A method and system for measuring torsion parameters

Abstract

The present invention relates to the technical field of material performance evaluation, and discloses a method and system for measuring torsion parameters. The method is implemented by relying on a measurement system based on a laser pulse force source; the torsion parameters include a torsion stiffness coefficient; the method for measuring the torsion stiffness coefficient includes: configuring three workpieces to be measured, forming three workpiece combinations to be measured in groups of two; symmetrically clamping each workpiece combination to be measured in a workpiece fixture of the system, and calculating the sum of the torsion stiffness coefficients of each workpiece combination to be measured according to the vibration natural frequency of the system under two working conditions with and without a calibration beam and the known moment of inertia of the calibration beam, and then calculating and obtaining the torsion stiffness coefficient of each workpiece combination to be measured. The torsion parameters also include a torsion angle range; the method for measuring the torsion angle range is: a pointer and a dial are installed on the system shaft, and under the action of an external torque, the safe working range of the workpiece to be measured is measured according to the pointer indication read from the dial. The present invention is easy to operate and has high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of material performance evaluation, and in particular to a method and system for measuring torsion parameters. Background Art

[0002] High-precision measurement of torsional stiffness coefficient is of great significance for ensuring the quality and performance of products, and is an indispensable part of engineering design and scientific research. Torsional stiffness coefficient is an important parameter for evaluating the ability of materials or structures to resist torsional deformation. It is usually used to describe the degree of rigidity of shafts, rods, wires or similar structures when subjected to torque. By accurately measuring the torsional stiffness coefficient, the optimization design method can be used to ensure that the product has good stability and reliability during use. For existing mechanical parts or structures, measuring their torsional stiffness coefficient can help engineers evaluate whether the performance of these parts or structures meets the design requirements and how they are characterized in practical applications. In the research and development of new materials and the application of new processes, high-precision measurement of torsional stiffness coefficient is also required, which not only helps to understand the basic properties of materials, but also guides the design and selection of new materials to meet the needs of specific applications. Therefore, in the fields of mechanical design, material processing and fault diagnosis, it is of great practical significance to achieve high-precision measurement of torsional stiffness coefficient.

[0003] The torsional stiffness coefficient measurement method currently used is generally based on Hooke's law (i.e. The measurement principle is to fix one end of the specimen and apply a known torque to the other end. , and record the torsion angle generated by the torque Then, according to the formula The torsional stiffness coefficient is obtained by calculation. There are two key points in this measurement method. One is that a precision torque wrench or a dedicated high-precision torsion testing machine is required to ensure the accuracy of the applied torque; the other is that the torsion angle needs to be accurately measured, such as using an angle encoder. In addition, it is also necessary to ensure that the specimen is operated within a safe range and to avoid damage to the specimen due to excessive loading. However, the torque application devices currently used generally have large torques and low precision, especially when measuring small torsional stiffness coefficients. In addition, the measurement accuracy of the angle encoder is also low, and it is easily affected by external environmental vibration and noise. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for measuring torsion parameters, which utilizes laser irradiation to generate instantaneous pulse excitation to provide initial kinetic energy for the measuring system. The size of the laser pulse excitation and the size of the force arm and the measuring arm will not affect the measuring result, and has the advantages of high measurement accuracy and simple operation. In addition, by comprehensively using the pointer and dial of the measuring system, the maximum working safety range of the workpiece to be measured can be measured, which can avoid damage to the test piece due to excessive loading.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for measuring a torsion parameter, the method being implemented by a measurement system based on a laser pulse force source; the torsion parameter includes a torsion stiffness coefficient; the method for measuring the torsion stiffness coefficient includes the following steps:

[0007] S10. Configure three workpieces to be tested, two by two to form a combination of three workpieces to be tested;

[0008] S11. Clamp each workpiece to be measured symmetrically in the workpiece fixture configured by the measuring system, and measure the vibration natural frequency of the system under two working conditions: with and without the calibration beam. oh n1 , oh n0 and the known moment of inertia of the calibration beam , calculate the sum of the torsional stiffness coefficients of each combination of workpieces to be tested, respectively X , Y and Z ;

[0009] S12. Calculate the torsional stiffness coefficient of each workpiece to be tested by the following method: k 1. k 2. k 3:

[0010] ,

[0011] ,

[0012] .

