KR850001688B1 - Multiaxial tireness examiner - Google Patents

Abstract

No content.

Description

Multiaxial Fatigue Testing Machine

1 is a side view of the multiaxial fatigue tester of the present invention.

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a schematic diagram illustrating a principle.

4 is a vector diagram showing kinematic principles.

5 is a cross-sectional view of the main parts of the mechanism arranged on the main shaft.

6 is a structural explanatory diagram of a phase plate.

7 is a structural explanatory diagram of an eccentric plate.

8 is a screw arrangement of the soft rods for the average stress control.

9 is a part view of the specimen holder (V block).

10 is an arrangement diagram of three load cells for moment measurement.

11 is an explanatory diagram of a control circuit unit.

12 is a schematic diagram of an additive subtraction circuit according to a load cell output.

13 is a detailed view of an additive subtraction circuit.

14 is a control circuit configuration diagram.

15 is a detailed view of a control circuit.

Figure 16 shows the electromagnetic wave that occurs in interrupt control.

Figure 17 shows the analog-digital converter.

18 is a schematic diagram of an electrical circuit.

19 is a stress state diagram.

20 is a bending and torsional fatigue test results of the present invention and the existing tester.

Figure 21 is a graph of the results of the multi-axis fatigue test is a unique function of the tester of the present invention.

The present invention provides fatigue and torsional fatigue of the phase, bending and torsional phase fatigue, bending and torsional phase fatigue, It relates to a multi-axis fatigue tester that enables the average stress test for each of them.

In the automobile industry, which serves as a modern living tool, such a multi-axis fatigue phenomenon is common in crankshafts and other general shafts.

However, in the fatigue tester, many fatigue testers such as the German company Scheuck have been manufactured so far, but these fatigue testers were able to apply simple load state methods such as bending fatigue and torsional fatigue. Given the combined loads of torsion and torsion, it is impossible to give a more realistic test state, which is the life of the fatigue test.

On the contrary, the present invention allows a combination of bending and torsional loads of various states to be arbitrarily given as desired by the user, as well as to test each independent load state. The structure of the tester can be classified into four parts according to its role: driving part, specimen, measuring part, and circuit part.

1 and 2 of the accompanying drawings are axial views and cross-sectional views of the tester of the present invention, in which the driving part, the specimen, and the measuring part are shown well.

The following describes the test procedure in the operation sequence.

The drive unit transmits the power generated from the motor to the specimen in a state desired by the user. After adjusting the test load state (referred to in the detailed description of each part) to the phase plate 5 and the eccentric plate 6, 6 ', and connecting the power with the electric switch of the circuit part separately configured, the variable speed electric motor ( Power is generated in 1) and transmitted to the pulley 4 on the main shaft 3, 3 'via the timing belt 2 to be selected for accurate transmission thereof, and the phase plate 5, the eccentric plate (described later) 6) 6 '. The power transmitted back to the connecting rod 7 is transferred to the specimen 9 through the specimen holder (V-block) 8 whose position changes with the rotation of the eccentric plates 6, 6 'and can be tested. Will be.

The measuring part of the tester is composed of a load cell and a rotation speed measuring device. The load applied to the specimen 9 is sensed in the load cell 10 through the specimen fixing plate 8 'and this value is read numerically by the regulator via the circuit section. As the rotation speed measuring device 11 (11 '), the repeated rotation speed (cycle number) of a fatigue test can be known.

The function of each part is described in detail as follows. The drive unit is constituted by an electric motor 1, a timing belt 2, a main shaft 3, a phase plate 5, an eccentric plate 6, 6 ', a connecting rod 7, and a specimen fixing stand 8. The phase plate and the eccentric plate have the function of changing the magnitude and phase of bending and torsional loads of the multiaxial fatigue tester. The principle is shown in FIG. 3 and FIG.

3 is a schematic diagram of the operation principle of the multi-axis fatigue tester of the present invention. The torsional displacement of the specimen and the bending displacement were represented by B and B, respectively. The scale value of the eccentric plate adjusted before the test and the displacement generated in the specimen are the same as the formula (I) (Ⅱ) when the scale of the right eccentric plate is R and the scale of the left eccentric plate is L.

