JP6861661B2 - Squeak crack estimation device and squeak crack estimation method - Google Patents

Description

The present invention relates to a squeak crack estimation device and a squeak crack estimation method for estimating the occurrence of squeak cracks that may occur at the top of the rail and the gauge corner.

The crown, which is the contact portion of the rail with the wheels, is affected by the load from the wheels, friction, and the like, and is subjected to metal fatigue. It is known that when this metal fatigue progresses, cracks called squeak cracks occur. In particular, it is known that cracks called squeak cracks, which are arranged at narrow intervals at a certain angle with respect to the traveling direction of the train, occur mainly at the gauge corners of the outer rail of the curved section.

Since the squeak cracks generated at the gauge corners are biased toward the constant velocity part, it is not easy to find the cracks by the rail flaw detector. Further, the squeak cracks generated on the side of the head may hinder ultrasonic flaw detection by the rail flaw detector because the cracks may be connected to each other and lead to peeling when growing. Therefore, if the occurrence and progress of squeak cracks can be predicted accurately when making a rail maintenance management plan, it will be possible to replace the rails in a timely and appropriate manner, and at the same time, it is expected to have an economic effect as well as ensuring safety.

The present inventors have already proposed a technique for predicting a rail wear shape by multibody dynamics and an analysis result thereof (see Non-Patent Document 1). In addition, a method has been proposed in which the stress and strain generated in the rail are obtained using multibody dynamics analysis software, the crack surface that can occur in the crown of the rail is searched from the obtained stress, and the generation life of squeak cracks is evaluated. (See Non-Patent Document 2).

Masahiro Tsujie, 2 others "Abrasion shape prediction using MBD software and its consideration", JSME Proceedings C, 2013, Vol. 79, No. 806, p.3376-3388 Hiroyuki Matsuda, 5 outsiders "Attempt to predict the life of rail squeak cracks", Proceedings of the 15th Railway Technology and Policy Union Symposium, 2008, p.537-540

However, the above-mentioned conventional proposals either use multibody dynamics analysis software to predict the rail wear shape, or similarly use multibody dynamics analysis software to evaluate the life of cracks. None of the proposals have been able to quantitatively estimate the occurrence of blemishes based on the wear / fatigue balance due to the contact between the rail and the wheel.

Therefore, an object of the present invention is to provide a squeak crack estimation device and a squeak crack estimation method capable of quantitatively estimating the occurrence of squeak cracks.

As a result of diligent research based on the above-mentioned problems, the present inventor can calculate the growth rate of rail wear and the growth rate of cracks in the rail by using the force acting on the rail when the vehicle travels on the rail. It was possible, and it was found that the occurrence of cracks can be estimated based on these relationships.

Therefore, the squeak crack estimation device of the present invention is a squeak crack estimation device that estimates the occurrence of squeak cracks that may occur at the gauge corner portion and the top of the rail, and is a vehicle model data for setting a model of a simulated vehicle and a model of the simulated rail. A storage unit that stores rail model data, and a vehicle motion analysis unit that calculates the force acting on the simulated rail when the simulated vehicle runs on the simulated rail using the vehicle model data and rail model data. The wear progress analysis unit that calculates the wear growth rate of the simulated rail using the force calculated by the vehicle motion analysis unit, and the crack growth speed that can occur in the simulated rail using the force calculated by the vehicle motion analysis unit. It is characterized by having a crack growth analysis unit for calculating the above and a squeak crack estimation unit for estimating whether or not a squeak crack occurs in the simulated rail using the wear growth rate and the crack growth rate.

Here, the wear progress analysis unit is calculated by the rail contact analysis unit and the rail contact analysis unit that calculate the contact stress in the contact surface between the simulated vehicle and the simulated rail using the force calculated by the vehicle motion analysis unit. The configuration may include a wear amount calculation unit that calculates the progress rate of wear of the simulated rail based on the contact stress.

Further, the wear progress analysis unit has a rail model data update unit that updates the rail model data based on the wear amount calculated by the wear amount calculation unit, and the vehicle motion analysis unit is updated by the rail model data update unit. It is possible to calculate the force acting on the simulated rail using the rail model data.

Further, the crack growth analysis unit includes a crack generation condition determination unit that determines whether or not a crack occurs in the simulated rail based on the contact stress calculated by the rail contact analysis unit, and a crack generation condition determination unit. It is possible to have a configuration having a crack growth amount calculation unit for calculating the crack growth rate that can occur on the simulated rail when it is determined that a crack is generated.

The crack growth analysis unit has an initial value setting unit that sets initial values of parameters required for the determination operation by the crack generation condition determination unit, and the crack generation condition determination unit is set by the initial value setting unit. It is possible to determine whether or not a crack occurs in the simulated rail by using the initial value of the parameter.

Further, the squeak crack estimation method of the present invention is executed by a squeak crack estimation device having a storage unit for storing vehicle model data for setting a model of a simulated vehicle and rail model data for setting a model of a simulated rail, and is executed by a gauge corner. This is a squeak crack estimation method that estimates the occurrence of squeak cracks that may occur on the rail and the top of the rail, and is a force that acts on the simulated rail when the simulated vehicle travels on the simulated rail using vehicle model data and rail model data. Is calculated, the calculated force is used to calculate the wear growth rate of the simulated rail, and the calculated force is used to calculate the crack growth rate that can occur in the simulated rail. It is characterized in that it is estimated whether or not squeak cracks occur in the simulated rail using and.

In the squeak crack estimation device of the present invention configured as described above, the vehicle motion analysis unit that calculates the force acting on the simulated rail when the simulated vehicle travels on the simulated rail using the vehicle model data and the rail model data. , The wear progress analysis unit that calculates the wear progress rate of the simulated rail using the force calculated by the vehicle motion analysis unit, and the crack growth that can occur in the simulated rail using the force calculated by the vehicle motion analysis unit. It has a crack growth analysis unit that calculates the speed, and a squeak crack estimation unit that estimates whether or not squeak cracks occur in the simulated rail using the wear growth speed and the crack growth speed.

