# US 2022/0034831 A1 · Method of diagnosing the lifetime of structures and system for diagnosing the same

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- Number: US 2022/0034831 A1
- Document ID: US20220034831A1
- Status: Published application
- Kind: A1
- Application number: 17/178,399
- Filed: 2021-02-18
- Published: 2022-02-03
- Earliest claimed: 2020-07-31
- Assignees: MACTEC Corp.
- Applicants: MACTEC Corp.
- Inventors: Young Suk Kim; Sung Soo Kim
- Web page: https://patentgrep.com/patent/US20220034831A1

## CPC

- G01N 25/20: by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity (calorimeters per se G01K)
- G01N 33/204: Structure thereof, e.g. crystal structure
- G01M 5/0041: {by determining deflection or stress}
- G01M 99/00: Subject matter not provided for in other groups of this subclass
- G01M 99/002: {Thermal testing (flaw detection G01N25/72)}
- 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)}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

The present invention relates to a method of diagnosing the lifetime of a structure and a system for diagnosing the same, the method comprises a step for preparing a structure to be measured; a step for measuring an amount of exothermic or endothermic heat of the structure; a step for measuring an amount of entropy decrease of the structure by using the measured amount of exothermic or endothermic heat; and a step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease.

## Claims

### Claim 1

A method of diagnosing the lifetime of a structure comprising;
a step for preparing a structure to be measured;
a step for measuring an amount of exothermic or endothermic heat of the structure;
a step for determining an amount of entropy decrease of the structure from the measured amount of exothermic or endothermic heat; and
a step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease.

### Claim 2 (depends on 1)

The method of diagnosing the lifetime of the structure of claim 1, wherein the step for diagnosing the remaining lifetime of the structure utilizes a relationship between the amount of entropy decrease or the amount of exothermic or endothermic heat at the end of life and the amount of entropy decrease or the amount of exothermic or endothermic heat at an arbitrary time.

### Claim 3 (depends on 2)

The method of diagnosing the lifetime of the structure of claim 2, wherein the relationship is defined as
tL=k(HL/Hi)[(TP−T)/TP]2 exp [+QΔS/R(1/T−1/TP)],
wherein, k is an intrinsic constant, R is the gas constant, TP is the peak temperature where the maximum amount of heat is released, QΔS is an activation energy for entropy decrease, T is an operating temperature, HL is an amount of exothermic or endothermic heat at the end of life, and Hi is an amount of exothermic or endothermic heat at an arbitrary time.

### Claim 4 (depends on 3)

The method of diagnosing the lifetime of the structure of claim 3, wherein, the activation energy for entropy decrease QΔS is determined by the Kissinger method where the peak temperature where the maximum amount of heat is released is plotted as a function of heating rate.

### Claim 5 (depends on 1)

The method of diagnosing the lifetime of the structure of claim 1, further comprising,
a step for measuring an actual compressive stress value of the structure; and
a step for correcting the predicted remaining lifetime based on the difference between the measured compressive stress value, and the predicted compressive stress value obtaining from the measured amount of exothermic or endothermic heat.

### Claim 6 (depends on 1)

The method of diagnosing the lifetime of the structure of claim 1, wherein measurements of the amount of exothermic or endothermic heat are performed by Differential Scanning calorimetry (DSC), Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), Thermomechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA), or a combination thereof.

### Claim 7

A method of diagnosing the lifetime of a structure comprising;
a step for preparing a structure to be measured;
a step for measuring the magnitude of compressive stress of the structure;
a step for measuring an amount of entropy decrease of the structure by using the measured magnitude of compressive stress; and
a step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease.

### Claim 8 (depends on 7)

The method of diagnosing the lifetime of the structure of claim 7, wherein the step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease utilizes the relationship between the amount of entropy decrease or the magnitude of compressive stress at the end of life of the structure and the amount of entropy decrease or the magnitude of compressive stress of the structure at an arbitrary time, which is defined as:
tL=k(σL/σi)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)],
wherein, k is an intrinsic constant, R is the gas constant, TP is the peak temperature of exothermic heat, QΔS is an activation energy for entropy decrease, T is an operating temperature, σL is a magnitude of compressive stress at the end of life, and σi is a magnitude of compressive stress at an arbitrary time.

### Claim 9

A method of diagnosing the lifetime of a structure comprising;
a step for preparing a structure to be measured;
a step for measuring an amount of lattice contraction of the structure;
a step for measuring an amount of entropy decrease of the structure by using the measured amount of lattice contraction; and
a step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease.

