Material life order determination method and program

Abstract

To determine, easily in a short time, the order of the lives of different types of materials.SOLUTION: A material life order determination method of an embodiment includes: a step of determining an arithmetic expression for calculating the time from an initial state until when a predetermined deteriorated state is reached, for each material of hot-dip plated steel material, resin material, and coated steel material; and a step of providing the arithmetic expression determined for each material with a physical property value indicating the initial physical property of the corresponding material, and determining the order of the lives of the materials on the basis of the time of the materials calculated from the arithmetic expression.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method and a program for determining a material life ranking. [Background technology]

[0002] For example, when deciding on the materials that will make up each part of a plant (such as the materials that will make up electrical conduits, cables, cable racks, etc.), a long-life, inexpensive material is generally selected from among multiple candidate materials.To select materials, evaluation tests, such as exposure tests and accelerated aging tests (hereinafter referred to as "accelerated tests"), may be conducted to evaluate the lifespan (or durability) of each material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-175554 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-333201 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-238282 Summary of the Invention [Problem to be solved by the invention]

[0004] When selecting materials, it is particularly desirable to be able to compare the lifespans of different materials (multiple materials of different types) and determine their ranking (order when ranked from longest to shortest lifespan). However, because factors that affect the deterioration of each material type are different, simply conducting evaluation tests and comparing the test results will not allow for a correct understanding of the ranking of different materials' lifespans. Even if evaluation tests are conducted, it is difficult to find a test method that can accurately determine the ranking of different materials' lifespans, and the various tests and verification of the test results required for this purpose require a great deal of time and effort.

[0005] The problem to be solved by the present invention is to provide a method and program for determining the order of life spans of materials, which makes it possible to easily determine the order of life spans of different materials in a short time. [Means for solving the problem]

[0006] The method for determining the material life ranking of an embodiment includes the steps of determining an arithmetic formula for calculating the time it takes for each material, such as hot-dip galvanized steel, resin material, and painted steel, to reach a predetermined deterioration state from its initial state, and providing physical property values ​​indicating the initial physical properties of the corresponding material to the arithmetic formula determined for each material, and determining the life ranking of each material based on the time for each material calculated from the arithmetic formula. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a system including facilities and devices used to implement the material life ranking determination method according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of an information processing device that independently performs the process of determining the lifespan ranking of each material. [Figure 3] FIG. 3 is a diagram showing an example of a processing procedure for realizing the material life ranking determination method in the configuration of FIG. [Figure 4] FIG. 4 is a diagram showing a phenomenon that occurs when a hot-dip galvanized steel material deteriorates. [Figure 5] FIG. 5 is a diagram showing a phenomenon that occurs when a resin material deteriorates. [Figure 6] FIG. 6 is a diagram showing the phenomenon that occurs when coated steel deteriorates. [Figure 7] FIG. 7 is a diagram showing an example of the procedure of an accelerated deterioration test (accelerated test). [Figure 8] FIG. 8 is a diagram showing the concept of a graph obtained by measuring the amount of coating loss per unit area at predetermined time intervals in an accelerated test of hot-dip galvanized steel material Mp. [Figure 9]FIG. 9 is a diagram showing the concept of a graph obtained by measuring the amount of strength reduction at predetermined time intervals in an accelerated test of a resin material Mr. [Figure 10] FIG. 10 is a diagram showing the concept of a graph obtained by measuring the number of peeled squares of the coating film in a cross-cut test at predetermined time intervals in an accelerated test of coated steel material Mc. [Figure 11] FIG. 11 shows a specific example of a graph obtained by measuring the change in weight of a hot-dip galvanized steel material Mp at predetermined time intervals in an accelerated test on a sample of the hot-dip galvanized steel material Mp. [Figure 12A] FIG. 12A is a diagram showing a specific example of a graph obtained by measuring the tensile strength of a resin material Mr at predetermined time intervals in an accelerated test on a sample of the resin material Mr. [Figure 12B] FIG. 12B is a diagram showing an example of a logarithmic graph that uses a different scale from that of the graph of FIG. 12A to easily grasp the characteristics of the portion indicated by the box 72 in FIG. 12A. [Figure 13] FIG. 13 shows a specific example of a graph obtained by measuring the peeled area ratio of the paint film of a coated steel material Mc by a cross-cut test at predetermined time intervals in an accelerated test on a coated steel material Mc sample. [Figure 14] FIG. 14 is a diagram showing an example of the configuration of a system including facilities and devices used to implement the material life ranking determination method according to the second embodiment. [Figure 15] FIG. 15 is a diagram showing an example of an information processing device that independently performs the process of determining the lifespan ranking of each material. [Figure 16] FIG. 16 is a diagram showing an example of a processing procedure for realizing the material life ranking determination method in the configuration of FIG. [Figure 17A] FIG. 17A is a diagram showing a specific example of a graph obtained by measuring the tensile strength of a resin material Mr at predetermined time intervals in an immersion test on a sample of the resin material Mr. [Figure 17B] FIG. 17B is a diagram showing an example of a logarithmic graph that uses a different scale from that of the graph of FIG. 17A to easily grasp the characteristics of the portion indicated by the box 75 in FIG. 17A. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings.

[0009] [First embodiment] First, the first embodiment will be described.

[0010] (System Configuration) 1 shows an example of the configuration of a system including facilities and devices used to implement the material life ranking determination method according to the first embodiment. However, the configuration shown here is only an example, and the present invention is not limited to this example, and may be modified as appropriate by partially changing it, etc.

