Using Scrap Pieces in Layup

Talk Composites - The Forum for Advanced Composites

Back

Using Scrap Pieces in Layup

Author	Message
d3ntr0n	d d3ntr0n posted 6 Years Ago Topic Details
d Group: Forum Members Posts: 10, Visits: 94	I am laying up a part which is essentially half of a tube with an outer diameter of 18 inches. My reinforcement is 10 oz/sq yd fiberglass and I'm using vacuum infusion. My reinforcement pattern is +45, -45, 0, 90. My question is, how bad of an effect would it have on the strength of the part if for the second layer of 45 degree reinforcement, I used two large triangular scrap pieces to form the rectangular piece needed? The break between the two pieces would form a helical shape in the final part, and the layer made from scraps would be sandwiched between two continuous unbroken layers. Any input will be greatly appreciated.
	Reply Like 1
Steve Broad	Steve Broad posted 6 Years Ago Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x d3ntr0n - 10/5/2018 11:52:34 PM I am laying up a part which is essentially half of a tube with an outer diameter of 18 inches. My reinforcement is 10 oz/sq yd fiberglass and I'm using vacuum infusion. My reinforcement pattern is +45, -45, 0, 90. My question is, how bad of an effect would it have on the strength of the part if for the second layer of 45 degree reinforcement, I used two large triangular scrap pieces to form the rectangular piece needed? The break between the two pieces would form a helical shape in the final part, and the layer made from scraps would be sandwiched between two continuous unbroken layers. Any input will be greatly appreciated. When making large, sculptured shapes you have to use multiple pieces, even for the surface layer so there isn't a problem. In fact, the small overlap will add slightly to the stiffness of the part :-)
	Reply Like 1
Hanaldo	Hanaldo posted 6 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Cant say if there is or isnt a problem without knowing the actual application and what is required from the part. There is a difference between making things in a single piece and making things with a join. For the average DIY hobbyist making mostly cosmetic items at home to their own specifications (and that isnt meant in a negative way), then it is highly unlikely you would notice and as Steve mentioned, you simply over-compensate by having a sufficient overlap. If this is a piece you are making to suit specs that have been engineered, then it could well be a problem. But it doesnt sound like that is the case?
	Reply Like 1
d3ntr0n	d d3ntr0n posted 6 Years Ago Post Details
d Group: Forum Members Posts: 10, Visits: 94	+x Hanaldo - 10/6/2018 11:12:33 AM Cant say if there is or isnt a problem without knowing the actual application and what is required from the part. There is a difference between making things in a single piece and making things with a join. For the average DIY hobbyist making mostly cosmetic items at home to their own specifications (and that isnt meant in a negative way), then it is highly unlikely you would notice and as Steve mentioned, you simply over-compensate by having a sufficient overlap. If this is a piece you are making to suit specs that have been engineered, then it could well be a problem. But it doesnt sound like that is the case? Its a prototype for an engineered part, so it is being used to test other mechanisms, and it's going to need to survive being dropped a few feet onto a pad several times without cracking. In fact its just a piece of a larger tube having a total length of about 7 feet. Thanks Hanaldo, for your advice in both threads. Really helpful, and I think since it is unknown exactly how the tube will impact the ground its best to just use full sheets and save the scrap for some other purpose to be determined.
	Reply Like 1
Furrari	F Furrari posted 6 Years Ago Post Details
F Group: Awaiting Activation Posts: 63, Visits: 99	+x d3ntr0n - 10/6/2018 4:07:59 PM +x Hanaldo - 10/6/2018 11:12:33 AM Cant say if there is or isnt a problem without knowing the actual application and what is required from the part. There is a difference between making things in a single piece and making things with a join. For the average DIY hobbyist making mostly cosmetic items at home to their own specifications (and that isnt meant in a negative way), then it is highly unlikely you would notice and as Steve mentioned, you simply over-compensate by having a sufficient overlap. If this is a piece you are making to suit specs that have been engineered, then it could well be a problem. But it doesnt sound like that is the case? Its a prototype for an engineered part, so it is being used to test other mechanisms, and it's going to need to survive being dropped a few feet onto a pad several times without cracking. In fact its just a piece of a larger tube having a total length of about 7 feet. Thanks Hanaldo, for your advice in both threads. Really helpful, and I think since it is unknown exactly how the tube will impact the ground its best to just use full sheets and save the scrap for some other purpose to be determined.
	Reply Like 1
Furrari	F Furrari posted 6 Years Ago Post Details
F Group: Awaiting Activation Posts: 63, Visits: 99	Steve. That’s an awesome looking bit of work. I haven’t the experience to do that yet but I hope to one day. The project I am currently working on is too big to do in one without using a lot of cf. now the relevant bit. I’ve pinched some bodyelsees idea, I’m doing it in two parts of cf with one of them turned over so that the weave forms a V and then using five rows of 15mm tow across the joint. This both strengthens it and looks superb in the sun as the three patens catch the sun and flash. I hope this helps dn3 and alays his worry about joint pieces. M.
	Reply Like 1
d3ntr0n	d d3ntr0n posted 6 Years Ago Post Details
d Group: Forum Members Posts: 10, Visits: 94	+x Furrari - 10/8/2018 8:29:13 AM Steve. That’s an awesome looking bit of work. I haven’t the experience to do that yet but I hope to one day. The project I am currently working on is too big to do in one without using a lot of cf. now the relevant bit. I’ve pinched some bodyelsees idea, I’m doing it in two parts of cf with one of them turned over so that the weave forms a V and then using five rows of 15mm tow across the joint. This both strengthens it and looks superb in the sun as the three patens catch the sun and flash. I hope this helps dn3 and alays his worry about joint pieces.M. Hey man thanks for the input. I may be able to get some photos at some point.
	Reply Like 1