### Claim 10 (depends on 9)

The method of diagnosing the lifetime of the structure of claim 9, wherein the step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease utilizes the relationship between the amount of entropy decrease or the amount of lattice contraction at the end of life of the structure and the amount of entropy decrease or the amount of lattice contraction of the structure at an arbitrary time, which is defined as:
tL=k(ΔaL/Δai)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)],
wherein, k is an intrinsic constant, R is the gas constant, TP is the peak temperature where the maximum amount of heat is released, QΔS is an activation energy for entropy decrease, T is an operating temperature, ΔaL is an amount of lattice contraction of the structure at the end of life, and Δai is an amount of lattice contraction of the structure at an arbitrary time.

### Claim 11

A method of diagnosing the lifetime of a structure comprising;
a step for preparing a structure to be measured;
a step for measuring the physical properties of the structure;
a step for measuring an amount of entropy decrease of the structure from the measured changes in physical properties; and
a step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease,
wherein the physical properties include hardness, thermoelectric power, electrical resistance, Barkuhausen noise amplitude, shear modulus, elastic modulus or Young's modulus, or a combination thereof of the structure.

### Claim 12 (depends on 11)

The method of diagnosing the lifetime of the structure of claim 11, wherein the step for diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease utilizes the relationship between the amount of entropy decrease or the amount of changes in physical properties at the end of life of the structure and the amount of entropy decrease or the amount of changes in physical properties at an arbitrary time, which is defined as:
tL=k(ΔΠL/ΔΠi)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)],
wherein, k is an intrinsic constant, R is the gas constant, TP is the peak temperature where the maximum amount of heat is released, QΔS is an activation energy for entropy decrease, T is an operating temperature, ΔΠL is an amount of changes in physical properties of the structure at the end of life, and ΔΠi is an amount of changes in physical properties of the structure at an arbitrary time.

### Claim 13

A system for diagnosing the lifetime of a structure comprising:
a measuring device which measures an amount of exothermic or endothermic heat of the structure, a magnitude of compressive stress of the structure, an amount of lattice contraction of the structure, or the physical properties of the structure; and
an electronic device for measuring an amount of entropy decrease of the structure by using the measured amount of exothermic or endothermic heat, the measured magnitude of compressive stress, the measured amount of lattice contraction, or the measured changes in physical properties provided from the measuring device, and diagnosing the remaining lifetime of the structure from the measured amount of entropy decrease,
wherein the physical properties include hardness, thermoelectric power, electrical resistance, Barkuhausen noise amplitude, shear modulus, elastic modulus or Young's modulus, or a combination thereof of the structure.

### Claim 14 (depends on 13)

The system for diagnosing the lifetime of the structure of claim 13, wherein the electronic device uses relationships between entropy decrease, an amount of exothermic or endothermic heat, an amount of lattice contraction, an amount of changes in physical properties or a magnitude of compressive stress at the end of life of the structure, and an amount of entropy decrease, an amount of exothermic or endothermic heat, an amount of lattice contraction, an amount of changes in physical properties or a magnitude of compressive stress of the structure at an arbitrary time.

### Claim 15 (depends on 13)

The system for diagnosing the lifetime of the structure of claim 13, wherein the above relationships are defined as tL=k(HL/Hi)[(TP−T)/TP]2 exp [+QΔS/R(1/T−1/TP)], tL=k(σL/σi)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)], tL=k(ΔaL/Δai)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)], or tL=k(ΔΠL/ΔΠi)[(TP−T)/TP]2 exp [+QΔS/R*(1/T−1/TP)],
wherein k is an intrinsic constant, R is the gas constant, TP is the peak temperature where the maximum amount of heat is released, QΔS is an activation energy for entropy decrease, T is an operating temperature, HL is an amount of exothermic or endothermic heat at the end of life of the structure, and Hi is an amount of exothermic or endothermic heat at an arbitrary time, σL is a magnitude of compressive stress at the end of life of the structure, σi is a magnitude of compressive stress at an arbitrary time, ΔaL is an amount of lattice contraction at the end of life of the structure, Δai is an amount of lattice contraction of the structure at an arbitrary time, ΔΠL is an amount of changes in physical properties of the structure at the end of life, and ΔΠi is an amount of changes in physical properties of the structure at an arbitrary time.

### Claim 16 (depends on 13)

The system for diagnosing the lifetime of the structure of claim 13, wherein the activation energy for entropy decrease, QΔS is determined by the Kissinger method where the peak temperature where the maximum amount of heat is evolved is plotted as a function of heating rate.

### Claim 17 (depends on 13)

The system for diagnosing the lifetime of the structure of claim 13, wherein the electronic device measures the actual compressive stress of the structure, and corrects the predicted remaining lifetime from a difference between the measured compressive stress value and the predicted compressive stress value obtaining from the measured amount of exothermic or endothermic heat.