Are all negative curves destructive / vulnerable?

[Big Thud Joe]

Finally saved up to get some custom inflatables made, I'm in the process of getting a lifesize figure made, but am also fantasizing of getting a large inflatable foot / boot made, once refined, then getting quite a few dozen made.

Think of the older inflatable santa clauses from the 70s and 80s, rmember the bottom inflatable part was black beach ball PVC resembling a boot.

I would like to get a huge shape of the boot portion, about 64 inch tall, and the bottom soul part about 10 to 12 inch wide and about 24 inch long. It would basically resemble an inflatable cylinder at the top, with the foot portion coming out at the bottom.

My only question is, even with welded / reinforced seams, and reverse seams, would the negative curve at the top of the foot section be vulnerable. I'm actually hoping that the seams can be made strong enough, that a thinner gauged PVC can be used, something like 0.12mm.

I'm wont be sitting on these, or popping them, more so just for poking up my balls, and rubbing the curved section into that part as this is what ultimately arouses me.

Is there anyway around this, or is this just physics of air pressure and the curve shape? THe template will basically be two halves (left and right) joined together, with a round circle to fill in the top.

[frenchy]

Re: Are all negative curves destructive / vulnerable?

Negative curves always need reinforcement since the stress pulls a disproportionate amount in that area relative to the rest of the material. I would use a slightly thicker material and an extra piece of reinforcement material on the negative curve.

[EthylTheAardvark]

Re: Are all negative curves destructive / vulnerable?

Designing them as a separate chamber seems to help. You can minimize the stress on the curves if it's not all one piece.

[Big Thud Joe]

Re: Are all negative curves destructive / vulnerable?

Negative curves always need reinforcement since the stress pulls a disproportionate amount in that area relative to the rest of the material. I would use a slightly thicker material and an extra piece of reinforcement material on the negative curve.

Yeah, good point, I spose they can add a reinforcement strip on the inside of the inflatable, directly underneath the curve. My arousal always comes from holding lighter and thinner PVCs (give extra sense of vulnerability), so I'm hoping I can get away with the reinforcement strip on the inside, with a welded seam construction.

Seperate chaimbers ruin the nuance and the visual appeal for me, so not really sure on this. I'll suggest the reinforcement in the schematics, but if in the end it's not going to hold up, then this particular looner fantasy will most probably stay that.

[Whale Rider]

Re: Are all negative curves destructive / vulnerable?

the mechanical stress on a negative curve is much higher than on a straight seam so yes these places need more attention...

[loonerlee]

Re: Are all negative curves destructive / vulnerable?

Negative seems on shosu I've found are week and would recommend reinforcing. But can only speak for shosu products I've purchased and not other manufacturers.

[Whale Rider]

Re: Are all negative curves destructive / vulnerable?

Negative seems on shosu I've found are week and would recommend reinforcing. But can only speak for shosu products I've purchased and not other manufacturers.

where exactly?