Stabilizer Leg Suspension

Actually this was my first project of all that can be seen in the blog. Although I have done small projects and designs and 3D models before, this was my first serious and professional project, and the one which made me start in this world.

Novatives Original Design

The project consisted in a competition or a tender in the website of Grab Cad, where one company (Novative) wanted some help finishing the design of a Hand Truck. The Hand truck was prepare to load weights of 700 Lb, and using one stabilizer Leg, the workers could move the weights without problems for the factory.

The main problem was the Suspension of the Stabilizer Leg, which had to resist the weight of the load without brake. They thought using one spring and a Shock suspensions that it wasn't enought; that's why they were asking for help and creating this contest.

The features of the original design of Novative were the following:

The first and second images is the static anaylisis of the leg suspension, while the third are the dimensions and the value of all the parameters of their problem.

After give all the parameters, they uploaded their model (handtruck and leg suspension) so we could see them in a CAD software.

the handtruck + leg suspension opened in catia

Original leg stabilizer

here in pdf: https://mega.co.nz/#!KRhADQia!43RnBr_54sOwXRuIrD-hjFvom9tZUl6xz57lO4BpWgo

After take a look, analyse and done some operations, it was clear that the design they did wasn't able to resiste the weight and forces they wanted. specially with a shock spring that can resit 1200 Lb of force.

To finish the specifications, Novative comented that they wanted to maintanin as many pieces as the original, which meaned not modifying the design in excess.

My Design

The first thing was the operations. How is it possible that the design can resist that weight. weight that could be increased up to 900 Lb!!

The three options were the following:

-increase the angle between the shoch spring suspension and the stinger wheelleg welment.

-use two springs, one in the original position and add a second one that can take part or half of the force weigh

-A complete new design

The third option is the last of the three, because it could be used just in case the other two weren't possible or compatible with what the client wanted.

So I started with the first one, engaging the shock suspension in the rear part of the leg welmentl and in an upper place of the handtruck. This configuration started to be to complicated; adding many new pieces and probably having many problems when I would do the stress analysis.

Then, I decided to focus in the two springs shock suspension option. I could maintanin the leg welment (without modificatons) and I would just have to create a new braket that substitute the two semi-brakets of the original design.


With calculations done, I determined that the angles of the springs are 45º and 61º, as it can be seen in the folowing image.

sheet with some operations and the angles of the configuration selected

After the calculations, the two shock springs suspensions have to resist a 1200Lb force compression (the maximum permited) and the force of the conexion between the braket casign and the leg weldment is 1463.72Lb in the opposite direction.

The design has to be closed for when h rear leg is not necessary, so I added some pockets or guides that the pins could follow and let the system close.

Image of the hadntruck+rear strider  in catia (springs removed)

Image of the handtruck+rear strider wheel in close position

Due to the high values of the force, and the design, I had to added some reinforced parts in both sdes, in the rear and at the botton, so the braket casign could resist them without braking, deformating to much or cross the plastic point.

The material selected was a steel with an E of 2e9 and a poisson ratio of 0.30.

Analysis in Abaqus cae of the braket casign stress without reinforcements

Analysis in Abaqus cae of the braket casing stress with the reinforcements

Altough is not 100% finished, the improvemets are small, and the configuration was ready to a client analysis.

My design was finally the 10 best, and altohugh I didn't get the best prize, I got one lower and the satisfaction of finishing in a good position being my first design in the professional world of the Cad engineering.

https://grabcad.com/challenges/stabilizer-leg-suspension-challenge/results

As it can be seen in this link, my design had the 10th best punctuation.

Flying car challenge

As part of a Grabcad challenge, I decided to be invlolved in a design of a flying car. The project or tender was promoved by Terrafugia, which wanted to see new designs in order to make the image of the new terrafugia TX-1 better.

My design was made using Catia V5, and the renders using KeyShot.

The characteristics of the design were the following:

Lift Body TF-X Car

This design is based in the idea of being able to fly. A flying car is a complex vehicle, because it is difficult to make a secure model that is able to go in a highway an at the same time can fly.