[0011] The system shown in the example of FIG. 1 includes equipment 40 for conducting exposure tests and real-environment simulation tests, and one or more information processing devices (computers) 50 for performing various types of information processing. The information processing device 50 includes, as various functions, an evaluation parameter extraction unit 51, a life calculation formula determination unit 52, and a life ranking determination unit 53. Some or all of these functions are realized as functions of a program executed by a processor of the information processing device 50. In addition, the information processing device 50 includes storage units D1 and D2 for storing various types of information. The storage units D1 and D2 may be located in locations other than the information processing device 50 (for example, in a cloud storage device accessible from the information processing device 50).

[0012] In this embodiment, the equipment 40 and the information processing device 50 are used to perform various processes on three types of materials, namely, hot-dip galvanized steel, resin material, and coated steel, which are used for electrical conduits and the like, so that the ranking of the life spans of the three types of materials can be easily determined in a short time. Note that, although the present embodiment employs hot-dip galvanized steel, which contains zinc, as an example of hot-dip galvanized steel, hot-dip galvanized steel (hot-dip aluminum-plated steel, etc.) containing metals with relatively low melting points, such as aluminum and tin, in addition to zinc, may also be employed instead.

[0013] As shown in FIG. 1, in equipment 40, an exposure test or a simulated real-world test is conducted on samples of each material: hot-dip galvanized steel material Mp, resin material Mr, and painted steel material Mc for testing. However, the accelerated aging test described below is used for the test. Details of the accelerated aging test will be described later. From the test results, deterioration progression data showing changes in the progression of deterioration for each material is obtained. The deterioration progression data includes information showing changes over time in the values ​​of one or more physical properties (physical property values) of the material.

[0014] In the information processing device 50, various information processes are performed by the functions of an evaluation parameter extraction unit 51, a life calculation formula determination unit 52, and a life order determination unit 53.

[0015] The evaluation parameter extraction unit 51 has a function of extracting evaluation parameters for each material from the deterioration progress data for each material and generating time-varying data indicating the time-varying changes in the evaluation parameters for each material. The evaluation parameters are parameters indicating the values ​​of physical properties (physical property values) that are predetermined as being suitable for evaluating the degree of deterioration of the material. Specific examples of evaluation parameters will be described later. The generated evaluation parameters for each material and their time-varying data are stored in the memory unit D1.

[0016] The life calculation formula determination unit 52 has a function of determining a life calculation formula for each material using the evaluation parameters for each material and their time-varying change data stored in the memory unit D1. The life calculation formula for each material is a mathematical formula for calculating the time it takes for each material to reach a predetermined deterioration state from its initial state (e.g., its current state) under a specified environment for each of hot-dip galvanized steel, resin material, and painted steel material, which are prepared in advance as selection candidates for materials used in electrical conduits, etc. Specific examples of the life calculation formula for each material will be described later. The determined life calculation formula for each material is stored in the memory unit D2.

[0017] The life ranking determination unit 53 is a function that determines the ranking of the life of each material using a life calculation formula for each material stored in the memory unit D2, for each of three types of hot-dip galvanized steel material, resin material, and painted steel material that are prepared in advance as selection candidates.

[0018] That is, the life ranking determination unit 53 receives the initial property values ​​of the evaluation parameters of each material (for example, property values ​​indicating the current properties) from the outside, applies the received initial property values ​​to the calculation formulas for each material, and compares the calculation results calculated from the calculation formulas for each material to determine the life ranking of each material. The determination result is output to a display device or the like.

[0019] In this way, once the life calculation formula for each material is determined by the life calculation formula determination unit 52, it becomes possible to easily determine the ranking of lifespans in a short time for various combinations of the three materials, hot-dip galvanized steel, resin material, and painted steel, by using the life calculation formula for each material. However, in this case, the materials to be subjected to life ranking determination must be placed in an environment equivalent to the environment of the above-mentioned test.

[0020] The process of determining the lifespan order of each material performed by the lifespan order determining unit 53 can be performed independently by an information processing device other than the information processing device 50.

[0021] FIG. 2 shows an example of an information processing device that independently performs the process of determining the lifespan ranking of each material.

[0022] The information processing device 60 shown in FIG. 2 includes a lifespan ranking determination unit 61 and a storage unit D3.

[0023] 2 has the same function as the lifespan order determining unit 53 in Fig. 1. This function is realized as a function of a program executed by the processor of the information processing device 60.

[0024] The storage unit D3 stores the same lifespan calculation formula for each material as determined by the above-mentioned lifespan calculation formula determination unit 52. The storage unit D3 may be located in a location other than the information processing device 60, for example, in a storage device on a network (on the cloud) that can be accessed from the information processing device 60.

[0025] The life ranking determination unit 61 in Fig. 2 determines the ranking of the life of each material using a life calculation formula for each material stored in the memory unit D3 for three types of hot-dip galvanized steel material, resin material, and coated steel material that have been prepared in advance as selection candidates. That is, the life ranking determination unit 61 inputs the initial physical property values ​​of the evaluation parameters of each material prepared in advance as selection candidates from the outside, applies each input initial physical property value to the calculation formula for each material (substitutes it for the corresponding variable), and compares the calculation results calculated from the calculation formula for each material to determine the ranking of the life of each material. The determination result is output to a display device or the like.

[0026] (Processing Procedure) FIG. 3 shows an example of a processing procedure for implementing the material life ranking determination method in the configuration of FIG.

[0027] The processes in steps S11 to S15 shown in FIG. 3 will be explained in order.

[0028] In step S11, the deterioration mechanisms of hot-dip galvanized steel, resin, and painted steel materials in the usage environment are identified. The usage environment is assumed to be an indoor humidity environment (an environment with standard indoor humidity). Salt and corrosive gases are also assumed to have standard indoor concentrations.

[0029] 4 to 6 show the phenomena that occur when hot-dip galvanized steel material, resin material, and painted steel material deteriorate.