B = 1/2 (R + L) (Ⅰ)

T = 1/2 (R-L) (II)

Bending displacement B is expressed as the sum of both eccentric plates, and torsional displacement T is represented by the difference between both eccentric plates. The torsional deformation angle θ is represented by the formula (III).

( Ⅲ )θ = arc sin

(Ⅲ)

Where 2D is the distance between the two eccentric plates.

, 비틀림 변위를

, 오른쪽 및 왼쪽 편심판의 운동을

, 실제로 시편에서 나타나는 굽힘과 비틀림의 위상각을

, 위상판에서 조절하는 각도를 A라 하면 다음 관계식(Ⅳ)(Ⅴ)을 만족한다.4 is a vector diagram showing the kinematic principle of the scale value and displacement of the eccentric plate and the phase plate. Set the bending deflection of the specimen in any state with 0 as no load applied to the specimen.

Torsional displacement

Movement of the right and left eccentric,

The phase angles of bending and twisting

If the angle adjusted by the phase plate is A, the following relation (IV) (V) is satisfied.

Where 254 is the length of the specimen holder 8 of the bulb, in mm.

는 입력데이터(input)로 R,L,A는 출력결과(output)가 된다.R, L and phase plate control of the eccentric plate control of the multiaxial fatigue tester using the above equation (IV) (V) to obtain the experimental state as desired, namely bending displacement B, torsion angle θ, and phase angle of bending and torsion. Find each A. At this time, the computer was used to improve the efficiency of calculation.

Is input data, and R, L, and A are output results.

FIG. 5 shows the main side 3, 3 ', and the power generated from the motor 1 is biased through the timing belt 2, the pulley 4, and the main side 3, 3' as described above. It is passed to judgment (6) (6 '). The spindle support 11a is provided with a rotation speed measurement number 11 which is part of the measurement unit.

6 is a diagram of a phase plate, whose function is to change the phase of bending and torsional loads as described above.

This phase plate is composed of two parts so that relative motion between eccentric plates can occur as the phase angle is adjusted. The main shaft (3) (3 ') is divided into two parts and fixed one by one. One part thereof is fixed to the main shaft 3 receiving the force transmission through the timing belt as shown in FIG. 6, which is referred to as the driving plate 5a, and the circumference is divided into 360 equal parts to indicate the angle. The phase plate attached to the other main side 3 'is referred to as driven plate 5b so that only 0 points are displayed so as to indicate the angle of the drive plate.

The small circle in Fig. 6 is the bolt hole 5c for fixing the two phase plates.

7 shows the eccentric plates 6 and 6 ', which function to control the magnitude of the bending displacement and the torsional displacement. There are two left and right eccentric plates, each of which consists of an inner eccentric 6a, an outer eccentric 6b and an eccentric backing 6c. The inner circumference 6a was scaled so that the movement distance of the circumference was represented by the stroke of the connecting rod 7 so that the bending displacement could be adjusted from 0 to 140 mm.

The size of the outer core 6b was much larger than the minimum that could make two pin holes and four connecting bolt holes on the outer core. In order to facilitate the adjustment of the eccentric plate, between the inner eccentric plate 6a and the outer eccentric plate 6b, a taper is placed on each other, and the groove 6e is dug into the inner eccentric plate 6a so that the handle can be fitted.

8 shows a connecting rod (7) connecting the eccentric (6) and the specimen holder (8). Both ends of the connecting rods were made with opposite threaded parts (7a) so that when the connecting rods (7) were rotated in one direction, the assembly parts became sleepy or tightened so that the overall length was shortened or lengthened so that the average load could be given to the specimen. .

In addition, both ends of the connecting rod (7) to the eccentric plate (6) and the specimen holder (8) is freely connected and the force is accurately transmitted from the eccentric plate (6) and the spindle (3) (3 ') to the connecting rod (7) The bearing assembly is connected. At the top of the connecting rod, a mono bearing (Moo Bearing) (7b) was used, and at the bottom, a ball bearing (7c) fastened with a piston pin was used.

9 is a component diagram of the specimen fixture, which not only fixes the specimen 9 but is also connected to the connecting rod 7 so as to move up and down during the experiment. A steel ball 8a is contacted at one end of the specimen to come out of the specimen holder 8 as shown in FIG. 1 so that a dial gage can be attached to the reinforcing plate 12 to measure bending displacement. will be. It can also be used as a torsional displacement by grabbing arbitrary points on the specimen holder 8 and measuring displacements from each other at symmetry points on the length of the holder.

In the figure, reference numeral 8b is a V block, 8c is a fastening pin, 8d is a side plate, 8e is a top plate, and 8f is a bottom plate. The measuring unit includes a load cell for measuring load and a rotation speed measuring device for measuring the number of cycles.

FIG. 10 shows load cells 10-A, B, and C arranged to separate and measure the bending and torsional loads applied to the specimen. FIG. 10a shows the position of the three load cells, FIG. 10b shows the fixed relationship with the specimen when viewed from the side, FIG. 10c shows the shear force distribution between the specimen and the test fixture specimen, and FIG. 10d shows the test force between the specimen and the test fixture specimen. Moment distribution is shown.

Only one load cell can measure only one tensile and compressive load perpendicular to the plane, and only two load cells can measure only one moment such as bending moment or torsional moment. will be. The measurement of three load cells is called F _A , F _B , F _C , and the bending moment at any point X is MX, bending stress δx, torsion moment MT, and torsional stress τ from points A and B where two load cells are in a straight line. The relationship is as shown in equation (VI)-(-).

Since the moment at point D becomes zero, the bending moment is shown in equation (VI).

Mx = (X + 100) ・ F _C −X ・ (F _A + F _B ) = F _C- (F _A + F _B ) · X + 100F _C (Ⅵ)

이므로 임의의 점에 대한 굽힘응력은 식(Ⅶ)과 같다.Also, in a circular beam subjected to simple bending stress, the bending moment is

Therefore, the bending stress at any point is given by equation (Ⅶ).

In other words, by measuring the loads applied to three load cells, the maximum bending stresses applied to any cross section of the specimen can be calculated by the equations (VI) and (Ⅶ). The torsional moment is also written by the equation.

Mr = │F _A -F _B │.50 (Ⅷ)

이므로 비틀림응력은 식(Ⅷ)으로 나타난다.In cylinders subjected to simple torsion stresses, the torsional moment is

Therefore, the torsion stress is represented by the equation (Ⅷ).

By measuring the loads at points A and B, the maximum torsional stress of the specimen can be calculated.

The speed measuring device is part of the measuring part and installed on the main shaft and the pedestal one by one.

As shown in FIG. 5, a hole is drilled in the circular plate 11 attached to the main shaft 3 'to measure the same number of revolutions as the rotation of the main shaft, which is an optical device. The speed of rotation was counted by detecting the light passing through the hole of the circular plate. The circuit part calculates the load measured in the load cell as a bending and torsional load (Fig. 12), a circuit which stops the tester when a crack occurs in the specimen (Fig. 14), and a circuit showing the electrical flow of the tester (Fig. 18). It consists of).

11 is an explanatory diagram of a control circuit part from a load cell to a motor. Each value from the load cell is calculated according to the addition and subtraction circuits, and this value is compared with the reference value already set on the controller so that the tester stops when a crack occurs in the specimen. The relay driver of the motor operates to stop the motor.

Where F _A, F _B, F _C is a signal from the load cell, the value is a dynamic strain amplifier (dynamic strain amplifier) (4) (4 ') which amplifies through is calculated on the X _T about the torsional load peak detector (peak The maximum value is detected by a detector (C5) and then compared in the comparator (C6) with the reference value of the torsional load set in the Himi tester.

About the bending load to the addition operation for the F _A, F _{B B} X obtains the load. This is calculated by the calculation of the load F _C and the bending load Y _B is calculated. The maximum value is detected by the peak detector C5 and then compared in the comparator with the reference value of the bending load set in the test gas phase. In the comparison of the two loads, the bending load and the torsion load, if any one of the values is smaller than the reference value, the relay drive is activated to stop the motor.

FIG. 12 is a schematic diagram illustrating a process of adding and subtracting in an electronic circuit, in which an input is adjusted in a bias regulator C7 (C7 ') and passed through a buffer circuit C8 and C8'. Through C9) and C9 ', an addition and subtraction is selected from the polarity switch C10 and C10', and calculated by the adder and subtractor, and output to the output unit C11.

