Accession Number : ADA309605

Title :   Designing for Impact Resistance with Unidirectional Fiber Composites.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Chamis, Christos C. ; Hanson, Morgan P. ; Serafini, Tito T.

PDF Url : ADA309605

Report Date : AUG 1971

Pagination or Media Count : 44

Abstract : Composite micromechanics and macromechanics and the miniature Izod impact test are used to investigate the impact resistance of unidirectional composites. Several composite systems are examined both theoretically and experimentally. The composites are classified theoretically relative to their impact resistance for longitudinal, transverse, and shear modes. Experimental results are reported only for Izod impact with the fibers either parallel or transverse to the cantilever longitudinal axis. Impact resistance design criteria which evolved during this investigation are used to design hybrid composites with improved impact resistance. This is illustrated theoretically and demonstrated experimentally. Approximate design procedures using the impact factor are described. The results show that in-situ fiber and matrix elongation-to-fracture, matrix modulus, fabrication process, fiber and void volume ratios, and microresidual stresses are variables which affect the impact resistance. The ranking of composite impact resistance on the basis of measured and predicted results was in excellent agreement.

Descriptors :   *FIBER REINFORCED COMPOSITES, *IMPACT STRENGTH, STRESS STRAIN RELATIONS, STRESS ANALYSIS, IMPACT TESTS, STRUCTURAL ANALYSIS, STIFFNESS, MODULUS OF ELASTICITY, METAL MATRIX COMPOSITES, FRACTURE(MECHANICS), SHEAR STRESSES, RESIDUAL STRESS, EPOXY COMPOSITES, DESIGN CRITERIA, FAILURE(MECHANICS), MICROMECHANICS, CRYOGENICS, THERMAL STRESSES, ELONGATION, DELAMINATION, SHEAR STRENGTH.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE