SYSTEM AND METHOD FOR DETECTING THE PRESENCE OF LIQUID WATER IN SANDWICH STRUCTURES

Abstract

A system for detecting liquid water in a sandwich structure, the sandwich structure comprising two outer skins and a honeycomb core that rigidly interconnects the outer skins, and wherein is obtained a plurality of cells closed at opposite ends by the two outer skins, the cells being further configured to be in fluid communication with each other, wherein the system comprises at least one sensor placed within one of said cells, the sensor being sensitive to the presence of free liquid water within the cells, and a processing unit configured to receive an output signal provided by the sensor and issue a warning in case of the presence of free liquid water within the cells.

Claims

1. A system for detecting liquid water in a sandwich structure, the sandwich structure comprising two outer skins and a honeycomb core that rigidly interconnects the outer skins, and wherein is obtained a plurality of cells closed at opposite ends by the two outer skins, said cells being further configured to be in fluid communication with each other, wherein the system comprises at least one sensor placed within one of said cells, said sensor being sensitive to the presence of free liquid water within said cells, and a processing unit configured to receive an output signal provided by the sensor and issue a warning in case of the presence of free liquid water within said cells.

2. System according to claim 1, wherein said sensor is a humidity sensor, and the processing unit is configured to issue a warning in case of relative humidity detected by the sensor equal to about 100%.

3. System according to claim 1, wherein said outer skins are made of metal material or of composite material, comprising a matrix of fiber-reinforced resin.

4. A system according to any of claims 1, wherein said honeycomb core is made of metallic material or of non-metallic material, reinforced with aramid or glass fibers.

5. A method for detecting liquid water in a sandwich structure, the sandwich structure comprising two outer skins and a honeycomb core that rigidly interconnects the outer skins, and wherein is obtained a plurality of cells, closed at opposite ends by the two outer skins, said cells being further configured to be in fluid communication with each other, there being provided at least one sensor placed within one of said cells, said sensor being sensitive to the presence of free liquid water within said cells, wherein the method comprises: receiving an output signal provided by the sensor and issuing a warning in case of the presence of free liquid water within said cells.

6. A method according to claim 5, wherein said sensor is a humidity sensor, and wherein the method comprises: issuing a warning in case of relative humidity detected by the sensor (19) equal to about 100%.

7. A method according to claim 5, wherein said outer skins are made of metal material or of composite material, comprising a matrix of fiber-reinforced resin.

8. A method according to any one of claims 5, wherein said honeycomb core is made of metal material or of non-metal material, reinforced with aramid or glass fibers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Some preferred but non-limiting embodiments will now be described; making reference to the accompanying drawings, wherein:

[0016] FIG. 1 is a schematic cross-section view of a portion of a sandwich panel, fitted with a monitoring system according to the invention; and

[0017] FIG. 2 is a schematic plan view of the portion of the sandwich panel shown in FIG. 1.

DETAILED DESCRIPTION

[0018] With reference to the figures, a portion of a sandwich structure is represented, indicated collectively at 10.

[0019] The sandwich structure 10 comprises two outer skins respectively 11 and 13, and a honeycomb core 15 that rigidly interconnects the outer skins 11 and 13.

[0020] The outer skins 11, 13 may be made of metallic material or composite material, comprising a fiber-reinforced resin matrix.

[0021] The honeycomb core 15 may be made of metallic material or composite material, comprising a fiber-reinforced resin matrix.

[0022] The skins 11 and 13 are fixed on the two opposite sides of the honeycomb core 15, for example, by means of a structural adhesive.

[0023] In the core 15 therefore is obtained a plurality of cells 16 that are closed on opposite ends by the two outer skins 11 and 13. The cells 16 are also configured to be in fluid communication with each other, for example, through holes made in the walls of the honeycomb material that separate the cells 16 from each other. In FIG. 2, the passages for the fluid are schematically represented by dashes 17 that interconnect adjacent cells 16.

[0024] At least one sensor 19 is located within one of the cells 16. Such sensor 19 is sensitive to the presence of free liquid water inside the cells 16. In particular, the sensor 19 is a humidity sensor. In the presence of liquid water, the humidity in the volume inside the core 15 is about 100%, since the core 15 is made in such a way as to allow intercommunication between the cells 16.

[0025] The use of a humidity sensor, for example based on the measurement of electrical capacity, allows the presence of water to be signaled through the reading of internal humidity equal to 100% (with the measurement tolerance of the sensor).

[0026] A processing unit 20, arranged, for example, on board an aircraft on which the sandwich structure 10 is present, is configured to receive an output signal from the sensor 19. The processing unit 20 may be connected to the sensor 19 by wire or wirelessly.

[0027] Based on the output signal provided by the sensor 19, the processing unit 20 may emit a visual and/or audible warning if free liquid water is present in the cells 16 of the sandwich structure 10.