Material impact test method

Abstract

The application provides a material impact test platform device and method, which comprises a base, an absorber arranged on the base, and a base frame arranged on the base; an input rod and an output rod are sequentially arranged on the base frame from top to bottom, and a standard sample is arranged between the ends of the input rod and the output rod close to each other; an impact platform is arranged at the end of the input rod away from the output rod, and the end of the output rod away from the input rod is connected with the absorber; a fixing plate is arranged at the top of the base frame, a mass block lifting device is arranged on the fixing plate, the impact platform is located at the position of the fixing plate, and the mass block lifting device is used for lifting the mass block; when the mass block falls, the mass block impacts on the impact platform; a strain gauge is arranged on the output rod, and the strain gauge is symmetrically pasted on the outer sidewall of the output rod along the diameter direction of the output rod. The application has simple structure, simple operation mode and low cost, and is used for obtaining high-precision material dynamic test results under limited experimental conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material dynamic mechanical test, in particular, to a material impact test platform device and method. BACKGROUND

[0002] The dynamic mechanical properties of materials are very complex, which depend on many factors, not only related to the internal structure of the material itself, but also affected by external loading rate, loading size, environmental temperature, humidity and pressure and other factors. The response behavior of many materials under dynamic loading is very different from that under static loading conditions.

[0003] At present, the use environment of underwater equipment gradually changes to the middle and deep sea. Facing more complex and harsh underwater environment, higher requirements are put forward for the performance of the equipment. Among them, the impact resistance performance, as a performance directly related to the life of underwater equipment, is gradually valued. The impact resistance performance of underwater equipment refers to the ability of underwater equipment to withstand a certain impact load. This performance usually needs to be verified by underwater dynamic impact test, but due to the long preparation period and high cost of underwater dynamic impact test, and the uncertainty of test working conditions for small equipment, the development of equipment impact resistance technology will still be biased towards the establishment and simulation evaluation of numerical model, and the actual underwater dynamic impact test of some key components.

[0004] The establishment of underwater equipment impact dynamics numerical model mainly depends on the establishment of material dynamic constitutive model. The stress-strain curve of material under dynamic loading is obtained through material dynamic mechanical test, the test data is converted into material dynamic constitutive model parameters, the material dynamic mechanical test model is established in the finite element software and the material constitutive model is assigned to the sample, and the parameters are adjusted through finite element simulation to make the numerical calculation results close to the test results, so that the material dynamic constitutive model is established. After the material dynamic constitutive model is assigned to the underwater equipment structure model, the impact dynamics numerical analysis is carried out, and the numerical results closer to the actual working condition can be obtained. Compared with the previous static strength analysis and checking of the equipment in the design stage, the addition of dynamic analysis has stronger guiding significance for the structure design of underwater equipment.

[0005] In the study of compression mechanical properties of materials, different test devices are usually selected for different loading rates. Hydraulic servo material testing machine can provide quasi-static loading conditions at 10 0 s -1 strain rate; drop hammer test technology can provide high loading conditions at 10 0 -10 2 s -1 medium strain rate; split Hopkinson pressure bar test technology is to obtain material at 102 -10 4 s -1 The main test means for dynamic response of materials in high strain rate range; light gas gun loading and plane wave generator obtain 10 4 s -1 The above dynamic loading of ultra-high strain rate.

[0006] The patent document with publication number CN214622129U discloses an impact resistance test device for building material detection, which comprises an impact frame body. The impact frame body is inserted into the top of the bottom plate, and the bottom of the impact frame body is provided with a circular truncated cone-shaped impact block. However, the patent document still has the defects of long test preparation period, high cost, and uncertainty of small equipment test working conditions. SUMMARY

[0007] In view of the defects in the prior art, the purpose of the present application is to provide a material impact test platform device and method.

[0008] The material impact test platform device provided by the present application comprises a base, wherein an absorber is arranged on the base, and a base frame is arranged on the base.

[0009] An input rod and an output rod are sequentially arranged from top to bottom on the base frame, and a standard sample is placed between the ends of the input rod and the output rod close to each other. An impact platform is arranged at the end of the input rod away from the output rod, and the end of the output rod away from the input rod is connected with the absorber.

[0010] A fixing plate is arranged at the top of the base frame, a mass block lifting device is arranged on the fixing plate, the impact platform is located at the position of the fixing plate, and the mass block lifting device is used for lifting the mass block. When the mass block descends, the mass block impacts on the impact platform.

[0011] A strain gauge is arranged on the output rod, and the strain gauge is symmetrically pasted on the outer sidewall of the output rod along the diameter direction of the output rod.

[0012] Preferably, a first linear bearing, a second linear bearing and a sample outer protective sleeve are arranged on the base frame.

[0013] The first linear bearing and the second linear bearing are fixedly arranged on the base frame, and the two ends of the standard sample protective sleeve are respectively connected with the first linear bearing and the second linear bearing.

[0014] The input rod is arranged through the first linear bearing, the output rod is arranged through the second linear bearing; one end of the input rod close to the standard sample is located in the sample outer protective sleeve, one end of the output rod close to the standard sample is located in the sample outer protective sleeve, and the standard sample is located in the sample outer protective sleeve.

