JP3045626B2 - Degradation diagnosis method for laminated products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing deterioration of a laminated product used as a structural material or an insulating material of various devices.

[0002]

2. Description of the Related Art Conventionally, in electrical equipment, a laminated product using a thermosetting resin is often used because of its abundant use results, good productivity, and the ability to manufacture large products. I have. In particular, among the laminates, the most versatile paper phenol laminate is an insulating material and has been often used as a mechanical structural material since ancient times. In general, electrical equipment is operated at a temperature higher than room temperature, so the laminated products used in electrical equipment may gradually deteriorate in mechanical strength due to aging due to long-term operation, causing an accident. is there. For this reason, from the relationship between the residual tensile strength ratio (assuming the strength of a new product is 100) and the heating time (days) shown in FIG. 8, for example, FIG. The heat resistance temperature of the laminate is determined from the life curve shown, and the electric device is operated at a temperature equal to or lower than the heat resistance temperature of the laminate. The residual tensile strength is an example of mechanical strength.
You.

As a conventional method for diagnosing deterioration of a laminated product, for example, a test piece for measuring mechanical strength having a shape as shown in FIG. 10 is cut out from a paper phenol laminated product used in electric equipment, and a tensile tester is used. Generally, a method is used in which the static tensile strength of the test piece is measured using the method, and the degree of deterioration of the test piece is diagnosed from the measured value.

[0004]

Since the conventional method for diagnosing deterioration of a laminated product is constructed as described above, the laminated product used in the electric equipment is removed from the electric equipment, and a predetermined shape is formed from the laminated product. Must be cut out of
There was a problem that the laminate was destroyed.

In addition, the degree of deterioration of a laminated product used in a place where a static stress is applied among electric appliances can be evaluated. There was a problem that it could not be evaluated.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to perform a nondestructive or a very small number of samples to diagnose deterioration of a laminated product used in an electric device. It is still another object of the present invention to provide a method for diagnosing deterioration of a laminated product, which can perform a deterioration diagnosis even when the laminated product is used in a place where electrical equipment is subjected to repeated fatigue stress.

[0007]

According to a first aspect of the present invention, there is provided a method for diagnosing deterioration of a laminated product, wherein a relationship between mechanical strength and hardness when a heating temperature of the laminated product is changed is obtained for each heating temperature. The hardness of the laminate to be measured at a predetermined heating temperature is measured, and the relationship between the measured value and the mechanical strength and hardness is analyzed.
Based on the Arrhenius equation and compensation effect
The out equations to estimate the mechanical strength of該被measurement laminate, is diagnostic of the degree of deterioration of the measured laminate based on this estimate.

In the method for diagnosing deterioration of a laminated product according to the second aspect of the present invention, the relationship between mechanical strength and hardness, and the relationship between mechanical strength and heating time when the heating temperature of the laminated product is changed, The hardness is determined at each heating temperature, and the hardness of the laminate to be measured at a predetermined heating temperature is measured, and the relationship between the measured value and the mechanical strength and hardness can be analyzed.
The mechanical strength of the laminate to be measured is estimated by an equation derived based on the compensation effect and the estimated value, and the degree of deterioration and the remaining life of the laminate to be measured are estimated based on the estimated value and the relationship between the mechanical strength and the heating time. It is to diagnose.

Further, when the degradation diagnostic method of the laminate according to the invention of claim 3, for changing the heating temperature of the laminate, mechanically strong
Obtained relation between degree and linear expansion coefficient for each of the heating temperature, to measure the linear expansion coefficient at a given heating temperature of the measured laminate, and this measured value, the relationship between the mechanical strength and the linear expansion coefficient Based on the estimated mechanical strength of the laminate to be measured,
The degree of deterioration of the laminate to be measured is diagnosed based on the estimated value.

Further, when the degradation diagnostic method of the laminate according to the invention of claim 4, for changing the heating temperature of the laminate, mechanically strong
The relationship between the degree and the linear expansion coefficient, and the relationship between the mechanical strength and the heating time are determined for each heating temperature, and the linear expansion coefficient at a predetermined heating temperature of the laminate to be measured is measured. based on the relationship between the mechanical strength and the linear expansion coefficient, estimates the mechanical strength of該被measurement laminate, and this estimate, mechanical
The purpose of the present invention is to diagnose the degree of deterioration and the remaining life of the laminate to be measured based on the relationship between the strength and the heating time.