[0013] As a possible implementation, the vibration natural frequency of the measuring system with and without the calibration beam is oh n1 , oh n0 They are calculated by the following formula:

[0014] ;

[0015] in, oh n for oh n1 , oh n0 Universal expressions; oh d To measure the vibration frequency of the system; g is the damping ratio of the measurement system.

[0016] As a possible implementation, measuring the vibration frequency of the system oh d Calculated by the following formula:

[0017] ;

[0018] in, m is the number of vibration cycle intervals; The output of the system response acquisition device configured for the measurement system is m+i extreme points; The output of the acquisition device configured for the measurement system i An extreme point.

[0019] As a possible implementation, the damping ratio of the measuring system g Calculated by the following formula:

[0020] ,

[0021] ,

[0022] ,

[0023] in, The output of the system response acquisition device configured for the measurement system is i extremum; The output of the acquisition device configured for the measurement system m+i extreme values, Λ represents logarithmic reduction, a Represents the logarithmic decay rate factor.

[0024] As a possible implementation method, the sum of the torsional stiffness coefficients of each combination of workpieces to be tested is calculated using the following formula:

[0025] ,

[0026] in, k for X , Y and Z Express.

[0027] As a possible implementation method, a dial and a pointer are installed on the rotating shaft of the measuring system, and the pointer rotates synchronously with the rotating shaft; the torsion parameter also includes the torsion angle range ,in, Determined by:

[0028] Under the working condition without the calibration beam, the swing arm of the measuring system has no external force and the pointer is stable. The pointer reading from the dial is i 0; Slowly apply external force clockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. The pointer reading on the dial is i 1, ;

[0029] Determine by the following method: Slowly apply external force counterclockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be measured is not damaged, and read the pointer reading from the dial. i 2, .

[0030] In a second aspect, the present invention provides a measurement system based on a laser pulse force source, which is used to perform the measurement method provided in the first aspect; the measurement system comprises:

[0031] A support frame, wherein the upper portion of the support frame has a first support end and a second support end;

[0032] A rotating shaft, which is arranged between the first supporting end and the second supporting end, that is, a central cross section of the rotating shaft is coplanar with a symmetry plane of the first supporting end and the second supporting end;

[0033] Two groups of workpiece clamps, each of which coaxially clamps the workpiece to be measured; one end of one group of workpiece clamps is fixedly connected to the first support end, and the other end is coaxially fixedly connected to the top end of the rotating shaft; one end of the other group of workpiece clamps is fixedly connected to the second support end, and the other end is coaxially fixedly connected to the bottom end of the rotating shaft;

[0034] A swing arm, the swing arm is fixedly connected to the rotating shaft in a symmetrical manner at both ends;

[0035] The calibration beam is fixedly connected to the rotating shaft in a symmetrical manner at both ends when the calibration beam is present, and is located at the upper end or the lower end of the swing arm; when the calibration beam is not present, it is removed from the rotating shaft;

[0036] Two groups of working fluid fixtures, each group of working fluid fixtures holds working fluid; one group of working fluid fixtures is fastened to one end of the swing arm, and the other group of working fluid fixtures is fastened to the other end of the swing arm;

[0037] Two groups of lasers, one group of lasers is set corresponding to each group of working fluid fixtures, and the laser light generated by the lasers is used to ablate the working fluid;

[0038] A system response acquisition device, which is arranged at one end of the swing arm and is used to output a plurality of extreme value points and their corresponding extreme values;

[0039] A damping device, the damping device is arranged at the other end of the swing arm;

