A cantilever drop hammer impact load test device and impact load correction method

Abstract

The present application belongs to the field of aircraft component load testing, and particularly relates to a cantilever drop hammer impact load test device and an impact load correction method, which is composed of a mounting seat 1, a loading cantilever 4, a drop hammer constraint tube 5, a mass block 6 and a release mechanism. A loading point is designed on the loading cantilever, on which a force sensor 3 is installed, and connected to a test piece 9 through an adapter 8. The release mechanism releases the drop hammer mass block after lifting it to a certain height, generates an impact load at the impact point of the loading cantilever, and transmits it to the force sensor through the loading cantilever, applies an impact load to the test piece, and solves the problem that the impact load measured by the sensor is affected by the inertial force, resulting in insufficient impact force test accuracy.

Description

Technical Field

[0001] The present application belongs to the field of aircraft component load testing, and in particular relates to a cantilever drop hammer impact load test device and an impact load correction method. Background Art

[0002] Aircraft engines will be subjected to impact loads under certain extreme working conditions. Impact loading tests on engine components are usually carried out to assess the impact resistance of the components. This is used to verify the impact resistance of components in the early stages of major tests such as whole-machine containment tests, and to provide an effective verification method for structural improvements of components.

[0003] During the impact loading test on the structural parts, since the test parts are usually flexible components, the test parts will produce certain deformation during the loading process, and the deformation will produce large acceleration. In addition, for the impact loading of the structural parts, an adapter is often required to be installed between the force sensor and the loading position of the structural parts to transmit the impact force. The adapter produces displacement and acceleration following the test part. The acceleration of both the test part and the adapter will affect the impact force transmitted to the test part, resulting in errors.

[0004] In the structural impact test, the sensor is used as a force measuring element to test the impact force applied to the test piece. For the traditional impact test bench, the sensor is installed on the rigid test bench, the impact load is applied to the test piece, and then the impact force is transmitted to the sensor. The deformation or movement displacement caused by the impact load applied to the test piece mainly acts on the test piece, and does not cause the sensor to produce a large movement displacement or a large acceleration. At this time, the inertial force of the sensor itself can be ignored compared with the measured impact force. When conducting the impact loading test of the structural part, the sensor is connected to the test piece through an adapter. The large deformation of the test piece causes the sensor to move simultaneously with it and generate acceleration, thereby introducing an inertial force on the sensor. This inertial force will affect the test accuracy of the sensor, so a method is needed to correct the inertial force of the sensor caused by the impact. At present, there are no relevant reports on the correction method of the sensor test results of structural parts under impact load. Summary of the invention

[0005] In order to solve the above problems, the present application provides a cantilever drop hammer impact load test device, which is characterized by comprising:

[0006] The impact loading structure has a support arm connected vertically to each other, one end of which is hinged to the mounting seat through a hinge point; the support arm has a first wall surface and a second wall surface opposite to the first wall surface;

[0007] The second wall surface is connected to a flexible support member, one end of the flexible support member is fixed to the table surface, and the other end supports the second wall surface, and the flexible support member supports the impact loading structure to make the first wall surface horizontal;

[0008] The first wall surface has an impact point, at which a drop weight restraint cylinder with an axis perpendicular to the ground is installed. The drop weight restraint cylinder has a mass block inside the cylinder that slides axially along the drop weight restraint cylinder, and the mass block is connected to a release mechanism installed on the drop weight restraint cylinder.

[0009] Preferably, the flexible support member comprises a spring or a combination of multiple springs.

[0010] Preferably, the combination of the plurality of springs comprises a plurality of springs connected in parallel or in series.

[0011] Preferably, the flexible support member comprises an elastic cantilever beam with one end fixed, and a free end of the cantilever beam supports the second wall surface.

[0012] Preferably, the flexible support comprises a buffer.

[0013] Preferably, the elastic coefficient K of the flexible support member, the stroke L of the flexible support member, and the weight G of the impact loading structure satisfy that G is greater than KL / 3 and less than KL / 2. The above technical features are obtained through data collection from multiple tests, and the elastic coefficient K is within the said range, which can make the test results more accurate.

[0014] A cantilever drop hammer impact load inertia force correction method, using a cantilever drop hammer impact load test device, the method is specifically as follows:

[0015] Step S1: Connect the test piece to a position on the first wall through an adapter and a force sensor; release the mass block to the impact point at a preset height, and obtain the first impact force F displayed by the force sensor. C (t);

[0016] Step S2: Remove the test piece, install the acceleration sensor on the force sensor, release the mass block to the impact point at a preset height, and obtain the second impact force F displayed by the force sensor. G (t); obtain the acceleration a(t) measured by the acceleration sensor;

[0017] Step S3: Determine the equivalent mass m of the inertial force generated by the acceleration sensor and the adapter e ;

[0018] Step S4: Obtain the mass of the acceleration sensor and the adapter, and based on the equivalent mass m e and acceleration a(t), determine the corrected impact force of the acceleration sensor and the adapter;

[0019] Step S5: Based on the modified impact force, modify the first impact force F C (t) The impact force F(t) borne by the test piece is obtained after correction.

[0020] Preferably, the second impact force F G The acceleration a(t) is the peak value during the test.

[0021] Preferably, the equivalent mass m of multiple tests is obtained ei , take the average value of multiple tests as the final equivalent mass m e .

[0022] Preferably, the equivalent mass m of the preset time period t1 to t2 is selected e (t), and the equivalent mass m is obtained by integrating and averaging e .

[0023] Advantages of this application include:

[0024] 1. A specific method for inertia force correction of cantilever drop hammer impact loading is given;

[0025] 2. Using different support forms can produce different accelerations for the sensor, so that the relationship between the equivalent mass of the acceleration and the change of acceleration can be corrected, and the correction of the sensor test results can be further refined.

[0026] 3. The present invention can solve the problem of difficulty in obtaining the equivalent mass of the sensor itself, thereby effectively calculating the inertial force, and can effectively improve the accuracy of impact load testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a connection diagram of a cantilever drop hammer impact load test device and a test piece 9 in a preferred embodiment of the present application;

[0028] Figure 2 It is a connection diagram of a cantilever drop hammer impact load test device without the test piece 9 in a preferred embodiment of the present application;

[0029] Figure 3 The flexible support 2 is a schematic diagram of a spring;

[0030] Figure 4 The flexible support 2 is a schematic diagram of a parallel spring;

[0031] Figure 5 The flexible support 2 is a schematic diagram of a series spring;

[0032] Figure 6 The flexible support 2 is a schematic diagram of a buffer;

[0033] Figure 7 The flexible support 2 is a schematic diagram of a cantilever beam. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0035] like Figure 1 As shown, a cantilever drop hammer impact load test device is characterized by comprising:

[0036] The impact loading structure 4 has a support arm vertically connected to each other, one end of which is hinged to the mounting base 1 through a hinge point; the support arm has a first wall surface and a second wall surface opposite to the first wall surface;

[0037] The second wall surface is connected with a flexible support member 2, one end of the flexible support member 2 is fixed to the table surface, and the other end supports the second wall surface, and the flexible support member 2 supports the impact loading structure 4 to make the first wall surface horizontal;

[0038] The first wall surface has an impact point, at which a drop hammer constraint cylinder 5 with an axis perpendicular to the ground is installed. The drop hammer constraint cylinder 5 has a mass block 6 inside the cylinder that slides axially along the drop hammer constraint cylinder 5. The mass block 6 is connected to a release mechanism 7 installed on the drop hammer constraint cylinder 5.

[0039] The stiffness of the flexible support determines the Figure 2 How much acceleration can be generated by the impact loading form, thereby obtaining the equivalent mass corresponding to different accelerations, so the structure of the flexible support 2 is very important. It first needs to be able to bear the weight of the loading cantilever and the force sensor to maintain the static balance of the loading cantilever and the force sensor before impact loading; more importantly, the flexible support needs to provide different support stiffness to generate different accelerations for the force sensor under impact loading conditions. The forms of flexible supports include:

[0040] 1. Spring, stiffness can be easily selected or adjusted through spring parameters.

[0041] 2 spring components, connected in series through springs such as Figure 4 And parallel connection Figure 5 By means of this method, support components with different elastic coefficients K, i.e., support stiffness, can be adjusted.

[0042] 3. Cantilever beam method, such as Figure 7 After the cross-sectional size of the cantilever is determined, the support stiffness that changes continuously within a certain range can be adjusted by using different lengths of the cantilever.

[0043] 4 Hydraulic buffers, such as Figure 6 , can be used as an acceleration adjustment device to supplement the above stiffness adjustment flexible support.

[0044] Furthermore, the elastic coefficient K of the flexible support member 2, the stroke L of the flexible support member 2, and the weight G of the impact loading structure 4 satisfy that G is greater than KL / 3 and less than KL / 2. The above technical features are obtained through data collection from multiple tests, and the elastic coefficient K is within the said range, which can make the test results more accurate.

[0045] A cantilever drop hammer impact load inertia force correction method, using a cantilever drop hammer impact load test device, the method is specifically as follows:

[0046] Step S1: Connect the test piece 9 to a position on the first wall through the adapter 8 and the force sensor 3; release the mass block 6 to the impact point at a preset height, and obtain the first impact force F displayed by the force sensor 3 C (t), such as Figure 1 As shown;

[0047] Step S2: Remove the test piece 9, install the acceleration sensor 11 on the force sensor 3, release the mass block 6 to the impact point at a preset height, and obtain the second impact force F displayed by the force sensor 3 G (t); obtain the acceleration a(t) measured by the acceleration sensor 11;

[0048] Step S3: Determine the equivalent mass m of the inertial force generated by the acceleration sensor 11 and the adapter 8 e ;