[0030] In the hot-dip galvanized steel material Mp shown in Figure 4, moisture and oxygen in the air cause corrosion of the coating on the steel material, resulting in a reduction in the coated area as shown by reference numeral 11. Salt also contributes to the progression of this corrosion. Eventually, the steel material, which is the underlying metal, is exposed, and corrosion of the steel material progresses, leading to penetration.

[0031] In the resin material Mr shown in FIG. 5, moisture penetrates into the resin skeleton, causing the strength to decrease, and eventually cracks or breaks as shown by reference numeral 21 occur.

[0032] In the coated steel material Mc shown in Figure 6, moisture and oxygen penetrate the coating, reducing adhesion to the underlying metal, causing peeling of the coating as shown by reference numeral 31 and blistering and cracking of the coating as shown by reference numeral 32. When the underlying metal is exposed, corrosion of that area progresses, eventually leading to perforation.

[0033] As described above, different types of materials exhibit different degradation mechanisms even under the same environment. In other words, even when the same accelerated test is performed, the acceleration of degradation varies for each material. Therefore, it is particularly difficult to obtain results consistent with actual environments, especially for tests with stronger acceleration. Conversely, when performing an accelerated test within a range that matches the actual environment, the acceleration must be weakened, resulting in a longer test time. In light of this, this embodiment performs an accelerated degradation test (hereinafter abbreviated as "accelerated test") on each material, which exhibits a gradual acceleration that ensures that the order of degradation between materials is consistent with that in actual environments, thereby enabling test results with a certain level of accuracy to be obtained in a short period of time.

[0034] In step S12, exposure tests and simulated real-world tests are conducted on the hot-dip galvanized steel material Mp, the resin material Mr, and the painted steel material Mc, respectively, to simulate a real environment. Data on the progression of deterioration is then obtained from these test results. In this example, accelerated tests conforming to ISO 16539 are conducted as simulated real-world tests. Accelerated tests conforming to ISO 16539 are characterized by relatively gradual acceleration. While this example does not assume environments with high salt concentrations, such as coastal areas, some salt is present in real-world environments, so artificial seawater is sprayed. Figure 7 shows an example of the accelerated test procedure.

[0035] As shown in Figure 7, in the accelerated test, each material was sprayed with artificial seawater (amount of salt deposited during artificial seawater spraying: 1000 mg / m 2 ]) (Step S1), followed by repeated wet and dry treatment (here, eight cycles of "dry conditions of 60°C and 35% RH for three hours" and "wet conditions of 40°C and 95% RH for three hours") (Step S2), followed by washing and drying treatment (Step S3). Next, each material is sprayed with artificial seawater (amount of salt deposited when spraying artificial seawater: 1000 [mg / m 2 ]) is performed (step S4), followed by a wet / dry cycle (here, 11 cycles of "a temperature of 60° and a humidity of 35% RH for 3 hours" and "a temperature of 40° and a humidity of 95% RH for 3 hours") (step S5), and then a cleaning and drying process is performed (step S6).

[0036] In step S13, evaluation parameters for each material that change due to deterioration are extracted from the deterioration progress data for each material obtained by the accelerated test, and data on the change over time of the evaluation parameters is obtained. The data on the change over time of the evaluation parameters is used to determine a life calculation formula for each material in the process described below.

[0037] Hereinafter, the evaluation parameters for the hot-dip galvanized steel material Mp, the resin material Mr, and the coated steel material Mc will be explained in order.

[0038] (Evaluation parameters for hot-dip galvanized steel Mp) As mentioned above, the hot-dip galvanized steel material Mp experiences phenomena such as a decrease in the coated area as deterioration progresses. Therefore, in a test of the hot-dip galvanized steel material Mp, if the change in the amount of coating loss per unit area of ​​the hot-dip galvanized steel material Mp is measured over time, it is possible to grasp the progress of deterioration of the coated area. Figure 8 shows the change in the amount of coating loss per unit area [mg / m] at predetermined time intervals in an accelerated test of the hot-dip galvanized steel material Mp. 2 The horizontal axis shows the test time [h], and the vertical axis shows the amount of plating loss per unit area [mg / m 2 The graph shows multiple measurement points taken at different times. P11 in the graph is the measurement start point, P14 is the point where red rust appears, and P12 and P13 are measurement points taken at certain times between P11 and P14.

[0039] As can be seen from the graph in Figure 8, in the time range Tp, the plating loss per unit area [mg / m 2

[0043] It is possible to grasp the trend of change in the weight [g] of the hot-dip galvanized steel material Mp. However, the deterioration of the hot-dip galvanized steel material Mp is not limited to a decrease in the coated portion, but progresses to the point where the steel material, which is the base metal, is exposed and even penetrates. Therefore, in this embodiment, the weight change [g] of the hot-dip galvanized steel material Mp is adopted as an evaluation parameter for the hot-dip galvanized steel material Mp.

[0040] Therefore, during testing of the hot-dip galvanized steel material Mp, data on the change in weight [g] over time can be obtained by measuring the change in weight [g] of the hot-dip galvanized steel material Mp over time.

[0041] (Evaluation parameters for resin material Mr) As mentioned above, the strength of resin material Mr decreases as deterioration progresses. Therefore, by measuring the change in the amount of strength loss over time in a test of resin material Mr, it is possible to grasp the progression of deterioration of resin material Mr. Figure 9 shows the concept of a graph obtained by measuring the amount of strength loss [MPa] at predetermined time intervals in an accelerated test of resin material Mr. The horizontal axis represents the test time [h], and the vertical axis represents the amount of strength loss [MPa]. The graph shows multiple measurement points measured at multiple different times. P21 in the graph represents the measurement start point, P24 represents the predetermined point of strength loss of resin material Mr, and P22 and P23 represent measurement points at certain times between P21 and P24.

