Accession Number : AD0748099
Title : Stress Wave Damage in Advanced Concept Materials.
Descriptive Note : Final rept.,
Corporate Author : EFFECTS TECHNOLOGY INC SANTA BARBARA CALIF
Personal Author(s) : Tuler,Floyd R. ; Graham,Marlyn E.
Report Date : JUL 1972
Pagination or Media Count : 185
Abstract : The resistance to damage from impulsive loading in three-dimensionally graphite reinforced phenolic composite materials was examined experimentally. Material specimens were impacted using an exploding foil apparatus and the relative importance between strengthening and attenuation to the impact resistance of the materials was determined. The stress wave induced damage was characterized for various impact velocities and pulse durations from both visual and microscopic examination of the recovered specimens. Stress wave attenuation was measured through several thicknesses of each material using quartz gages, and the micromechanical behavior of the Z direction fiber bundles and the surrounding material was determined using high magnification streak photography. Stress wave attenuation in the 3D graphite reinforced phenolic composite materials was found to be strongly increased by increased modulus of the reinforcement in the direction of wave propagation, and increased porosity. Introduction of the high modulus fibers causes a greater spreading of the wave front which leads to a decreased composite stress. Increased porosity increases the attenuation in the matrix which leads to a further reduction in the composite stress. The specimen rear face stresses for matrix cracking and fiber fracture were not significantly affected by the variations in reinforcement modulus and matrix porosity. Thus, it was shown that only increased attenuation contributed to increasing the damage resistance of 3D graphite reinforced composite materials. (Author, modified-PL)
Descriptors : (*REINFORCED PLASTICS, SHOCK RESISTANCE), IMPACT SHOCK, COMPOSITE MATERIALS, CARBON FIBERS, SHOCK WAVES, IMPACT TESTS, PHENOLIC PLASTICS, POROUS MATERIALS, DAMAGE
Subject Categories : Laminates and Composite Materials
Distribution Statement : APPROVED FOR PUBLIC RELEASE