Method and device for predicting a life expectancy of a product containing a plurality of components

• US 7,831,396 B2
• Filed: 11/25/2005
• Issued: 11/09/2010
• Est. Priority Date: 12/16/2004
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Becker, Rolf, Hahn, Christopher, Wostradowski, Uwe, Voigtlaender, Klaus, Muench, Reinhold, Durdevic, Ivica, Rupp, Thomas, Breibach, Joerg, Duerr, Johannes, Jaeckle, Philippe, Chabaud, Antoine, Ehrhardt, Hendrik
• Primary Examiner(s): Feliciano; Eliseo Ramos
• Assistant Examiner(s): Desta; Elias
• Application Number:
  US11/793,342
• Publication Number:
  US 20090119029A1
• Time in Patent Office: 1,810 Days
• Field of Search: 702/34, 702/185, 702/189, 714/25, 714/47, 324/158.1, 324/763, 700/21, 340/653
• US Class Current: 702/34
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 2219/37253 Fail estimation as function of lapsed time of use

Abstract

A method and a device are for predicting a life expectancy of a product, which includes at least two components. The life expectancy is ascertained as a function of an assumed field loading of the product. The components of the product are acted upon by different loadings and are operated, in each instance, at the different loadings until they fail. An end-of-life curve of the component is recorded on the basis of the load-dependent failure times of a component. An EOL curve of the product is ascertained such that at the different loadings, it includes the EOL curve of the components which has, in each instance, the shortest failure time at the corresponding loading. The anticipated service life of the product is determined as a functional value of the EOL curve of the product as a function of the predefined loading of the product.

Claims

1. A method for predicting a life expectancy of a product, having at least two components, as a function of a predefined loading of the product, comprising:

acting upon the components of the product by different loadings;

operating each component at the different loadings until failure;

storing obtained failure times for each component as a function of each of the loadings;

recording a corresponding end-of-life (EOL) curve of each component as a function of the load-dependent failure times of the component;

ascertaining an EOL curve of the product, so that at each of the different loadings, it includes the EOL curve of a component which has a shortest failure time at the corresponding loading; and

determining an anticipated service life of the product as a functional value of the EOL curve of the product as a function of the predefined loading of the product;

wherein the components of the product are loaded by at least one of (a) a specific, absolute operating temperature and (b) a temperature fluctuation of a particular amplitude within a specific period of time, and

wherein the different loadings are in a number of loading classes, and for each loading class a distance of a duration of a predefined loading of a component to a corresponding value on the EOL curve of the component is determined and summed up according to Palmgren-Miner.

2. The method according to claim 1, wherein the method is used for producing a reliability verification for the product by checking if the EOL curve of the product is above a specifiable loading for a specifiable period of time, and if this is so, the reliability verification for the product is considered to be produced.

3. The method according to claim 1, wherein the EOL curves of the components are extrapolated to lower loadings.

4. The method according to claim 1, wherein the EOL curves of the components are interpolated between discrete values of the failure times at the different loadings at which the EOL curves are recorded.

6. The method according to claim 1, wherein an EOL curve of a component includes at least two points that result from the failure times of the component at different loadings.

5. A method for predicting a life expectancy of a product, having at least two components, as a function of a predefined loading of the product, comprising:

acting upon the components of the product by different loadings;

operating each component at the different loadings until failure;

storing obtained failure times for each component as a function of each of the loadings;

recording a corresponding end-of-life (EOL) curve of each component as a function of the load-dependent failure times of the component;

ascertaining an EOL curve of the product, so that at each of the different loadings, it includes the EOL curve of a component which has a shortest failure time at the corresponding loading; and

determining an anticipated service life of the product as a functional value of the EOL curve of the product as a function of the predefined loading of the product;

wherein the components of the product are loaded by at least one of (a) a specific, absolute operating temperature and (b) a temperature fluctuation of a particular amplitude within a specific period of time, and

wherein within the scope of a thermal loading of the product, an accelerated reliability verification is conducted at a specific temperature above a specifiable field loading, for a specific period of time less than a duration of a field loading;

the specific temperature and the specific period of time being adjusted to one another such that a mechanical loading of the product and a thermomechanical loading of the product are accelerated by approximately the same factor.

