Optimizing and calculation of section modulus of the car hood

Objective

This project aims to find the section modulus of the front hood and optimize it to achieve the best results.

Introduction

Section modulus is a geometric property for a given cross-section used in the design of beams and flexural members. Other geometric properties used in the design include an area for tension and shear, the radius of gyration for compression, and the moment of inertia and polar moment of inertia for stiffness. Any relationship between these properties is highly dependent on the shape in question. Equations for the section moduli of common shapes are given below. These are two types of section moduli, the elastic section modulus, and the plastic section modulus. The section moduli of different profiles can also be found as numerical values for common profiles in tables listing properties of such.

The elastic section modulus is defined as S = I/y

Where,

S = Section modulus

I = Moment of inertia

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

It is also often used to determine the yield moment (M y) such that

M y = S X σ _y

Where

σ _y = yield strength of the material

M _y = yield moment

Ʃ _y for stainless steel is 520MPA

y = 438.4065 mm

Calculation of the section modulus :

BEFORE OPTIMIZATION :

We can get the results like max and mini moment of inertia, principal length, section length and area using the section inertia analysis command

Moment of inertia (max) = 4.86086184*10⁶ (mm⁴)

Moment of inertial (min) = 1.42511269*10⁴(mm⁴)

Here S = I/y

For MOI (max)

S = 4.86086184*10⁶(mm⁴)/438.4065mm

S = 11087.56791mm³

For MOI (min) :

S = 1.42511269*10⁴(mm⁴)/438.4065mm

S = 32.50665 mm³

Here

M _y = S X σ _y

M _y = 32.50665 x 520*10⁶ N/mm²

M _y = 16903*10⁶ Nmm

After Optimization :

For getting the better results hood inner panel is offseted to 1.0 mm

Moment of inertia (max) = 4.859704298 x 10⁶ mm⁴

Moment of inertial (min) = 1.466998662 x 10⁴ mm⁴

Here S = I/y

For MOI (max)

S = 4.859704298x 10⁶ mm⁴/438.4065mm

S = 11084.92757

For MOI (min) :

S =1.466998662 x 10⁴ mm⁴/438.4065mm

S =33.46206459 mm

Here

M _y = S X σ _y

M _y = 33.46206459 x 520 x10⁶ N/mm²

M _y = 17400 x 10⁶ N/ mm

Conclusion :

Thus, the section modulus of the front hood was calculated and compared with the optimized value for finding a better result. From this report, we can conclude that by increasing the sectional area of the hood the strength and bending moment of the hood also increases.