[0042] As can be seen from the graph in Figure 9, within the time range Tr, the tendency of change in the strength reduction amount [MPa] can be grasped from P21, P22, P22, P24. The change over time in the strength reduction amount [MPa] of the resin material Mr can be obtained from the tensile strength [MPa] obtained by a tensile test of the resin material Mr. Therefore, in this embodiment, the tensile strength [MPa] of the resin material Mr is adopted as an evaluation parameter for the resin material Mr.

[0043] Therefore, during testing of the resin material Mr, data on the change over time in the tensile strength [MPa] of the resin material Mr can be obtained by measuring the change over time in the tensile strength of the resin material Mr.

[0044] (Evaluation parameters for coated steel material Mc) As previously mentioned, as deterioration progresses, paint peeling and other problems increase with the progression of coating degradation. Therefore, measuring the change over time in the amount of paint peeling per unit area during testing of coated steel Mc can be used to understand the progression of coating degradation. The change over time in the amount of paint peeling per unit area can be determined from the number of peeled squares or the peeled area percentage (%) measured in a cross-cut test (a test in which adhesive tape is applied to a grid-shaped piece of coating and then peeled off to check the adhesion of the coating). Figure 10 shows the concept of a graph obtained by measuring the number of peeled squares of the coating during a cross-cut test at specified time intervals during accelerated testing of coated steel Mc. The horizontal axis represents the test time (h), and the vertical axis represents the number of peeled squares of the coating. The graph shows multiple measurement points taken at different time points. In the graph, P31 represents the measurement start point, P34 represents the point where red rust occurs, and P32 and P33 represent measurement points at certain times between P31 and P34.

[0045] 10, in the time range Tc, the trend of change in the number of peeled squares of the paint film or the peeled area ratio [%] can be grasped from P31, P32, P33, and P34. Therefore, in this embodiment, the number of peeled squares of the paint film or the peeled area ratio [%] obtained by the cross-cut test is used as an evaluation parameter for the coated steel material Mc.

[0046] Therefore, during testing of the coated steel material Mc, data on the change over time in the number of peeled squares or peeled area ratio of the coating film can be obtained by measuring the change over time in the number of peeled squares or peeled area ratio in the cross-cut test.

[0047] In step S14, a life calculation formula for each material is determined from data on the change over time of the evaluation parameters for each material obtained by performing an accelerated test.

[0048] Hereinafter, the life calculation formulas for the hot-dip galvanized steel material Mp, the resin material Mr, and the coated steel material Mc will be explained in order.

[0049] (Life calculation formula for hot-dip galvanized steel material Mp) The life calculation formula for the hot-dip galvanized steel material Mp can be found from the data on the change in weight of the hot-dip galvanized steel material Mp over time described above.

[0050] Figure 11 shows a specific example of a graph obtained by measuring the weight change [g] of a hot-dip galvanized steel material Mp at predetermined time intervals in an accelerated test on a sample of hot-dip galvanized steel material Mp. The horizontal axis represents the test time [h], and the vertical axis represents the amount of coating loss per unit area [mg / m 2 In the graph, multiple measurement points measured at multiple different times are plotted.

[0051] 11, the weight change [g] of the hot-dip galvanized steel material Mp can be expressed as a function (e.g., a linear function) of time [h] as shown by line 71. The function can be obtained by using a mathematical technique such as the least squares method.

[0052] The function shown by line 71 indicates that as time passes, ZnO increases due to the progression of plating corrosion, and the weight of the material increases. The weight increase per unit time indicated by the slope of the function, i.e., the rate of weight change, is 0.0001 [g / h], which converts to a weight increase per year (24 hours x 365 days) of 0.876 [g / y].

[0053] As described above, the deterioration of the hot-dip galvanized steel material Mp does not only result in a decrease in the coated portion, but also in the exposure of the steel material as the base metal, and progresses to the point of penetration. Therefore, in this embodiment, the point at which the coated steel material Mc is penetrated is defined as the end of the life of the coated steel material Mc.

[0054] Assuming that the Zn component of the initial plating eventually becomes ZnO due to deterioration, the weight increase of 0.876 [g / y] corresponds to the amount of corrosion product. The corrosion rate can be calculated from the density of ZnO and the area of ​​the sample. If the density of ZnO is 5.606 [g / cm 3], the corrosion rate is 0.0122 [mm / y]. This is the specific acceleration factor in the life calculation formula for hot-dip galvanized steel material, which will be described later.

[0055] Taking into account the sacrificial protection period of zinc, the corrosion period of steel, and the acceleration factor (10 times) in the accelerated test, the life calculation formula for hot-dip galvanized steel can be expressed by the following formula (1).

[0056] T=(t p / 0.0122)+{(t p / 0.02)+(t m / 0.0009)} / 10 …(1) Here, T is the time from the initial stage to the end of life. p is the initial plating thickness, t m indicates the initial steel thickness. "0.0122" indicates the corrosion rate of the plating [mm / y] in the accelerated test obtained from the graph in Figure 11 mentioned above. "0.02" indicates the rate at which the protective effect of the Zn oxide decreases [mm / y] in the exposure test, and "0.0009" indicates the corrosion rate of the steel [mm / y] in the exposure test. These values ​​are based on the results of exposure tests shown in reliable literature (literature values). "10" indicates the acceleration factor in the accelerated test, and is used to convert the deterioration time in the exposure test to the deterioration time in the accelerated test.

[0057] t in the above equation (1) p , t m By substituting the measured values ​​of the initial coating thickness and the initial steel thickness of the hot-dip galvanized steel prepared as a material selection candidate into the above, the calculation result of equation (1) can be obtained.

[0058] (Life calculation formula for resin material Mr) The formula for calculating the lifespan of the resin material Mr can be found from the data on the change over time in the tensile strength [MPa] of the resin material Mr.