By doing so, it is possible to quantitatively estimate the occurrence of cracks based on the contact state between the simulated rail and the wheels of the simulated vehicle.

Here, the wear progress analysis unit is calculated by the rail contact analysis unit and the rail contact analysis unit that calculate the contact stress in the contact surface between the simulated vehicle and the simulated rail using the force calculated by the vehicle motion analysis unit. Since it has a wear amount calculation unit that calculates the wear progress rate of the simulated rail based on the contact stress, it is possible to more accurately and quantitatively perform the wear progress rate calculation process of the simulated rail by the wear progress analysis unit. As a result, the occurrence of squeak cracks can be estimated more quantitatively.

Further, the wear progress analysis unit has a rail model data update unit that updates the rail model data based on the wear amount calculated by the wear amount calculation unit, and the vehicle motion analysis unit has the rail updated by the rail model data update unit. Since the force acting on the simulated rail is calculated using the model data, the force acting on the simulated rail can be calculated by accurately feeding back the amount of wear of the simulated rail, and as a result, the occurrence of squeak cracks is more quantified. Can be estimated.

Further, the crack growth analysis unit determines whether or not a crack occurs in the simulated rail based on the contact stress calculated by the rail contact analysis unit, and a crack generation condition determination unit and a crack generation condition determination unit. Since it has a crack growth amount calculation unit that calculates the crack growth rate that can occur on the simulated rail when it is determined that a crack will occur, the crack growth analysis unit can generate a crack growth rate on the simulated rail. The calculation process can be performed more accurately and quantitatively, and as a result, the occurrence of squeak cracks can be estimated more quantitatively.

Then, the crack growth analysis unit has an initial value setting unit for setting the initial value of the parameter required for the determination operation by the crack generation condition determination unit, and the crack generation condition determination unit has the parameter set by the initial value setting unit. Since it is determined whether or not a crack occurs in the simulated rail using the initial value of, the occurrence of cracks can be quantitatively estimated based on the contact state between the simulated rail and the wheel of the simulated vehicle.

Further, in the squeak crack estimation method of the present invention, the force acting on the simulated rail when the simulated vehicle travels on the simulated rail is calculated using the vehicle model data and the rail model data, and the calculated force is used to calculate the simulated rail. Calculate the growth rate of wear, calculate the growth rate of cracks that can occur in the simulated rail using the calculated force, and use the growth rate of wear and the growth rate of cracks to see if creaking cracks occur in the simulated rail. Since it is estimated whether or not it is present, the occurrence of cracks can be quantitatively estimated based on the contact state between the simulated rail and the wheel of the simulated vehicle.

It is a block diagram which shows the schematic structure of the squeak crack estimation system which is this embodiment. It is a flowchart which shows an example of the whole operation of the squeak crack estimation apparatus which is this embodiment. It is a flowchart which shows an example of the crack growth analysis processing of the squeak crack estimation apparatus which is this embodiment. It is a figure which shows an example of the vehicle model data used for the squeak crack estimation apparatus of this embodiment. It is a figure which shows an example of the rail model data used for the squeak crack estimation apparatus of this embodiment. It is a figure which shows an example of the rail model data used for the squeak crack estimation apparatus of this embodiment. It is a figure which shows an example of the rail model data used for the squeak crack estimation apparatus of this embodiment. It is a figure for demonstrating the analysis process in the rail contact analysis part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the analysis process in the rail contact analysis part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the determination process in the crack generation condition determination part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the determination process in the crack generation condition determination part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the determination process in the crack generation condition determination part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the determination process in the crack growth amount calculation part of the squeak crack estimation apparatus which is this embodiment. It is a figure for demonstrating the determination process in the crack growth amount calculation part of the squeak crack estimation apparatus which is this embodiment.

(Outline explanation of squeak crack estimation system)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the squeak crack estimation system S according to the present embodiment.

The squeak crack estimation system S of the present embodiment includes a squeak crack estimation device 10, an input device 11, and a display device 12.

The squeak crack estimation device (hereinafter abbreviated as an estimation device) 10 of the present embodiment is, for example, a personal computer or the like, and includes a control unit 20, a storage unit 21, an input interface (I / F) 22, and an output interface (I / F). F) has 23.

The control unit 20 has an arithmetic element such as a CPU. The illustrated control program stored in the storage unit 21 is executed when the estimation device 10 is started, and based on this control program, the control unit 20 controls the entire estimation device 10 including the storage unit 21 and the like. At the same time, the functions as the display control unit 30, the vehicle motion analysis unit 31, the wear growth analysis unit 32, the crack growth analysis unit 33, and the squeak crack estimation unit 34 are executed. The operation of each of these functional units will be described later.

The storage unit 21 has a large-capacity storage medium such as a hard disk drive and a semiconductor storage medium such as ROM and RAM. The above-mentioned control program is stored in the storage unit 21, and various data required for the control operation of the control unit 20 are temporarily stored.

Further, the storage unit 21 stores vehicle model data 40, rail model data 41, rail shape data 42, stress data 43, wear amount data 44, crack occurrence initial value data 45, and crack growth amount data 46. ing. Of these data, the stress data 43, the wear amount data 44, and the crack growth amount data 46 may be stored in the storage unit 21 at least temporarily. Details of these data will be described later.

The input interface 22 receives various inputs from the input device 11 connected to the estimation device 10 and outputs them to the control unit 20. The input device 11 of this embodiment is, for example, a keyboard, a mouse, or the like, and can perform coordinate designation input on the display screen of the display device 12, which will be described later.