[0015] Preferably, the absorber comprises an absorber bottom plate, an absorber outer ring, a spring, an absorber rod, an absorber inner ring and a limit pin.

[0016] The absorber inner ring and the absorber outer ring are arranged on the absorber bottom plate, and the absorber inner ring is arranged in the absorber outer ring.

[0017] The limit pin is arranged on the absorber inner ring, one end of the spring is connected and arranged on the limit pin, and the other end of the spring is connected and arranged on the absorber outer ring.

[0018] One end of the absorber rod is located in the absorber inner ring, and the limit pin is used for abutting and limiting one end of the absorber rod; the other end of the absorber rod is arranged in abutment with the output rod.

[0019] Preferably, the mass block comprises an incident wave shaper, a mass block lower part, a speed measurement assembly and a mass block upper part.

[0020] The mass block upper part and the mass block lower part are connected and arranged, an upper hollow groove is arranged in the mass block upper part, a lower hollow groove is arranged in the mass block lower part, and the upper hollow groove and the lower hollow groove form a mounting groove.

[0021] The speed measurement assembly is located in the mounting groove, and the speed measurement assembly is arranged on the bottom side wall of the lower hollow groove.

[0022] Preferably, the mass block lifting device comprises a guide rod, a third linear bearing, a lifting plate, a top plate, a servo motor, a shaft coupling, a ball screw pair and an electromagnet.

[0023] The top plate and the lifting plate are sequentially arranged from top to bottom, the third linear bearing is arranged on the lifting plate, one end of the guide rod is connected and arranged on the fixed plate, and the other end of the guide rod is connected and arranged on the top plate through the third linear bearing.

[0024] The servo motor is arranged on the top plate, the nut of the ball screw pair is fixedly arranged on the lifting plate, one end of the screw rod of the ball screw pair is connected and arranged with the rotating end of the servo motor through the shaft coupling, and the other end of the screw rod of the ball screw pair is arranged in abutment with the impact platform.

[0025] The electromagnet is fixedly arranged on the lifting plate, and the electromagnet is used for adsorbing or releasing the mass block.

[0026] Preferably, a protection barrel is detachably arranged on the fixed plate, and the impact platform is located in the protection barrel.

[0027] The application also provides a material impact test method based on the material impact test platform device, and specifically comprises the following steps:

[0028] Step 1: check whether there is foreign matter in the first linear bearing, the second linear bearing, the third linear bearing and the ball screw pair, check whether the surface of the input rod and the output rod is intact, and after checking that there is no foreign matter and no damage, install the test platform device;

[0029] Step 2: adjust the vertical position of the mass block lifting device according to the required strain rate, use the level to level the mass block lifting device, connect the electromagnet to the power supply, install the mass block after the power supply is connected;

[0030] Step 3: install the standard sample between the input rod and the output rod, use adhesive to bond the upper and lower surfaces of the standard sample with the input rod and the output rod respectively, adjust the position of the mass block to the theoretical height value, release the electromagnet, make the mass block impact the platform, obtain the acceleration-time curve before the mass block impacts the platform, and the response waveform on the input rod and the output rod;

[0031] Step 4: according to the acceleration-time curve obtained in step 3, calculate the maximum speed of the mass block falling to the impact platform by formula, calculate the actual strain rate according to the maximum speed, compare the actual strain rate with the theoretical strain rate, calculate the height difference of the mass block, and adjust the height of the mass block to make the height of the mass block meet the strain rate required by the test;

[0032] Step 5: after adjusting the test platform device according to step 4, use a standard sample with the same material as the input rod and the output rod to test, record the acceleration and waveform data, and when the actual obtained parameters differ from the theoretical values by less than 10%, it is determined that the test platform device has been adjusted to a state that can be tested, otherwise, repeat steps 4 and 5 until the error is adjusted to within 10%;

[0033] Step 6: install the standard material sample required for dynamic mechanical test between the input rod and the output rod, use adhesive to bond the upper and lower surfaces of the standard sample with the input rod and the output rod respectively, install the protective sleeve of the sample, release the electromagnet, make the mass block impact on the impact platform, and obtain the acceleration-time curve and the stress response-time curve of the input rod-output rod;

[0034] Step 7: measure the incident signal ε by the strain gaugei and the reflected signal epsilon r The average stress, strain and strain rate in the standard sample are calculated by a three-wave formula, and the stress-strain curve of the sample at the strain rate is obtained.

[0035] Preferably, in step 4, the input rod and output rod response waveforms obtained in step 3 are observed, and it is observed whether the waveforms meet the test requirements; if the influence of the high-frequency components generated by the collision on the loading waveform exceeds a preset value, an incident wave shaper is installed on the mass block, and the high-frequency components caused by the direct collision are filtered through the incident wave shaper.

[0036] Preferably, when the hard material is tested, the material of the input rod and the output rod is a 40Cr steel rod or a metal material with the same hardness as the hard material.

[0037] When the soft material is tested, the material of the input rod and the output rod is a LY12 aluminum rod or a metal material with the same hardness as the soft material.

[0038] Preferably, the strain gauge is a metal type body strain gauge or a semiconductor type body strain gauge.

