KR-102963322-B1 - Evaluation Method of Residual Life of Railroad Vehicles by Prediction of Fatigue Strength of Railroad Vehicles Considering Corrosion Effect

Abstract

The present invention provides a method for evaluating the remaining lifespan of a railway vehicle based on a railway vehicle fatigue strength prediction technique that considers the corrosion impact, wherein a corrosion formula considering the characteristics of a coating material for corrosion prevention and the vehicle's operating environment is defined in a parameter form, the amount of corrosion at a specific point in time is calculated, the amount of strength reduction is calculated based on this, the fatigue strength is predicted after converting it into an acting force according to the service period, and the remaining lifespan is calculated based on this.

Inventors

• 전현규

Assignees

• 한국철도기술연구원

Dates

Publication Date

20260511

Application Date

20230519

Claims (7)

1. A first step in which a fatigue load according to the operating environment of a railway vehicle is measured, and the amount of corrosion of the railway vehicle at a first point in time is measured; A second step in which a corrosion progression prediction chart is created based on the amount of corrosion measured in the first step, the characteristics of the coating material, and the operating environment of the railway vehicle; A third step in which the amount of corrosion at a second time point is calculated by the corrosion progression prediction curve created in the second step above, and the strength reduction rate is calculated by applying the calculated value; and A fourth step in which the remaining life of the railway vehicle is calculated based on corrosion progression by performing a cumulative fatigue life evaluation considering the strength reduction rate calculated in the third step above; In the first step above, the measurement of the amount of corrosion at the first time point measures the reduction in thickness of the railway vehicle by ultrasound, and In the second step above, if the corrosion progression prediction chart is defined with the x-axis as the year of use and the y-axis as the corrosion rate, the region where the characteristics of the coating material are maintained and no corrosion occurs is designated as Region I, and the region where the maintenance of the coating material's characteristics ends and corrosion occurs is designated as Region II, the boundary between Region I and Region II is determined by the lifespan of the coating material. The creation of the above corrosion progression prediction curve is such that the slope of the above corrosion progression prediction curve is 0 up to the lifespan of the coating material, and after the lifespan of the coating material, the slope of the above corrosion progression prediction curve is a first-order, second-order, or third-order function, and The slope of the above corrosion progression prediction curve is determined by whether the railway vehicle operating environment is within a certain zone or outside a certain zone in the sea, and In the above third step, the strength reduction rate is determined by the following Equation 1, and (Equation 1) Strength reduction rate = Stress at major locations with corrosion ( t1 ) / Stress at major locations without corrosion ( t2 ) In the above fourth step, the remaining lifespan of the railway vehicle is calculated by calculating a corrosion correction factor based on the amount of corrosion of the railway vehicle calculated at the above second time point, and A method for evaluating the remaining life of a railway vehicle using a railway vehicle fatigue strength prediction technique that considers the degree of corrosion influence, characterized by calculating a corrected dynamic load by applying the amount of corrosion to create an SN curve representing the relationship between N, the number of times the vehicle withstood repetition, and stress S, obtaining N, the number of times the vehicle withstood repetition in the horizontal section of the curve from the SN curve, and converting N into the number of operations to calculate the remaining life of the railway vehicle.
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Description

Evaluation Method of Residual Life of Railroad Vehicles by Prediction of Fatigue Strength of Railroad Vehicles Considering Corrosion Effect The present invention relates to a method for evaluating the remaining lifespan of a railway vehicle using a fatigue strength prediction technique that considers the degree of corrosion influence. More specifically, regarding the evaluation of the remaining lifespan of a railway vehicle, the invention relates to a method for evaluating the remaining lifespan of a railway vehicle using a fatigue strength prediction technique that considers the characteristics of a coating material for corrosion prevention and the vehicle's operating environment, defining a corrosion formula in a parameter form, calculating the amount of corrosion at a specific point in time, calculating the amount of strength degradation based on this, converting it into a force acting over the service period, predicting the fatigue strength, and calculating the remaining lifespan of the railway vehicle based on this. Key parameters determining the expected lifespan of railway vehicles used for extended periods include fatigue loads applied during service operation and thickness degradation caused by metal corrosion. While cumulative fatigue life assessment techniques are used to calculate the expected lifespan under cyclic loading, methods for quantitatively calculating the impact of strength degradation due to corrosion on the expected lifespan are not well-established. Metal corrosion is a major parameter that degrades the strength of structures; if not considered during the fatigue life assessment phase, the evaluation is performed as if the strength remains constant, which has the side effect of overestimating the remaining life. However, to date, no technique has been proposed to incorporate strength degradation caused by corrosion into the fatigue life assessment of railway vehicles. Figure 1 is a configuration diagram of a railway vehicle remaining life evaluation system based on a railway vehicle fatigue strength prediction technique considering the corrosion effect according to one embodiment of the present invention. FIG. 2 is a conceptual diagram of a railway vehicle remaining life evaluation system based on a railway vehicle fatigue strength prediction technique considering the degree of corrosion influence according to one embodiment of the present invention. FIG. 3 is a flowchart of a method for evaluating the remaining life of a railway vehicle according to a railway vehicle fatigue strength prediction technique considering the degree of corrosion influence according to one embodiment of the present invention. FIG. 4 is a diagram illustrating the total load, static load, and dynamic load of a railway vehicle in a method for evaluating the remaining life of a railway vehicle according to a railway vehicle fatigue strength prediction technique considering the corrosion effect according to an embodiment of the present invention. FIG. 5 is an example of a corrosion progression prediction curve according to the service life in a method for evaluating the remaining life of a railway vehicle based on a railway vehicle fatigue strength prediction technique considering the corrosion influence according to one embodiment of the present invention. Figure 6 is an example diagram of the calculation of the fatigue damage rate according to the corrosion period in the method for evaluating the remaining life of a railway vehicle according to the railway vehicle fatigue strength prediction technique considering the degree of corrosion influence according to one embodiment of the present invention. Figure 7 shows that in a method for evaluating the remaining life of a railway vehicle according to a railway vehicle fatigue strength prediction technique considering the degree of corrosion influence according to one embodiment of the present invention, the fatigue load is corrected by considering the amount of corrosion in the applied load. FIG. 8 is an example of an SN curve in a method for evaluating the remaining life of a railway vehicle according to a railway vehicle fatigue strength prediction technique considering the corrosion effect according to an embodiment of the present invention. Figure 9 is a test waveform of Evaluation Example 1 of the present invention. FIG. 10 is a cycle counting diagram of Evaluation Example 1 of the present invention. Figure 11 is a remaining life evaluation diagram of Evaluation Example 1 of the present invention without considering corrosion. Figure 12 shows the calculation of the amount of corrosion at the 30-year mark, calculated considering the corrosion of Evaluation Example 2 of the present invention. FIG. 13 is a remaining lifespan evaluation diagram calculated at the 30-year mark considering the corrosion of Evaluation Example 2 of the present invention. Figure 14 is a remaining lifespan evaluation diagram calculated at the 35-year mark considering the corrosion o