The output interface 23 receives the output signal output from the control unit 20, particularly the display control unit 30, and outputs the output signal to the display device 12. The display device 12 of this embodiment is, for example, a liquid crystal display device, and displays a display screen on a display surface (not shown) based on a display control signal output via the output interface 23.

Next, each functional unit configured in the control unit 20 will be described.

The display control unit 30 generates a display control signal for generating a display screen on the display device 12 as a result of processing by the control unit 20 and each functional unit configured in the control unit 20, and outputs this display control signal. Output to the display device 12 via the output interface 23.

The vehicle motion analysis unit 31 was similarly set by the vehicle model data 40 on the simulated rail set by the rail model data 41 by using the vehicle model data 40 and the rail model data 41 stored in the storage unit 21. The force acting on the simulated rail when the simulated vehicle runs is calculated. Specifically, the calculation process by the vehicle motion analysis unit 31 can be performed by multibody dynamics analysis software represented by SIMPACK and VAMPIRE (both are trade names).

This multibody dynamics analysis software is a tool for efficiently performing dynamic analysis of multibody models including elastic bodies. More specifically, the multibody dynamics analysis software applies the measured shapes of wheels and rails to any vehicle model, and analyzes the behavior of the vehicle when passing through the rails and the contact between the wheels / rails.

In the vehicle motion analysis unit 31 of the present embodiment, rail model data 41 such as the curve radius, alignment, and rail shape of the target section and vehicle model data 40 such as vehicle specifications and train speed are input to the multibody dynamics analysis software. Then, from the traveling simulation result, the force acting on the simulated rail when the simulated vehicle similarly set by the vehicle model data 40 travels on the simulated rail set by the rail model data 41 is calculated. Since the processing content of the vehicle motion analysis unit 31 according to the present embodiment and the multibody dynamics analysis software itself are known, further detailed description thereof will be simplified in this specification.

The wear progress analysis unit 32 calculates the wear progress speed of the simulated rail using the force calculated by the vehicle motion analysis unit 31. The wear progress analysis unit 32 of the present embodiment includes a rail contact analysis unit 32a, a wear amount calculation unit 32b, and a rail model data update unit 32c.

The rail contact analysis unit 32a calculates the contact stress in the contact surface between the simulated vehicle 50 and the simulated rail 51 by using the force calculated by the vehicle motion analysis unit 31. The wear amount calculation unit 32b calculates the progress rate of wear of the simulated rail based on the contact stress calculated by the rail contact analysis unit 32a. The rail model data update unit 32c updates the rail model data 41 (including the rail shape data 42) based on the wear amount calculated by the wear amount calculation unit 32b. Then, the vehicle motion analysis unit 31 calculates the force acting on the simulated rail 51 using the rail model data 41 updated by the rail model data update unit 32c.

The crack growth analysis unit 33 calculates the crack growth speed that can occur in the simulated rail 51 by using the force calculated by the vehicle motion analysis unit 31. The crack growth analysis unit 33 of the present embodiment includes an initial value setting unit 33a, a crack generation condition determination unit 33b, and a crack growth amount calculation unit 33c.

The initial value setting unit 33a sets the initial values of the parameters necessary for the determination operation by the crack generation condition determination unit 33b, which will be described later. The crack generation condition determination unit 33b determines whether or not a crack occurs in the simulated rail 51 based on the contact stress calculated by the rail contact analysis unit 32a. Preferably, the crack generation condition determination unit 33b determines whether or not a crack occurs in the simulated rail 51 by using the initial value of the parameter set by the initial value setting unit 33a. The crack growth amount calculation unit 33c calculates the crack growth rate that can occur on the simulated rail when the crack generation condition determination unit 33b determines that a crack will occur.

The squeak crack estimation unit 34 is the wear growth analysis unit 32, particularly the wear growth rate calculated by the wear amount calculation unit 32b, and the crack growth analysis unit 33, particularly the crack growth amount calculation unit 33c. It is estimated whether or not squeak cracks occur in the simulated rail using the traveling speed.

Each functional unit constituting the control unit 20 will be described in detail later.

(Operation of squeak crack estimation device)
Next, the operation of the squeak crack estimation system S according to the present embodiment will be described with reference to the flowcharts of FIGS. 2 to 3. It should be noted that repetitive explanations may be omitted for the details of the explanations of the respective parts constituting the control unit 20.

FIG. 2 is a diagram for explaining the squeak crack estimation device 10 according to the present embodiment. When the operation of the squeak crack estimation device 10 is started, first, in step S10, the vehicle motion analysis unit 31 performs vehicle motion analysis processing using the vehicle model data 40 and the rail model data 41 stored in the storage unit 21. More specifically, a process of calculating the force acting on the simulated rail when the simulated vehicle travels on the simulated rail 51 is performed.

(A) Vehicle motion analysis The outline of the simulated vehicle and the simulated rail used in step S10 is shown in FIG. 4, and the cross-sectional shape of the simulated rail, that is, the details of the rail shape data 42 are shown in FIGS. 5 to 7. The simulated vehicle 50 (only the bogie portion is shown in FIG. 4) simulated a conventional line commuter vehicle and was run at an average running speed. The wheel shape of the simulated vehicle 50 used the design shape of the modified arc tread, and the cross-sectional shape of the simulated rail 51 adopted that of the JIS 50 kgN rail. In the calculation process by the vehicle motion analysis unit 31, the absolute coordinate system was set with the X-axis as the extension direction of the simulated rail 51, the Y-axis as the sleeper direction of the simulated rail, and the Z-axis as the vertical direction.

In addition to the track specifications, the wear shape of the rail is greatly affected by the conditions of the traveling vehicle, especially the surface where the wheel and the rail are in contact (hereinafter referred to as "wheel tread"). However, like the rail, the wheel tread wears according to the distance traveled, and the situation varies greatly depending on the line section (for example, the ratio of a straight line to a curved line) traveled. Since the vehicle motion analysis unit 31 of the present embodiment pays attention to the shape change of the rail due to wear, the wheel shape does not consider the shape change due to wear, and only the wheel having the tread surface of the design shape passes through. did.

