Hello
I'm still a beginner when it comes to simulation and I want to do a static study on the chassis of my robot to make sure it's robust at the beginning there are pink and green dots, I didn't understand what the green dots are.
My second question is that I find it difficult to define fixed geometry.
Thank you in advance for your help .
Good evening Senda
The pink or green dots show correspond to the connection nodes and it also shows that you want to do a simulation in "beam" mode.
In short
- Pink dot (magenta) connections connect two or more beam members
- the green dot connections are connected to only one member and therefore disconnected (not relational) from the other beams.
I don't recommend you to do a beam simulation but rather do a shell (volume) simulation. It's hard to explain why because it's quite technical.
I have set myself the following bestial rule "any profile (IPN UPN, Tube or square or rectangular tube) that is less than 300 mm I treat it as a shell".
You will also see the deformations of your different profiles much better.
A little tip When we do RDM, we talk about a beam even if it is a small IPN. In solidworks, the beam mode is not used, for example, for mechanically welded frames
Kind regards
Hello
In theory, as this frame is only made up of members, a beam simulation would be quite suitable. However, provided that certain criteria are met. In particular, all the neutral fibers of the same plane must intersect (so no green dots). On the other hand, the beam approximation is only valid if the cross-section is small in relation to the length. Generally, it is considered that the length must be at least 4 times the cross-section (so indeed, an IPE 100 of 300 mm long does not meet this criterion for example).
A simplification in the shell makes it possible to free yourself from these constraints. Elements such as sheet metal (floor, reinforcements, etc.) can also be integrated into the model. However, this is not yet a volume study as such, as the thicknesses are replaced by surfaces only.
Hello chamade
Thank you for these clarifications and your remark about the volume. Indeed, I expressed myself badly between shell and volume elements because it seemed to me that there were profiles that met these criteria. Anyway, thank you for your remark.
Continue! I think above all that in the model there are connection errors due certainly to a play or even excessive play.
Indeed, some links appear in green when they should be in magenta (if I understand correctly the image which is not very large).
The diameter of the sphere can be changed among other things to improve the connection (in connection group (treat as a connection for a clearance less than)
It seems to be an assembly of an aluminum profile like Bosch Rexroth
It also seems to me that the plates for fixing the frame in the ground or fixing on another unknown element are missing. There is also a lack of reinforcement gussets, or even bracing (because of the offset loads)
Brief! Brief!
should post us its building so that we can give better information because I feel that there will be other questions: during the networking and execution of the study. As it is a frame for a robot, it means that there will be different remote loads that are not in the frame.
I feel like we're going to have a lot of fun :-)
Hello, Thank you for your answers.
In fact I made two mechanically welded structures in stainless steel:
1- The profiles are 202*20*1.2 square tubes
2-20*1.2 angle irons
That's why there are green dots that I think present the connection between the two structures.
My robot is mobile, it has two-wheel drive and a roller.
Hello Sendahajamor
202 mm is very small, isn't it??? It's a typo! huh says! 20x20x1.2
As a curiosity:
- what is the weight of your robot
- What is the load weight at the end of the arm.
- What is the offset in Cm of the load when the arm is at its maximum extended position (the furthest from the center of the robot's base)
- Where are your wheels placed (we can deduce this from the shape of your frame)
Also tell us if we can close your topic :-)
Enjoy WE
Hello
Haha yes a typo 20 and not 202.
The weight of the robot 40Kg, two drive wheels behind and a roller in front.
No, it is not fenced
Hello Sendahajamor
Great :-) hihihi
Good! Have you taken into account the remote load at the end of the robot's arm because with the leverage it changes the result of the simulation quite a bit. The centering of the CG of the robot with the arm fully folded is the basis of the simu.
I'm not even talking about the risk of tipping over the tripod :-)
How can we help you since your post is not closed.
Kind regards