Posted by Scott Ellis (216.87.95.64) on May 04, 2002 at 20:44:16:
In Reply to: computer aided design posted by James Barton on May 04, 2002 at 11:34:07:
Hi James, thanks for your post.
You are absolutely right. I have looked for such a thing and as far as I know there is none available. I am all fired up to write a Java based CAD/modeling application targeted specifically for PM enthusiasts. There are so many times that I have wanted one myself. Plus, I am a software engineer by trade so this stuff is my bread and butter. ;)
Creating a truly useful software application involves following a careful plan. The first step is gathering requirements, specifically "use cases."
I would like to invite the entire Bessler/PM community to join the effort in producing this software by spending a little time thinking about something they would like the software to do. Write it down in the form of a use case and send it to me. I will collect them and begin the high level architecture and design of the system. Later, I will implement the functionality based on the use cases.
Use cases are simple, high level outlines of how a user might interact with the program. Here are 3 off the top of my head, to give you an idea:
Use Case 1
Goal: create a model of a spinning disk.
1. select object type "disk"
2. specify diameter, weight, material, etc.
3. create the disk and place the disk in the work area
4. create a speed bearing and place it in the center of the disk
5. set the coefficient of friction of the bearing to N units
6. create a fixed rod and place the bearing on it
7. spin the disk by applying force X at location Y for duration Z.
8. watch the disk respond to the force by spinning up then slowing down to a stop. View real time reports such as rpm, kinetic energy, and moment of inertia.
Use Case 2
Goal: add a weighted pendulum to the disk
1. select object type "pendulum"
2. specify the pendulum type, 1-dim, 2-dim, spring, etc.
3. specify arm length, weight, coefficient of friction, etc.
4. attach the pendulum to the disk at point X, Y, Z
5. spin the disk by applying force X at location Y for duration Z.
6. watch as the disk spins up, the pendulum swings, and the whole thing slowly comes to a stop
Use case 3
Goal: add a spring
1. choose object type "spring"
2. select parameters such a size and spring force
3. attach one end of the spring to the pendulum arm, the other to the disk
4. spin the disk and see how it behaves
This is by no means going to be an easy project. But hopefully we can reuse a LOT of work out there that has already been done. I have seen lots of programs that do little pieces of the problem, but none that put it all together.
What do you all think?
Best,
Scott
:
: Can anyone recommend a freeware cad program with gravity, friction etc variables? If some one could write a simple/flexible cad package for gravity wheels it would have amazing consequences.