[0039] The strain gauge forms a half-bridge circuit, a single-arm circuit or a full-bridge circuit.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] 1. The present application combines a drop hammer type impact test device and a Hopkinson pressure bar test system, and designs a longitudinal material dynamic mechanics test device, which improves the test precision compared with the drop hammer type test device and reduces the device volume compared with the Hopkinson pressure bar test system, and can be used for dynamic mechanics test of most types of materials.

[0042] 2. The mass block lifting device of the present application can realize impact loading of a test sample in a medium strain rate to large strain rate range.

[0043] 3. The present application uses a standard sample to calibrate the test device multiple times during the test process, effectively improving the test precision and the reliability of the test data.

[0044] 4. The present application has a simple structure, is convenient to install, and has certain economy and convenience. BRIEF DESCRIPTION OF DRAWINGS

[0045] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0046] Figure 1Overall structure schematic diagram of the material impact test platform device of the present application;

[0047] Figure 2 Structure schematic diagram of the absorber;

[0048] Figure 3 Structure schematic diagram of the mass block;

[0049] Figure 4 Structure schematic diagram of the mass block lifting device;

[0050] Figure 5 Top view of the mass block lifting device;

[0051] Figure 6 Arrangement wiring diagram of the strain gauge;

[0052] Figure 7 Operation method flow chart of the material impact test method of the present application.

[0053] Shown in the figure are:

[0054] Base 1 speed measuring assembly 903

[0055] Absorber 2 mass block upper portion 904

[0056] Absorber bottom plate 201 electromagnet 10

[0057] Absorber outer ring 202 mass block lifting device 11

[0058] Spring 203 guide rod 1101

[0059] Absorption rod 204 third linear bearing 1102

[0060] Absorber inner ring 205 lifting plate 1103

[0061] Limiting pin 206 top plate 1104

[0062] Base frame 3 servo motor 1105

[0063] First linear bearing 4 shaft coupling 1106

[0064] Sample outer protective sleeve 5 ball screw 1107

[0065] Fixed plate 6 input rod 12

[0066] Impact platform 7 strain gauge 13

[0067] Protective barrel 8 standard sample 14

[0068] Mass block 9 output rod 15

[0069] Limiting ring 16 of incident wave shaper 901

[0070] Second linear bearing 17 of mass lower part 902 DETAILED DESCRIPTION

[0071] The application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are within the scope of protection of the application.

[0072] Example 1

[0073] As Figures 1-7 shown, the embodiment provides a material impact test platform device, comprising: a base 1, an absorber 2 is arranged on the base 1, a base frame 3 is arranged on the base 1, an input rod 12 and an output rod 15 are arranged on the base frame 3 in sequence from top to bottom, a standard sample 14 is placed between the ends of the input rod 12 and the output rod 15 close to each other, an impact platform 7 is arranged at the end of the input rod 12 away from the output rod 15, the end of the output rod 15 away from the input rod 12 is connected with the absorber 2, a fixed plate 6 is arranged at the top of the base frame 3, a mass block lifting device 11 is arranged on the fixed plate 6, the impact platform 7 is located at the position of the fixed plate 6, and the mass block lifting device 11 is used for lifting a mass block 9; when the mass block 9 descends, the mass block 9 impacts on the impact platform 7, a strain gauge 13 is arranged on the output rod 15, and the strain gauge 13 is symmetrically pasted on the outer side wall of the output rod 15 along the diameter direction of the output rod 15.

[0074] The mass block lifting device 11 comprises a guide rod 1101, a third linear bearing 1102, a lifting plate 1103, a top plate 1104, a servo motor 1105, a shaft coupling 1106, a ball screw pair 1107, and an electromagnet 10. The top plate 1104 and the lifting plate 1103 are arranged in sequence from top to bottom, the third linear bearing 1102 is arranged on the lifting plate 1103, one end of the guide rod 1101 is connected to the fixed plate 6, the other end of the guide rod 1101 passes through the third linear bearing 1102 and is connected to the top plate 1104, the servo motor 1105 is arranged on the top plate 1104, the nut of the ball screw pair 1107 is fixedly arranged on the lifting plate 1103, one end of the screw rod of the ball screw pair 1107 is connected to the rotating end of the servo motor 1105 through the shaft coupling 1106, the other end of the screw rod of the ball screw pair 1107 is guided to the impact platform 7, and the electromagnet 10 is fixedly arranged on the lifting plate 1103. The electromagnet 10 is used for adsorbing or releasing the mass block 9.

[0075] The mass block 9 comprises an incident wave shaper 901, a mass block lower part 902, a velocity measurement assembly 903, and a mass block upper part 904, the mass block upper part 904 and the mass block lower part 902 are connected and arranged, the mass block upper part 904 is internally provided with an upper hollow groove, the mass block lower part 902 is internally provided with a lower hollow groove, the upper hollow groove and the lower hollow groove form an installation groove, the velocity measurement assembly 903 is located in the installation groove, and the velocity measurement assembly 903 is arranged on the bottom side wall of the lower hollow groove.

