Structural Integrity of Competition Defenses?

[Schnabel]

Originally Posted by 3175student17

At Southfield, one drawbridge split in two through normal game play...

No it didn't.

[CJ_Elliott]

I remember at Northern Lights the portcullis being sent up so hard that a bar that I didn't even know was there came onto the field.

[logank013]

Originally Posted by Schnabel

No it didn't.

Did it not split? or was it beyond normal gameplay. If it was beyond normal gameplay, what causes it to break?

[spydan]

Originally Posted by CJ_Elliott

I remember at Northern Lights the portcullis being sent up so hard that a bar that I didn't even know was there came onto the field.

There is a bar zip tied onto the top bar of the portcullis to weigh it down and offset the strength of the springs.

[Anthony Galea]

Originally Posted by Schnabel

No it didn't.

https://youtu.be/_lu2J4Cp7dU?t=1m16s

Is that not normal gameplay? Or is the word split what is wrong?

[cadandcookies]

Originally Posted by Sperkowsky

The actual drawbridge material is very resistant to breaking (Lexan) you can bend it at 180 degree angle and it still wouldn't crack. The reason they have fallen apart is because of the harsh angle on the hinge causing the lexan to break free.

That's not entirely accurate-- here's a couple of pictures from the break at Northern Lights. As you can see, it's very clearly a break-- not the polycarbonate 'breaking free.'

Edit: I had the wrong context when I responded to this, and I don't think this is highly relevant to the post I quoted. It is relevant to the general discussion of defense durability though so I'm leaving it here.

[northstardon]

Originally Posted by Jon Stratis

In Duluth, we had the same low bar fabric issues as everyone else, but making replacements out of bumper fabric worked perfectly fine after we got them on the field. We had one drawbridge break - the lexan broke clean off at the base, and didn't even slow the robot down. Other than a few busted zip ties, that was really about it!

Speaking of Duluth (while apologizing for going off-topic for a moment)...

Congratulations, Woodie Flowers Finalist. If your nomination didn't mention all of the support you also provide here on CD, it should have.

[Schnabel]

Originally Posted by 3175student17

https://youtu.be/_lu2J4Cp7dU?t=1m16s

Is that not normal gameplay? Or is the word split what is wrong?

A split implies the lexan actually cracked. What you are seeing is the drawbridge acting as designed. I'm pretty sure having teams deal with the two pieces of lexan was not an intentional added challenge, it's just how the drawbridge is designed.

[jweston]

Based on what I've seen so far, aside from the low bar flaps being torn up and the cheval de frise at Palmetto, the major structures are generally not prone to severe damage. There are lot of scuffs of course and they become dislodged, resulting in match halts or complete match replays. These field elements are remarkably durable considering the amount of force and sharp edges they regularly endure. At Waterbury, there was a robot that accidentally hung from the high goal (yes, I know, a foul and doesn't count as scaling). The tower didn't seem to be any worse for wear from it.

[arc25565]

At the Greater Toronto central regional, the sally port lost the lexan on on the supports several times. That defense really got torn up. It will be interesting to see the state of the defenses in the later regionals.

[MarcD79]

In Waterbury we started seeing problems with the pegboard s-hooks that we were told to use, due to the tight clearance of the drilled holes for the pins designated for that purpose, aka they wouldn't push in. We saw it mostly on the Rock wall, then more on the other defenses after they were switched into a spot vacated by the Rock wall. Those robots that didn't adjust their designs to accommodate the rock wall height were the ones that slammed up & over. Most others with Pneumatic tires flowed over. There was a lot of force generated to cause the damages. Except for the mounting design, I thought the defenses were built fairly well. By Sunday morning we had destroyed all the s-hooks & switched back to the pins, which now fit (loosely) into the holes. Now the rock wall started jumping up. We finally gaff-taped across the front/back of the defense to the floor mount & that worked. This is not a solution, just a band-aid.
The low goal curtain was damaged many time & we taped them back together. We got more curtains made up from the school sewing class with a slightly smoother material & they lasted longer.
I have a few suggestions to correct the problems with defenses lifting up, but there is not enough down time or personnel in between weekends to fix them. Obviously this is occurring throughout competitions & I hope they come up with a solution