The other restrictions like the vertical takeoff and landing make it even much difficult.

For that reason, the basic design of this car is the body of the car can generate the enough lift force, so the wing does not have to be too long.

In a conventional plane, the wings are the heart of the plane, because are the only part that generate the lift force. However, the wings are almost always fixed, except in the ship based planes. Even in these cases, the wings that can be folded are design for being park in less space.

With a lift body, the wing can be reduced to the minimum, and can be easier foldable. The idea is based in some projects that improved the idea of the lift body planes like the X-24

Body

The body is made using two different airfoils, the Goettingen 561, and the 518. Both were chosen due to their flat lower side, that better to adapt in a car, and was more similar to the original drawing imagined.

These airfoils also were selected because have a really god lift features, a characteristic that this flying car will need. Being a slow plane, the lift coefficient of the airfoil is very important.

The body is designed for 4 people, two in the front seats, and to in the back seats. However, both pair of seats is more separated than in normal cars. The reason, is because between them is the place for the wings, and since the wings have to resist a good part of the weight if the car, need thickness area for the structure.

The doors are completely transparent so the passengers can enjoy the flight. The doors are opened and closed in a similar way to the Mercedes 300SL.

The body has two areas grooved so the wings can fit in the car configuration. This transition (the grooved area) has to be designed very carefully, so will not increase too much the parasite drag of the car.

The body has a lot of space to install the batteries (probably in the bottom of the body) and for the motors.

The wing

The wing is straight and rectangular. The reason for being straight is obviously the only configuration for a plane that won’t go in transonic or close to supersonic speeds.

The reason for the rectangular configuration is because it is the easiest and cheapest configuration. An elliptical or trapezoidal wing would cause more problems manufacturing.

Although the rectangular wing has more induced drag than the other two, it has more surface than the other both options, what give more lift coefficient, especially for a plane with such a less aspect ratio.  At the same time is the safest wing, because it can be controlled easier even if the plane has stall problems.

The elliptical configuration is much less safe, so I reject it, even if has the best aerodynamic features.

 The airfoil used was a NACA 4415, although in a more advanced analysis other airfoil can replaced it; especially a common body/wing airfoil.

The wings can be folded turning 90º in a horizontal axis, in a similar way to the carrier ship fighters like the F-18 Hornet.

Stabilizers

Two stabilizers inclined are installed in the rear of the car before the Duct fan. Even in high angle of attack conditions, the duct fan will sure that the air will pass through the stabilizers. The localization is provisional, so it could change after some aerodynamic analysis.

Propellers

The propellers used are a simple example, and can be changed. The simple model has 3 blades, although the number of blades cannot be chosen until some calculations are done.

The propellers can rotate 90º or even more so the car can takeoff/land in vertical.

Duct Fan

The Duct fan is going to propel the car through the air, it is installed in the back of the car, with no many interaction so the air can go through it with less problem.

One idea that cannot be said now (until some calculations) is that the position of the duct fan could help the air to be laminar for more time when it goes through the body of the car. This would increase the aerodynamic features; but it depends on many factors, and should be analyses with determination using a CFD software and a wind-tunnel.

The rear lights of the car are installed in the duct fan cage, so the other cars can have an idea of it height at night.

Other improvements and options

The first improvement is to install a solar panel on the roof of the car, that will increase the energy of the batteries, and then the range of the model.

The other improve is the configuration of the propels. The option is to use a propeller to propels the model, and two or four duct fan to lift it. The propeller has more efficiency propels a plane in different envelope of a flight.

On the other side, the duct fan is better for smaller speeds abut high rpm, with higher efficiency for vertical taking off and landing

Also I made a little and not so good looking video jajaja. The software used was Catia, which is not the best making renders and video renders. I am still improving in Keyshot to learn how to make video renders.

As a conclusion, I want to say that this design is based in the lift body idea, so the entire design has its limitations. 

Rolls Royce 250

This is a request of an aerospace engineer that wanted a 3D print of a turboengine RR250. The model was developed using the software Catia V5, and the renders with Keyshot 4