As an example, as shown in FIG. 5, the rail shape data 42, which is the coordinate data constituting the shape of the simulated rail 51, is arranged at 400 points at intervals of 0.4 mm from the top surface of the rail and the side surface 25 mm below the top surface of the rail. When the wear of the rail is not taken into consideration, the rail shape may be modeled as constant as shown in FIG. 6, but when the wear changes in the longitudinal direction as in the vehicle motion analysis unit 31 of the present embodiment, the wear may change. , The cross-sectional shape must be changed sequentially. Therefore, in the present embodiment, the points of interest in the rail cross section are arranged in the longitudinal direction of the rail, for example, every 5 m, and the cross-sectional shapes of the adjacent points of interest are spline-interpolated to generate the rail cross section in the longitudinal direction (FIG. 7). .. The rail shape data 42 may be stored in the storage unit 21 in advance, or may be created in the process of step S10. As will be described later, the rail shape data 42 is updated by the rail model data updating unit 32c.

(B) Rail Contact Analysis Next, in step S11, the rail contact analysis unit 32a of the wear progress analysis unit 32 uses the force calculated by the vehicle motion analysis unit 31 in step S10 to use the simulated vehicle 50 and the simulated rail 51. Performs a process of calculating the contact stress in the contact surface with.

The vehicle motion analysis unit 31 calculates the contact position between the wheels of the simulated vehicle 50 and the simulated rail 51 and the force acting on the contact portion, but detailed results cannot be obtained for the distribution of contact stress. Therefore, in the rail contact analysis unit 32a of the present embodiment, the stress distribution in the contact surface was calculated using the contact radius in the cross-sectional direction calculated by Hertz's contact theory.

ここでａ（ｉ）、ｂ（ｉ）は、それぞれ接触部ＣＰの楕円の長径（レール長手方向）、短径（断面方向）の接触半幅である。 As a result of the analysis by the vehicle motion analysis unit 31, it is assumed that the contact point C and the force N in the normal direction at the contact point (hereinafter referred to as "contact force") N are given as shown in FIG. The observation point in FIG. 8 is the YY coordinate system of the cross-sectional shape of the simulated rail 51. In the rail contact analysis unit 32a of the present embodiment, the contact points C are considered up to 10 points as an example, and 1, 2, 3, ..., I, ..., Respectively toward the positive direction of the Y axis, respectively. It is set to 10. The observation points constituting the cross-sectional shape of the simulated rail 51 are 1, 2, 3, ..., I, ..., 400 from the negative direction of the Y axis. An enlarged view of the contact portion CP of FIG. 8 is shown in FIG. At each contact point C, the axis parallel to the contact surface is defined as η (i), and the contact force N is considered to be distributed in an elliptical shape with the center of the contact point C as the maximum value.
_{The maximum stress PMax} (i) at each contact point can be expressed by using the contact force N (i) between the wheel of the simulated vehicle 50 and the simulated rail 51 calculated by the vehicle motion analysis unit 31. Assuming that the number of contact points C between the rail and the wheel is Q, the maximum stress is considered as follows.

Here, a (i) and b (i) are contact half widths of the ellipse of the contact portion CP in the major axis (rail longitudinal direction) and minor axis (cross-sectional direction), respectively.

ここでＣ（ｉ）は車両運動解析部３１により算出される接触点中心である。 Assuming that the angle formed by the axis η (i) parallel to the contact surface and the Y axis is θ _i , the contact range on the Y axis is expressed by the following equation.

Here, C (i) is the center of the contact point calculated by the vehicle motion analysis unit 31.

Since the contact stress is distributed in the contact surface as shown in FIG. 9, it can be described by the following equation.

The contact stress P (i, j) calculated by the equation (4) is stored in the storage unit 21 as stress data 43 at least temporarily.

(C) Wear amount calculation Next, in step S12, the wear amount calculation unit 32b of the wear progress analysis unit 32 is based on the contact stress P (i, j) calculated by the rail contact analysis unit 32a in step S11. The progress rate of wear of the simulated rail 51 is calculated.

ただし、Ｗは摩耗体積、Ｆは接触荷重、Ｈは接触する物体のうち柔らかい方の材料硬さ（ここではレール材のビッカーズ硬さ）である。またsはすべり距離である。ｋは摩耗係数であり、材料固有の値である。 Wear due to rolling contact between wheels and rails is considered to be mainly adhesive wear, and several wear rules representing adhesive wear have been proposed so far. In the wear amount calculation unit 32b of the present embodiment, Archard's wear prediction formula (JF Archard, “Contact and Rubbing of Flat Surface”, J.Appl.Phys, Vol.24, 1953, pp.981-988) is applied. did. Archard's wear prediction formula is given by the following formula (5).

However, W is the wear volume, F is the contact load, and H is the material hardness of the softer of the objects in contact (here, the Vickers hardness of the rail material). Also, s is the sliding distance. k is a wear coefficient, which is a value peculiar to the material.

ここでｄは摩耗深さ、Ｐは接触面圧、δは単位長さあたりのすべり距離（すべり率と等価）であり、本発明者らが行った室内摩耗試験結果より2.54×10^-4とした。 From the formula (5), the wear depth at each contact point C of the simulated rail 51 is given by the following formula (6).

Here, d is the wear depth, P is the contact surface pressure, and δ is the slip distance per unit length (equivalent to the slip ratio), which is 2.54 × 10 ^{-4 from the results of the indoor wear test conducted by the present inventors.} did.

Since the wear shape prediction model in the wear amount calculation unit 32b of the present embodiment focuses on the macroscopic wear between the wheels / rails, the slip / fixation region in the contact surface is not distinguished and is constant. did.

