JPH07917Y2 - Instrumented drop weight impact tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an instrumented drop weight impact tester. This drop weight impact tester has a ruler, photocell, A / D converter, tester, pressure converter, microprocessor,
It consists of a power amplifier, an oscilloscope, a disk driver, a printer, and a plotter.

Prior Art Conventional impact testers come in two types.

Pendulum type (IZOD and CHARPY, etc.) and falling weight type. Although the pendulum method allows simple and rapid testing, it is limited to measuring the energy absorbed during the fracture of the material under test and does not reveal the actual changes in the material during the fracture process. Also, it is not possible to test a sample that simulates the shape of an actual object. This is because the impact velocity and sample shape are fixed. In the case of the conventional drop weight type, it is necessary to prepare an extremely large number of samples. Moreover, testing is time consuming and complicated statistical analysis must be used. The obtained data are also inferior to the pendulum data.

Recent advances in information science and automatic control technology have realized the application of a computerized drop weight impact method that is simple, fast, and requires a small number of samples. With the aid of sensors and computers, actual fracture process data and impact resistance characteristics at high impact velocity are obtained. These types of impact testers consist of mechanical impact test equipment, pressure transducers and signal indicating members. The effectiveness and accuracy of such devices depends on the function and construction of the individual components. Unfortunately, these prior art drop weight impact testers neglect the effect of velocity on energy. When calculating the energy absorbed E = ∫FVdt when a material breaks down, one of the widely used methods is modified by a correction factor, assuming the striker drop velocity is constant during the impact process. Is to get. In another method, the initial impact velocity V = √2gh is obtained according to the equation of motion of a free-falling object, and the velocities at various points are obtained using the equation of motion of general physics, and the energy absorbed at the time of impact is then obtained. Is integrated to obtain the value of E. The velocity values theoretically derived by these two methods are completely different from those obtained by actual instrument measurements.

To overcome these shortcomings of the prior art, the inventor conducted a research study, manufactured a test model, and finally completed a novel velocity measuring device for an instrumented drop weight impact tester. did. It enables the measurement of changes in the speed value of the striker.

SUMMARY OF THE INVENTION The main purpose of the invention is to provide a means for measuring the actual speed value of a striker at various points during the impact process. These measurements will better represent the actual impact conditions.

Another object of the present invention is to provide a versatile, automatic and highly accurate dynamic instrumented drop weight impact tester.

These objects are, according to the invention, an instrumented drop weight impact tester comprising a frame means, a pressure converter, an A / D converter, a microprocessor and a display means,
The drop weight impact tester is equipped with a photocell velocity measuring device for measuring the velocity during the impact process, the photocell velocity measuring device being provided with a grooved guide adjacent to the sample holder on the frame means of the tester. It comprises a concave photovoltaic device which is adjustable between high and low positions on a rod, and a ruler attached to the striker for measuring the speed of the striker when it falls, the ruler being the grooved guide. Guided vertically along the rod and passing through the photovoltaic device, the photovoltaic device actuates the speed measurement trigger means via a comparison by a comparator, and further cooperates with the appropriate software to calculate the speed change value, And finally, various relevant data during the impact test process through the operation of software and hardware of the microprocessor in connection with the collected pressure data. In order to calculate, characterized by issuing a signal according to changes in the cutoff or intensity of the light emitted from the light source caused by the passage of the ruler, it is achieved by the instrument of been dropped weight impact tester.

In the drop weight impact tester configured as described above, when the striker falls, the ruler attached to the striker is vertically guided along the grooved guide rod and passes through the photovoltaic device, The photovoltaic device emits a signal in accordance with the interruption or change in intensity of the light beam from the light source caused by the passage of the ruler. The signal actuates the speed measurement trigger means via a comparison by a comparator, further cooperates with the appropriate software to calculate the speed value, and finally, in connection with the pressure data collected, the software and said Various relevant data are calculated during the impact test process through the operation of the microprocessor hardware.

The improved structure, features and practical operation of the present invention will be apparent from the following detailed description with reference to the drawings.