[0059] Figure 12A shows a specific example of a graph obtained by measuring the tensile strength [MPa] of resin material Mr at predetermined time intervals in an accelerated test on a sample of resin material Mr. The horizontal axis represents the test time [h], and the vertical axis represents the tensile strength [MPa]. The graph shows the measurement results measured at multiple different time points (a bar graph showing the distribution of multiple tensile strength measurement points at each time point). Multiple samples were used here.

[0060] 12A, from test time 0 [h] to 500 [h], the tensile strength [MPa] tends to increase as time passes, but after test time 500 [h], the tensile strength [MPa] tends to decrease as time passes, as shown in the area within box 72. In addition, the distribution of tensile strength at each time point tends to become wider (the tensile strength varies more).

[0061] Figure 12B shows an example of a logarithmic graph that uses a different scale from the graph in Figure 12A to easily grasp the characteristics of the part indicated by box 72 in Figure 12A. The horizontal axis represents the test time [h], and the vertical axis represents the tensile strength (here, the average tensile strength at each time) [MPa]. The graph shows measurement results (distribution of multiple measurement points represented as a bar graph) measured at multiple different time points.

[0062] 12B, the tensile strength [MPa] of the resin material Mr can be expressed as a function (e.g., a linear function) of time [h] as shown by line 73. This function can be obtained using a mathematical technique such as the least squares method.

[0063] The function shown by line 73 indicates that the strength of the resin material Mr decreases over time due to the progression of degradation. The decrease in tensile strength per unit time indicated by the slope of the function, i.e., the rate at which the tensile strength changes, is converted to a decrease in tensile strength per year (24 hours x 365 days) of -0.4 [MPa / y]. This forms the intrinsic acceleration coefficient in the formula for calculating the lifespan of the resin material, which will be described later.

[0064] The variation in tensile strength is kept within a certain range until the tensile strength of the resin material Mr drops by approximately 20% from its maximum value, i.e., its initial tensile strength (initial strength), and measurement results can be obtained with sufficient accuracy to determine the lifespan ranking, which will be described later. Therefore, in this embodiment, the point at which the tensile strength of the resin material Mr drops by 20% from its initial strength is defined as the end of the lifespan of the resin material Mr.

[0065] Assuming that the strength starts to decrease 500 hours after the start of the test, the life calculation formula for the resin material can be expressed as the following formula (2).

[0066] T=(500×10+10 (65-0.8A) / 0.4 ) / 8760 …(2) Here, T represents the time from the initial state to the end of life. A represents the initial strength, and 0.8" represents a 20% decrease. "65" represents the maximum tensile strength [MPa] in the accelerated test obtained from the graph in Figure 12B, "0.4" represents the rate of decrease in tensile strength [MPa / y] in the accelerated test obtained from the graph in Figure 12B, and "8760" represents the coefficient used to convert hours [h] to years [y].

[0067] The calculation result of equation (2) can be obtained by substituting the measured value of the initial strength of the resin material prepared as a candidate material for selection into A in equation (2) above.

[0068] (Life calculation formula for painted steel Mc) The formula for calculating the life of the coated steel material Mc can be found from the data on the change over time in the peeled area ratio of the coating of the coated steel material Mc obtained by the cross-cut test described above.

[0069] Figure 13 shows a specific example of a graph obtained by measuring the peeled area ratio [%] of the paint film on a painted steel sample Mc using a cross-cut test at specified time intervals in an accelerated test on the painted steel sample Mc. The horizontal axis represents the test time [h], and the vertical axis represents the peeled area ratio [%]. The graph plots multiple measurement points taken at multiple different times.

[0070] 13, the peeled area ratio [%] of the coating film on the coated steel material Mc can be expressed as a function (e.g., a linear function) of time [h], as shown by line 74. This function can be obtained using a mathematical technique such as the least squares method.

[0071] The function shown by line 74 indicates that as time passes, the amount of peeling of the paint film increases due to the progression of deterioration, and the peeled area ratio [%] of the paint film increases. The increase in the peeled area ratio per unit time indicated by the slope of the function, i.e., the rate at which the peeled area ratio changes, is 43.8 [% / y] when converted to the increase in the peeled area ratio per year (24 hours x 365 days). This forms the intrinsic acceleration coefficient in the formula for calculating the lifespan of coated steel, which will be described later.

[0072] The cross-cut test was performed in accordance with JIS K 5600-5-6. In this test, a photograph of the appearance of the sample after peeling the adhesive tape was processed using an image processing software program to calculate the peeled area ratio. This standard classifies the test results into six levels (classifications 0 to 5) according to the peeled area ratio, and states that classifications 0 to 3, in ascending order of peeled area ratio, are suitable for general use. Therefore, in this embodiment, the standard was set at 35% as shown in classification 4, and the point at which the peeled area ratio exceeded 35% was defined as the end of life of the coated steel material Mc.

[0073] Taking into account the peeled area ratio of the coating film and the corrosion period of the steel material, the calculation formula for the life of the coated steel material Mc can be expressed as the following equation (3).

[0074] T={(35-B) / 43.8}+{t m / (0.0009×10)} …(3) Here, T indicates the time from the initial stage to the end of life. "35" indicates the peeling area ratio [%] that is the standard for life, "B" indicates the initial peeling area ratio, and "t m" indicates the initial steel thickness. "43.8" indicates the rate of increase [% / y] in the spalled area ratio in the accelerated test obtained from the graph in Figure 13. "0.0009" indicates the corrosion rate [mm / y] of the steel in the exposure test, as in equation (1). "10" indicates the acceleration factor in the accelerated test, and is used to convert the deterioration time in the exposure test to the deterioration time in the accelerated test.