[0040] The processor includes a storage unit and a computing unit. The storage unit is used to store a plurality of extreme value points output by the system response acquisition device and the extreme value corresponding to each extreme value point. The computing unit reads the first m+i Extreme Points , No. i Extreme Points , Number of interval cycles m Calculate the vibration frequency of the measurement system oh d According to i Extreme Value , No. m+i Extreme Value , Number of interval cycles m Calculate the parameter Λ, and then calculate the logarithmic decay rate factor based on the parameter Λ a , and finally based on a Calculate the damping ratio of the measurement system g ; Based on the vibration frequency of the measuring system oh d and the damping ratio of the measurement system g Calculate the vibration natural frequency of the measurement system with and without the calibration beam oh n1 , oh n0 ; According to the vibration natural frequency of the measuring system under two working conditions with and without the calibration beam oh n1 , oh n0 and the known moment of inertia of the calibration beam , calculate the sum of the torsional stiffness coefficients of each combination of workpieces to be tested, respectively X , Y and Z ; The torsional stiffness coefficient of each workpiece to be tested is calculated as follows k 1. k 2. k 3:

[0041] ,

[0042] ,

[0043] .

[0044] As a possible implementation method, a dial and a pointer are installed on the rotating shaft of the measuring system, and the pointer rotates synchronously with the rotating shaft; the calculation unit is also used to obtain the working condition without the calibration beam, and the swing arm of the measuring system has an angle of rotation when no external force is applied and the pointer is stable. i 0, slowly apply external force clockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. i 1. Based on Calculate and obtain the lower limit value of the torsion range;

[0045] The calculation unit is also used to obtain the time when an external force is slowly applied counterclockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. i 2. Based on Calculate the upper limit of the torsion range.

[0046] As a possible implementation, the thickness of the working fluid is 60 μm to 300 μm; the diameter of the laser focus spot is 50 μm to 500 μm.

[0047] As a possible implementation, the measuring system further includes a limiter, which includes a fine-pitch bolt and a limit head; wherein the fine-pitch bolt penetrates the side wall of the support frame and is coaxially connected to the limit head, and an adjustable gap is provided between the limit head and the rotating shaft; and / or,

[0048] The swing arm is a hollow swing arm; and / or,

[0049] Each workpiece clamp comprises a coaxially arranged fixed chuck and a movable chuck, wherein the fixed chuck is tightly connected to the supporting end of the support frame, and the movable chuck is connected to the end of the rotating shaft and rotates with the rotating shaft; the two ends of the workpiece to be measured are respectively inserted into the end faces of the fixed chuck and the movable chuck against each other; and / or,

[0050] Each working fluid fixture comprises a fixture base, which is a step plate structure with increasing height from one end fixed to the swing arm to the cantilever end; wherein, a mounting hole is provided on the step for placing the working fluid, and after the working fluid is clamped in the mounting hole, it is fastened in sequence by an annular pre-tightening buckle and a cover plate; and / or, the damping device is an eddy current damper, and the damping plate included in it is fastened to one end of the swing arm.

[0051] Compared with the prior art, the present invention has the following effects:

[0052] 1. The torsion parameter measurement method proposed in the present invention can measure both the torsion stiffness coefficient of the specimen and the torsion angle amplitude of the specimen. When measuring the torsion stiffness coefficient of the specimen, the present invention uses laser irradiation to generate instantaneous pulse excitation to provide initial kinetic energy for the measurement system, breaking through the problem that the traditional measurement method must provide a torque with known size and high precision. By applying lasers of different energies, the variation law of the torsion stiffness coefficient of the specimen to be tested with different torsion angles can be studied. In particular, when the energy of a single laser pulse is low, the kinetic energy generated by its micro-ablation is very small, and an extremely small torsion stiffness coefficient (less than 10 -4 The laser itself has good stability and repeatability, so the repeatability and linearity of the measurement method of the present invention are good. In addition, the present invention is instantaneous and non-contact, can be remotely operated, has the advantages of simple operation, and the invention belongs to a non-destructive testing method and will not cause damage to the workpiece to be tested.

