ENGINEERING PROPERTIES OF LAMINATES 5-5 



This test program was limited to those basic properties considered to be of immediate 

 need to designers and fabricators. Additional spare panels were fabricated and are being 

 retained for future testing on fatigue, creep and stress rupture properties. 



Materials and Method of Fabrication 



To properly evaluate the properties, 2 36 2 inch x 20 inch test panels were fabricated 

 by the contact molding method. Tests were made on 65 00 specimens cut from these panels, 

 and the results were statistically analyzed. The following is a list of reinforcements, resin 

 system and the molding method used to fabricate these panels. 



Mat: Chopped strand mat conforming to Military Specification MIL -M- 156 17 -A, 

 2 ounces per square foot in weight and having a high solubility polyester binder. 



Woven Roving: Style HG 56 or BS 6055 with approximately equal strength in both 

 directions and weighing approximately 25-27 oz. per yard, or equivalent. 



Cloth: Style 1000-150 conforming to Military Specification MIL-Y-1140-C, plain 

 weave construction weighing 9. 66 ounces per square yard, or equivalent. For sim- 

 plicity this material is designated as 10 ounce cloth. 



All of the fiberglass reinforcement had a high wet strength Silane, Garan or 136 

 type finish. 



Cloth and woven roving laminates were parallel laminated; warp direction of all 

 plies were laid up in the same direction. 



A blend of approximately 90 per cent rigid and 10 per cent flexible polyester resins 

 or a suitable modified polyester resin with equal properties was used. The difficult 

 task of selecting resin systems, without appearing to be arbitrary, leads to this widely 

 used formulation compromise which has been representative of good practice. All rigid 

 resin used conformed to Military Specification MIL -R -7575 -A. 



The catalyst system used and methods of lay up conformed to the resin manu- 

 facturer's recommendations. 



The laminates represent the result of good shop practice with close adherence to 

 the resin manufacturer's process specifications for producing boat hulls and other large 

 structures using the contact or hand lay up method. No special post cure by heat or 

 other procedure was used to produce improved panels. 



Types of Laminates: 



Ml = Mat - 2 ounces per square foot 



M2 = Woven roving - 25-27 ounces per square yard 



M3 = Cloth - 10 ounces per square yard 



M4 = Mat with 1 ply of 10 ounce cloth on each face 



M5 = Woven roving with 1 ply of 10 ounce cloth on each face 