[0076] The base frame 3 is provided with a first linear bearing 4, a second linear bearing 17, and a sample outer protective sleeve 5, the first linear bearing 4 and the second linear bearing 17 are fixedly arranged on the base frame 3, the two ends of the standard sample 14 protective sleeve are respectively connected to the first linear bearing 4 and the second linear bearing 17, the input rod 12 passes through the first linear bearing 4, the output rod 15 passes through the second linear bearing 17, the end of the input rod 12 close to the standard sample 14 is located in the sample outer protective sleeve 5, the end of the output rod 15 close to the standard sample 14 is located in the sample outer protective sleeve 5, and the standard sample 14 is located in the sample outer protective sleeve 5.

[0077] The absorber 2 comprises an absorber bottom plate 201, an absorber outer ring 202, a spring 203, an absorbing rod 204, an absorber inner ring 205, and a limiting pin 206, the absorber inner ring 205 and the absorber outer ring 202 are arranged on the absorber bottom plate 201, the absorber inner ring 205 is arranged in the absorber outer ring 202, the limiting pin 206 is arranged on the absorber inner ring 205, one end of the spring 203 is connected to the limiting pin 206, the other end of the spring 203 is connected to the absorber outer ring 202, one end of the absorbing rod 204 is located in the absorber inner ring 205, the limiting pin 206 is used for abutting against one end of the absorbing rod 204, and the other end of the absorbing rod 204 is abutted against the output rod 15.

[0078] The fixed plate 6 is detachably provided with a protective barrel 8, and the impact platform 7 is located in the protective barrel 8.

[0079] The material impact test platform device of the embodiment further comprises a limiting ring 16, the material can be rubber or engineering plastic, the limiting ring 16 is connected to the output rod 15 through gluing or screw connection, and the limiting ring 16 is used for stopping the movement of the input rod 12, the standard sample 14, and the output rod 15 when the input rod 12 reaches a certain displacement during loading on one side, at this time, the input rod 12, the standard sample 14, and the output rod 15 still maintain a connected state, a stress wave propagates among them, and the absorbing rod 204 is separated from the output rod 15 and impacts the absorber bottom plate 201.

[0080] The embodiment further provides a material impact test method, which is based on the material impact test platform device and specifically comprises the following steps.

[0081] Step 1: Check the first linear bearing 4, the second linear bearing 17, the third linear bearing 1102, the ball screw pair 1107 for foreign matter, and check the surface of the input rod 12 and the output rod 15 for damage. After checking for foreign matter and damage, install the test platform device;

[0082] Step 2: Adjust the vertical position of the mass block lifting device 11 according to the desired strain rate, use a level to level the mass block lifting device 11, and connect the electromagnet 10 to the power supply. After connecting the power supply, install the mass block 9;

[0083] Step 3: Install the standard specimen 14 between the input rod 12 and the output rod 15, use adhesive to bond the upper and lower surfaces of the standard specimen 14 to the input rod 12 and the output rod 15 respectively, adjust the position of the mass block 9 to the theoretical height value, release the electromagnet 10, and make the mass block 9 impact the platform, obtain the acceleration-time curve before the mass block 9 impacts the platform, and the response waveform on the input rod 12 and the output rod 15;

[0084] Step 4: Calculate the maximum speed of the mass block 9 falling onto the impact platform 7 according to the acceleration-time curve obtained in Step 3, calculate the actual strain rate according to the maximum speed, compare the actual strain rate with the theoretical strain rate, calculate the height difference of the mass block 9, and adjust the height of the mass block 9 to make the height of the mass block 9 meet the strain rate required for this test. Observe the response waveform of the input rod 12 and the output rod 15 obtained in Step 3, and observe whether the waveform meets the test requirements. If the high-frequency component generated by the collision exceeds the preset value, install an incident wave shaper 901 on the mass block 9 to filter the high-frequency component caused by direct collision;

[0085] Step 5: After adjusting the test platform device according to Step 4, use a standard specimen 14 made of the same material as the input rod 12 and the output rod 15 to conduct a test, and record the acceleration and waveform data. When the actual obtained parameters differ from the theoretical values by less than 10%, it is determined that the test platform device has been adjusted to a state where testing can be conducted. Otherwise, repeat Steps 4 and 5 until the error is adjusted to within 10%;

[0086] Step 6: Install the standard material specimen to be tested for dynamic mechanics between the input rod 12 and the output rod 15, use adhesive to bond the upper and lower surfaces of the standard specimen 14 to the input rod 12 and the output rod 15 respectively, install the specimen outer protective sleeve 15, release the electromagnet 10, and make the mass block 9 impact the impact platform 7, obtain the acceleration-time curve and the stress response-time curve of the input rod 12 and the output rod 15;

[0087] Step 7: Measure the incident signal ε by strain gauge 13i and the reflected signal epsilon r The average stress, strain and strain rate in the standard sample 14 are calculated by a three-wave formula to obtain the stress-strain curve of the sample at the strain rate.

[0088] The strain gauge 13 is a metallic body type strain gauge 13 or a semiconductor body type strain gauge 13, and the strain gauge 13 forms a half-bridge circuit, a single-arm circuit or a full-bridge circuit.

[0089] When the hard material is tested, the input rod 12 and the output rod 15 are made of 40Cr steel rods or metal materials with the same hardness as the hard material, and when the soft material is tested, the input rod 12 and the output rod 15 are made of LY12 aluminum rods or metal materials with the same hardness as the soft material.

