Accession Number : ADA325402

Title :   Effect of Repair on the Electromagnetic Shielding Properties of Composite Materials.

Descriptive Note : Technical note,

Corporate Author : DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO)

Personal Author(s) : Gardner, C. L. ; Apps, R. ; Russell, A. J.

PDF Url : ADA325402

Report Date : JAN 1997

Pagination or Media Count : 21

Abstract : Composite materials are increasingly being used for the construction of aircraft because of their superior physical properties. Maintenance of adequate electromagnetic (EM) shielding inside the aircraft is often a concern because of the increasing use of sensitive avionics. Degradation of EM shielding provided by the skin of the aircraft during repair can be of particular concern. In this report, we present results of measurements that we have made to examine the effect of repair on the magnetic and electric shielding properties of carbon/epoxy laminates. In carrying out this study, we have used the conventional repair techniques that are used for repair of the CF-18 aircraft. These methods include the application of epoxy bonded carbon/epoxy and titanium patches, and the use of a bolted aluminum rapid repair (battle) patch. In all cases the patches were applied over a 75 mm hole in an 8-ply AS-4 carbon/epoxy laminate. The results show that the use of a carbon/epoxy or a titanium patch results in a degradation of the magnetic shielding of the carbon/epoxy laminates by as much as 40 dB. This large degradation is attributed to the loss of electrical contact between the patch material and the laminate. The degradation of magnetic shielding with a bolted aluminum patch is less severe ( 20 dB) because the bolts provide some electrical contact between the patch and the laminate. Similar results are presented for the effect of repair on electrical shielding. Limited results are presented that show that shielding can be substantially improved by providing electrical contact between the laminate and the patch material.

Descriptors :   *DEGRADATION, *COMPOSITE MATERIALS, *CARBON, *REPAIR, *ALUMINUM, *EPOXY LAMINATES, *ELECTROMAGNETIC SHIELDING, AVIONICS, AIRCRAFT INDUSTRY, CANADA, TITANIUM, BOLTS, ELECTRIC CONTACTS.

Subject Categories : Electromagnetic Shielding
      Laminates and Composite Materials
      Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE