A method for on-site measurement and correction of impact force of pendulum impact testing machine

Abstract

The present invention discloses a method for correcting the impact force of a pendulum impact tester on-site, comprising: fixing one end of a standard force sensor to a force sensor of the pendulum impact tester, and fixing the other end of the standard force sensor to a counterweight; lifting the impact hammer to a certain angle, and starting the first impact after release, the force sensor measures the test impact force, and the standard force sensor measures the calibration impact force; exchanging the positions of the standard force sensor and the counterweight, lifting the impact hammer to the same angle, and starting the second impact after release, the force sensor measures the test impact force, and the standard force sensor measures the calibration impact force; according to the impact forces obtained from the two impacts, the corrected impact force and the inertia force correction coefficient of the force value measurement system of the pendulum impact tester are calculated. The present invention can solve the accurate impact force value, and obtain the inertia force correction coefficient of the impact tester, and effectively improve the accuracy of the on-site measurement of the impact force.

Description

Technical Field

[0001] The invention belongs to the field of experiment and test technology, and in particular relates to an on-site measurement and correction method for the impact force of a pendulum impact testing machine. Background Art

[0002] Impact test is a test method used to evaluate the performance of materials, structures or devices under impact loads. A pendulum impact tester is usually used to simulate the impact force and waveform in actual use, which can evaluate the durability and reliability of materials or devices. The force calibration of the impact tester is an important guarantee for the accuracy of impact force measurement. Impact testers are equipped with force sensors, most of which cannot be disassembled. For the on-site force verification test of pendulum impact testers, standard force sensors are usually connected in series to calibrate and test the impact force. However, due to the superposition of the inertia effect of the standard force sensor itself and the inertia effect of the original force measurement system of the impact tester, the measurement of the on-site value of the impact force leads to large errors in the direct measurement results, which affects the accuracy of the force calibration of the impact tester. Therefore, there is an urgent need for a method to achieve accurate measurement and correction of the impact force on site. Summary of the invention

[0003] The purpose of the present invention is to provide an on-site measurement correction method for the impact force of a pendulum impact testing machine, which can calculate an accurate impact force value and obtain an inertia force correction coefficient of a force value measurement system of the impact testing machine, thereby effectively improving the accuracy of on-site measurement of the impact force.

[0004] In order to achieve the above object, one aspect of the present invention provides a method for on-site measurement and correction of the impact force of a pendulum impact testing machine, comprising:

[0005] Step S1: one end of the standard force sensor is fixedly connected to the force sensor of the pendulum impact testing machine, and the other end of the standard force sensor is fixedly connected to the counterweight block;

[0006] Step S2: the impact hammer is lifted to a certain angle, and the first impact is started after being released, the force sensor measures the first test impact force f1, and the standard force sensor measures the first calibration impact force F2;

[0007] Step S3: swapping the positions of the standard force sensor and the counterweight block, wherein one end of the counterweight block is fixedly connected to the force sensor, and the other end of the counterweight block is fixedly connected to the standard force sensor;

[0008] Step S4: lifting the impact hammer to the same angle as step S2, and starting the second impact after releasing it, the force sensor measures the second test impact force F1′, and the standard force sensor measures the second calibration impact force F2′;

[0009] Step S5: Calculate and obtain the corrected measured impact force F:

[0010]

[0011] Among them, Ms is the mass of the counterweight, m2 is the mass of the standard force sensor, and m e2 is the equivalent mass of the internal sensitive end of the standard force sensor;

[0012] In addition, the inertial force correction coefficient δ of the force measurement system of the pendulum impact tester is calculated:

[0013]

[0014] in, The force measurement system of the pendulum impact testing machine consists of a force sensor and an impact hammer.

[0015] Preferably, the inertial force correction coefficient δ is used to correct the impact force Fc obtained when the impact force is measured using only the force value measurement system of the pendulum impact tester, and the correction value F′ is obtained:

[0016] F′=δ·Fc.

[0017] Preferably, the effective mass Mc of the impact structure of the pendulum impact tester is estimated as follows:

[0018]

[0019] The on-site measurement correction method for the impact force of a pendulum impact tester according to the above aspects of the present invention can calculate an accurate impact force value and obtain an inertia force correction coefficient of the impact tester force value measurement system, thereby effectively improving the accuracy of on-site impact force measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0021] Figure 1 It is an application schematic diagram of an on-site measurement correction method of an impact force of a pendulum impact testing machine according to an embodiment of the present invention;

[0022] Figure 2 The present invention is a flowchart of an on-site measurement and correction method of an impact force of a pendulum impact testing machine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present invention provides a method for on-site measurement and correction of the impact force of a pendulum impact tester, such as Figure 1 The figure shows the correction of the impact force field measurement of the pendulum impact tester based on the displacement of the counterweight. Figure 1 In the figure, the impact hammer 1 and the force sensor 2 form the force measurement system of the pendulum impact tester, and the standard force sensor 3 and the counterweight block 4 are connected in series to form an impact force calibration device, which is connected to the force measurement system of the pendulum impact tester. When the whole is lifted to a certain angle and released, it reaches a horizontal position and hits the impacted object to generate impact force. The standard force sensor 3 and the counterweight block 4 can be connected by a fixed thread, and the standard force sensor 3 can be installed at the left and right ends of the counterweight block 4.