[0053] 2. In the torsion parameter measurement method proposed in the present invention, when measuring the torsion stiffness coefficient of the test piece, the size of the laser pulse excitation and the size of the force arm and the measurement arm will not affect the measurement result, and the measurement accuracy is high.

[0054] 3. The torsion parameter measurement method proposed in the present invention measures the torsion angle amplitude of the test piece through a pointer and a dial installed on the system shaft. Specifically, under the action of external torque, the safe working range of the workpiece to be measured is measured according to the pointer indication read from the dial. The measurement has high accuracy and will not damage the workpiece.

[0055] 4. The measurement system based on the laser pulse force source proposed in the present invention adopts a hollow swing arm, which can improve the natural frequency and sensitivity of the measurement system; the use of two groups of symmetrically arranged lasers can significantly increase the number of measurements on the one hand, without the need for frequent replacement of the ablative working fluid, and can effectively improve the test efficiency; on the other hand, it helps to improve the stability of the swing arm and improve the measurement accuracy.

[0056] 5. The measurement system based on the laser pulse force source proposed in the present invention can limit excessive torsion angles to protect the workpiece to be measured and the measurement system by adjusting the gap between the limit head and the rotating shaft through fine-thread bolts, and avoid component damage during system movement, component replacement, and workpiece testing; in addition, the system adopts an eddy current damper, which can accelerate the swing arm to enter a balanced state, shorten the transient process, and improve measurement efficiency; on the other hand, it can also effectively reduce the impact of environmental noise on measurement, and improve the signal-to-noise ratio and measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0058] Figure 1 A flow chart of a method for measuring torsion parameters provided by an embodiment of the present invention;

[0059] Figure 2 A dynamic principle diagram of a measurement system based on a laser pulse force source provided by an embodiment of the present invention;

[0060] Figure 3 to Figure 4 , Figure 9 to Figure 10 A structural diagram of a measurement system based on a laser pulse force source provided in an embodiment of the present invention;

[0061] Figure 5 to Figure 6 A schematic diagram of a workpiece fixture structure in a measurement system based on a laser pulse force source provided in an embodiment of the present invention;

[0062] Figure 7 A schematic diagram of the structure of a working fluid fixture in a measurement system based on a laser pulse force source provided in an embodiment of the present invention;

[0063] Figure 8 A schematic diagram of a processor in a measurement system based on a laser pulse force source provided by an embodiment of the present invention;

[0064] Figure 11 The system responses corresponding to the combination of 1# and 2# in the embodiment of the present invention are as follows: (a) without the calibration beam and (b) with the calibration beam;

[0065] Figure 12 The system responses corresponding to the combination of 1# and 3# in the embodiment of the present invention are as follows: (a) without the calibration beam and (b) with the calibration beam;

[0066] Figure 13 The system responses corresponding to the combination of 2# and 3# in the embodiment of the present invention are as follows: (a) without the calibrated beam and (b) with the calibrated beam.

[0067] Reference numerals:

[0068] 10-support frame, 100-first support end, 101-second support end, 11-rotating shaft, 110-dial, 111-pointer, 12-workpiece fixture, 120-fixed chuck, 121-moving chuck, 13-swing arm, 14-calibration beam, 15-working fluid fixture, 150-fixed fixture base, 1500-mounting hole, 1501-annular pre-tightening buckle, 1502-cover plate, 16-laser, 17-system response acquisition device, 170-displacement sensor, 171-system response acquisition board, 18-damping device, 180-damping plate, 19-processor, 190-storage unit, 191-computing unit, 20-limiter, 200-fine thread bolt, 201-limit head, 30-working fluid. DETAILED DESCRIPTION