[0075] Substitute the initial peeling area ratio measurement value of the coated steel material prepared as a material selection candidate into B in the above equation (3), and calculate t m By substituting the initial measured steel thickness into , the calculation result of equation (3) can be obtained.

[0076] In step S15, the lifespan ranking of each material is determined using the lifespan calculation formula determined for each material for three types of hot-dip galvanized steel material, resin material, and painted steel material that have been prepared in advance as selection candidates. That is, the initial physical property values ​​measured for each material are input to the lifespan calculation formula for each material, and the results calculated from these lifespan calculation formulas are compared, thereby determining the lifespan ranking of each material.

[0077] According to the first embodiment, it is possible to easily determine the order of life spans of three candidate materials, hot-dip galvanized steel, resin material, and painted steel, in a short time.

[0078] [Second embodiment] Next, a second embodiment will be described, focusing on the differences from the first embodiment.

[0079] (System Configuration) Fig. 14 shows an example of the configuration of a system including facilities and devices used to realize the material life ranking determination method according to the second embodiment. Elements common to those in Fig. 1 are given the same reference numerals.

[0080] The system shown in the example of FIG. 14 includes, as test equipment, equipment 40 for performing exposure tests and real-world environment simulation tests (however, accelerated tests are applied) shown in FIG. 1, as well as equipment 41 for performing highly accelerated tests. Highly accelerated tests have the advantage of being more accelerating than accelerated tests, accelerating the progression of deterioration, and shortening the test time. Accelerated tests have been described above. Highly accelerated tests do not necessarily have to be performed on all three types of materials. This embodiment shows an example in which highly accelerated tests are performed only on resin materials. Specific examples of highly accelerated tests will be described later.

[0081] 14 further includes an intrinsic acceleration coefficient calculation unit 54 as an additional function. The process performed by the life order determination unit 53 is also different from that shown in FIG.

[0082] As shown in Figure 14, for each of the test hot-dip galvanized steel material Mp, resin material Mr, and painted steel material Mc, an exposure test or a real-environment simulation test (however, an accelerated test is applied) is conducted in facility 40, and a highly accelerated test is conducted in facility 50. The environment in which the highly accelerated test is conducted may be different from that in which the accelerated test is conducted (for example, the test may be conducted under conditions with higher humidity). From the results of each test, deterioration progression data showing the changes in the progression of deterioration for each material is obtained.

[0083] In the information processing device 50, various information processes are performed by the functions of an evaluation parameter extraction unit 51, an intrinsic acceleration coefficient calculation unit 54, a life calculation formula determination unit 52, and a life order determination unit 53.

[0084] The functions of the evaluation parameter extraction unit 51 and the life calculation formula determination unit 52 are as described above.

[0085] The intrinsic acceleration coefficient calculation unit 54 is a function that calculates the intrinsic acceleration coefficient for each material using the evaluation parameters for each material and their time-varying change data stored in the memory unit D1. The intrinsic acceleration coefficient is a coefficient that indicates the acceleration of deterioration, which differs for each material and test.

[0086] The intrinsic acceleration coefficient is used to determine a coefficient (conversion coefficient) used in a conversion formula for converting the calculation result of the life calculation formula based on the highly accelerated test into the calculation result of the life calculation formula based on the accelerated test. Specific examples of the intrinsic acceleration coefficient, conversion formula, and conversion coefficient will be described later. The determined intrinsic acceleration coefficient for each material is stored in memory unit D2.

[0087] The life calculation formula determination unit 52 has a function of determining a life calculation formula for each material using the evaluation parameters for each material and their time-varying change data stored in the memory unit D1. For hot-dip galvanized steel materials and painted steel materials, a life calculation formula based on accelerated testing is determined, and for resin materials, a life calculation formula based on highly accelerated testing is determined. The determined life calculation formula for each material is stored in the memory unit D2.

[0088] The life ranking determination unit 53 is a function that determines the ranking of the life of each material using the life calculation formula for each material and the specific acceleration coefficient for each material stored in the memory unit D2, for each of three types of hot-dip galvanized steel material, resin material, and painted steel material that are prepared in advance as selection candidates.

[0089] If there is a life calculation formula based on a highly accelerated test among the life calculation formulas for each material stored in the memory unit D2, the life ranking determination unit 53 creates a conversion formula for converting the calculation result of the life calculation formula based on the highly accelerated test into the calculation result of the life calculation formula based on an accelerated test. By using the conversion formula, it is possible to obtain calculation results equivalent to those obtained when an accelerated test is performed.

[0090] In this embodiment, since there is a life calculation formula for resin materials based on a highly accelerated test, a conversion formula for resin materials is created. The conversion formula includes a conversion coefficient for resin materials. The life ranking determination unit 53 determines the conversion coefficient for resin materials based on the inherent acceleration coefficient for resin materials. Details of this will be described later.

[0091] The life ranking determination unit 53 receives the initial property values ​​of the evaluation parameters of each material from the outside, applies the received initial property values ​​to the calculation formula or conversion formula for each material, and compares the calculation results calculated from the calculation formula or conversion formula for each material to determine the life ranking of each material. The determination result is output to a display device or the like.

[0092] In this embodiment, for resin materials, initial physical property values ​​are input to a conversion formula for the resin material, and calculation results are obtained from the conversion formula. For hot-dip galvanized steel materials and painted steel materials, initial physical property values ​​are input to the life calculation formula for each material, and calculation results are obtained from the life calculation formula for each material. These calculation results are then compared to determine the ranking of the lifespans of each material.

[0093] In this way, once the life calculation formula or conversion formula for each material is determined by the life calculation formula determination unit 52, it becomes possible to easily determine the ranking of lifespans in a short time for various combinations of the three types of materials, i.e., hot-dip galvanized steel, resin material, and painted steel, by using the life calculation formula or conversion formula for each material.

