# 3D Static Analysis of a Automotive Suspension

1. Dec 4, 2015

### Leon666

Hello, my name is Leon and I attend to a Mechanical Engineering College.
(I'm sorry for any grammar mistakes, English is not my first language)

I'm trying to calculate the reactions of a Formula SAE car's suspension to the chassis, but I'm getting some strange answers. I hope someone here can help me.

1. The problem statement, all variables and given/known data
Here's the layout of the suspension, and free body diagram:
(Every connection is spherical, i.e, no torque is transmitted. Except the connection of point 0 to member 6-7)

And the coordinates of each point:

2. Relevant equations
Next thing I did was to try and set up the equations of a static analysis.
The first 3 equations are setting up the know forces of braking (Fx0), lateral grip (Fy0) and weight (Fz0).
The rest of the equations are simple forces and torques sum.

But here's the odd thing, If I take the last sum of torques equation (which is Mxx around 5) and replace it by the equation of sum of torques Myy around 5 I get diferent answers... Am I overlooking some basic principle? I've checked and rechecked for math errors about 10 times now, without luck.

3. The attempt at a solution
Here's the solution I'm getting from this system of equations (I've used excel to solve it):

I have attached the excel sheet in case anyone wants to take a look.

#### Attached Files:

• ###### Suspensão - Análise Estática de Cargas - No macros.xlsx
File size:
417.2 KB
Views:
27
Last edited: Dec 4, 2015
2. Dec 9, 2015