[0090] The embodiment is designed for the case of limited test conditions to study the response of underwater equipment under impact loading, and is mainly used for studying the dynamic response of materials under impact loading and providing material test data for studying the response of the overall equipment under impact loading.

[0091] The embodiment studies the response and test method of materials under dynamic loading, and proposes a material impact test platform device, which has a simple structure, an operation mode and a low cost, and is used for obtaining a material dynamic test result with high accuracy under limited experimental conditions.

[0092] The embodiment designs an impact platform device with adjustable strain rate for the common underwater impact loading condition, i.e., the impact loading condition in the medium strain rate to high strain rate range, to realize loading on the test material in a large strain rate range, and combines the drop hammer test technology and the split Hopkinson pressure bar test technology, and optimizes the structure, test process and test method of the test platform, so that the impact platform device has high test accuracy under the premise of low cost and small size.

[0093] The material dynamic mechanics test using the impact platform device of the embodiment may be affected by five aspects, and the embodiment proposes a method to reduce the influence of the five factors:

[0094] a. To avoid the poor parallelism of the mass block and the impact platform surface, which causes uneven stress on the platform when the two impact, the embodiment uses a level to level the two when installing the impact platform surface and the mass block lifting device, so as to ensure that the mass block maintains surface contact with the platform when falling onto the impact platform surface;

[0095] b. In order to enable the impact test platform to obtain the dynamic response of the material in a larger strain rate range, a variable height mass block lifting device is designed in the embodiment, so that the falling height of the mass block can be adjusted in a larger range;

[0096] c. In order to ensure that the input rod, the sample and the output rod only move in the vertical direction when being impacted, linear bearings are used for the input rod and the output rod in the embodiment to limit their horizontal degrees of freedom, and the input rod, the sample and the output rod are connected by adhesion, so as to ensure that the test piece will not be loose during the test, thereby meeting the condition requirements of the one-dimensional wave theory during the test;

[0097] d. In order to weaken and delay the secondary wave loading effect, an absorber is connected to the rear end of the output rod in the embodiment, which is mainly used for absorbing the kinetic energy of the output rod, so as to prevent the unloading wave reflected from the end face of the output rod from interfering with the normal transmission signal;

[0098] e. In order to facilitate later data calculation, the mass block, the input rod and the output rod used in the impact device need to be made of the same material. When the mass block impacts the input rod, a stress square wave with a wave speed of C0 will be generated due to the same wave impedance of the two, and when the stress wave reaches the sample, a wave will be reflected back to the input rod due to the different wave impedance of the sample and the incident rod, and a wave will be transmitted through the sample into the output rod. The two pulse signals can be measured by the strain gauges attached to the input rod and the output rod, and the stress, strain and strain rate of the sample can be calculated from the data.

[0099] Example 2

[0100] Those skilled in the art can understand the embodiment as a more specific description of embodiment 1.

[0101] The application designs a use method of the impact test platform device, the use method of the test platform and the material dynamic mechanical test method, which comprises the following steps:

[0102] Step S1, the first linear bearing 4, the second linear bearing 17, the third linear bearing 1102, the ball screw pair 1107, the input rod 12 and the output rod 15 are inspected to confirm that there is no foreign matter in the bearings and the ball screw pair, and the surface of the input rod 12 and the output rod 15 is intact without damage, then the test device is installed;

[0103] Step S2, the vertical position of the mass block lifting device 11 is adjusted according to the required strain rate, the lifting device 11 is leveled using a level, and the lifting device 11 is installed on the test device, the electromagnet 10 at the top of the lifting device 11 is connected to the power supply, and then the mass block 9 is installed;

[0104] Step S3, a standard sample 14 with the same material as the input rod 12 and the output rod 15 is installed between the input rod 12 and the output rod 15, the upper and lower surfaces of the standard sample 14 are bonded with the input rod 12 and the output rod 15 respectively by using adhesive, the position of the mass block 9 is adjusted to the theoretical height value, the electromagnet 10 is released, the mass block 9 impacts on the impact platform 7, the acceleration-time curve before the mass block impacts on the impact platform and the response waveform on the input and output rods are obtained;

[0105] Step S4, the maximum speed of the mass block when falling to the impact platform is calculated by the formula from the acceleration-time curve obtained in step S3, the actual strain rate is calculated from the speed, the mass block height difference is calculated after comparing the actual strain rate with the theoretical strain rate, the mass block height is adjusted to meet the strain rate required by the test, the response waveform of the input rod and the output rod obtained in step S3 is observed to see whether the waveform meets the test requirement, if the high frequency component generated by the collision has a great influence on the loading waveform, an incident wave shaper 901 is needed to be installed at the impact platform 7 to filter the high frequency component caused by the direct collision, so as to reduce the dispersion effect of the wave;

[0106] Step S5, after the impact test platform device is adjusted according to step S4, a standard sample 14 with the same material as the input rod 12 and the output rod 15 is used for test again, the acceleration and the waveform data are recorded, when the actual obtained parameters differ from the theoretical values by less than 10%, it is considered that the test platform device has been adjusted to the state that the test can be carried out, otherwise, steps S4 and S5 are repeated until the error is adjusted to less than 10%;