The wear amount (wear depth d) calculated in step S12 is stored in the storage unit 21 at least temporarily as wear amount data 44.

Next, in step S13, the crack growth analysis unit 33 calculates the crack growth speed that can occur in the simulated rail 51 using the force calculated by the vehicle motion analysis unit 31 in step S10.

(D) Crack Growth Analysis The details of the crack growth analysis process in step S13 will be described with reference to the flowchart of FIG.

(D-1) In the initial value setting step S20, the initial value setting unit 33a of the crack growth analysis unit 33 initially determines the parameters required for the determination operation by the crack generation condition determination unit 33b, which is performed in step S21 described later. Set the value. The initial values set by the initial value setting unit 33a are parameters related to the calculation of the distribution of the ferrite phase, the pearlite phase, and the non-metallic material in the simulated rail 51, the distortion of the crystal grains, the origin of the crack, and the direction of the slip line. .. The initial value setting unit 33a sets these parameters by generating random numbers.

The initial value of the parameter set by the initial value setting unit 33a is stored in the storage unit 21 at least temporarily as the crack occurrence initial value data 45.

(D-2) Determination of Crack Generation Condition Next, in step S21, the crack generation condition determination unit 33b of the crack growth analysis unit 33 uses the initial values of the parameters set by the initial value setting unit 33a. In step S11, the condition for crack generation in the simulated rail 51 is calculated based on the contact stress P calculated by the rail contact analysis unit 32a, and then in step S22, the crack generation condition determination unit 33b comes to the simulated rail 51. Determine if a crack occurs. Then, if it is determined that a crack has occurred in the simulated rail 51 (YES in step S22), the program proceeds to step S23, and if it is determined that no crack has occurred in the simulated rail 51, the program returns to step S14.

The distribution of the ferrite phase, pearlite phase, and non-metallic material that are the seeds of cracks, and the deflection direction (layer direction) and boundary direction that are the crack directions (slip lines) are randomized by the initial value setting unit 33a in step S20. It is determined, but whether or not these cracks actually grow depends on whether or not the crack direction exists within a predetermined threshold angle with respect to the plastic flow direction. When this condition is satisfied, the crack seeds of the crystal grains are activated, and the crack generation condition can be evaluated.

The rail steel in the simulated rail 51 is composed of (a) a ferrite phase, (b) a pearlite phase, and (c) a non-ferrous metal material. Here, the activation conditions and growth rules of the crack species in each phase will be described.

(A) Ferrite phase In the ferrite phase, cracks grow inside the crystal grains. It has crack seeds inside the crystal grains, and the deflection direction (layer direction) is the crack direction (slip line). If the crack direction is within a defined threshold angle with respect to the plastic flow direction, the crack seeds are activated.

(B) Pearlite phase In the pearlite phase, cracks grow inside or at the boundaries of the crystal grains. In the pearlite phase, the crack seeds are placed on the boundary. The rules for generating crack seeds in the pearlite phase are illustrated as shown in FIG.

The crack seed 60 in the pearlite phase is the intersection of a straight line 63 connecting a randomly generated point 61 and a center of gravity 62 and a boundary line 64 (step 1). In the case where the pearlite phases are adjacent to each other, if the crack seed 60 of the adjacent element already exists on the boundary line 64, the crack seed 60 is generated on the other boundary line 64 (step). 2).

The activity and development of crack seeds in the pearlite phase shall be subject to the following rules.
(1) Interface extension crack: When the direction of the grain interface where the crack seeds are arranged is within the threshold angle defined with respect to the plastic flow direction, the crack seeds are activated and the cracks are crystal grains. Proceed on the interface.
(2) Internally propagated cracks in crystal grains: If the deflection direction (layer direction) of the crystal grains is within the threshold angle set with respect to the plastic flow direction, the crack seeds are activated and cracks propagate in the crystal grains. .. In (1) and (2), (1) has priority.
(3) When a crack that has propagated at the grain interface of the pearlite phase collides with the ferrite phase, it is assumed that the crack has stopped until it merges with the crack that has propagated in the ferrite phase.
(4) Use the same crack growth rule as the ferrite phase.

(C) Non-metallic material The non-metallic material shall be present only in the pearlite phase and its position shall be the position of the crack seed. Therefore, the conditions for generating seeds of non-metallic materials are the same as those for the pearlite phase. Among the several pearlite phases that have come to include non-metallic materials is the image that the species is used as a seed for non-metallic materials.

Cracks in non-metallic materials propagate at grain boundaries. If the direction of the grain interface of the crack seed is within the threshold angle defined with respect to the plastic flow direction, the crack seed is activated.

The crack growth rule in step 1 is the same as that of the pearlite phase, but the idea of step 2 is different. When the cumulative shear strain becomes large, the deformation progresses, and the longer diagonal line of the non-metal after the deformation exceeds the specified value (three times the crystal grain size), the crack grows according to the rule of step 2.

For the crack in step 2 in a non-metallic material, the direction in which the tips of the connected cracks are connected is the crack direction. If this direction is not within the specified threshold angle with respect to the plastic flow direction, it shall not advance.

In the crack generation condition determination unit 33b of the present embodiment, the cumulative shear strain is calculated for the non-metallic material, and the deformation amount is calculated from the value. As shown in FIG. 11, when a square is distorted into a rhombus due to deformation, the threshold angle defined with respect to the plastic flow direction becomes apparently large. Further, when proceeding to step 2, the connection is determined based on the tip distance of the crack, and this distance also changes with the deformation. Re-evaluating the threshold angle and crack tip distance with deformation is called dynamic determination of species and distance.

で補正させる。先端座標は１次変換行列

により写像させた点で評価する。 The threshold angle θ is

To correct with. Tip coordinates are linear transformation matrix

Evaluate by the point mapped by.