Further, the deterioration diagnosis method of the laminate according to the invention of claim 5, the mechanical strength <br/> to the relationship between the inflection point temperature of the thermo-mechanical properties curve in the case of changing the heating temperature of the laminate Determined for each heating temperature, measure the inflection point temperature of the thermo-mechanical characteristic curve at a predetermined heating temperature of the laminate to be measured, this measured value, the inflection point temperature of the mechanical strength and the thermo-mechanical characteristic curve and The mechanical strength of the laminate to be measured is estimated based on the relationship, and the degree of deterioration of the laminate to be measured is diagnosed based on the estimated value.

Further, when the degradation diagnostic method of the laminate according to the invention of claim 6, for changing the heating temperature of the laminate, mechanically strong
Relationship between the inflection point temperature in degrees and thermomechanical properties curve, and the machine
Obtained relation between the intensity retention heating time for each heating temperature, measured inflection point temperature thermomechanical characteristic curve at a given heating temperature of the measured laminate, and this measured value, the machine
Based on the relationship between the strength and the inflection point temperature of the thermo-mechanical characteristic curve,
Estimating the mechanical strength of該被measurement laminate, and this estimate, the machine
The degree of deterioration and the remaining life of the laminate to be measured are diagnosed based on the relationship between mechanical strength and heating time.

Further, when the degradation diagnostic method of the laminate according to the invention of claim 7, for changing the heating temperature of the laminate, mechanically strong
The relationship between the degree and the number of repetitions until breaking, and the relationship between the number of repetitions and the heating time, respectively, and from these relationships, the operating time and the operating time at a predetermined operating temperature of the electrical device on which the laminate is mounted Find the relationship with the number of operations,
Here, the operating temperature of the electrical device is measured, and the remaining life of the laminated product is diagnosed based on the measured value and the relationship between the operating time and the number of operations.

Further, when the degradation diagnostic method of the laminate according to the invention of claim 8, for changing the heating temperature of the laminate, mechanically strong
The relationship between the degree and the number of repetitions until breaking, and the relationship between the number of repetitions and the heating time were determined, and the relationship between the life of the laminate at a predetermined mechanical strength and the heat resistant temperature was determined from these relationships. The operating temperature of the electrical device in the relationship is estimated from the static mechanical strength of the laminate, and the rupture life of the laminate is diagnosed based on the number of operations of the electrical device.

[0015]

In accordance with the first aspect of the present invention, the method for diagnosing deterioration of a laminated article measures the degree of deterioration of the measured laminated article in a non-destructive manner by measuring the hardness of the measured laminated article at a predetermined heating temperature.

In the method for diagnosing deterioration of a laminated product according to the second aspect of the present invention, the degree of deterioration and the remaining life of the measured laminated product are non-destructively measured by measuring the hardness of the measured laminated product at a predetermined heating temperature. Diagnose with

In the method for diagnosing deterioration of a laminated product according to the third aspect of the present invention, the degree of deterioration of the measured laminated product is measured by measuring the coefficient of linear expansion at a predetermined heating temperature. Diagnose with a sample of about mg.

In the method for diagnosing deterioration of a laminated product according to the present invention, the degree of deterioration and the remaining life of the measured laminated product are measured by measuring a linear expansion coefficient of the measured laminated product at a predetermined heating temperature. Diagnosis is based on a sample of only several tens of mg.

In the method for diagnosing deterioration of a laminated product according to the present invention, the temperature of an inflection point of a thermo-mechanical characteristic curve at a predetermined heating temperature of the measured laminated product is measured. The degree of deterioration is diagnosed using only a few tens of mg of sample.

In the method of diagnosing deterioration of a laminated product according to the present invention, the temperature of the inflection point of the thermomechanical characteristic curve at a predetermined heating temperature of the measured laminated product is measured. The degree of deterioration and the remaining life are diagnosed with samples of only several tens of mg.

According to a seventh aspect of the present invention, there is provided a method for diagnosing deterioration of a laminated product, wherein a remaining life of the laminated product is diagnosed by measuring an operating temperature of the electric equipment.