[0094] The process of determining the lifespan order of each material performed by the lifespan order determining unit 53 can be performed independently by an information processing device other than the information processing device 50.

[0095] FIG. 15 shows an example of an information processing device that independently performs the process of determining the lifespan ranking of each material.

[0096] An information processing device 60 shown in FIG. 15 includes a lifespan ranking determination unit 61 and a storage unit D3.

[0097] 15 has the same function as the lifespan order determining unit 53 in Fig. 14. This function is realized as a function of a program executed by the processor of the information processing device 60.

[0098] The storage unit D3 stores the life calculation formula for each material determined by the above-mentioned life calculation formula determination unit 52 and the same intrinsic acceleration coefficient as calculated by the above-mentioned intrinsic acceleration coefficient calculation unit 54. The storage unit D3 may be arranged in a location other than the information processing device 60, for example, in a storage device on a network (on the cloud) that can be accessed from the information processing device 60.

[0099] The life ranking determination unit 61 in Fig. 15 determines the ranking of the life of each material using a life calculation formula or conversion formula for each material stored in the memory unit D3 for each of three types of materials prepared in advance as selection candidates: hot-dip galvanized steel, resin material, and coated steel. That is, the life ranking determination unit 61 inputs the initial physical property values ​​of the evaluation parameters of each material prepared in advance as selection candidates from the outside, applies each input initial physical property value to the calculation formula or conversion formula for each material (substitutes it for the corresponding variable), and compares the calculation results calculated from the calculation formula or conversion formula for each material to determine the ranking of the life of each material. The determination result is output to a display device or the like.

[0100] (Processing Procedure) FIG. 16 shows an example of a processing procedure for implementing the material life ranking determination method in the configuration of FIG.

[0101] The processes in steps S21 to S27 shown in FIG. 16 will be explained in order.

[0102] In step S21, similar to step S11 described above, the deterioration mechanisms of the hot-dip galvanized steel material, the resin material, and the painted steel material in the usage environment are identified.

[0103] In step S22, an exposure test or a real-environment simulation test (however, an accelerated test) is performed, similar to step S12 described above. In step S23, a highly accelerated test is performed. In this embodiment, the highly accelerated test is performed only on the resin material.

[0104] In step S24, evaluation parameters for each material that change due to deterioration are extracted from the deterioration progress data for each material obtained by performing each test, and data on the change over time of the evaluation parameters is obtained.

[0105] In step S25, a specific acceleration coefficient indicating the acceleration of deterioration, which differs for each material and each test, is calculated. The processing in step S25 may be performed after the processing in step S26, which will be described later.

[0106] In step S26, a life calculation formula for each material is determined from data on the change over time of the evaluation parameters for each material obtained by performing each test.

[0107] The formula for calculating the life based on the accelerated test is as described above.

[0108] Below, a life calculation formula based on a highly accelerated test performed on the resin material Mr will be explained.

[0109] In this embodiment, an example of a highly accelerated test for the resin material Mr is shown, in which a sample of the resin material Mr is immersed in pure water at room temperature (a test to examine changes in the tensile strength of the resin after immersion in pure water). The immersion test has a stronger acceleration effect than the accelerated test described above, and can speed up the progression of deterioration and shorten the test time.

[0110] (Life calculation formula for resin material Mr) Figure 17A shows a specific example of a graph obtained by measuring the tensile strength [MPa] of resin material Mr at predetermined time intervals in an immersion test on a sample of resin material Mr. The horizontal axis represents the test time [h], and the vertical axis represents the tensile strength [MPa]. The graph shows measurement results measured at multiple different time points (a bar graph showing the distribution of multiple tensile strength measurement points at each time point). Multiple samples were used here.

[0111] As can be seen from the graph in Figure 17A, from test time 0 [h] to 672 [h], the tensile strength [MPa] tends to increase as time passes, but from test time 672 [h] onwards, as shown in the area within box 75, the tensile strength [MPa] tends to decrease as time passes.

[0112] Figure 17B shows an example of a logarithmic graph that uses a different scale from the graph in Figure 17A to more clearly represent the characteristics of the portion indicated by box 75 in Figure 17A. The horizontal axis represents the test time [h], and the vertical axis represents the tensile strength (here, the average tensile strength at each time) [MPa]. The graph shows measurement results (distribution of multiple measurement points represented as a bar graph) taken at multiple different time points.

[0113] 17B, ​​the tensile strength [MPa] of the resin material Mr can be expressed as a function (e.g., a linear function) of time [h] as shown by line 76. This function can be obtained by using a mathematical technique such as the least squares method.

[0114] The function shown by line 76 indicates that the strength of the resin material Mr decreases over time due to the progression of degradation. The decrease in tensile strength per unit time indicated by the slope of the function, i.e., the rate at which the tensile strength changes, is converted to a decrease in tensile strength per year (24 hours x 365 days) of -1.9 MPa / y. This is the intrinsic acceleration coefficient in the resin material life calculation formula described below.

[0115] The variation in tensile strength is kept within a certain range until the tensile strength of the resin material Mr drops by approximately 20% from its maximum value, i.e., its initial tensile strength (initial strength), and measurement results can be obtained with sufficient accuracy to determine the lifespan ranking, which will be described later. Therefore, in this embodiment, the point at which the tensile strength of the resin material Mr drops by 20% from its initial strength is defined as the end of the lifespan of the resin material Mr.

[0116] Assuming that the strength starts to decrease 672 hours after the start of the test, the life calculation formula for the resin material can be expressed as the following formula (4).