The crack generation conditions determined by the crack generation condition determination unit 33b of the present embodiment are (a) crack generation conditions due to ratcheting, (b) crack generation conditions due to fatigue, and (c) these. There are three conditions, the earliest of them. Ratcheting is a condition when the cumulative shear strain exceeds a specified value, and is a condition generated by deformation. Fatigue is a condition when the actual number of cycles exceeds the limit number of cycles calculated by various models.

(A) Crack generation conditions by ratcheting (a-1) Cumulative shear strain model Material properties (initial shear yield stress, fracture limit shear strain) are assigned to each element of ferrite and pearlite. The initial shear yield stress follows the following equation.
[Number 8]
k ₀ = 0.8 × 10 ⁶ H _n (7)
here,
k ₀ : Initial shear yield stress H _n : Nano hardness. H _n is a ferrite phase or a pearlite phase and has the following values.

The limit shear strain γ _c of fracture shall be the following value for both ferrite and pearlite.
[Number 9]
γ _c = 11 (8)

ここで、

である。 In the crack generation condition determination unit 33b of the present embodiment, a model in which shear strain accumulates as the load cycle progresses is adopted. The model adopts the following.

here,

Is.

Cracks occur when the ^{total cumulative shear strain γ ij} in each element of ferrite pearlite obtained by equation (7) _{exceeds the fracture limit shear strain γ c} initially assigned to each element. And.

The parameters α and β are ferrite and pearlite and have the following values.

The cumulative shear strain is calculated from the stress value of the wheel / rail contact calculated by the rail contact analysis unit 32a. Although the calculation of cumulative shear strain is the required maximum orthogonal shear stress τ ^j _{zx (max)} is the stress value using the results of the wheel / rail contact analysis by rail contacting analyzer 32a.

Here, the cumulative shear strain also considers the grain boundary ferrite portion. In the case of the ferrite phase, the cumulative shear strain of the crystal grains calculated from the material characteristics of ferrite is used, but in the case of the pearlite phase, the volume ratio is the cumulative shear strain obtained from the material characteristics of the grain boundaries and the crystal grains. Multiply and add up.

Here, if the cumulative shear strain of pearlite is rp and the cumulative shear strain of the ferrite phase is rf, the total cumulative shear strain is
[Number 12]
rp × (1-Ab / Aa) + rf × Ab / Aa (12)
Will be. The cumulative shear strain obtained by such calculation is retained in each crystal grain. The value of the total cumulative shear strain obtained above is used to determine the occurrence of cracks due to ratcheting.

上記の式は式（７）〜（１１）に対応したものである。これらの式からある行（同じ高さの粒子群）のひずみを求めることができ、車輪通過ごとの垂直方向の変位は、Δε^ｉｊ×（ある行の高さ）で求められる。 (A-2) Cumulative vertical strain model Although it is not related to the crack generation conditions, the same method as the cumulative shear strain is used when calculating the vertical deformation.

The above equation corresponds to equations (7) to (11). From these equations, the strain of a certain row (particle group of the same height) can be obtained, and the vertical displacement for each wheel passage is calculated by Δε ^ij × (height of a certain row).

ここで、すべり帯の長さｄは、図１２に示すように、各結晶粒において、重心６２を通り塑性流動方向に伸ばした直線６３がそれぞれ界面６４と交わる線分の長さとする。 (B) Conditions for crack generation due to fatigue Crack generation due to fatigue shall occur when the number of load cycles exceeds N obtained by the following equation (17).

Here, as shown in FIG. 12, the length d of the slip zone is the length of a line segment in which a straight line 63 extending through the center of gravity 62 and extending in the plastic flow direction intersects the interface 64 in each crystal grain.

Further, the decomposition shear stress range Δτ _res is calculated by the following equation (18).
[Number 15]
Δτ _res = τ _max −τ _min (18)
Here, τ _max and τ _min can be obtained from the results of wheel / rail contact analysis by the rail contact analysis unit 32a. The coordinates for stress evaluation are virtual crack seeds, and the direction is virtual crack growth method.

(D-3) In the crack growth amount calculation step S23, since it was determined by the crack generation condition determination unit 33b that a crack will occur (YES in step S22), the crack growth amount calculation of the crack growth analysis unit 33 The unit 33c calculates the growth rate of cracks that can occur in the simulated rail 51.

The crack growth rules for the crack growth amount calculated by the crack growth amount calculation unit 33c are common to the ferrite phase, the pearlite phase, and the non-metallic material.

The crack growth algorithm in the crack growth amount calculation unit 33c of the present embodiment is HA Suharutono, K. Potter, A. Schram and H. Zenner, “Multiaxial Fatigue and Deformation: Testing and Prediction”, ASTM STP 1387, Based on 2000, pp.323.

式（２０）は、スリップラインに沿って働くせん断応力の変動幅を表しており、Δσ_ｘ、Δσ_ｙ、Δσ_ｘｙはＸ、Ｙ軸で定義される垂直応力とせん断応力の変動幅である。き裂進展量算出部３３ｃでは、き裂発生条件判定部３３ｂで求めた値を用いてき裂進展量を算出する。 (A) First step As shown in FIG. 13, the crack extending in the crystal grain is from the origin (crack seed) 60 of the crack 65 along the slip line (crack direction) 66. Proceed according to 19). Here, a is the length of the crack and N is the number of stress loads.

Equation (20) represents the fluctuation range of the shear stress acting along the slip line, and Δσ _x , Δσ _y , and Δσ _xy are the fluctuation widths of the normal stress and the shear stress defined on the X and Y axes. The crack growth amount calculation unit 33c calculates the crack growth amount using the value obtained by the crack generation condition determination unit 33b.