In the method for diagnosing deterioration of a laminated product according to the present invention, the operating temperature of the electrical equipment in the relationship between the life of the laminated product and the heat resistant temperature at a predetermined residual mechanical strength is determined.
By estimating from the static mechanical strength of the laminate, the rupture life of the laminate is diagnosed based on the number of operations of the electric device.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 shows the relationship between the residual tensile strength and the hardness of a heat-degraded paper phenol laminate according to one embodiment of the present invention. For the test, a test piece having a shape shown in FIG. 10 cut out from a paper phenol laminate was used. The heat-aging test specimen was vacuum-dried in advance at 100 ° C. for 3 days, immersed in oil, placed in a special heating tank together with insulating oil, filled with nitrogen gas in the space above the oil surface, and then heated to 160 ° C., 170 ° C., 180 ° C.
The specimen was forcibly heated and degraded at three different heating temperatures, and the tensile strength and hardness of the test piece after heating were measured.

From the test results shown in FIG. 1, there is a good correlation between the tensile strength residual ratio and the hardness, and the hardness tends to decrease almost linearly with the decrease in the tensile strength regardless of the heat deterioration condition. . The hardness tester is small enough to fit in the palm of the hand and has excellent portability. For this reason, if the hardness of the laminated product is measured at the time of periodic inspection of electric equipment, the residual tensile strength of the laminated product can be estimated nondestructively.

From the relationship between the residual tensile strength and the heating time shown in FIG. 8, it is clear that the regression equation of the Arrhenius curve obtained by using the residual tensile strength as a parameter is represented by the following equation (1). Was.

[0026]

(Equation 1)

Here, a and b are constants of the compensation effect, and a = 8.56 × 10 ⁶ h and b = −1.43 × 10 ⁻³ mol / cal. Therefore, if the life time t _{1 at} one point temperature T ₁ is known, the life time t _{2 at} another temperature T ₂ is obtained. Can be requested.

Therefore, by using the equation (1), the operating temperature of the electric equipment can be estimated in the following procedure. The residual tensile strength is estimated from the result of the hardness measurement of the laminate.
Time t ₁ crossing the remaining rate from the 160 ° C. curve in FIG.
Read. The absolute temperature of 160 ° C. was T ₁ , the operation time of the electric equipment was t ₂ , and the operation temperature of the laminate was T ₂ (1)
If you make the equation, T ₂ is required. From the above results, if you know the residual tensile strength of the laminate and the operation time of the electrical equipment,
Estimating the average operating temperature of the electrical equipment using equation (1),
When operated under the same conditions in the future, the time required for the tensile strength remaining rate, which is the life of the laminate, to be reduced, is determined, and the remaining life of the laminate can be diagnosed.

As described above, according to the method for diagnosing deterioration of a laminated product of this embodiment, a good correlation is found between the tensile strength and the hardness of the test piece in which the deterioration conditions such as the heating temperature and the heating time are changed. Thus, the degree of deterioration of the laminated product can be diagnosed nondestructively by measuring the hardness of the laminated product. In addition, the operating temperature of the electrical equipment can be estimated from the regression equation obtained from the Arrhenius curve of the tensile strength residual ratio, and therefore, the time until the tensile strength residual ratio, which is the life of the laminated product, decreases, can be obtained. The remaining life can be diagnosed.

Embodiment 2 FIG. FIG. 2 shows the results of a heat analysis of a paper phenol laminate product that has been heat-degraded as another embodiment of the present invention, and shows the relationship between the residual tensile strength and the linear expansion coefficient. From the test results shown in FIG. 2, the coefficient of linear expansion decreases as the tensile strength decreases as the linear expansion coefficient deteriorates. From this, it is possible to estimate the residual tensile strength of the laminated product by taking a few tens of mg of a sample from the end of the laminated product at the time of periodic inspection of the electric equipment and measuring the linear expansion coefficient. Further, if the operating temperature of the electric device is estimated using the equation (1), the remaining life of the laminated product can be diagnosed. As described above, by measuring the linear expansion coefficient of the laminated product, the degree of deterioration and the remaining life of the laminated product can be diagnosed with a small number of samples.

