Method and systems for estimating remaining service life of a component subject to stress

• US 8,255,171 B2
• Filed: 10/28/2008
• Issued: 08/28/2012
• Est. Priority Date: 10/28/2008
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Balestra, Chester Lee
• Primary Examiner(s): Wachsman, Hal
• Application Number:
  US12/259,450
• Publication Number:
  US 20100106430A1
• Time in Patent Office: 1,400 Days
• Field of Search: 702/35, 702/34, 702/42
• US Class Current: 702/35
• CPC Class Codes: G01M 13/02 Gearings; Transmission mechanisms

Abstract

A method for determining when a ceramic component on a platform should be replaced. The method includes determining parameters for the ceramic component, the parameters include empirically determined a critical stress intensity factor, and a geometry factor for the ceramic component. The method also includes determining a relationship between platform operational parameters to the generation of stress at the surface of interest of the ceramic component, determining an initial crack size of a crack within the ceramic component at installation, tracking operational parameters of the platform throughout a course of usage of the ceramic component, calculating the corresponding stress at the crack location due to the tracked operational parameters, and calculating a numerical solution that illustrates a crack growth rate velocity and tracks a size of the crack over time. The ceramic component is replaced based on the crack growth rate velocity and the size of the crack.

Claims

1. A method for determining when a ceramic component of a platform should be replaced, said method comprising:

determining parameters comprising v_o, K_c, n, and ψ

r for the ceramic component, where v_o and n are empirically determined based on the ceramic component, K_c is a critical stress intensity factor, and ψ

r is a geometry factor for the ceramic component;

receiving, at a processor, the parameters, platform operational parameters, and measurements associated with generation of stress at a surface of interest of the ceramic component;

determining, using the processor, a relationship between the platform operational parameters and the measurements associated with generation of stress at the surface of interest of the ceramic component;

receiving, at the processor, an initial crack size of a crack within the ceramic component;

tracking the platform operational parameters throughout a course of usage of the ceramic component, wherein tracked operational parameters are formed and stored on a non-transitory computer readable storage medium;

receiving, at the processor, the tracked operational parameters;

calculating, using the processor, the stress at the crack due to the tracked operational parameters;

calculating, using the processor, a numerical solution that describes a crack growth rate and a size of the crack; and

estimating, using the processor, when the ceramic component should be replaced based on the crack growth rate and the size of the crack.

2. The method according to claim 1 wherein calculating the numerical solution comprises solving an equation comprising:

3. The method according to claim 2 wherein the level of applied tensile stress is a function of time.

4. The method according to claim 2 further comprising:

analyzing profiles of at least one of K/K_c and a derivative comprising dc/dt as a function of time to determine if a minimum value of the K/Kc has been reached or the derivative has become positive.

5. The method according to claim 1 wherein determining the parameters v_o, K_c, n, and ψ

r for the ceramic component comprises determining v_o, K_c, and n from at least one of published literature relating to the ceramic component and measurements of test samples of material comprising the ceramic component.

6. The method according to claim 1 wherein tracking the platform operational parameters of the platform comprises:

tracking at least one of temperature, pressure altitude, velocity, and acceleration using data from sensors connected to the platform; and

wherein calculating the stress includes using the data.

7. The method according to claim 1 wherein determining the initial crack size comprises at least one of:

determining the initial crack size based on an inspection of the crack; and

using initial crack size data supplied by a supplier of the ceramic component.

8. The method according to claim 1 wherein calculating the stress and calculating the numerical solution are performed as one or both of a real time calculation by a platform computer during platform operation and after platform operation.

9. The method according to claim 1 further comprising:

using anticipated operational parameters for the platform to generate an anticipated crack growth rate and to calculate an anticipated life for the ceramic component.

10. The method according to claim 9 further comprising:

planning maintenance for the platform based on the anticipated life.

11. A system for estimating a remaining service life for a component deployed on a platform, said system comprising a computer and a non-transitory computer readable storage medium storing a database accessible by said computer:

said database including first data comprising parameters comprising v_o, K_c, n, and ψ

r for the component, where v_o and n are empirically determined parameters based on the component, K_c is a critical stress intensity factor, and ψ

r is a geometry factor for the component, and wherein the database further includes second data comprising a relationship between platform operational parameters and measurements associated with generation of stress at a surface of interest of the component;

said computer configured to receive the first data and the second data, to track operational parameters of the platform during deployment of the component, wherein after tracking the operational parameters the computer is further configured to store tracked operational parameters, and wherein the computer is further configured to calculate a stress on the component due to the tracked operational parameters, and calculate a numerical solution that describes a crack growth rate and a size of a crack within the component; and

wherein said computer is further configured to estimate the remaining service life for the component based on the crack growth rate and the size of the crack.

12. The system according to claim 11 wherein, to calculate the numerical solution, said computer is further programmed to solve an equation comprising:

13. The system according to claim 12, wherein said computer is further programmed to analyze profiles of at least one of K/Kc and a derivative comprising dc/dt as a function of time to determine if a minimum value of the K/Kc has been reached or the derivative has become positive.

14. The system according to claim 11 wherein, to track the platform operational parameters, said computer is further programmed to:

track at least one of temperature, pressure altitude, velocity, and acceleration using third data from sensors connected to the platform; and

wherein calculating the stress includes using the third data.

15. The system according to claim 11 wherein said database includes third data comprising an initial crack size of the crack within the component at installation.

16. The system according to claim 11 wherein said computer comprises at least one of:

a platform-based computer further programmed to calculate the stress due to the tracked operational parameters and to calculate the numerical solution as a real time calculation during platform operation; and

a computer programmed to calculate the stress due to the tracked operational parameters and to calculate the numerical solution after platform operation.

17. The system according to claim 11 wherein said computer is further programmed to use anticipated operational parameters for the platform entered into said computer to generate an anticipated crack growth rate.

18. The system according to claim 11 wherein said computer is further programmed to generate a maintenance plan for the platform based on the remaining service life.