ただし、複数のき裂が結合した場合、き裂の長さを、最も長くなる先端同士の直線距離で定義する。また、き裂面はその直線方向で定義し、θはその角度である。き裂の角度が塑性流動方向に対し定められた閾値角度内に含まれない場合は進展しない。Δεは、この面にかかる垂直歪みの変動幅である。 (B) Second step The plurality of cracks are bonded to each other when the distance between the tips thereof is within 25% of the crystal grain size and the length of the crack itself reaches 75% of the crystal grain size. However, the shape of the crack immediately before the bond does not change after the bond. Further, when the crack length reaches three times the crystal grain size, the crack grows according to the following equation (21).

However, when multiple cracks are combined, the length of the crack is defined by the linear distance between the longest tips. The crack surface is defined in the linear direction, and θ is the angle. If the crack angle is not within the threshold angle defined for the plastic flow direction, it will not grow. Δε is the fluctuation range of the vertical distortion applied to this surface.

At this stage, since the vertical strain with respect to the crack surface propagates only during tension, when the strain value in Eq. (22) becomes negative, Δε is calculatedly replaced with 0. When the crack growth calculated by the equation (19) is larger than the result of the equation (21), the value of the equation (19) is used.

In the crack growth amount calculation unit 33c of the present embodiment, it is possible to give the distortion of the crystal grains from the regular hexagonal shape as the initial structure. This distorted shape is given using an algorithm based on Toshihiko Hoshide, Kousuke Kawabata, Tatsuo Inoue, JSME Proceedings A, Vol. 55, 1989, pp.222, as shown in FIG. , Each vertex of the hexagon is randomly moved within the range of 0 <r <ζ L. Here, L is the length of one side of a regular hexagon, and determines the size of each crystal grain. ζ is a parameter representing the magnitude of distortion.

If the crystal grains are distorted from a regular hexagon, the crystal grain size cannot be defined correctly. Therefore, in the present embodiment, the crystal grain size used for determining the crack bond and selecting the crack growth rate equation is defined as twice the radius before the crystal grains are distorted (that is, 2 L).

In the crack growth amount calculation unit 33c of the present embodiment, the following wear model is implemented. Since it is physically impossible for cracks to grow in the worn region, the crack growth amount calculation unit 33c performs a process in which the cracks in the worn region do not grow.

この摩耗深さΔｚ（ｘ，ｙ）は接触面が一要素分移動する際に摩耗する量である。車輪の接触面は、ある面積を持って移動するため、車輪通過１サイクルにおいて一要素が摩耗する量は、接触面積分を重ね合わせた量となる。 The wear depth of the Archard wear model described above can be calculated by the following formula.

This wear depth Δz (x, y) is the amount of wear when the contact surface moves by one element. Since the contact surface of the wheel moves with a certain area, the amount of wear of one element in one cycle of passing the wheel is the sum of the contact areas.

ここで、ｚは接触面からの深さ、Ａ＝２、ｄ＝１５μｍ（影響深さ）とする。 Further, in the crack growth amount calculation unit 33c of the present embodiment, a roughness contact model is implemented. Roughness contact is defined by multiplying the orthogonal shear stress (normal stress) by the following equation (common to the first and second steps).

Here, z is the depth from the contact surface, A = 2, d = 15 μm (influence depth).

The crack growth amount calculated in steps S13 and FIG. 3 is stored in the storage unit 21 at least temporarily as the crack growth amount data 46.

(E) Squeak crack estimation Returning to FIG. 2, in step S14, the squeak crack estimation unit 34 uses the wear growth analysis unit 32, particularly the wear growth speed calculated by the wear amount calculation unit 32b, and the crack growth analysis unit. 33, in particular, the crack growth rate calculated by the crack growth amount calculation unit 33c is used to estimate whether or not squeak cracks occur in the simulated rail 51. Then, if it is estimated that the simulated rail 51 will have a squeak crack (YES in step S14), the squeak crack estimation unit 34 displays on the display device 12 that the simulated rail 51 is estimated to have a squeak crack in step S15. On the other hand, if it is estimated that the simulated rail 51 does not crack (NO in step S14), the program proceeds to step S16.

(F) Rail model data update In step S16, the rail model data update unit 32c of the wear progress analysis unit 32 has rail model data 41 (including rail shape data 42) based on the wear amount calculated by the wear amount calculation unit 32b. To update. Then, the program returns to step S10, and the vehicle motion analysis unit 31 calculates the force acting on the simulated rail 51 using the rail model data 41 updated by the rail model data update unit 32c.

(Effect of this embodiment)
In the squeak crack estimation device 10 of the present embodiment configured as described above, the force acting on the simulated rail 51 when the simulated vehicle 50 travels on the simulated rail 51 using the vehicle model data 40 and the rail model data 41. Calculated by the vehicle motion analysis unit 31 for calculating the above, the wear progress analysis unit 32 for calculating the wear progress rate of the simulated rail 51 using the force calculated by the vehicle motion analysis unit 31, and the vehicle motion analysis unit 31. Whether or not squeak cracks occur in the simulated rail 51 using the crack growth analysis unit 33 that calculates the crack growth rate that can occur in the simulated rail 51 using force, and the wear growth rate and the crack growth rate. It has a squeak crack estimation unit 34 for estimating.

By doing so, it is possible to quantitatively estimate the occurrence of cracks based on the contact state between the simulated rail 51 and the wheels of the simulated vehicle 50.

Here, the wear progress analysis unit 32 uses the force calculated by the vehicle motion analysis unit 31 to calculate the contact stress in the contact surface between the simulated vehicle 50 and the simulated rail 51, and the rail contact analysis unit 32a and the rail contact. Since it has a wear amount calculation unit 32b that calculates the wear progress rate of the simulated rail 51 based on the contact stress calculated by the analysis unit 32a, the wear progress analysis unit 32 performs the wear progress rate calculation process of the simulated rail 51. It can be performed more accurately and quantitatively, and as a result, the occurrence of squeak cracks can be estimated more quantitatively.