Embodiment 3 FIG. FIG. 3 shows the results of a test conducted on a heat-degraded paper phenol laminate by a thermal analyzer as another embodiment of the present invention. The tensile strength residual ratio and the inflection point of the thermomechanical characteristic curve (TMA curve) are shown. It shows the relationship between the temperatures. From the test results shown in FIG. 3, there is a tendency that the inflection point temperature of the TMA curve shifts to a higher temperature side as the tensile strength decreases. From this,
By taking a few tens of mg of a small sample from the end of the laminate at the time of periodic inspection of electrical equipment and measuring the inflection point temperature of the TMA curve, the residual tensile strength of the laminate can be estimated. Further, if the operating temperature of the electric device is estimated using the equation (1), the remaining life of the laminated product can be diagnosed. As described above, the TM
By measuring the inflection point temperature of the A curve, it is possible to diagnose the degree of deterioration and the remaining life of the laminate with a small number of samples.

Embodiment 4 FIG. FIG. 4 shows an SN curve of a paper phenol laminate degraded by changing the heating temperature and the heating time as one embodiment of the present invention. FIG. 5 is based on the measurement result of FIG.
For example, a life evaluation curve is shown, assuming that the operating temperature of the electric device is 100 ° C. and the time when the repeated tensile fatigue strength of the laminated product is reduced to 50% of that of a new product is the life. This life evaluation curve was created in the following procedure.

The SN of the 160 ° C. heat-degraded product shown in FIG.
From the curve, the number of repetitions n ₁ , n ₂ and n ₃ crossing the tensile fatigue strength of 50% is read. The same applies to the products deteriorated by heating at 170 ° C. and 180 ° C. FIG. 6 shows the result of plotting the relationship between the heating time and the number of repetitions n ₁ , n ₂ , n _{3 using} the heating temperature as a parameter. The heating times t ₃ , t ₄ , t ₅ , and t ₆ that exceed the number of repetitions 10, 10, ³ , 10 ⁴ , and 10 ⁵ are read from the curve at 160 ° C. in FIG. 1
The same reading is performed for 70 ° C. and 180 ° C. FIG. 7 shows the results of plotting the relationship between the heating temperature (reciprocal of the absolute temperature) and the heating times t ₃ , t ₄ , t ₅ , and t _{6 using} the number of repetitions as a parameter. 7 operation temperature 100 ° C. and repeat count 10, 10 ³ to 10 ^4, 10 ⁵ times crosses heating time t _7, t _8, reads the t _9, t _10. If the number of repetitions is read as the number of operations of the electric device and the heating time is read as the operating time, a life evaluation curve at an operating temperature of 100 ° C. shown in FIG. 5 can be created. If the operating temperature of the electric device is measured from the life evaluation curve in FIG. 5, the remaining life of the laminated product, that is, the rupture life at the limit stress, can be estimated from the number of operations of the electric device.

Embodiment 5 FIG. In the fourth embodiment, when creating the life evaluation curve,
It is necessary to measure the operating temperature of electrical equipment. for that reason,
In this embodiment, the operating temperature of the electric device is accurately estimated from the tensile strength of the laminated product, the number of years of actual use of the electric device, and the life curve of FIG. Therefore, from the average operating temperature of the electric device estimated from the residual mechanical strength of the laminate used in the electric device and the life evaluation curve, the rupture life at the limit stress can be diagnosed by the number of operations of the electric device.

In the above embodiment, the case of a paper phenol laminate was described.
Needless to say, it can also be used for deterioration diagnosis of epoxy resin and plastic laminates. In addition, although the case where the laminated product is used for an electric device has been described, it is needless to say that the laminated product can also be used for deterioration diagnosis of a laminated product used for a device other than the electric device.

[0036]

As described above, according to the first aspect of the present invention, the hardness of the laminate to be measured is measured, and the relationship between the measured value and the mechanical strength and hardness can be analyzed.
Since the degree of deterioration of the laminate to be measured is diagnosed by an equation derived based on the compensation effect, the degree of deterioration of the laminate can be diagnosed nondestructively.

According to the second aspect of the present invention, the hardness of the laminate to be measured can be measured, and the relationship between the measured value and the mechanical strength and the hardness, and the relationship between the mechanical strength and the heating time can be analyzed.
Derived based on the Arrhenius equation and the compensation effect
Since the configuration is such that the degree of deterioration and the remaining life of the laminate to be measured are diagnosed by the formula, there is an effect that the degree of deterioration and the remaining life of the laminate can be diagnosed nondestructively.