[0069] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0070] It should be noted that when an element is referred to as being "fixed on" or "set on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0071] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0072] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0073] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0074] The embodiment of the present invention proposes a method and system for measuring torsion parameters, which can measure the torsion stiffness coefficient and torsion angle amplitude of a test piece. The method uses laser irradiation to generate instantaneous pulse excitation to provide initial kinetic energy for the measurement system, so that it performs damped free vibration, and then records the system response of the measurement system under two working conditions without and with the calibration beam. The corresponding vibration frequency and damping ratio are calculated by reading different extreme points and extreme value information under the two working conditions, and then the system natural frequency under the two working conditions is obtained. Then, the sum of the torsion stiffness coefficients of the workpieces to be measured at the upper and lower ends of the measurement system is calculated in combination with the known moment of inertia of the calibration beam. In order to obtain the torsion stiffness coefficient of each workpiece to be measured, the third workpiece to be measured is introduced in the present embodiment, so that the three workpieces to be measured are combined in pairs, and the sum of the torsion stiffness coefficients corresponding to each combination is obtained, and then the torsion stiffness coefficients of each of the three workpieces to be measured are obtained by solving the simultaneous equations. Compared with the vibration period of the measurement system, the laser pulse excitation action time proposed in the present embodiment is extremely short, instantaneous and non-contact, and can be remotely operated. In addition, the size of the laser pulse excitation and the size of the force arm and the measuring arm will not affect the measurement result. Therefore, the measurement method proposed in this embodiment has the advantages of high measurement accuracy and simple operation. Moreover, the present invention belongs to non-destructive testing and will not cause damage to the workpiece to be measured. Furthermore, by comprehensively using the pointer and the dial of the measurement system, the maximum working safety range of the workpiece to be measured can be measured.

[0075] In a first aspect, an embodiment of the present invention provides a method for measuring a torsion parameter. The method is implemented by a measurement system based on a laser pulse force source. The torsion parameter includes a torsion stiffness coefficient.

[0076] See also Figure 1 , the method for measuring the torsional stiffness coefficient includes the following steps:

[0077] S10. Configure three workpieces to be tested, two by two to form a combination of three workpieces to be tested;

[0078] As an example, three workpieces to be tested are configured, numbered 1#, 2# and 3# respectively. There are three situations in which two workpieces are grouped together, namely, three combinations of workpieces to be tested, namely, 1# and 2# combination, 1# and 3# combination, and 2# and 3# combination.

[0079] S11. Clamp each workpiece to be measured symmetrically in the workpiece fixture configured by the measuring system, and measure the vibration natural frequency of the system under two working conditions: with and without the calibration beam. oh n1 , oh n0 and the known moment of inertia of the calibration beam , calculate the sum of the torsional stiffness coefficients of each combination of workpieces to be tested, respectively X , Y and Z ;

[0080] As an example, assume that the torsional stiffness coefficients of the workpieces to be tested, numbered 1#, 2#, and 3#, are k 1. k 2. k 3. X represents the sum of the torsional stiffness coefficients of each workpiece to be tested in the 1# and 2# combinations, then Similarly, assuming Y represents the sum of the torsional stiffness coefficients of each workpiece to be tested in the 1# and 3# combinations, then , assuming Z represents the sum of the torsional stiffness coefficients of each workpiece to be tested in the 2# and 3# combinations, then .

[0081] As a possible implementation, the vibration natural frequency of the measuring system with and without the calibration beam is oh n1 , oh n0 They are calculated by the following formula:

[0082] ;

[0083] in, oh n for oh n1 , oh n0 Universal expressions; oh d To measure the vibration frequency of the system; g is the damping ratio of the measurement system.

[0084] As a possible implementation, measuring the vibration frequency of the system oh d Calculated by the following formula:

[0085] ;

[0086] in,m is the number of vibration cycle intervals; The output of the system response acquisition device configured for the measurement system is m+i extreme points; The output of the acquisition device configured for the measurement system i An extreme point.