The details thereof are explained in FIG. 13. The input signal is input to the inputs KA and HB of the buffer circuits Cl2 and Cl2 ', and the bias voltage is adjusted from bias Cl3 (Cl3') to operate from 0 to 100%. The point can be moved arbitrarily. Next to the buffer circuit is a gain regulator (Cl4) (Cl4 '). If two signals are added, the signal can be doubled, so use a variable resistor to attenuate the signal below 1.0 magnification.

This signal passes through the gain regulator and then decides whether to add or subtract from the polarity switch Cl5 (Cl5 '). The two inputs A and B adjust the output of the result calculated by the adder / subtractor (Cl6) with the zero controller (Cl7), and the gain of the adder is adjusted to 1.25 or 5 as necessary.

FIG. 14 is a control process used to obtain the number of cycles until a crack occurs in the specimen by stopping the motor when the specimen is cracked while the tester is in operation. The principle is that when a crack occurs in the specimen, the cross-sectional area of the specimen decreases, and the voltage sensed by the dynamic strain gauge drops, so that the motor stops when it falls below the preset reference value.

The magnitude of the load generated in the specimen is detected by the load cell and subjected to the addition and subtraction circuits for the baffled bending and torsional stress states shown in FIG. 13. The maximum values shown here are the peak detector, It is shown through a chopper and a filter. After the chopper first detects the maximum voltage over a period of time, it ignores the previous maximum and takes a new value to obtain the next maximum.

Here, the value displayed through the maximum detector passes through a comparator compared to a reference voltage previously given by the set point generatar. This phenomenon is simultaneously applied to the maximum value generated in circuit b. Any of the maximum values generated in circuit a and circuit b is lower than the reference voltage, and current flows through a logic signal detector (OR gate). If the power supply to the motor is interrupted and the motor stops, if the value is higher than the reference value, the motor continues to operate.

A detailed view thereof is shown in FIG. Here, the maximum detector is composed of a diode and a capacitor as (Cl8) and (Cl8 '), and stores the maximum signal of + in the capacitor. TP ₁ (Cl9) and TP ₂ (19 ') represent the measurement points and are connected to a resistor to prevent electric shock. Since diodes cannot reverse current, there is no way to detect even if the input signal is low, so it is charged and discharged periodically using (C20) (C20 ').

The chopper uses a solid state relay C2l and a transistor C22. The chopper driver C23 receives a signal from a mono stable vibrator C24 and C25. The signal passed through the chopper mitigates the electrical shock due to switching in the filter (C26) (C26 ') and when the comparator (C27) (C27') is higher than the reference value compared to the reference value of the tester, the comparator output is zero. If it is reversed, set it to 12V.

In this detailed view, C28 is a set point generator of FIG. 14, C29 is a logic one-state detector circuit, and C30 is a circuit of a motor operating state by a relay driver. .

FIG. 16 shows the waveform generated at the contact point of the chopper driver. Waveform 1) shows the output voltage waveform of the monostable vibrator (C24 in FIG. 15) which moves when the chopper contact of FIG. This shows the output voltage waveform of the monostable vibrator (C25 in FIG. 15) that moves when the contact is downward. It is a signal to discharge the chopper through TR (C2l).

FIG. 17 shows an analog signal flowing through a circuit as a digit. The analog signal is converted into a digit while the input signal C31 passes through the circuit, and is represented numerically in the output signal C32.

18 is a schematic diagram of an electrical circuit for starting and stopping a motor used in the tester of the present invention. When starting the motor after connecting the power switch C34 to the motor C42, the contact R1-1 of the control relay R1 in the regulator C36 is brought into contact with the terminal bus C45. The power supply is connected to the stop switch C33 and the start switch C43.

If you press the button of the start switch to connect the power, the power is applied to the motor operation contact point (C38). When you press the motor operation switch button, the motor operation indicator (C37) lights up and the motor (C42) starts to operate. . When the motor is operated in this way, the test is started and the speed is adjusted in the speed controller (C40) to maintain the proper test state.

Then, if a crack occurs in the specimen, as shown in FIG. 14, the current flows through the relay R1, and the contact R1-1 is opened to open the motor operation switch C38, and the motor operation indicator C37 turns off. The test stops because (C35) is broken and the motor (C42) stops.

The configuration of the tester is as described above, and the results shown in the multiaxial fatigue tester of the present invention are as follows.

Here, the function of the tester is shown in the graph shown in FIG. 19. When the load state under test is divided into cross sections and expressed as stress, ① indicates the magnitude of bending stress and ② indicates the magnitude of torsional shear stress, which is represented by the control of the eccentric plate 6 shown in FIG. . ③ is obtained by adjusting the phase plate 5 as a phase difference between the bending stress and the torsional stress. ④ is the bending average stress and appears as a control of the connecting rod (7).

The tester therefore exhibits a complex stress state as a combination of these stresses. Conventional testers with the ability to test such complex loading conditions are not currently in production. Therefore, it is impossible to compare this tester with the conventional tester as a specific test result for the multiaxial load state.

However, in addition to the combined load and torsional load conditions, the tester also has the ability to fatigue test simple bending and torsional loads.

For reference, the testable field of this tester is shown in Table 1 as a table.

TABLE 1

Possible test with multiaxial fatigue tester

Note; W: With, O: Without

In addition, since there are many conventional testers for simple load conditions such as bending load and torsional load, it is possible to perform a batch comparison of fatigue test result data between a conventional tester and the present invention tester. For this purpose, Figure 20 compares the data for each of the bending and torsional stresses from the multiaxial fatigue tester with those from the German Schenck fatigue tester.

From this graph, it can be seen that the results of the multi-axis fatigue test and the crank fatigue test of the present invention are very similar. In particular, the characteristics of the fatigue test results vary significantly depending on various factors in the calculation of the service life even if the same stress state is given.

For example, the slope of the test result is within the same trend, considering that the value varies depending on the material, processing condition, and fabrication process of the specimen, as well as the result is distributed in a fairly large section even in the same experimental condition and the same tester. It can be seen. Therefore, the test results using the multi-axis fatigue tester show the same test results as the Senk's fatigue tester in the fatigue test of bending stress and torsion stress. have. In addition, the complex stress state of bending and torsion, which is a unique feature of the multiaxial fatigue tester, is a combination of reliable bending and torsional stresses.

FIG. 21 shows the test results for the combined state of bending stress and torsion stress, which is a unique function of the multiaxial fatigue tester. FIG. 21 is a diagram explaining the state under which bending stress and torsion stress are simultaneously received. The abscissa axis BB represents the state of bending stress, and the ordinate axis TT represents the state of torsion stress. These results show that the same lifespan results are drawn first with the SLEE line at constant lifetime, which is the theoretical line in multiaxial fatigue, and under any combination of arbitrary bending and torsional stresses. SLEE line

Here, in the test results which have reached the end of 10 ⁵ cycles, the t point is when only the torsion stress is applied to the specimen and the b point is when only bending stress is applied. When a conventional tester is used, it can be shown by the stress-life graph shown in FIG. 20 as a test for a short axis state, and this value is shown on the BB line or the TT line in FIG. Therefore, the test results in multiaxial fatigue are unique as shown in FIG.

As described above, the multiaxial fatigue tester of the present invention completely eliminates the defects of the conventional uniaxial fatigue theory and sufficiently considers the stability and economic efficiency of the site where the composite stress acts. In other words, it is possible to mechanically input a situation in which bending stresses and torsional stresses are combined as an arbitrary variable, and to measure data of the test results in a complex manner so that the basic design data of mechanical elements and components can be greatly calculated. It works.

Claims (2)

(Correction) Two eccentric plates (6) (6 ') to adjust the respective inner eccentric plates to adjust the magnitude of the bending and torsional loads, to apply each of the bending and torsional loads, or to give a phase difference between the two loads. A phase plate (5) with adjustable phase angle and a connecting rod (7) with adjustable ends with opposite screws on both ends to apply an average load to the bending load as motors (1), timing belts (2), Machine-type multi-axis fatigue tester, characterized in that consisting of the main shaft (3), the phase plate (5), the eccentric plate (6) (6, connecting rod (7), the specimen holder (8). (Correction) an addition and subtraction circuit for calculating the torsional load and the bending load by amplifying the values of the signals F _A , F _B , and F _C from the three load cells 10 through a dynamic strain amplifer; Series of comparators (C6) (6 ') that detect the measured bending and torsional load values through a peak detector (C5) (C5') and compare whether they are greater or less than the reference value already set on the regulator. Measuring circuit.

Images