Accession Number : ADA305629

Title :   The Significance of Defects in CFRP Bonded Honeycomb Structures and Non-Destructive Test Methods for Their Destruction.

Corporate Author : FULMER RESEARCH LABS STOKE POGES (UNITED KINGDOM)

Personal Author(s) : Crocker, R. L. ; Bowyer, W. H.

PDF Url : ADA305629

Report Date : MAY 1978

Pagination or Media Count : 116

Abstract : Carbon Fibre Reinforced Plastic (CFRP) skinned aluminium honeycomb sandwich materials are becoming well established in the aerospace industry. These materials exhibit high specific strength and high specific stiffness. The types of structure for which they are suitable are those which require a large stiffness to mass ratio such as side-walls, solar arrays, antenna dishes etc. Whilst a great deal is known about the behaviour of these materials there are certain areas where neither theoretical nor physical studies have so far been successfully undertaken. One of these is the problem of defects within the material and their effect on its properties. Lack of this information hampers the spacecraft designer in making a reasonable estimate of the practical properties of the materials at his disposal with the consequent risk of structural over-design. A study has been undertaken at Fulmer Research Institute in conjunction with ESTFC to identify the defects that occur in CFRP/Al sandwich materials and to assess the significance of these defects in terms of overall mechanical properties. A range of defects have been considered and all have been shown to have significant effects on laminate strength. Available non-destructive test methods have been reviewed and evaluated using specimens containing deliberately introduced defects. It has been recommended that the optimum NDT practice which is presently available involves a combination of visual examination, roller probe coupled ultrasonics and X-radiography. The performance of other techniques including holographic interferometry, laser speckle pattern interferometry and thermography is discussed. (MM)

Descriptors :   *SPACECRAFT, *NONDESTRUCTIVE TESTING, *FIBER REINFORCED COMPOSITES, *HONEYCOMB STRUCTURES, VIBRATION, LAMINATES, STIFFNESS, CRACKING(FRACTURING), DEFLECTION, CARBON FIBERS, STRENGTH(MECHANICS), DEFECTS(MATERIALS), HOLOGRAPHY, ULTRASONICS, HIGH STRENGTH, ALUMINUM, BONDED JOINTS, ANTENNAS, VISUAL INSPECTION, BONDING, AEROSPACE INDUSTRY, PLASTICS, ACOUSTIC EMISSIONS, THERMAL STRESSES, THERMOGRAPHY, CYCLIC LOADS, SANDWICH CONSTRUCTION, SOLAR PANELS, SPECULAR REFLECTION, FIBER REINFORCEMENT, SPECKLE INTERFEROMETRY.

Subject Categories : Laminates and Composite Materials
      Unmanned Spacecraft
      Manned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE