The determination of mechanical properties of sandwich composites manufactured by hand-lay up and vacuum infusion methods and strain energy release rate has been taken into account for tension and shear mode

Composite materials widely used in the world are getting more and more important day by day. Sandwich composites have been studied from composite materials, which are widely using in defense industry, marine industry, aviation industry, etc. At the beginning of the reasons we prefer sandwich composites are maritime and yacht sector which is developed due to being surrounded by the sea around our country. Composite materials used in marine and yacht manufacturing are sandwich construction. It consists of a nucleus and skins surrounding nucleus. In addition, hand lay-up and vacuum infusion methods are preferred in yacht manufacturing. Sandwich composite materials produced by hand lay-up and vacuum infusion are manufactured according to suitable conditions for the yacht industry (outer skin is more layered than inner skin, by using chopped strand to outermost for distribute the load etc.), then mechanical values are increased by using curing process. For the calculation of the mechanical values of the manufactured samples, compression test, tensile test, side compression test, DCB test and MCSB test were applied. As a result of these experiments, it was seen that the sample produced by using vacuum infusion method was 1.5-2 times more resistant than the sample produced by using hand lay-up method. Examining Mode 1 and Mode 2 stresses, the energy needed to fracture the first cracks on the same longitudinal samples increases as the length of the first cracks increases. This increase is increase of 200-250 percent in the sample made by using vacuum infusion method and increase of 140-220 percent in the sample made by using hand lay-up method.