Accession Number : ADA138658

Title :   Moisture Transport in Composites during Repair Work,

Corporate Author : NAVAL SURFACE WEAPONS CENTER SILVER SPRING MD

Personal Author(s) : Augl,J M

PDF Url : ADA138658

Report Date : Sep 1983

Pagination or Media Count : 33

Abstract : The increased use of composites for structural materials in modern Naval aircraft (wing skins) requires reliable repair techniques for damaged areas (holes or delaminations). It is desirable to carry out these repairs under field or depot conditions by adhesively bonding a metal or composite patch over the damaged area. The problem is to prevent excessive void formation in the adhesive bond caused by evaporation of water during the curing process. Moisture that had been sorbed into the composite may diffuse into the adhesive. If the partial pressure of water dissolved in the still liquid adhesive exceeds the environmental (applied) pressure voids may form rapidly and reduce the load carrying strength of the bonded patch. An interactive desk top computer program was written for predicting the moisture profiles in the composite and the adhesive during the whole course of predrying and patch bonding. Thus it should be possible to get a better understanding of the problem and to obtain guidance for an experimental approach to optimize repair procedures. The underlying principles for the modeling are discussed and a specific example of moisture transport using a metal patch is given. (Author)

Descriptors :   *LOGISTICS SUPPORT, *REPAIR, *AIRFRAMES, *COMPOSITE MATERIALS, *BUBBLES, *MOISTURE, TRANSPORT, ADHESIVE BONDING, COMPOSITE WINGS, SKIN(STRUCTURAL), MONITORING, MOISTURE CONTENT, COMPUTER AIDED INSTRUCTION, COMPUTER APPLICATIONS, MACHINE CODING, RELIABILITY, VOIDS, PRESSURE, CURING, WATER, DIFFUSION, FINITE ELEMENT ANALYSIS, MECHANICAL PROPERTIES, DEFECTS(MATERIALS), VAPORIZATION

Subject Categories : Aircraft
      Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE