- #1
Tiago Carita
- 15
- 1
- TL;DR Summary
- Small Scooter - How to calculate forces involved in a small fall and dimension the frame to withstand those forces.
Hi Guys, first things first I’m Tiago
-= Introduction to my Many questions =-
I work as Inventor in several projects of small scale, doing mechanisms, 3d printing, or building them cutting, welding, using my Lathe or sending to laser cut, bending or (when lucky) sending to a local CNC, I design basic electronics and can handle electric powertrains, batteries, drivers and controllers, I handle very well Inventor or similar CAD packages.
I Have no formal training in engineering (did 2 years of Pure Math in Portugal, hated it, and a few classes on computer science in UK, still grabbing classes in EDx when I can) but got lost in the start of my career to videogame production and 3D Modelling, but gradually came back to Machines and things move and do other stuff.
I’ve been doing eyeball engineering, and that is looking to similar stuff and using the volumes and materials to achieve the same stiffness or strength, it is ok when I’m prototyping but I started to get less comfortable with this approach, and several questions have been bothering me specially because I tried to calculate them but could never validate if it was right, most people I approached, mechanics and physics professionals, where pretty evasive…
I’ve been scooped to a fun project doing electric micro vehicles, so my job initially was to prototype a scooter inside the required constrains, I’ve created two working prototypes from structure to electronics, and now I’m tasked of the third prototype that must meet strength, durability of street tests. I can do basic stress/strength analysis in software but more than that I need to know the Forces involved on those tests and after a couple of months I got courage to come here…
-= End of Small Talk =-
My scooter is a 3-wheeler with 2 in wheel Motors at the front of the scooter, it does not Tilt but has springs on each wheel.
The scooter Mass is 15 kg (it should be lower in production)
And it can support adults up to 100 Kg.
The idea is that maybe a user could just fall from a Curb to the road and this would at least keep the scooter intact, the largest curbs are around 15cm with a maximum 25cm.
So I did some research and found that I could calculate the Force of that fall using the following:
F = m.g.h
m = scoter mass + user mass = 115kg
g = 9,81m/s
h=0,25m
F = 282 Kgf
I understand that this is very simplistic and its probably the F upon reaching to the ground and nothing to do with the rest of the crash process.
My scooter has shocks and rubber to absorb 3cms (I have no idea how to dimension the strength of the shocks as as to resist the impact of r even to travel around besides the Mass divided by the 3 points of road contact.
And the person on that impact is not rigid on top of the scooter and can bend his/her Knees 15cm to absorb the shock.
And I know it can get a lot more dense, but I really don’t know what to pursuit and learn to Understand what are the maximum forced distributed to structure or even (another entirely different discipline probably.
Can you guys help me out, point me out to some learning material on this, Covid-19 has given me time to learn
Thank You,
Tiago Carita
PS - Sorry it got a bit chotic in the end has I understood the gap between what iIknow and what I need to learn...
-= Introduction to my Many questions =-
I work as Inventor in several projects of small scale, doing mechanisms, 3d printing, or building them cutting, welding, using my Lathe or sending to laser cut, bending or (when lucky) sending to a local CNC, I design basic electronics and can handle electric powertrains, batteries, drivers and controllers, I handle very well Inventor or similar CAD packages.
I Have no formal training in engineering (did 2 years of Pure Math in Portugal, hated it, and a few classes on computer science in UK, still grabbing classes in EDx when I can) but got lost in the start of my career to videogame production and 3D Modelling, but gradually came back to Machines and things move and do other stuff.
I’ve been doing eyeball engineering, and that is looking to similar stuff and using the volumes and materials to achieve the same stiffness or strength, it is ok when I’m prototyping but I started to get less comfortable with this approach, and several questions have been bothering me specially because I tried to calculate them but could never validate if it was right, most people I approached, mechanics and physics professionals, where pretty evasive…
I’ve been scooped to a fun project doing electric micro vehicles, so my job initially was to prototype a scooter inside the required constrains, I’ve created two working prototypes from structure to electronics, and now I’m tasked of the third prototype that must meet strength, durability of street tests. I can do basic stress/strength analysis in software but more than that I need to know the Forces involved on those tests and after a couple of months I got courage to come here…
-= End of Small Talk =-
My scooter is a 3-wheeler with 2 in wheel Motors at the front of the scooter, it does not Tilt but has springs on each wheel.
The scooter Mass is 15 kg (it should be lower in production)
And it can support adults up to 100 Kg.
The idea is that maybe a user could just fall from a Curb to the road and this would at least keep the scooter intact, the largest curbs are around 15cm with a maximum 25cm.
So I did some research and found that I could calculate the Force of that fall using the following:
F = m.g.h
m = scoter mass + user mass = 115kg
g = 9,81m/s
h=0,25m
F = 282 Kgf
I understand that this is very simplistic and its probably the F upon reaching to the ground and nothing to do with the rest of the crash process.
My scooter has shocks and rubber to absorb 3cms (I have no idea how to dimension the strength of the shocks as as to resist the impact of r even to travel around besides the Mass divided by the 3 points of road contact.
And the person on that impact is not rigid on top of the scooter and can bend his/her Knees 15cm to absorb the shock.
And I know it can get a lot more dense, but I really don’t know what to pursuit and learn to Understand what are the maximum forced distributed to structure or even (another entirely different discipline probably.
Can you guys help me out, point me out to some learning material on this, Covid-19 has given me time to learn

Thank You,
Tiago Carita
PS - Sorry it got a bit chotic in the end has I understood the gap between what iIknow and what I need to learn...