PROCEDURE FOR THE PROGNOSTIC OF A STRUCTURE SUBJECT TO LOADS

• US 20110087442A1
• Filed: 12/04/2009
• Published: 04/14/2011
• Est. Priority Date: 12/05/2008
• Status: Active Grant

• Current Assignee: Alenia Aeronautica SPA (Leonardo S.p.A.)
• Original Assignee: Alenia Aeronautica SPA (Leonardo S.p.A.)
• Inventors: Iannone, Michele
• Granted Patent: US 8,706,447 B2
• Time in Patent Office: Days
• US Class Current: 702/34
• CPC Class Codes: G01M 5/0041 by determining deflection or stress

Abstract

A method for prognostics of a structure subject to loads, particularly an aircraft structure, includes, detecting the state (strains) of the structure at multiple primary points and additional points. The loads acting on the structure associated with the state detected in the primary points are determined. Based on the determined loads, the state of the structure in the additional points is estimated. The estimated state of the structure is compared with the state detected in the additional points. A soundness state of the structure is assessed if the estimated and detected values of the state quantity are in agreement, or a defectiveness state of the structure if such values differ.

Claims

1. A method for prognostics of a structure subject to loads, particularly an aircraft structure, comprising the steps of:

providing a first database linking possible loads acting on the structure in operating conditions with a modified state of the structure, including values of a quantity indicative of the state of the structure as modified in the presence of said loads in a predetermined number of relevant points;

providing a second database linking changes of the state of the structure induced by pre-established defects in a predetermined number of relevant points of the structure, with possible classes of defects;

and, interactively;

detecting the values assumed by said quantity indicative of the state of the structure in a first plurality of primary detection points and in a second plurality of additional detection points;

determining from the first database the loads acting on the structure starting from the detected values of the state quantity;

estimating, based on the determined loads, the values of the state quantity in the additional detection points;

comparing between the estimated values and detected values of the state quantity in the additional detection points; and

determining a condition of integrity of the structure if the detected values and the estimated values of the state quantity substantially match except for predetermined tolerances, or a condition of defectiveness of the structure if said values of the state quantity differ taking into consideration the predetermined tolerances.

2. A method according to claim 1, comprising identifying a defect of the structure by associating the changes between the values assumed by the state quantity with a type of defect in the second database.

3. A method according to claim 1, wherein said relevant points of the structure are selected from a plurality of points of identification of the structure which are defined based on a predetermined mathematical model of said structure.

4. A method according to claim 3, wherein said relevant points on the structure are selected among the points that, according to said model, are capable of identifying a state condition of the structure which can be associated univocally with a load condition, with concentration in proximity of regions of greater structural criticality.

5. A method according to claim 1, wherein said quantity indicative of the state of the structure is the local strain of the structure.

6. A method according to claim 5, wherein the population of the first database comprises the bi-unique association between values of typical loads acting on the structure in operating conditions and measured or simulated strain values of the structure subject to said loads.

7. A method according to claim 5, wherein the population of the second database comprises the bi-unique association between measured values of the changes of strain in the structure induced by the same load vector in the presence of a defect in the structure and data of identification of a possible defect of the structure.

8. A method according to claim 1, wherein the type of defects includes at least one of data of:

the defect class;

the defect dimension;

the position of the defect in the structure.

9. A method according to claim 1, including estimating the contribution to the change of the state of the structure in said detection points due to changes in the properties of the structure material induced by the operating temperature.

10. A system for prognostics of a structure subject to loads, particularly an aircraft structure, comprising:

a first and a second plurality of detection sensors, located in primary detection points and additional comparison detection points, respectively;

first storage comprising a first database linking possible loads acting on the structure in operating conditions with a modified state of the structure, including values of a quantity indicative of the state of the structure as modified in the presence of said loads in a predetermined number of relevant points;

second storage comprising a second database linking changes of the state of the structure induced by pre-established defects in a predetermined number of relevant points of the structure, with possible classes of defects; and

a processor arranged for carrying out a method according to claim 1.

11. A system according to claim 10, wherein said detection sensors include sensors of the strain in the structure.

12. A system according to claim 10, comprising temperature sensors positioned in proximity of said detection points.

13. A system according to claim 10, wherein said processor is arranged for identifying a class of defect of the structure, concentrated or distributed, selected from the group of surface or bulk modifications comprising a hole, a filled hole, the insertion of a connection member, a damage due to a crash, delamination, porosity, a region of the structure differently rich in resins or fibres.

14. A computer program or set of programs to be run on a processing system, comprising one or more code modules for carrying out a method for prognostics of a structure subject to loads according to claim 1.