[0107] Step S6, the standard material sample 14 to be tested for dynamic mechanics is installed between the input rod 12 and the output rod 15, the upper and lower surfaces of the sample are bonded with the input rod and the output rod respectively by using adhesive, the protective sleeve 5 is installed, the electromagnet 10 is released, the mass block 9 impacts on the platform, the acceleration-time curve and the stress response-time curve of the input and output rods are obtained;

[0108] Step S7, the incident signal ε i and the reflected signal ε r measured by the strain gauge are used to calculate the average stress, strain and strain rate in the sample by the three-wave formula, that is, the stress-strain curve of the sample at the strain rate is obtained, the formula is as follows:

[0109]

[0110] Wherein, ε s is the compression strain of the standard sample, is the compression strain rate of the standard sample, c0is the wave speed of the elastic compression wave, l0is the length of the standard sample, ε i is the incident strain pulse, εr - reflected strain pulse, ε t - transmitted strain pulse, σ s - stress in the standard specimen, P s - pressure acting on the standard specimen, A s - cross-sectional area of the standard specimen, E - modulus of elasticity of the rod, A - cross-sectional area of the rod.

[0111] Further, in step S1, the input rod and the output rod can be made of 40Cr steel rod and LY12 aluminum rod respectively or metal materials with the same hardness when testing hard and soft materials; the strain gauge can be selected according to the test requirements, which can be a metal type strain gauge or a semiconductor type strain gauge; the strain gauge half-bridge circuit can be replaced by a single-arm circuit or a full-bridge circuit according to the test accuracy requirements; the mass block lifting device can be replaced by a pulley combination device or other lifting mechanisms.

[0112] Further, in step S2, the lifting device top electromagnet for fixing the mass block can be replaced by a steel wire rope pulley combination device or other mechanical fixing devices; the acceleration sensor can be replaced by a photoelectric speed measuring instrument or other types of speed measuring instruments for measuring the maximum speed of the mass block before contacting the impact platform.

[0113] Further, in step S4, the incident waveform shaper material includes but is not limited to brass, rubber, and silicone rubber, etc.; the stress response waveforms of the input rod and the output rod should be consistent.

[0114] The impact test platform device of the embodiment reduces the cost under limited test conditions to solve the material dynamic mechanics test problem and obtain more accurate material dynamic mechanics response parameters, thereby providing basic data for underwater equipment impact resistance design and establishing a numerical analysis model.

[0115] Example 3

[0116] Those skilled in the art can understand the embodiment as a more specific description of embodiment 1.

[0117] The application designs a test device for impacting an experimental platform by using a mass block to generate a compression stress wave, bonding strain gauges on the upper and lower sides of the metal rods on the test piece and connecting an ultra-dynamic strain meter to record the stress pulse signal changing with time during the impact process, and the specific use method includes the following steps:

[0118] Step one, check the first linear bearing 4, the second linear bearing 17, the third linear bearing 1102, the ball screw pair 1107, the input rod 12 and the output rod 15 to confirm that there is no foreign matter in the bearings and the ball screw pair, and the surface of the input rod and the output rod is intact without damage, then install the test device according to Figure 1 the test device.

[0119] Use a level to level the base 1 and install the absorber 2 in the center of the base. The absorber 2 is installed as follows: Figure 2 As shown, the absorber inner ring 205 is installed on the absorber base plate 201, the limit pin 206 is inserted into the absorber inner ring opening, the spring 203 is installed at the rear of the limit pin, and the absorber outer ring 202 is installed at the other end of the spring; after the absorber is installed, the base frame 3, the guide rod 1101 and the ball screw pair 1107 are installed on the base respectively; the first linear bearing 4 and the second linear bearing 17 are installed on the base frame; the fixing plate 6 is installed on the top of the base frame; the mass block lifting device 11 is installed on the top of the guide rod and the ball screw pair. The mass block lifting device is as shown in FIG. Figure 4 As shown, the linear bearing 1102 and the ball screw pair bearing 1107 are installed on the lifting plate 1103, and the servo motor 1105 is installed on the top plate 1104. After completion, the servo motor shaft, the ball screw pair shaft and the coupling 1106 are connected, and the top plate is installed on the upper end of the guide rod; the electromagnet 10 is installed on the lifting plate; before the test, the strain gauge 13 is pasted at the non-contact position between the output rod and the bearing. The strain gauges are symmetrically pasted on both sides of the outer circle of the rod along the rod diameter direction, as shown in FIG. Figure 6 A half-bridge circuit is formed, and the absorption rod 204, the output rod 15, the sample 14, the input rod 12, and the platform 7 are pressed Figure 1 Install from bottom to top, apply lubricant on the contact surface of the input and output rods and the bearings, and on the input rod. After completion, use a spirit level to level the impact table of the device; install the protective barrel 8 on the fixed plate.

[0120] Step 2: Install the mass block 9, install the acceleration sensor 903 in the empty slot 902 at the lower end of the mass block, pass the sensor cable through the corresponding hole 904 at the upper end of the mass block, and then align the upper and lower ends of the mass block; connect the servo motor 1105 and the electromagnet 10, install the mass block under the electromagnet, and adjust the vertical position of the mass block and the lifting device 11 according to the strain rate required.

[0121] Step three, connect the strain gauge 13 to the ultra-dynamic strain gauge, connect the strain gauge and acceleration sensor to the data acquisition device and connect them to the computer, and connect the electromagnet and servo motor to the controller respectively; install a standard sample 14 made of the same material as the input rod 12 and the output rod 15 between the input and output rods, use adhesive to bond the upper and lower surfaces of the sample to the input and output rods respectively, adjust the position of the mass block 9 to the theoretical height value, release the electromagnet 10, and make the mass block 9 impact the table 7, obtain the acceleration-time curve before the mass block impacts the table, and the response waveform on the input and output rods.

[0122] Step four, the maximum velocity of the mass 9 falling to the impact platform 7 is calculated by the acceleration-time curve obtained in step three through the acceleration integral formula, the actual strain rate is calculated from the velocity, compared with the theoretical strain rate, the mass height difference is calculated, and the mass height is adjusted to meet the strain rate required by the test. The input and output rod response waveform obtained in step three is observed to see if the waveform meets the test requirements. If the high-frequency component generated by the collision has a greater impact on the loading waveform, an incident wave shaper 901 needs to be installed at the impact platform to filter the high-frequency component caused by direct collision, thereby reducing the dispersion effect of the wave.

[0123] Step five, after adjusting the impact test platform device according to step four, a standard sample 14 with the same material as the input and output rods is used for testing, and the acceleration and waveform data are recorded. When the actual obtained parameters differ from the theoretical values by less than 20%, it is considered that the test platform device has been adjusted to a state where the test can be performed, otherwise steps four and five are repeated until the error is adjusted to within 20%.

[0124] Step six, the standard material sample 14 to be subjected to dynamic mechanical testing is installed between the input and output rods, and an adhesive is used to bond the upper and lower surfaces of the sample to the input and output rods, respectively. The protective sleeve 5 is installed, the electromagnet 10 is released, the mass 9 impacts the platform 7, and the acceleration-time curve and the stress response-time curve of the input and output rods are obtained.

[0125] Step seven, the incident signal εi and the reflected signal εr measured by the strain gauge 13 are used to calculate the average stress, strain and strain rate in the sample through the three-wave formula, i.e. the stress-strain curve of the sample at the strain rate is obtained. The formula is as follows:

[0126]

[0127] The present application has a simple structure, an easy operation mode and a low cost, and is used for obtaining a material dynamic test result with high accuracy under limited experimental conditions.

[0128] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0129] The specific embodiments of the present application are described above. It needs to be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be combined with each other at will without conflict.

Claims

1. A material impact test method, characterized in that: A material impact test platform device is used, the material impact test platform device comprising: a base (1), an absorber (2) being provided on the base (1), and a base frame (3) being provided on the base (1); An input rod (12) and an output rod (15) are arranged on the base frame (3) in sequence from top to bottom, and a standard sample (14) is placed between the ends of the input rod (12) and the output rod (15) that are close to each other; an impact platform (7) is arranged at the end of the input rod (12) away from the output rod (15), and the end of the output rod (15) away from the input rod (12) is connected to the absorber (2); The base frame (3) is provided with a first linear bearing (4), a second linear bearing (17) and a sample outer protective cover (5); The first linear bearing (4) and the second linear bearing (17) are both fixedly arranged on the base frame (3), and the two ends of the sample outer protective cover (5) are connected to the first linear bearing (4) and the second linear bearing (17) respectively; The input rod (12) is arranged through the first linear bearing (4), and the output rod (15) is arranged through the second linear bearing (17); the ends of the input rod (12) and the output rod (15) close to the standard specimen (14) are both located in the specimen outer protective sleeve (5); A fixing plate (6) is provided at the top of the base frame (3), a mass block lifting device (11) is provided on the fixing plate (6), the impact platform (7) is located at the position of the fixing plate (6), and the mass block lifting device (11) is used to lift the mass block (9); when the mass block (9) descends, the mass block (9) impacts the impact platform (7); The mass block lifting device (11) comprises a third linear bearing (1102), a lifting plate (1103) and an electromagnet (10); The third linear bearing (1102) is arranged on the lifting plate (1103); The electromagnet (10) is fixedly arranged on the lifting plate (1103), and the electromagnet (10) is used to absorb or release the mass block (9); The output rod (15) is provided with a strain gauge (13), and the strain gauge (13) is symmetrically attached to the outer side wall of the output rod (15) along the rod diameter direction of the output rod (15); The specific steps include: Step 1: Check whether there are any foreign objects in the first linear bearing (4), the second linear bearing (17), the third linear bearing (1102), and the ball screw pair (1107), and check whether the surfaces of the input rod (12) and the output rod (15) are intact. After checking that there are no foreign objects and no damage, install the test platform device; Step 2: According to the strain rate to be obtained, adjust the vertical position of the mass block lifting device (11), use a level to level the mass block lifting device (11), connect the electromagnet (10) to the power supply, and install the mass block (9) after the power supply is connected; Step 3: Install the standard sample (14) between the input rod (12) and the output rod (15), use adhesive to bond the upper and lower surfaces of the standard sample (14) to the input rod (12) and the output rod (15), respectively, adjust the position of the mass block (9) to the theoretical height value, release the electromagnet (10), and make the mass block (9) impact the table surface of the impact platform (7), and obtain the acceleration-time curve before the mass block (9) impacts the table surface, as well as the response waveforms on the input rod (12) and the output rod (15); Step 4: Based on the acceleration-time curve obtained in step 3, the maximum velocity of the mass block (9) when it falls to the impact platform (7) is calculated by the formula, the actual strain rate is calculated based on the maximum velocity, the actual strain rate is compared with the theoretical strain rate, the height difference of the mass block (9) is calculated, and the height of the mass block (9) is adjusted so that the height of the mass block (9) meets the strain rate required for this test; Step 5: After adjusting the test platform device according to step 4, use a standard specimen (14) made of the same material as the input rod (12) and the output rod (15) to conduct the test, and record the acceleration and waveform data. When the actual parameters obtained differ from the theoretical values ​​by less than 10%, it is determined that the test platform device has been adjusted to a state where the test can be conducted. Otherwise, repeat steps 4 and 5 until the error is adjusted to within 10%. Step 6: Install the standard material sample to be subjected to the dynamic mechanical test between the input rod (12) and the output rod (15), use adhesive to bond the upper and lower surfaces of the standard material sample to the input rod (12) and the output rod (15), respectively, install the sample outer protective cover (5), release the electromagnet (10), and make the mass block (9) impact on the impact platform (7), and obtain the acceleration-time curve and the stress response-time curve of the input rod (12)-output rod (15); Step 7: Measure the incident signal ε using the strain gauge (13) i and reflected signal ε r The average stress, strain and strain rate in the standard material sample are calculated by the three-wave formula, and the stress-strain curve of the standard material sample at the strain rate is obtained.