[0087] As a possible implementation, the damping ratio of the measuring system g Calculated by the following formula:

[0088] ,

[0089] ,

[0090] ,

[0091] in, The output of the system response acquisition device configured for the measurement system is i extreme values; The output of the acquisition device configured for the measurement system m+i extreme values, Λ represents logarithmic reduction, a Represents the logarithmic decay rate factor.

[0092] As a possible implementation method, the sum of the torsional stiffness coefficients of each combination of workpieces to be tested is calculated using the following formula:

[0093] ,

[0094] in, k for X , Y and Z Express.

[0095] S12. Calculate the torsional stiffness coefficient of each workpiece to be tested by the following method: k 1. k 2. k 3:

[0096] ,

[0097] ,

[0098] .

[0099] The technical solution of the present invention is further described below in conjunction with the accompanying drawings. When no calibration beam is added, the dynamic principle of the measurement system under the action of the laser pulse force is as follows: Figure 2 Assume that the damping coefficient of the measurement system is c, the torque generated by damping is , the torsional stiffness coefficient of the workpiece to be tested is k The corresponding restoring torque is ; The moment of inertia of the entire measurement system is J , and its corresponding moment of inertia is The interaction time between a single pulse laser and a substance is extremely short, usually less than the ms level, and can even reach the ps and fs level. Therefore, the time for the pulse force to act on the swing arm is also extremely short, much shorter than the vibration period of the measurement system. Therefore, the laser pulse can be regarded as an ideal instantaneous pulse excitation. The pulse force generated by the laser ablation medium acts vertically on the swing arm, and the force arm is L f , then the corresponding impulse force excitation is ,in is the Dirac function. Under the excitation of the laser pulse, the measurement system undergoes damped free vibration and gradually dissipates energy until it returns to the equilibrium position. Its dynamic control equation is:

[0100] (1)

[0101] When the torsion angle is small, the linear displacement and angular displacement There is the following approximate relationship:

[0102] (2)

[0103] in,

[0104] L s For the measuring arm.

[0105] Equation (1) can be rewritten into the following standard form:

[0106] (3)

[0107] in, is the damping ratio of the measurement system, oh n is the natural frequency of the measurement system.

[0108] (4)

[0109] The solution of equation (3) can be expressed as:

[0110] (5)

[0111] in, is the natural frequency of the measurement system.

[0112] Then we can get the impulse The maximum value of the measurement system response under the action is:

[0113] (6)

[0114] For impulse I The system response under the action i Maximum points:

[0115] (7)

[0116] in:

[0117] (8)

[0118] β is the phase difference caused by damping.

[0119] According to the system response formula (5), the corresponding next extreme point The corresponding maximum value is:

[0120] (9)

[0121] According to the above formula, the ratio of two adjacent amplitudes can be obtained as:

[0122] (10)

[0123] In actual calculations, the logarithmic reduction Λ can be used instead of the reduction factor or Or the strength of the damping:

[0124] (11)

[0125] or Independent of time, the ratio of any two adjacent amplitudes is or .therefore, m The amplitude ratio before and after the oscillation is:

[0126] (12)

[0127] Then Λ can be expressed as:

[0128] (13)

[0129] Combining formula (11), the damping ratio can be obtained g (positive value):

[0130] (14)

[0131] in:

[0132] (15)

[0133] a Represents the logarithmic decay rate factor.

