Composite structure and method for barely visible impact damage detection

Patent metadata

Field	Value
Publication number	US-2019061309-A1
Application number	US-201816176305-A
Country	US
Kind code	A1
Filing date	Oct 31, 2018
Priority date	Oct 13, 2015
Publication date	Feb 28, 2019
Grant date	—

Abstract

A composite structure including a composite body having an outer surface, wherein the composite body is elongated along a span axis, and a detection layer connected to the outer surface of the composite body, the detection layer including a plurality of strips, wherein each strip comprises a plurality of glass fibers embedded in a matrix material, is elongated along a detection axis, the detection axis being substantially aligned with the span axis, and is spaced a non-zero distance apart from adjacent strips such that a discontinuity is defined between adjacent strips.

First claim

What is claimed is:

1 . A composite structure comprising:
a composite body having an outer surface, wherein the composite body is elongated along a span axis; and a detection layer connected to the outer surface of the composite body, the detection layer comprising a plurality of strips, wherein each strip of the plurality of strips:
comprises a plurality of glass fibers embedded in a matrix material,
is elongated along a detection axis, the detection axis being substantially aligned with the span axis, and
is spaced a non-zero distance apart from adjacent strips of the plurality of strips such that a discontinuity is defined between adjacent strips of the plurality of strips.

2 . The composite structure of claim 1 wherein the detection axis is parallel with the span axis.

3 . The composite structure of claim 1 wherein the composite body comprises a plurality of carbon fibers embedded in a matrix material.

4 . The composite structure of claim 1 wherein the composite body comprises a laminate structure comprising a plurality of composite plies, wherein each ply of the plurality of composite plies comprises a plurality of carbon fibers and a matrix material.

5 . The composite structure of claim 1 wherein the detection layer has a total cross-sectional thickness ranging from about 0.003 inch to about 0.050 inch.

6 . The composite structure of claim 1 wherein the detection layer comprises a stacked structure comprising at least two plies.

7 . The composite structure of claim 6 wherein at least one ply of the stacked structure comprises a cross-sectional thickness ranging from about 0.003 inch to about 0.015 inch.

8 . The composite structure of claim 1 wherein the non-zero distance is at least 0.05 inch.

9 . The composite structure of claim 1 wherein the detection layer further comprises a first extension member and a second extension member, and wherein each strip of the plurality of strips extends from the first extension member to the second extension member.

10 . The composite structure of claim 1 wherein a portion of the composite body is visible at the discontinuity.

11 . The composite structure of claim 1 wherein the composite body is configured as a hat stringer comprising:
a web portion having a proximal portion and a distal portion; and
a base portion connected to the proximal portion of the web portion,
wherein the detection layer is connected to the distal portion of the web portion.

12 . The composite structure of claim 1 wherein the composite body is configured as a J-type stringer comprising:
a J-shaped web portion having a proximal portion and a distal portion; and
a base portion connected to the proximal portion of the web portion,
wherein the detection layer is connected to the distal portion of the web portion.

13 . The composite structure of claim 1 wherein the composite body is configured as an I-type stringer comprising:
a T-shaped web portion having a proximal portion and a distal portion; and
a base portion connected to the proximal portion of the web portion,
wherein the detection layer is connected to the distal portion of the web portion.

14 . The composite structure of claim 1 wherein the composite body is configured as a blade stringer comprising:
a web portion having a proximal portion and a distal portion; and
a base portion connected to the proximal portion of the web portion,
wherein the detection layer is connected to the distal portion of the web portion.

15 . The composite structure of claim 14 wherein the distal portion of the web portion of the blade stringer comprises a trimmed distal-most end.

16 . The composite structure of claim 1 further comprising an aircraft skin, wherein the composite body is connected to the aircraft skin.

17 . An aircraft comprising the composite structure of claim 1 .

18 . A method for detecting barely visible impact damage on a composite body, wherein the composite body comprises an outer surface and is elongated along a span axis, the method comprising:
connecting to the outer surface of the composite body a detection layer comprising a plurality of strips such that each strip of the plurality of strips is elongated along a detection axis that is substantially aligned with the span axis, wherein each strip of the plurality of strips comprises a plurality of glass fibers embedded in a matrix material.

19 . The method of claim 18 wherein the connecting comprises co-curing the detection layer with the composite body.

20 . The method of claim 18 wherein the connecting comprises bonding the detection layer to the composite body with an adhesive.

Assignees

• Boeing Co

Inventors

• Kwon Hyukbong
• Pham Khanh Mai
• Carlson Lisa C
• Hanson Garrett C

Classifications

• B32B2605/18

  Aircraft · CPC title

• B32B5/02 Primary

  characterised by structural features of a {fibrous or filamentary} layer {(layer formed of metallic wires B32B15/02; layer formed of natural mineral fibres B32B19/02; layer formed of wood fibres B32B21/02)} · CPC title

• B64C2001/0072

  from composite materials · CPC title

• B32B2260/023

  Two or more layers · CPC title

• B32B2307/732

  Dimensional properties · CPC title