2. The material impact test method according to claim 1, characterized in that: In step 4, the response waveforms of the input rod (12) and the output rod (15) obtained in step 3 are observed to see whether the waveforms meet the test requirements. If the influence of the high-frequency component generated by the collision on the loading waveform exceeds a preset value, an incident wave shaper (901) is installed on the mass block (9) to filter the high-frequency component caused by the direct collision through the incident wave shaper (901).

3. The material impact test method according to claim 1, characterized in that: When testing hard materials, the input rod (12) and the output rod (15) are made of 40Cr steel rod or a metal material with the same hardness as the hard material; When testing soft materials, the input rod (12) and the output rod (15) are made of LY12 aluminum rod or a metal material with the same hardness as the soft material.

4. The material impact test method according to claim 1, characterized in that: The strain gauge (13) is a metal-type body strain gauge or a semiconductor-type body strain gauge; The strain gauge (13) forms a half-bridge circuit, a single-arm circuit or a full-bridge circuit.

5. The material impact testing method according to claim 1, characterized in that: The absorber (2) comprises an absorber bottom plate (201), an absorber outer ring (202), a spring (203), an absorber rod (204), an absorber inner ring (205), and a limit pin (206); The absorber inner ring (205) and the absorber outer ring (202) are arranged on the absorber bottom plate (201), and the absorber inner ring (205) is arranged inside the absorber outer ring (202); The limiting pin (206) is arranged on the absorber inner ring (205), one end of the spring (203) is connected to the limiting pin (206), and the other end of the spring (203) is connected to the absorber outer ring (202); One end of the absorption rod (204) is located in the absorber inner ring (205), and the limiting pin (206) is used to abut and limit one end of the absorption rod (204); the other end of the absorption rod (204) is arranged to abut against the output rod (15).

6. The material impact testing method according to claim 1, characterized in that: The mass block (9) comprises an incident wave shaper (901), a mass block lower portion (902), a velocity measurement component (903), and a mass block upper portion (904); The mass block upper portion (904) and the mass block lower portion (902) are connected and arranged, an upper hollow groove is provided in the mass block upper portion (904), and a lower hollow groove is provided in the mass block lower portion (902), and the upper hollow groove and the lower hollow groove form a mounting groove; The speed measuring component (903) is located in the installation groove, and the speed measuring component (903) is arranged on the bottom side wall of the lower empty groove.

7. The material impact testing method according to claim 1, characterized in that: The mass lifting device (11) comprises a guide rod (1101), a top plate (1104), a servo motor (1105), a coupling (1106), and a ball screw pair (1107); The top plate (1104) and the lifting plate (1103) are arranged in sequence from top to bottom, one end of the guide rod (1101) is connected to the fixed plate (6), and the other end of the guide rod (1101) passes through the third linear bearing (1102) and is connected to the top plate (1104); The servo motor (1105) is arranged on the top plate (1104), the nut of the ball screw pair (1107) is fixedly arranged on the lifting plate (1103), one end of the screw rod of the ball screw pair (1107) is connected to the rotating end of the servo motor (1105) through the coupling (1106), and the other end of the screw rod of the ball screw pair (1107) is guided to the impact platform (7).

8. The material impact testing method according to claim 1, characterized in that: A protective barrel (8) is detachably provided on the fixing plate (6), and the impact platform (7) is located inside the protective barrel (8).

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