[0117] T=(672+10 (56.6-0.8A) / 1.9 ) / 8760 …(4) Here, T represents the time from the initial state to the end of life. A represents the initial strength, and 0.8" represents a 20% decrease. "56.6" represents the maximum tensile strength [MPa] in the accelerated test obtained from the graph in Figure 17B, "1.9" represents the rate of decrease in tensile strength [MPa / y] in the accelerated test obtained from the graph in Figure 17B, and "8760" represents the coefficient used to convert hours [h] to years [y].

[0118] The calculation result of equation (4) can be obtained by substituting the measured value of the initial strength of the resin material prepared as a candidate material for selection into A in equation (4) above.

[0119] In this embodiment, a conversion formula is created for converting the calculation result of the life calculation formula based on the highly accelerated test into the calculation result of the life calculation formula based on the accelerated test for a resin material. The conversion formula can be created based on formulas (2) and (4), and can be expressed as the following formula (5).

[0120] T = 0.74 × (t / 8760) + (10 (1.1a-0.8A) / 0.2b / 8760) …(5) where: t: Strength decrease start time a: Maximum strength b: Gradient of the strength reduction range A: Initial strength These parameters t, a, b, and A are values ​​obtained in an immersion test.

[0121] "0.74" in formula (5) is a ratio coefficient indicating the ratio between the coefficient "500" in formula (2) and the coefficient "672" in formula (4). Also, "1.1" in formula (5) is a ratio coefficient indicating the ratio between the coefficient "65" in formula (2) and the coefficient "56.6" in formula (4). "0.2" in formula (5) is a ratio coefficient indicating the ratio between the coefficient "0.4" in formula (2) and the coefficient "1.9" in formula (4).

[0122] Therefore, for resin materials, by using equation (4), the calculation results of the life calculation formula based on the highly accelerated test can be converted into the calculation results of the life calculation formula based on the accelerated test.

[0123] In step S27, the life ranking of each material is determined using a life calculation formula or conversion formula determined for each material for three types of hot-dip galvanized steel material, resin material, and painted steel material that have been prepared in advance as selection candidates. That is, the initial physical property values ​​measured for each material are applied to the life calculation formula or conversion formula for each material, and the results calculated from these life calculation formulas or conversion formulas are compared to determine the life ranking of each material.

[0124] In this embodiment, for resin materials, calculation results are obtained from the conversion formula for resin materials, while for hot-dip galvanized steel materials and painted steel materials, calculation results are obtained from the life calculation formulas for each material, and the ranking of the lifespan of each material is determined by comparing these calculation results.

[0125] As mentioned above, by using equation (5), the results of immersion tests can be converted into accelerated test results, making it possible to compare them with the results of accelerated tests of materials other than resins. In this immersion test, the strength began to decrease after 672 hours, so it is estimated that it is possible to obtain enough data to determine the slope of strength decrease in tests up to about 2000 hours as a guideline. Therefore, if appropriate highly accelerated tests are conducted on materials other than resins as well as resins, it can be said that it is possible to rank-order materials in tests up to about 2000 hours.

[0126] According to the second embodiment, it is possible to shorten the test time for at least one of the three types of materials: hot-dip galvanized steel material, resin material, and painted steel material.

[0127] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0128] 11...portion where corrosion has occurred, 21...portion where cracks or fractures have occurred, 31...portion where peeling has occurred, 32...portion where cracks have occurred, 40...equipment for exposure tests and real-environment simulation tests, 41...equipment for highly accelerated tests, 50...information processing device, 51...evaluation parameter extraction unit, 52...life calculation formula determination unit, 53...life ranking determination unit, 54...specific acceleration coefficient calculation unit, 60...information processing device, 61...rank determination unit, D1, D2, D3...memory unit, Mp...hot-dip galvanized steel material, Mr...resin material, Mc...painted steel material.

Claims

1. determining an arithmetic expression for calculating the time required for each of hot-dip plated steel material, resin material, and coated steel material to reach a predetermined deterioration state from an initial state; a step of inputting physical property values ​​indicating the initial physical properties of the corresponding materials into the arithmetic formulas determined for each of the materials, and determining the order of the lifespan of each material based on the time for each material calculated from the arithmetic formulas; A method for determining the material life sequence, including:

2. In the step of determining the arithmetic expression, determining the calculation formula using information indicating changes over time in predetermined physical property values ​​obtained by conducting an accelerated aging test for each material; The material life ranking determination method according to claim 1.

3. In the step of determining the arithmetic expression, determining the calculation formula using information indicating a change over time in a predetermined physical property value obtained by performing an accelerated deterioration test or a highly accelerated test that accelerates the progression of deterioration more rapidly than the accelerated deterioration test for each material; In the step of determining the rank, For the materials on which the accelerated aging test has been performed, a process is performed in which the calculation results of the arithmetic formula based on the highly accelerated test are converted into calculation results of the arithmetic formula based on the accelerated aging test, and then the ranking of the lifespan of each material is determined. The material life ranking determination method according to claim 1.

4. In the step of determining the arithmetic expression, For the hot-dip galvanized steel material, the calculation formula is determined using information indicating a change in weight of the hot-dip galvanized steel material. The material life ranking determination method according to claim 1 or 2.

5. In the step of determining the arithmetic expression, For the resin material, the calculation formula is determined using information indicating a change in tensile strength of the resin material. The material life ranking determination method according to claim 1 or 2.

6. In the step of determining the arithmetic expression, For the coated steel material, the calculation formula is determined using information indicating a change in peeling area ratio in a cross-cut test of the coated steel material. The material life ranking determination method according to claim 1 or 2.

7. On one or more computers, a function of storing an arithmetic formula for calculating the time it takes for each material, such as hot-dip plated steel, resin material, and coated steel, to reach a predetermined deterioration state from its initial state; a function of providing a physical property value indicating the initial physical property of the corresponding material to each of the calculation formulas for each material, and determining the order of the lifespan of each material based on the time for each material calculated from the calculation formula; A program to achieve this.

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