Failure Rate Estimation From Multiple Failure Mechanisms

• US 20150039244A1
• Filed: 07/23/2014
• Published: 02/05/2015
• Est. Priority Date: 07/31/2013
• Status: Abandoned Application

• Current Assignee: Ariel-University Research And Development Company Ltd.
• Original Assignee: Ariel-University Research And Development Company Ltd., BQR Reliability Engineering Ltd.
• Inventors: Bernstein, Joseph
• Application Number:
  US14/338,358
• Publication Number:
  US 20150039244A1
• Time in Patent Office: Days
• US Class Current: 702/34
• CPC Class Codes: G01M 99/007 by applying a load, e.g. for resistance or wear testing G01M99/001 takes precedence; testing the elasticity of structures G01M5/00
• CPC Class Codes: G01M 99/008 by doing functionality tests
• CPC Class Codes: G01N 2203/0067 Fracture or rupture
• CPC Class Codes: G01N 2203/0218 Calculations based on experimental data
• CPC Class Codes: G06F 17/18 for evaluating statistical data , e.g. average values, frequency distributions, probability functions, regression analysis forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: G07C 5/00 Registering or indicating the working of vehicles

Abstract

A computerized method for estimating reliability of a system at normal operating conditions. The computerized method includes enables of selection of a plurality of failure mechanisms FM_j of the system. The failure mechanisms FM_j are estimated to cause failures as time events during use of the system. The failure mechanisms FM_j are modeled by respective failure rate models. Failure rates are represented as matrix elements λ_ij which include respective adjustable parameters intrinsic to the failure rate models. Multiple test conditions TC_iare selected to accelerate the failure mechanisms FM_j. Batches i of the systems are tested during accelerated failure rate tests at the test conditions TC_i respectively.

Claims

1. A computerized method for estimating reliability of a system at normal operating conditions, the computerized method comprising:

enabling selecting of a plurality of failure mechanisms FM_j of the system, wherein the failure mechanisms FM_j are estimated to cause failures as time events during use of the system;

wherein the failure mechanisms FM_j are modeled by respective failure rate models, wherein failure rates are represented as matrix elements λ

_ij which include respective adjustable parameters intrinsic to the failure rate models;

wherein multiple test conditions TC_i are selected to accelerate the failure mechanisms FM_j, wherein batches i of the systems are tested during accelerated failure rate tests at the test conditions TC_i respectively;

wherein accelerated failure data including failures of the systems and respective times of the failures are tabulated for the systems of each batch i during the accelerated failure rate tests;

enabling summing the failure rates λ

_ij over the failure mechanisms FM_j to produce total failure rates λ

_i for each batch i of systems;

enabling simultaneously fitting the total failure rates λ

_i to the accelerated failure data to provide values of the adjustable parameters; and

enabling determining of a reliability metric of the system at the normal operating conditions using the failure rate models with the values of the adjustable parameters.

2. The computerized method of claim 1, wherein said enabling determining of the reliability metric is performed simultaneously for all the selected failure mechanisms.

3. The computerized method of claim 2. wherein the reliability metric is selected from the group consisting of:

a total acceleration factor, a mean time between failures and a total failure rate.

4. The computerized method of claim 1, further comprising:

enabling determining the order of dominance of the failure mechanisms, thereby providing a virtual failure analysis of the system.

5. The computerized method of claim 1, wherein an exponential probability distribution is used to model reliability for the failure mechanisms.

6. The computerized method of claim 5, wherein the failure rates λ

_ij estimated respectively from the failure rate models are additive to produce respectively a total failure rate λ

_i.

7. The computerized method of claim 5, wherein acceleration factors intrinsic to the failure rate models are additive to produce respectively a total acceleration factor.

8. The computerized method of claim 1, wherein a probability distribution other than an exponential probability distribution is used to model reliability respectively for at least one of the failure mechanisms.

9. The computerized method of claim 8, wherein the failure mechanisms are interdependent.

10. The computerized method of claim 8, wherein the failure mechanisms cause non-random failures as the time events.

11. The computerized method of claim 1, wherein the system for which the reliability is being estimated at normal operating conditions is selected from the group consisting of:

a product, equipment, building construction, vehicle, material, mechanical component, electronic device, data network and/or communications network.

12. A computer readable medium encoded with processing instructions for causing a processor to execute the computerized method of claim 1.