According to the third aspect of the present invention, the coefficient of linear expansion of the laminate to be measured is measured, and the degree of deterioration of the laminate to be measured is determined based on the measured value and the relationship between mechanical strength and coefficient of linear expansion. Is diagnosed, there is an effect that the degree of deterioration of the laminated product can be diagnosed with a few samples of about several tens of mg.

According to the fourth aspect of the invention, the coefficient of linear expansion of the laminate to be measured is measured, and the relationship between the measured value, the mechanical strength and the coefficient of linear expansion, and the relationship between the mechanical strength and the heating time are measured. Since the degree of deterioration and the remaining life of the laminate to be measured are diagnosed based on the relationship, there is an effect that the degree of deterioration and the remaining life of the laminate can be diagnosed with a few samples of about several tens of mg.

According to the invention of claim 5, the inflection point temperature of the thermomechanical characteristic curve of the laminate to be measured is measured, and the measured value, the mechanical strength and the inflection point temperature of the thermomechanical characteristic curve are measured. Since the configuration is such that the degree of deterioration of the laminate to be measured is diagnosed based on the relationship, there is an effect that the degree of deterioration of the laminate can be diagnosed with a small sample of about several tens of mg.

According to the sixth aspect of the present invention, the inflection point temperature of the thermomechanical characteristic curve of the laminate to be measured is measured, and the measured value, the mechanical strength and the inflection point temperature of the thermomechanical characteristic curve are measured. And the relationship between the mechanical strength and the heating time, the degree of deterioration and the remaining life of the laminate to be measured is configured to be diagnosed. There is an effect that diagnosis can be made with a small number of samples.

According to the invention of claim 7, the operating temperature of the electric device is measured, and the remaining life of the laminated product is diagnosed based on the measured value and the relationship between the operating time and the number of operations. With such a configuration, there is an effect that the rupture life at the critical stress of the laminated product can be diagnosed and managed based on the number of operations of the electric device.

According to the eighth aspect of the present invention, the predetermined device
Since the operating temperature of the electrical device in the relationship between the service life and the heat-resistant temperature in mechanical strength is estimated from the static mechanical strength of the laminate and the rupture life of the laminate is diagnosed, the limit of the laminate is limited. There is an effect that the rupture life due to stress can be diagnosed and managed based on the number of operations of the electric device.

[Brief description of the drawings]

FIG. 1 is a view showing the relationship between residual tensile strength and hardness of a paper-phenol laminate of Example 1 of the present invention.

FIG. 2 is a diagram showing the relationship between the residual tensile strength and the coefficient of linear expansion of the paper-phenol laminate of Example 2 of the present invention.

FIG. 3 is a diagram showing the relationship between the residual tensile strength of the paper phenol laminate of Example 3 of the present invention and the inflection point temperature of the TMA curve.

FIG. 4 is a diagram showing the relationship between the residual tensile strength of the paper-phenol laminate of Example 4 of the present invention and the number of repetitions until breakage.

FIG. 5 is a diagram illustrating a relationship between an operation time and the number of times of operation of an electric device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the number of repetitions until breaking of the paper phenol laminate of Example 4 of the present invention and the heating time.

FIG. 7 is a diagram showing the relationship between the heating time and the heating temperature of the paper phenol laminate of Example 4 of the present invention.

FIG. 8 is a diagram showing the relationship between residual tensile strength and heating time of a paper phenol laminate used in a conventional method for diagnosing deterioration of a laminate.

FIG. 9 is a diagram showing the relationship between the life and heat-resistant temperature of a conventional paper phenol laminate.

