Method and system for determining crack nucleation of a part subject to fretting fatigue
First Claim
1. A method for determining crack nucleation (Ni) for a part subject to fretting fatigue, comprising the steps of:
- A) performing at least one fretting fatigue test on at least one test specimen, wherein said at least one test specimen is comprised of material similar to said part, B) analyzing said at least one fretting fatigue test to determine a variation of stress intensity factor as a function of time (Q{N}) for said at least one test specimen, C) determining a relationship between said stress intensity factor as a function of time (Q{N}) and said crack nucleation (Ni) for said at least one test specimen, and D) determining a variation of stress intensity factor as a function of time (Q{N}) for said part under operating conditions and loads of said part, E) corresponding said variation of stress intensity factor as a function of time (Q{N}) for said part to said variation of stress intensity factor as a function of time (Q{N}) for said at least one test specimen to determine a crack nucleation (Ni) for said part.
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Abstract
A method for determining crack nucleation for a part subject to fretting fatigue. Fretting fatigue tests are performed on at least one test specimen having a material composition similar to the part. The results of the test are analyzed to determine a variation of stress intensity factor as a function of time which may be referred to as (Q{N}) for the test specimen. A relationship is then determined between (Q{N}) and crack nucleation (Ni) for the test specimen. A variation of stress intensity factor as a function of time (Q{N}) for the part is determined based on the operating conditions and loads of the part. The (Q{N}) for the part is then corresponded to the (Q{N}) for the test specimen to determine a crack nucleation value (Ni) for the part. In a preferred embodiment, a computer is programmed to conduct the analysis.
22 Citations
28 Claims
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1. A method for determining crack nucleation (Ni) for a part subject to fretting fatigue, comprising the steps of:
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A) performing at least one fretting fatigue test on at least one test specimen, wherein said at least one test specimen is comprised of material similar to said part, B) analyzing said at least one fretting fatigue test to determine a variation of stress intensity factor as a function of time (Q{N}) for said at least one test specimen, C) determining a relationship between said stress intensity factor as a function of time (Q{N}) and said crack nucleation (Ni) for said at least one test specimen, and D) determining a variation of stress intensity factor as a function of time (Q{N}) for said part under operating conditions and loads of said part, E) corresponding said variation of stress intensity factor as a function of time (Q{N}) for said part to said variation of stress intensity factor as a function of time (Q{N}) for said at least one test specimen to determine a crack nucleation (Ni) for said part. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 26, 27, 28)
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17. A computer system for determining crack nucleation (Ni) in a part subject to fretting fatigue, comprising:
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A) a computer processor, and B) a memory unit connected to said processor and storing a program for controlling the operation of said processor, said processor operative with said program in said memory to;
1) analyze the results of at least one fretting fatigue test to determine the variation of stress intensity factor as a function of time (Q{N}) for at least one test specimen, wherein said at least one fretting fatigue test was performed on at least one test specimen, wherein said at lest one test specimen is comprised of material similar to said at least one part, 2) determine a relationship between said stress intensity factor as a function of time (Q{N}) and said crack nucleation (Ni) for said at least one test specimen, 3) determine a variation of stress intensity factor as a function of time (Q{N}) for said part under the operating conditions and loads of said part, and 4) correspond said variation of stress intensity factor as a function of time (Q{N}) for said part to said variation of stress intensity factor as a function of time (Q{N}) for said at least one test specimen to determine a crack nucleation (Ni) for said part. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification