Composite Structures Having Bondlines with Matched Electrical Conductivity

a composite structure and electrical conductivity technology, applied in the direction of aircraft static dischargers, transportation items, aircraft maintenance, etc., can solve the problems of increasing the weight of the aircraft, generating undesirable electrical potentials, and adding manufacturing costs, so as to reduce the electrical potential across exposed portions, reduce aircraft weight and manufacturing costs

Inactive Publication Date: 2014-05-01
THE BOEING CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes methods for joining multiple composite structures together with matching electrical conductivities to reduce electrical potentials across exposed bondlines and eliminate the need for sealants, which can weigh more and increase manufacturing costs. The methods involve installing a scrim in the bond joint with the same electrical conductivity as the composite structures, which can be done by impregnating the scrim with adhesive and placing it between the two composite structures. The technical effects include reducing weight and manufacturing costs and improving lightning protection.

Problems solved by technology

A problem arises, however, when portions of the bondline are exposed to the ambient environment.
A lightning strike may generate an undesirable electrical potential across the bondline.
Although sealants are effective, they increase the weight of the aircraft, and are both time-consuming and labor-intensive, adding to manufacturing costs.

Method used

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  • Composite Structures Having Bondlines with Matched Electrical Conductivity
  • Composite Structures Having Bondlines with Matched Electrical Conductivity
  • Composite Structures Having Bondlines with Matched Electrical Conductivity

Examples

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Embodiment Construction

[0027]Referring first to FIGS. 1 and 2, a composite structure 20 comprises first and second composite pre-pregs 24, 26, which may be formed of by laying up pre-preg plies, such as a CFRP. In this example, the first and second pre-pregs 24, 26 together are joined together along a bondline 22 between a face 29 of the first pre-preg 24 and an edge 27 of the second pre-preg 26, effectively forming a butt joint 31. The bondline 22 includes exposed portions 28, 30 at the ends of the bondline 22, which are exposed to the surrounding ambient environment. As will be discussed below, the bondline 22 has an electrical conductivity σ1 and impedance Z1 that substantially match the electrical conductivity σ2 and impedance Z2 of each of the first and second pre-pregs 24, 26. This matching of the electrical conductivities σ1, σ2 and impedances Z1, Z2 reduces or eliminates build-up of an undesirable electrical potential or charge “V” (FIG. 2) between the pre-pregs 24, 26 along the exposed portions 2...

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Abstract

Two composite laminates are joined together by a bondline having portions exposed to the ambient environment. The bondline contains scrim having an electrical conductivity and impedance matched to that of the laminates in order to mitigate effects of lightning strikes.

Description

BACKGROUND INFORMATION[0001]1. Field[0002]This disclosure generally relates to techniques for bonding composite structures, and deals more particularly with methods for mitigating the effects of lightning strikes at bondlines.[0003]2. Background[0004]Fiber reinforced composite structures, such as, without limitation, carbon fiber reinforced plastics (CFRP) may be bonded together along a bondline using a structural adhesive. The bondline may be strengthened and reinforced by introducing one or more layers of scrim into the adhesive.[0005]In aircraft applications, areas of composite structures such as fuselage skins are sometimes repaired or reworked by adhesively bonding composite repair patches to the structure. In order to reduce the effects of lightning strikes on the repair patch, it is necessary to provide a continuous electrical path between the repair patch and the structure to which it is bonded in order to dissipate electrical current flow.[0006]In order to provide electrica...

Claims

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Application Information

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IPC IPC(8): B32B1/02B32B37/12B32B7/02F16B12/04B60K15/03B23P11/00
CPCB64D37/02B64D45/02B29L2031/3076B29C65/5021B29C65/5028B29C65/5057B29C66/112B29C66/1122B29C66/114B29C66/43B29C66/43441B29C66/7212B29L2031/7172B29C66/73141B29C66/72143B29C66/72141B64F5/40Y10T156/10Y10T403/47Y10T428/24942Y10T29/49826Y10T428/1352B29C65/4855B29K2307/04Y02T50/40
InventorACKERMAN, PATRICE K.HEIDLEBAUGH, DIANE L.
OwnerTHE BOEING CO