FIG. 10 is a view showing a test piece for measuring mechanical strength.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiaki Wadano 3-3-22 Nakanoshima, Kita-ku, Osaka-shi Within Kansai Electric Power Co., Inc. (72) Kenji Hayashi 3-2-22-2 Nakanoshima, Kita-ku, Osaka-Kansai Electric Power (72) Inventor Kazuya Higashihata 651 Tenwa, Ako City Mitsubishi Electric Corporation Ako Works (72) Inventor Akio Miyamoto 651 Tenka Ako City Mitsubishi Electric Corporation Ako Works (72) Inventor Itakura Isao 651 Tenwa, Ako-shi Ako Works, Mitsubishi Electric Corporation (56) References JP-A-57-104837 (JP, A) JP-A-63-134934 (JP, A) (58) Fields investigated (Int. Cl ^7, DB name) G01N 3/00 -. 3/62 G01M 19/00

Claims (8)

(57) [Claims] 1. A relationship between mechanical strength and hardness when a heating temperature of a laminate is changed, a hardness of a laminate to be measured at a predetermined heating temperature is measured, and the measured value is compared with the mechanical strength and hardness. Arrhenius equation and compensation to analyze the relationship with
A method for diagnosing the degree of deterioration of the laminate to be measured , using an equation derived based on the effect . 2. The relationship between the mechanical strength and the hardness and the relationship between the mechanical strength and the heating time when the heating temperature of the laminate is changed are determined, and the hardness at a predetermined heating temperature of the laminate to be measured is determined. Measured, the measured value, the relationship between the mechanical strength and the hardness, and the relationship between the mechanical strength and the heating time are analyzed.
Can be derived based on the Arrhenius equation and the compensation effect.
A method for diagnosing the degree of deterioration and the remaining life of the laminate to be measured by the following equation . 3. A machine in which a heating temperature of a laminated product is changed.
Determine the relationship between the strength and the coefficient of linear expansion, measure the coefficient of linear expansion at a predetermined heating temperature of the laminate to be measured, based on the measured value, the relationship between the mechanical strength and the coefficient of linear expansion, the laminate to be measured A method for diagnosing deterioration of a laminated product, comprising diagnosing the degree of deterioration of the product. 4. A machine for changing a heating temperature of a laminated product.
Relationship between strength and the linear expansion coefficient, and obtains the respective relationships between the heating time and the mechanical strength was measured linear expansion coefficient at a given heating temperature of the measured laminate, and this measured value, the machine
A method for diagnosing deterioration of a laminated product, comprising diagnosing a degree of deterioration and a remaining life of the laminate to be measured based on a relationship between mechanical strength and a coefficient of linear expansion, and a relationship between mechanical strength and heating time. 5. A machine in which a heating temperature of a laminated product is changed.
Obtained relation between strength and thermo-mechanical properties inflection point temperature curves were measured inflection point temperature thermomechanical characteristic curve at a given heating temperature of the measured laminate, and this measured value, the mechanical strength and heat A method for diagnosing deterioration of a laminated product, comprising diagnosing a degree of deterioration of the measured laminated product based on a relationship with an inflection point temperature of a mechanical characteristic curve. 6. A machine according to claim 1, wherein the heating temperature of the laminate is changed.
Intensity and relationship between the inflection point temperature of the thermo-mechanical characteristic curve, and, machine
Determined 械強degree and the heating time and the relationship of each to measure the inflection point temperature of the thermo-mechanical characteristic curve at a given heating temperature of the measured laminate, and this measurement variable of the mechanical strength and thermal mechanical characteristic curve A method for diagnosing deterioration of a laminated product, comprising diagnosing a degree of deterioration and a remaining life of the measured laminated product based on a relationship between a bending point temperature and a relationship between mechanical strength and heating time. 7. A machine for changing a heating temperature of a laminated product.
The relationship between the strength and the number of repetitions until breaking, and the relationship between the number of repetitions and the heating time are determined, and from these relationships, the operating time at a predetermined operating temperature of the electrical device on which the laminate is mounted is determined. Determine the relationship with the number of times of operation, measure the operating temperature of the electrical device, and this measured value,
A method for diagnosing deterioration of a laminated product, comprising diagnosing a remaining life of the laminated product based on a relationship between the operation time and the number of operations. 8. A machine according to claim 1, wherein the heating temperature of the laminate is changed.
The relationship between the strength and the number of repetitions before breaking, and the relationship between the number of repetitions and the heating time, respectively, and the electrical equipment in the relationship between the life and the heat resistant temperature at a predetermined mechanical strength determined from these relationships. A method for diagnosing deterioration of a laminated product, comprising estimating an operating temperature from static mechanical strength of the laminated product and diagnosing a rupture life of the laminated product.