[0049] According to the balance equation of the sensor under impact loading:

[0050] F G (t) = m e a(t)

[0051] m e =F G (t) / a(t)

[0052] Step S4: Obtain the mass of the acceleration sensor 11 and the adapter 8, and based on the equivalent mass m e and acceleration a(t), determine the corrected impact force of the acceleration sensor 11 and the adapter 8; specifically:

[0053] If an adapter is used between the sensor and the test piece, see Figure 1 The adapter is shown as 8. Then the mass of the adapter is included in the inertial force mass:

[0054] m E =m e +m z

[0055] m z is the mass of the acceleration sensor 11 and the adapter 8; m z Measured by weighing;

[0056] m E is the equivalent total mass of the acceleration sensor 11 and the adapter 8;

[0057] Step S5: Based on the modified impact force, modify the first impact force F C (t) The impact force F(t) on the test piece after correction is obtained.

[0058] For the test piece, according to its force balance equation, the corrected result of the impact force is:

[0059] F(t)=F C (t)+m E a(t)

[0060] Where, F(t) is the impact force borne by the test piece after correction.

[0061] Furthermore, the second impact force F G (t) is the peak value during the test, and the acceleration a(t) is the peak value during the test.

[0062] From this we can get:

[0063] m e =F Gmax / a max

[0064] Further:

[0065] F max =F Cmax +m E a max

[0066] The above formula does not take into account the positive and negative acceleration. In the actual test process, the positive and negative acceleration during the test needs to be taken into account in the calculation result.

[0067] according to Figure 1 The loading method shown, the impact force amplitude F max Should be smaller than F max , because the inertial force will balance part of the force, making the actual impact force smaller.

[0068] Furthermore, the equivalent mass m of multiple tests is obtained ei , take the average value of multiple tests as the final equivalent mass m e .

[0069] Furthermore, the equivalent mass m of the preset time period t1 to t2 is selected e (t), and the equivalent mass m is obtained by integrating and averaging e ,Right now:

[0070]

[0071] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for correcting the inertial force of a cantilever drop weight impact load, characterized in that: A cantilever drop hammer impact load test device is used, and the test device comprises: The impact loading structure (4) has a support arm vertically connected to each other, one end of which is hinged to the mounting seat (1) via a hinge point; the support arm has a first wall surface and a second wall surface opposite to the first wall surface; The second wall surface is connected to a flexible support member (2), one end of the flexible support member (2) is fixed to the table surface, and the other end supports the second wall surface, and the flexible support member (2) supports the impact loading structure (4) to make the first wall surface horizontal; The first wall surface has an impact point, a drop weight restraint cylinder (5) with an axis perpendicular to the ground is installed at the impact point, a mass block (6) is provided inside the drop weight restraint cylinder (5) and slides along the axial direction of the drop weight restraint cylinder (5), the mass block (6) is connected to a release mechanism (7), and the release mechanism (7) is installed on the drop weight restraint cylinder (5); The method comprises: Step S1: Connect the test piece (9) to a position on the first wall surface through the adapter (8) and the force sensor (3); release the mass block (6) to the impact point at a preset height, and obtain the first impact force F displayed by the force sensor (3). C (t); Step S2: The test piece (9) is removed, the acceleration sensor (11) is mounted on the force sensor (3), the mass block (6) is released to the impact point at a preset height, and a second impact force F displayed by the force sensor (3) is obtained. G (t); obtain the acceleration a(t) measured by the acceleration sensor (11); Step S3: Determine the equivalent mass m of the inertial force generated by the acceleration sensor (11) and the adapter (8) e ; Step S4: Obtain the masses of the acceleration sensor (11) and the adapter (8), and based on the equivalent mass m e and the acceleration a(t), determining the corrected impact force of the acceleration sensor (11) and the adapter (8); Step S5: Based on the modified impact force, modify the first impact force F C (t) The impact force F(t) borne by the test piece is obtained after correction.

2. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: The flexible support member (2) comprises a spring or a combination of multiple springs.

3. The cantilever drop weight impact load inertia force correction method according to claim 2, characterized in that: The combination of the plurality of springs includes a plurality of springs connected in parallel or in series.

4. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: The flexible support member (2) comprises an elastic cantilever beam with one end fixed, and the free end of the cantilever beam supports the second wall surface.

5. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: The flexible support (2) comprises a buffer.

6. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: The elastic coefficient K of the flexible support member (2), the travel L of the flexible support member (2), and the weight G of the impact loading structure (4) satisfy the following relationship: G is greater than KL / 3 and less than KL / 2.

7. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: Second impact force F G The acceleration a(t) is the peak value during the test.

8. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: Get the equivalent mass m of multiple tests ei , take the average value of multiple tests as the final equivalent mass m e .

9. The cantilever drop weight impact load inertia force correction method according to claim 1, characterized in that: Select the preset time period t1~t2 equivalent mass m e (t), and the equivalent mass m is obtained by integrating and averaging e .

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