[0025] The counterweight transposition is that during the first impact, the force sensor 2 is fixedly connected to one end of the standard force sensor 3, and the other end of the standard force sensor 3 is fixedly connected to the counterweight block 4; during the second impact, the counterweight is transposed, the force sensor 2 is fixedly connected to one end of the counterweight block 4, and the other end of the counterweight block is fixedly connected to the standard force sensor 3, and the two impact measurements need to ensure that the lifting angle is consistent, such as Figure 1 The actual impact force value and the inertia force correction coefficient of the force measurement system of the pendulum impact tester are calculated using the measurement results of the two impacts.

[0026] like Figure 2 As shown, the on-site measurement correction method of the impact force of the pendulum impact testing machine according to the embodiment of the present invention includes steps S1 to S5.

[0027] Step S1: one end of the standard force sensor 3 is fixedly connected to the force sensor 2, and the other end of the standard force sensor 3 is fixedly connected to the counterweight 4, and the standard force sensor 3 and the counterweight 4 form an impact force calibration device;

[0028] Step S2: lifting the impact hammer 1 to a certain angle θ, and starting the first impact after releasing it, to obtain the test impact force F1 of the force sensor 2 and the calibration impact force F2 of the standard force sensor 3;

[0029] Step S3: performing counterweight transposition, exchanging the positions of the standard force sensor 3 and the counterweight block 4, wherein one end of the counterweight block 4 is fixedly connected to the force sensor 2, and the other end of the counterweight block 4 is fixedly connected to the standard force sensor 3;

[0030] Step S4: lifting the impact hammer 1 to the same angle θ as in step S2, and starting a second impact after releasing it, to obtain a test impact force F1′ of the force sensor 2 and a calibration impact force F2′ of the standard force sensor 3;

[0031] Step S5: Correct and calculate the impact force F measured in the actual calibration and the inertia force correction coefficient δ of the force measurement system of the pendulum impact tester according to the following formula (I) and formula (II) respectively.

[0032] The corrected actual impact force satisfies the following relationship:

[0033]

[0034] Where Ms is the mass of the counterweight 4, m2 is the mass of the standard force sensor 3, and m e2 is the equivalent mass of the internal sensitive end of the standard force sensor 3.

[0035] The inertia force correction coefficient δ of the force value measurement system of the pendulum impact tester is calculated to satisfy the following relationship:

[0036]

[0037] In the formula, F av is the average value of the two impact force sensor 2 measurements, that is,

[0038] The derivation process of the above formula (I) and formula (II) is described below.

[0039] Assume that M is the mass of the impact hammer 1, m1 is the mass of the force sensor 2, m2 is the mass of the standard force sensor 3, Ms is the mass of the counterweight 4, km1 is the equivalent mass of the internal sensitive end of the force sensor 2 (k is generally between 0.1 and 0.5), m e2 is the equivalent mass of the internal sensitive end of the standard force sensor 3.

[0040] During the first impact, force sensor 2 measures the impact force F1, and standard force sensor 3 measures the impact force F2. According to Newton's second law, the following relationship is obtained:

[0041]

[0042] During the second impact, the force sensor 2 measures the impact force F1′, and the standard force sensor 3 measures the impact force F2′. According to Newton's second law, the following relationship is obtained:

[0043]

[0044] Since the lifting angles of the first and second impacts are the same, and the total mass does not change during the impact process, according to the law of conservation of energy, the acceleration a of the two impacts is the same as the actual impact force F, and the result is as follows:

[0045]

[0046] The expression of acceleration a is obtained by formula (3):

[0047]

[0048] The expression of the effective mass Mc of the impact structure of the impact testing machine is obtained by formula (3):

[0049]

[0050] According to equations (4) and (5), the expression of the actual impact force, , can be obtained, namely, the above equation (I):

[0051]

[0052] When the standard force sensor 3 and the counterweight 4 are not introduced for calibration, and only the force value measurement system of the pendulum impact tester is used for impact force measurement, the impact force Fc is obtained, which satisfies the following relationship:

[0053]

[0054] Then the expression of inertia force correction coefficient δ of impact testing machine force measurement system is obtained:

[0055]

[0056] According to the above formulas (1) and (2), we can obtain:

[0057]

[0058] F av is the average value of the two impact force sensor 2 measurements, that is,

[0059] Substituting equations (5) and (9) into equation (8) yields the expression for the inertia correction coefficient δ of the impact testing machine force measurement system, namely, equation (II):

[0060]

[0061] Therefore, the obtained inertia force correction coefficient δ can be used to correct the impact force Fc obtained when the impact force is measured using only the force measurement system of the pendulum impact tester, and the correction value F′ satisfies the following relationship:

[0062] F′=δ·Fc (III)

[0063] Through the above process, the effective mass Mc of the impact structure in the pendulum impact tester can also be estimated, that is, the above formula (5):

[0064]

[0065] The impact force on-site measurement correction method according to the embodiment of the present invention is further described in detail below through a specific example.

[0066] In this embodiment, the mass Ms of the counterweight 4 is set to 3 kg, the mass m2 of the force sensor 2 is set to 0.428 kg, and the equivalent mass m of the internal sensitive end of the force sensor 2 is set to e2 =0.214kg.

[0067] The impact force on-site measurement correction method of this embodiment includes:

[0068] Step S1: one end of the standard force sensor 3 is fixedly connected to the force sensor 2, and the other end of the standard force sensor 3 is fixedly connected to the counterweight 4, and the standard force sensor 3 and the counterweight 4 form an impact force calibration device;

[0069] Step S2: the impact hammer 1 is lifted to a certain angle θ=60°, and the first impact is started after release, so as to obtain a test impact force F1=220.365N of the force sensor 2 and a calibration impact force F2=223.455N of the standard force sensor 3;

[0070] Step S3: performing counterweight transposition, exchanging the positions of the standard force sensor 3 and the counterweight block 4, wherein one end of the counterweight block 4 is fixedly connected to the force sensor 2, and the other end of the counterweight block 4 is fixedly connected to the standard force sensor 3;

[0071] Step S4: lift the impact hammer 1 to the same angle θ=60°, and start the second impact after releasing it, so as to obtain the test impact force F1′=220.899N of the force sensor 2 and the calibration impact force F2′=252.479N of the standard force sensor 3;

[0072] Step S5: According to the above formula (I) and formula (II), the actual measured impact force F=254.549N and the pendulum impact tester inertia force correction coefficient δ=1.0034 are corrected and calculated.

[0073] The accuracy of the results calculated by the impact force field measurement correction method of the embodiment of the present invention is improved by 0.82% compared with the traditional calibration using only the standard force sensor 3; compared with the direct measurement method of the force sensor 2 without inertia force compensation and correction, the measurement accuracy is improved by 0.34%, which effectively improves the accuracy of on-site impact force measurement.

[0074] In summary, the on-site measurement correction method of the impact force of the embodiment of the present invention adopts a method combining counterweight and position switching to compensate for the inertial force introduced by the standard force sensor in the calibration of the force measurement system of the impact testing machine, calculate the accurate impact force value, and obtain the inertial force correction coefficient of the force measurement system of the impact testing machine, thereby effectively improving the accuracy of dynamic force measurement, thereby solving the following problems in the current on-site calibration and testing of the impact testing machine: (1) The original force measurement system of the impact testing machine has no inertial force correction compensation and has a large dynamic error; (2) The original force measurement system of the impact testing machine generally cannot be disassembled for inspection and can only be calibrated on-site using a standard force sensor. However, the inertial force error introduced by the standard force sensor is not corrected, resulting in inaccurate calibration results; (3) The impact structure of the impact testing machine is inconvenient to disassemble, and the effective mass involved in the impact process cannot be measured.

[0075] Compared with the prior art, the impact force on-site measurement correction method of the embodiment of the present invention has the following advantages:

[0076] (1) Under the same calibration conditions, the present invention uses a combination of a counterweight block and a standard force sensor to reduce the impact force measurement error caused by the standard force sensor;

[0077] (2) The present invention can effectively calculate the effective mass of the impact structure without disassembling the impact testing machine structure;

[0078] (3) The present invention utilizes the counterweight block and the standard force sensor to perform transposition, and two sets of test data are formed through two impact tests, so that the actual impact force value can be solved;

[0079] (4) The present invention can obtain the inertia force compensation correction coefficient of the impact testing machine force value measurement system through measurement correction, thereby improving the impact force measurement accuracy under the same measurement conditions.

[0080] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for on-site measurement and correction of the impact force of a pendulum impact testing machine, characterized in that: include: Step S1: one end of the standard force sensor is fixedly connected to the force sensor of the pendulum impact testing machine, and the other end of the standard force sensor is fixedly connected to the counterweight block; Step S2: the impact hammer is lifted to a certain angle, and the first impact is started after being released, the force sensor measures the first test impact force F1, and the standard force sensor measures the first calibration impact force F2; Step S3: swapping the positions of the standard force sensor and the counterweight block, wherein one end of the counterweight block is fixedly connected to the force sensor, and the other end of the counterweight block is fixedly connected to the standard force sensor; Step S4: lifting the impact hammer to the same angle as step S2, and starting the second impact after releasing it, the force sensor measures the second test impact force F1′, and the standard force sensor measures the second calibration impact force F2′; Step S5: Calculate and obtain the corrected impact force F: Among them, Ms is the mass of the counterweight, m2 is the mass of the standard force sensor, and m e2 is the equivalent mass of the internal sensitive end of the standard force sensor; In addition, the inertial force correction coefficient δ of the force measurement system of the pendulum impact tester is calculated: in, The force measurement system of the pendulum impact tester consists of a force sensor and an impact hammer; The inertia force correction coefficient δ is used to correct the impact force Fc obtained when the impact force is measured using only the force value measurement system of the pendulum impact tester, and the correction value F′ is obtained: F′=δ·Fc.

2. The method according to claim 1, characterized in that The effective mass Mc of the impact structure of the pendulum impact tester is estimated as follows:

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