Infusion Ripple Effect - I am stumped!

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Infusion Ripple Effect - I am stumped!

Author	Message
Matt Stevs	Matt Stevs posted 5 Years Ago HOT Topic Details
Group: Forum Members Posts: 6, Visits: 140	Hi all, I figured that I have done enough troubleshooting that I will post up on here and see if anyone can clue in. I am having a strange issue when I infuse flat sheet. I have attached some photos so you can take a look. Basically, once the sheet is cured, there is a faint holographic 'ripple' in the carbon. It almost looks like tiger stripes. Initially I thought it was a defect in the reinforcement, but I examined it very closely before infusing and it was not present. Then I thought maybe it was the placement of my infusion spiral, but again, with different orientations it did not change. Finally I thought I had it solved, I deduced that it was the vacuum pump causing 'waves' from the internal mechanisms and variation in vacuum strength during the motor cycles. So, I tried went from a 2 stage rotary vane vacuum pump, to a dry Gast diaphragm pump, and low and behold...The rippling was STILL there. So , needless to say, I am completely stumped.
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Lester Populaire	L Lester Populaire posted 5 Years Ago HOT Post Details
L Group: Forum Members Posts: 311, Visits: 13K	+x Matt Stevs - 5/10/2019 3:47:06 PM Hi all, I figured that I have done enough troubleshooting that I will post up on here and see if anyone can clue in. I am having a strange issue when I infuse flat sheet. I have attached some photos so you can take a look. Basically, once the sheet is cured, there is a faint holographic 'ripple' in the carbon. It almost looks like tiger stripes. Initially I thought it was a defect in the reinforcement, but I examined it very closely before infusing and it was not present. Then I thought maybe it was the placement of my infusion spiral, but again, with different orientations it did not change. Finally I thought I had it solved, I deduced that it was the vacuum pump causing 'waves' from the internal mechanisms and variation in vacuum strength during the motor cycles. So, I tried went from a 2 stage rotary vane vacuum pump, to a dry Gast diaphragm pump, and low and behold...The rippling was STILL there. So , needless to say, I am completely stumped. I guess this is because the vacuum flattens the fabric so you have less wavyness in the out of plane direction which might result in more wavyness in plane. Maybe try to stretch the fabric with a little tape before pulling a vacuum?
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Matt Stevs	Matt Stevs posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 140	+x Lester Populaire - 5/10/2019 5:50:43 PM +x Matt Stevs - 5/10/2019 3:47:06 PM Hi all, I figured that I have done enough troubleshooting that I will post up on here and see if anyone can clue in. I am having a strange issue when I infuse flat sheet. I have attached some photos so you can take a look. Basically, once the sheet is cured, there is a faint holographic 'ripple' in the carbon. It almost looks like tiger stripes. Initially I thought it was a defect in the reinforcement, but I examined it very closely before infusing and it was not present. Then I thought maybe it was the placement of my infusion spiral, but again, with different orientations it did not change. Finally I thought I had it solved, I deduced that it was the vacuum pump causing 'waves' from the internal mechanisms and variation in vacuum strength during the motor cycles. So, I tried went from a 2 stage rotary vane vacuum pump, to a dry Gast diaphragm pump, and low and behold...The rippling was STILL there. So , needless to say, I am completely stumped. I guess this is because the vacuum flattens the fabric so you have less wavyness in the out of plane direction which might result in more wavyness in plane. Maybe try to stretch the fabric with a little tape before pulling a vacuum? This is a great thought! I think you are on to something. Here is a photo of the toolside before infusing. The ripple is evident! I will try coating the fabric in spray tack and giving it a shot.
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Matt Stevs	Matt Stevs posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 140	I have never witnessed this before in moulded parts that I have made (with compound surfaces) in which I use spray tack, so there is a good chance it may solve the problem! And that also explains why this is not evident in prepregs as the resin acts like a binder to keep everything in place as vacuum is being applied.
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JasonFL	JasonFL posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 51, Visits: 707	Is it possible that resin line is skidding towards the cloth as vacuum is pulled? I see scotch tape, but thats pretty weak stuff compared to flash breaker tape. Reason I’m pointing out the resin line is because if it shifts at all, it will shift the flow media, which then can shift the plys before theyre locked down by full vacuum. Jason Edited 5 Years Ago by JasonFL
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Matt Stevs	Matt Stevs posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 140	+x JasonFL - 5/10/2019 8:29:21 PM Is it possible that resin line is skidding towards the cloth as vacuum is pulled? I see scotch tape, but thats pretty weak stuff compared to flash breaker tape. Reason I’m pointing out the resin line is because if it shifts at all, it will shift the flow media, which then can shift the plys before theyre locked down by full vacuum. I will try taping everything in place with flash tape!
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