Further, the wear progress analysis unit 32 has a rail model data update unit 32c that updates the rail model data 41 based on the wear amount calculated by the wear amount calculation unit 32b, and the vehicle motion analysis unit 31 has a rail model data update unit 31. Since the force acting on the simulated rail 51 is calculated using the rail model data 41 updated by 32c, the force acting on the simulated rail 51 can be calculated by accurately feeding back the amount of wear of the simulated rail 51. As a result, the occurrence of squeak cracks can be estimated more quantitatively.

Further, the crack growth analysis unit 33 has a crack generation condition determination unit 33b that determines whether or not a crack occurs in the simulated rail 51 based on the contact stress calculated by the rail contact analysis unit 32a, and a crack generation condition determination unit 33b. Since it has a crack growth amount calculation unit 33c that calculates the crack growth rate that can occur on the simulated rail 51 when it is determined by the generation condition determination unit 33b that a crack will occur, the simulated rail by the crack growth analysis unit 33. The crack growth rate calculation process that can occur in 51 can be performed more accurately and quantitatively, and as a result, the occurrence of squeak cracks can be estimated more quantitatively.

Then, the crack growth analysis unit 33 has an initial value setting unit 33a for setting initial values of parameters required for the determination operation by the crack generation condition determination unit 33b, and the crack generation condition determination unit 33b has the initial value setting unit 33a. Since it is determined whether or not cracks occur in the simulated rail 51 using the initial values of the parameters set by, the occurrence of cracks is quantified based on the contact state between the simulated rail 51 and the wheels of the simulated vehicle 50. Can be estimated.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments and examples, and design changes are made to the extent that the gist of the present invention is not deviated. Is included in the present invention.

For example, in the squeak crack estimation system S according to the above-described embodiment, the storage unit 21 is provided in the estimation device 10, but the storage unit 21 can be configured separately from the estimation device 10.

Then, in the above-described embodiment, the program for operating the estimation device 10 is stored and provided in the storage unit 21, but a DVD (Digital Versatile Disc) in which the program is stored is stored by using an optical disc drive or the like (not shown). ), A USB external storage device, a memory card, or the like may be connected, and the program may be read into the estimation device 10 from the DVD or the like and operated. Alternatively, a program may be stored in a server device on the Internet, a communication unit may be provided in the estimation device 10, and this program may be read into the estimation device 10 and operated. Further, in the above-described embodiment, the estimation device 10 is composed of a plurality of hardware elements, but it is also possible for the control unit 20 to realize the operation of a part of these hardware elements by the operation of the program.

S Estimating system 10 Estimating device 20 Control unit 21 Storage unit 30 Display control unit 31 Vehicle motion analysis unit 32 Wear evolution analysis unit 32a Rail contact analysis unit 32b Wear amount calculation unit 32c Rail model data update unit 33 Crack growth analysis unit 33a Initial Value setting unit 33b Crack occurrence condition determination unit 33c Crack growth amount calculation unit 34 Squeak crack estimation unit 40 Vehicle model data 41 Rail model data 50 Simulated vehicle 51 Simulated rail

Claims (6)

It is a squeak crack estimation device that estimates the occurrence of squeak cracks that may occur at the gauge corners and the top of the rail.
A storage unit that stores vehicle model data for setting a model of a simulated vehicle and rail model data for setting a model for a simulated rail, and the simulated vehicle on the simulated rail using the vehicle model data and the rail model data. A vehicle motion analysis unit that calculates the force acting on the simulated rail when traveling, and a wear progress analysis unit that calculates the wear progress rate of the simulated rail using the force calculated by the vehicle motion analysis unit. , The crack growth analysis unit that calculates the crack growth speed that can occur in the simulated rail using the force calculated by the vehicle motion analysis unit, and the wear growth speed and the crack growth speed. A squeak crack estimation device comprising a squeak crack estimation unit for estimating whether or not squeak cracks occur in the simulated rail. The wear progress analysis unit includes a rail contact analysis unit that calculates the contact stress in the contact surface between the simulated vehicle and the simulated rail using the force calculated by the vehicle motion analysis unit, and the rail contact analysis unit. The squeak crack estimation device according to claim 1, further comprising a wear amount calculation unit that calculates the progress rate of the wear of the simulated rail based on the contact stress calculated by the above. The wear progress analysis unit has a rail model data update unit that updates the rail model data based on the wear amount calculated by the wear amount calculation unit.
The squeak crack estimation device according to claim 2, wherein the vehicle motion analysis unit calculates the force acting on the simulated rail using the rail model data updated by the rail model data update unit. .. The crack growth analysis unit includes a crack generation condition determination unit that determines whether or not the crack is generated in the simulated rail based on the contact stress calculated by the rail contact analysis unit, and the crack generation condition determination unit. The invention according to claim 2 or 3, further comprising a crack growth amount calculation unit that calculates the crack growth rate that may occur on the simulated rail if the generation condition determination unit determines that the crack will occur. Rail crack estimation device. The crack growth analysis unit has an initial value setting unit for setting initial values of parameters required for a determination operation by the crack generation condition determination unit, and the crack generation condition determination unit is operated by the initial value setting unit. The squeak crack estimation device according to claim 4, wherein it is determined whether or not the crack occurs in the simulated rail using the set initial values of the parameters. Executed by a squeak crack estimation device having a storage unit for storing vehicle model data for setting a model of a simulated vehicle and rail model data for setting a model for a simulated rail, and squeak cracks that may occur at the gauge corner and the top of the rail. It is a squeak crack estimation method for estimating the occurrence,
Using the vehicle model data and the rail model data, a force acting on the simulated rail when the simulated vehicle travels on the simulated rail is calculated, and the calculated force is used to advance wear of the simulated rail. The velocity is calculated, the calculated force is used to calculate the crack growth rate that can occur in the simulated rail, and the wear growth rate and the crack growth rate are used to cause squeak cracks in the simulated rail. A squeak crack estimation method characterized by estimating whether or not it occurs.

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