulus Calculation:

Moment of Inertia (MOI), Imax = 4.834785190 x 10^6 [mm^4]

                                              = 4834785.190 [mm^4]

Moment of Inertia (MOI), Imin = 1.463443833 x 10^5 [mm^4]

                                              = 146344.3833  [mm^4]

Distance between the neutral axis and the extreme end of the object, y = 881.1 mm / 2 = 440.55 mm

Section Modulus, S = Moment of Inertia (MOI), I/ Distance between the neutral axis and the extreme end of the object (y)

S = I/y

For Maximum (MOI), S=(4834785.190 )/(440.55 )

S= 10,974.4301 mm^3

For Minimum (MOI), S=(146344.3833) / (440.55 )

S=332.1856 mm^3

2. Optimized Hood section modulus Calculation:

section modulus and inertia are directly proportional to each other

If we increase the section modulus, we can increase the capability of the hood to withstand higher inertia. since the cross-section value is more

I have increased the hood inner panel with an offset of 2.5mm to increase the section modulus.

Moment of Inertia (MOI), Imax = 4.809202167 x 10^6 [mm^4]

                                              = 4809202.167 [mm^4]

Moment of Inertia (MOI), Imin = 1.590781581 x 10^5 [mm^4]

                                              = 159078.1581  [mm^4]

Distance between the neutral axis and the extreme end of the object, y = 881.1 mm / 2 = 440.55 mm

Section Modulus, S = Moment of Inertia (MOI), I/ Distance between the neutral axis and the extreme end of the object (y)

S = I/y

For Maximum (MOI), S=(4809202.167 )/(440.55 )

S= 10,916.359 mm^3

For Minimum (MOI), S=(159078.1581) / (440.55 )

S= 361.08990 mm^3

Comparision Table 

• From the comparison table, we have achieved the section modulus result. 
• for a maximum moment of inertia, the section modulus value decreases after optimization but for a minimum moment of inertia the value increases.
• The minimum limit of deformation of the hood needs to be analyzed so we'll go with the minimum moment of inertia.
• After increasing the sectional area to 2.5 mm from the original the Section Modulus value increased which
• shows that the load-carrying capacity and resistance of the hood will also be increased simultaneously.

Conclusion:

Thus the section modulus of the Front Hood of a car was calculated and compared with the optimized hood and found the better result. Hence we can conclude that when the sectional area of the hood increases the stiffness and resistance of the hood strength will also be increased.