Method for determining remaining useful life of turbine components
First Claim
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1. A method for accumulating, in digital data processing circuits, a measure of cumulative component life damage DT incurred by a turbomachine component during use in an environment wherein creep of material in the component is a major factor in determining remaining useful life of the component, said component exhibiting predetermined but changing rates of creep strain ξ
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k as a function of corresponding successive elapsed time intervals Δ
tk at predetermined operating conditions after initiating each turbomachine cycle of operation, k being an integer 1,2, . . . n, said method comprising the steps of;
(a) for each of successive elapsed time intervals Δ
tk when said predetermined operating conditions prevail, generating in digital data processing circuits an incremental measure of component life damage Δ
Dk equal to the ratio of the time interval Δ
tk to a time-to-rupture trk for the rate of creep strain ξ
k corresponding to time interval Δ
tk ; and
(b) accumulating in said digital data processing circuits said incremental measures of component life damage Δ
Dk to generate therein said cumulative component life damage DT.
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Abstract
A method for determining the portion of life expended for a turbomachine component during a predetermined interval uses the rate at which creep strain accumulates to provide an indication of the portion of life expended.
44 Citations
11 Claims
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1. A method for accumulating, in digital data processing circuits, a measure of cumulative component life damage DT incurred by a turbomachine component during use in an environment wherein creep of material in the component is a major factor in determining remaining useful life of the component, said component exhibiting predetermined but changing rates of creep strain ξ
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k as a function of corresponding successive elapsed time intervals Δ
tk at predetermined operating conditions after initiating each turbomachine cycle of operation, k being an integer 1,2, . . . n, said method comprising the steps of;(a) for each of successive elapsed time intervals Δ
tk when said predetermined operating conditions prevail, generating in digital data processing circuits an incremental measure of component life damage Δ
Dk equal to the ratio of the time interval Δ
tk to a time-to-rupture trk for the rate of creep strain ξ
k corresponding to time interval Δ
tk ; and(b) accumulating in said digital data processing circuits said incremental measures of component life damage Δ
Dk to generate therein said cumulative component life damage DT. - View Dependent Claims (2, 3, 4)
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k as a function of corresponding successive elapsed time intervals Δ
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5. System apparatus for measuring cumulative component life damage to a turbomachine component employed in an environment wherein creep of material in the component is a major factor in determining the remaining useful life of the component, said component exhibiting predetermined but changing rates of creep strain, and hence correspondingly changing times-to-rupture, as a function of respectively corresponding successive elapsed time intervals at predetermined turbomachine component operating conditions, said apparatus comprising:
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(a) means for detecting the occurrence of said predetermined operating conditions; (b) means responsive to said detecting means for measuring said successive elapsed time intervals from each initial occurrence of said predetermined operating conditions so long as such operating conditions persist; (c) means for generating an incremental measure of component life damage for each said elapsed time interval based on the predetermined rate of creep strain and time-to-rupture prevailing during such time interval; and (d) means for generating a measure of cumulative component life damage by accumulating said incremental measures of component life damage. - View Dependent Claims (6, 7)
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8. A method of measuring cumulative component life damage to a turbomachine component employed in an environment wherein creep of material in the component is a major factor in determining the remaining useful life of the component, said component exhibiting predetermined but changing rates of creep strain, and hence correspondingly changing times-to-rupture, as a function of respectively corresponding successive elapsed time intervals at predetermined turbomachine component operating conditions, said method comprising the steps of:
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(a) detecting the occurrence of said predetermined operating conditions; (b) measuring said successive elapsed time intervals from each initial occurrence of said predetermined operating conditions so long as such operating conditions persist; (c) generating an incremental measure of component life damage for each said elapsed time interval based on the predetermined rate of creep strain and time-to-rupture prevailing during such time interval; and (d) generating a measure of cumulative component life damage by accumulating said incremental measures of component life damage.
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9. A machine system for accumulating a measure of cumulative component life damage DT incurred by a turbomachine component during use in an environment wherein creep of material in the component is a major factor in determining remaining useful life of the component, said component exhibiting predetermined but changing rates of creep strain ξ
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k as a function of corresponding elapsed time intervals Δ
tk at predetermined operating conditions after initiating each turbomachine cycle of operation, k being an integer 1,2 . . . n, said system comprising in combination;(a) circuit means for generating an incremental measure of component life damage Δ
Dk for each of successive elapsed time intervals Δ
tk when said predetermined operating conditions prevail, said incremental measure being equal to the ratio of the time interval Δ
tk to a time-to-rupture trk for the rate of creep strain ξ
k corresponding to time interval Δ
tk ; and(b) circuit means for accumulating said incremental measures of component life damage Δ
Dk to generate therein said cumulative component life damage DT.
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k as a function of corresponding elapsed time intervals Δ
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10. A method of measuring in situ the life expended for turbomachine component parts using digital data processing circuits to determine an indication of cumulative component part life damage incurred by cyclic use in an environment wherein creep of material in the component parts is a major factor in determining remaining useful life of the component parts, said parts exhibiting predetermined but changing rates of creep strain and correspondingly changing times-to-rupture, as a function of corresponding successive elapsed time intervals at predetermined temperature and velocity operating conditions, said method comprising the steps of:
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detecting the occurrence of said predetermined temperature and angular velocity conditions; measuring the successive elapsed time intervals upon the detection of each occurrence of said predetermined conditions; generating an incremental measure of a particular component part life damage for each said elapsed time intervals based on the predetermined rate of creep strain and time-to-rupture for said particular part prevailing during such time interval; generating a measure of cumulative component part life damage for said particular part by accumulating said incremental measures of component part life damage; and generating a measure of the estimated remaining useful life of said particular component part. - View Dependent Claims (11)
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Specification