7. A device for predicting a life expectancy of a product, that includes at least two components, as a function of a predefined loading of the product, comprising:

a device configured to retrieve stored end-of-life (EOL) curves of at least two of the components of the product, the EOL curves having been recorded beforehand as a function of ascertained, load-dependent failure times of the components;

a device configured to ascertain an EOL curve of the product, so that at different loadings, it includes the EOL curve of a component which has a shortest failure time at the corresponding loading; and

a device configured to determine an anticipated service life of the product as a functional value of the EOL curve of the product as a function of the predefined loading of the product;

wherein the components of the product are loaded by at least one of (a) a specific, absolute operating temperature and (b) a temperature fluctuation of a particular amplitude within a specific period of time, and

wherein the different loadings are in a number of loading classes, and for each loading class a distance of a duration of a predefined loading of a component to a corresponding value on the EOL curve of the component is determined and summed up according to Palmgren-Miner.

8. The device according to claim 7, wherein the EOL curves of the at least two components have been recorded by a manufacturer of each component.

9. The device according to claim 7, wherein the device is configured to produce a reliability verification for the product and includes a device configured to check if the EOL curve of the product is above a specifiable loading for a specifiable period of time, and if this is so, the reliability verification for the product is considered to be produced.

10. A non-transitory computer-readable storage medium for storing a computer program having a plurality of program codes for implementing, when the program codes are executed on a computer, a method for predicting a life expectancy of a product, having at least two components, as a function of a predefined loading of the product, the method including:

acting upon the components of the product by different loadings;

operating each component at the different loadings until failure;

storing obtained failure times for each component as a function of each of the loadings;

recording a corresponding end-of-life (EOL) curve of each component as a function of the load-dependent failure times of the component;

ascertaining an EOL curve of the product, so that at each of the different loadings, it includes the EOL curve of a component which has a shortest failure time at the corresponding loading; and

determining an anticipated service life of the product as a functional value of the EOL curve of the product as a function of the predefined loading of the product;

wherein the components of the product are loaded by at least one of (a) a specific, absolute operating temperature and (b) a temperature fluctuation of a particular amplitude within a specific period of time, and

wherein the different loadings are in a number of loading classes, and for each loading class a distance of a duration of a predefined loading of a component to a corresponding value on the EOL curve of the component is determined and summed up according to Palmgren-Miner.

11. A method for predicting a life expectancy of a product, having at least two components, as a function of a predefined loading of the product, comprising:

acting upon the components of the product by different loadings;

operating each component at the different loadings until failure;

storing obtained failure times for each component as a function of each of the loadings;

recording a corresponding end-of-life (EOL) curve of each component as a function of the load-dependent failure times of the component;

ascertaining an EOL curve of the product, so that at each of the different loadings, it includes the EOL curve of a component which has a shortest failure time at the corresponding loading; and

determining an anticipated service life of the product as a functional value of the EOL curve of the product as a function of the predefined loading of the product;

wherein the method is used for producing a reliability verification for the product by checking if the EOL curve of the product is above a specifiable loading for a specifiable period of time, and if this is so, the reliability verification for the product is considered to be produced, wherein the components of the product are loaded by at least one of (a) a specific, absolute operating temperature and (b) a temperature fluctuation of a particular amplitude within a specific period of time, wherein the different loadings are in a number of loading classes, and for each loading class a distance of a duration of a predefined loading of a component to a corresponding value on the EOL curve of the component is determined and summed up according to Palmgren-Miner.

12. The method according to claim 11, wherein within the scope of a thermal loading of the product, an accelerated reliability verification is conducted at a specific temperature above a specifiable field loading, for a specific period of time less than a duration of a field loading;

the specific temperature and the specific period of time being adjusted to one another such that a mechanical loading of the product and a thermomechanical loading of the product are accelerated by approximately the same factor.

13. The method according to claim 11, wherein the EOL curves of the components are at least one of (i) extrapolated to lower loadings, and (ii) interpolated between discrete values of the failure times at the different loadings at which the EOL curves are recorded, and wherein an EOL curve of a component includes at least two points that result from the failure times of the component at different loadings.

14. The method according to claim 13, wherein within the scope of a thermal loading of the product, an accelerated reliability verification is conducted at a specific temperature above a specifiable field loading, for a specific period of time less than a duration of a field loading;

the specific temperature and the specific period of time being adjusted to one another such that a mechanical loading of the product and a thermomechanical loading of the product are accelerated by approximately the same factor.