SPECIFIC EXAMPLE As shown in FIGS. 1 and 2, the pressure transducer used in the present invention has a pressure resistance in the range of 10,000 Ibs. The received shock pressure, expressed in voltage, is captured by the transducer 1 and amplified in the power amplifier 2 to provide accurate data. The impact energy changes to a source of impact strength by adding a counterweight to the drop striker 3. In the present invention, the impact energy is in the range of 2.8J-253J. The striker head 4 has a pendulum type impact tester [IZOD
(3 ″) or CHARPY (3 ″)] or other type that is similar to the functionality of other types of impact testers. The characteristics of the striker head 4 change according to the needs of various operations. The position of the drop striker 3 can be adjusted by the latch device 5 and the unlatching device 6. By turning the unlatching device 6, the striker can be dropped as shown in FIG. The bearing 7 is used to reduce friction when the striker falls. The ruler 8 is attached to the side surface of the striker 3. It is designed according to the receiving and transmitting working principle of the photovoltaic device and can be either a light-blocking slit ruler, a light-reflecting slit ruler or a light-reflecting display ruler. The former two rulers have narrow horizontal slits, while the latter have light and dark scales. Also, ruler 8
May be linear or non-linear in design. As shown in Figure 4,
The vertical grooved guide rod 9 guides the ruler through the photovoltaic device 11 when the striker 3 falls. In the case of the light-shielding slit ruler, when the ruler 8 passes through the concave portion of the photovoltaic device, the narrow slit blocks the light source and causes a potential difference.
In the case of a light-reflecting slit ruler or a light-reflecting ruler, the bright and dark fringes at that portion produce pulses of varying intensity. These pulses of varying potential or intensity pass through the comparator. After the comparison, the comparator generates a signal to activate the A / D converter 14, on the one hand to capture the pressure values at various intervals, and on the other hand to activate the speed measuring device 18 to block the light at each slit. Measure the time it takes to complete. The velocity value is then calculated using the already programmed formula. The height of the striker 3 can be determined by the scale on the stainless steel scale. Sample holder
12 can be a circle, a parallel anvil or a V-groove depending on the operating conditions or the actual shape of the sample. A clamping ring or plate and a twist wrench are attached to both sides of the sample holder to ensure a uniform pressure distribution within the sample.
The stop plate 13 is provided to reduce the impact. It consists of a layer of aluminum plate of varying thickness depending on the size and shape of the sample. This stop plate adjusts the stop height for the striker head. The PU flexible plate on top of each stop plate softens impact force, and striker head 3
Is to protect the. The overall structure is therefore a protective device to prevent the striker head from hitting the ground or steel plate after impact of the sample and damaging the transducer 1 in the striker.

The functions and operation of the computerized drop weight impact tester equipped with the new speed measuring device are described in FIGS.
It is shown in FIGS. For the operation, the sample is the holder first
Placed on 12. Next, rotate the latch release device 6,
The striker 3 is ready to fall. A ruler attached to the side of the striker slides down along the groove of the guide rod. When the striker head 4 is about to contact the sample, the ruler 8 is about to pass through the concave photovoltaic device 11. If the ruler is a light-shielding slit ruler, the narrow slits block the light source and generate a potential difference. If the ruler is a light-reflecting slit ruler or a light-reflecting ruler, pulses with varying intensities are generated. After comparing these potential-difference or varying-intensity pulses, the comparator sends a signal which activates the A / D converter 14 on the one hand and the speed measuring and signal triggering device 18 on the other hand. Time base generator
Fifteen determines at what time interval the converter collects a single piece of data. In the present invention, 25 in the range of 10 μs to 2560 μs
There are 6 selected data collection time intervals, up to 100,0 per second
Providing 00 data. When the striker head 4 impacts the sample, the pressure received by the sample is converted into voltage signals by the pressure converter 1 in the striker head 4, which are transmitted to the power amplifier 2. The power amplifier 2 consists of a resistance coil connected to a microprocessor 22 forming a circuit, which allows the system to be stable and the proper pressure range to be selected automatically. Converter 1
The weak voltage is amplified by the power amplifier 2 and then transmitted to the A / D converter 14 via the sample extracting and storing device 14 '. The signal is digitized into 12-bit form by converter 14 and stored in data storage system 16 until full. On the other hand, a speed measurement and signal trigger device 18
The time value collected by each shading slit is converted into a speed value by a pre-programmed formula, further counted by a counter 22 and stored in the random access memory of the microprocessor. Whether using a linear or non-linear ruler 8, various striker actual speed values can be obtained by incorporating speed calculation formulas into various programs. Basically, the light-blocking slit ruler utilizes the blocking of the light source by the light grating when the ruler passes through the photovoltaic device 11. This produces a series of pulses received by a receiver in the photovoltaic device which is transmitted to the comparator 17 for comparison. On the contrary, the light-reflecting slit ruler or the light-reflecting ruler utilizes a light source emitted from the angling photovoltaic device 11. When the ruler passes the photovoltaic device 11, a signal is emitted from the reflection of light by the light grating or the bright and dark stripes. After being received by the receiver, these signals are converted and then transmitted to the comparator 17 for comparison. For a light-reflecting slit ruler or light-reflecting ruler to be effective, the materials from which they are made must be able to reflect light within the wavelengths that can be received by the receiver. Customarily, stainless steel, aluminum, copper, alloys, coatings of light-reflecting paints, black-and-white or highly reflective printing materials are suitable materials for this kind of use.

Pre-stored pressure and velocity data in the data storage system may be stored in the disk by lining the disk driver 25 with the microprocessor 22. These data may be directly incorporated into the microprocessor software for processing the test results and then printed out on printer 23 or plotter 24 for further analysis. On the other hand, these data may be displayed on an XY recorder 20, oscilloscope or computer screen via an A / D converter.

Figures 6A, 6B and 6C illustrate the results obtained from an instrumented drop weight impact tester fitted with a novel velocity measuring device. The sample used in Figure 6A has a length and width of 10
Made of carbon fiber / epoxy resin composite material, cm, 2.6 cm thick. FIG. 6A shows the pressure-time and energy-time relationships. From the change of the curve, the maximum endurance pressure of the material is 2790.984N, the damage initiation damage energy is 6.0955J, the propagation damage energy during the process is 7.936J and the total impact absorption energy is
It turns out that it is 14.031J. The generation time is 0.45 msec. And the coefficient that determines the ductility index, that is, the tenacity or brittleness of the material is 1.302.

The sample used in Figure 6B is the same material as that of Figure 6A, a carbon fiber / epoxy composite.
These graphs represent the load-deflection and energy-deflection relationships. In addition, FIG. 6B provides similar data information to FIG. 6A and shows how the magnitude of the load affects the extent to which the material deflects during the entire failure process.
Figure 6C shows the speed-time and deflection-time relationships. From these curves it was found that there was a non-linear relationship and an irregular behavior between velocity-time and flexure-time, respectively. These show that the velocity change value has a great influence on the total integrated energy operation.

Therefore, this instrumented drop weight impact tester can accurately measure the speed fluctuation value (a result that cannot be obtained with the current impact tester), and it can be used by analysis and design engineers in real life. Impact information can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of an instrumented drop weight impact tester of the present invention, and FIG. 2 is a front elevational view of an embodiment of an instrumented drop weight impact tester of the present invention. FIG. 3 is an enlarged perspective view showing an upper portion of an embodiment of the instrumented drop weight impact tester of the present invention, FIG. 4 is a perspective view of a photocell speed measuring device, and FIG. 5 is a perspective view of the present invention. Flow chart of an embodiment of an instrumented drop weight impact tester, 6A, 6B and 6C is an actual object according to one embodiment of the instrumented drop weight impact tester of the present invention It is a graph which shows the test result obtained from the test. 1 ... Converter, 2 ... Power amplifier, 3 ... Drop striker, 4 ... Striker head, 5 ... Latch mechanism, 7 ... Bearing, 8 ... Ruler, 10 ... Scale,
11 ... Photovoltaic device, 12 ... Holder, 14 ... A / D converter, 16 ... Data storage device, 18 ... Speed measurement device, 22
…… Microprocessor.

Claims (10)

[Scope of utility model registration request] 1. A frame means, a pressure converter, an A / D converter,
An instrumented drop weight impact tester, comprising a microprocessor and display means, wherein the drop weight impact tester is equipped with a photovoltaic cell velocity measuring device for measuring velocity during the impact process. This photovoltaic cell speed measuring device is a concave photovoltaic cell device that is adjustable between high and low positions on a grooved guide rod adjacent to the sample holder on the frame means of the tester, and is attached to the striker when the striker falls. And a ruler for measuring its speed, the ruler is vertically guided along the grooved guide rod and passes through the photovoltaic device, and the photovoltaic device is compared by a comparator. Activating the velocity measurement trigger means, in addition to working with the appropriate software to calculate velocity change values, and finally in relation to the pressure data collected, the software and A signal is emitted in accordance with a change in the interception or intensity of a light beam from a light source caused by the passage of the ruler in order to calculate various relevant data during the impact test process through the operation of the microprocessor hardware. An instrumented drop weight impact tester. 2. The drop weight impact tester according to claim 1, wherein the ruler is a light-shielding slit ruler. 3. The drop weight impact tester according to claim 2, wherein the light-shielding slit ruler is designed linearly. 4. The drop weight impact tester according to claim 2, wherein the light shielding slit ruler is designed non-linearly. 5. The drop weight impact tester according to claim 1, wherein the ruler is a light reflection slit ruler. 6. The drop weight impact tester according to claim 5, wherein the light reflection slit ruler is designed linearly. 7. The drop weight impact tester according to claim 5, wherein the light reflection slit ruler is designed non-linearly. 8. The drop weight impact tester according to claim 1, wherein the ruler is a light reflection slit ruler. 9. The drop weight impact tester according to claim 8, wherein the light reflection slit ruler is designed linearly. 10. The drop weight impact tester according to claim 8, wherein the light reflection slit ruler is designed non-linearly.