Comparison of the Compression Response of Thick (6.35mm) and Thin (1.60mm) Dry and Moisture Saturated AS4/3501-6 Laminates.

摘要

The compression response of thick (6.35 mm) and thin (1.60mm) (O2/90)subs AS4/3501-6 laminates was compared for material in the dry and moisture saturated conditions. The thick specimens failed at 1055 MPa dry and 740 MPa wet. Comparable strengths for the thin specimens were 1090 and 957 MPa. There was no statistical difference in strength for the dry material of either thickness. The thick specimens absorbed significantly more water than the thin specimens, and consequently, showed a greater loss in compression strength. The elastic modulus was not affected by moisture in the thick or thin specimens. The gross failure mode of the dry and wet specimens of either thickness was very similar with slightly more delamination occurring in the wet specimens. The thick specimens typically exhibited angular cracks of 27 to 30 deg. partially across the specimen thickness. This was not observed in the thin specimens. Finite element techniques were used to determine shear stresses in the matrix for a fiber-matrix composite plate with an initial imperfection, and loaded in compression. These matrix shear stresses were used in a compression failure theory which showed reasonable agreement with experimental results. It appears that the detrimental influence of the moisture is the degradation of the matrix shear modulus at high compressive stresses with high moisture concentrations.