[0134] The system vibration frequency is determined by the difference in time between adjacent maximum points of the system oh d :

[0135] (16)

[0136] Then, combined with the damping ratio, the natural frequency of the measurement system can be calculated:

[0137] (17)

[0138] Assume that the moment of inertia of the measurement system without a calibration beam is J , and the moment of inertia of the calibration beam is By applying laser pulse force, the displacement sensor can be used to obtain the system displacement response under the two working conditions with and without the calibration beam. Then, combining the extreme point of the system response and formula (17), the vibration natural frequency of the measurement system under the two working conditions with and without the calibration beam can be obtained as oh n1 and oh n0 Since the stiffness coefficient of the measuring system remains unchanged in both working conditions with and without the calibration beam (the stiffness coefficient depends on the mechanical properties of the elastic component), there is a relationship:

[0139] (18)

[0140] Then, the moment of inertia of the measurement system without a calibration beam can be obtained as:

[0141] (19)

[0142] The stiffness coefficient can be measured from formulas (18) and (19):

[0143] (20)

[0144] Combining formulas (13) and (20), it can be seen that the torsional stiffness coefficient only depends on the extreme point signal of the free vibration of the measurement system under the two working conditions of with and without the calibration beam and the moment of inertia of the calibration beam, and has nothing to do with the size of the applied pulse excitation and the size of the force arm and the measurement arm. This also reflects that the torsional stiffness coefficient is an inherent property of the measurement system, and its size is independent of the external excitation properties. However, the accuracy of the moment of inertia of the calibration beam and the measured system response will directly affect the accuracy of the torsional stiffness coefficient measurement. The accuracy of its structural dimensions and the uniformity of the material density distribution can be effectively guaranteed by carefully selecting the manufacturing materials of the calibration beam and using fine processing technology. Then, the moment of inertia of the calibration beam can be accurately calculated by using theoretical formulas. In order to ensure the measurement accuracy of the system response, a high-precision, high-resolution displacement sensor can be used, and multiple measurements can be performed to reduce the influence of random errors and system errors in the measurement environment on the measurement results.

[0145] The torsional stiffness coefficients of the workpieces at the upper and lower ends are obtained by using formula (20), rather than the torsional stiffness coefficient of a single workpiece. In order to obtain the torsional stiffness coefficient of each workpiece, a third workpiece can be introduced to make the three workpieces in pairs. Then, by obtaining the sum of the torsional stiffness coefficients corresponding to each combination and solving the simultaneous equations, the torsional stiffness coefficients of the three workpieces can be determined. The specific method is as follows:

[0146] There are three workpieces to be tested, numbered 1#, 2# and 3#, and their corresponding torsional stiffness coefficients are k 1. k 2. k 3. There are three combinations of two: 1# and 2#, 1# and 3#, and 2# and 3#. According to the above calculation method, the torsional stiffness coefficient corresponding to the 1# and 2# combination conditions can be obtained: X , Torsional stiffness coefficient corresponding to 1# and 3# combined working conditions Y And the torsional stiffness coefficient corresponding to the 2# and 3# combined working conditions Z ,Right now:

[0147] (twenty one)

[0148] By solving the above iterative equations, the torsional stiffness coefficients of the three workpieces to be tested, 1#, 2# and 3#, can be obtained as follows:

[0149] ,

[0150] , (twenty two)

[0151] .

[0152] As a possible implementation method, a dial and a pointer are installed on the rotating shaft of the measuring system, and the pointer rotates synchronously with the rotating shaft; the torsion parameter also includes the torsion angle range ,in, Determined by:

[0153] Under the working condition without the calibration beam, the swing arm of the measuring system has no external force and the pointer is stable. The pointer reading from the dial is i 0; Slowly apply external force clockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. The pointer reading on the dial is i 1, ;

[0154] Determine by the following method: Slowly apply external force counterclockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be measured is not damaged, and read the pointer reading from the dial. i 2, .

[0155] In order to measure the maximum torsion angle of the workpiece to be measured and evaluate its maximum working range, it is necessary to install a dial and a pointer on the shaft without adding a calibration beam. The pointer rotates synchronously with the shaft and is used with the dial to record the torsion position of the workpiece to be measured. It is stipulated that clockwise readings are negative and counterclockwise readings are positive. Assuming that the swing arm is not subjected to external force and the pointer is stable, the pointer reading is i 0, slowly apply external force clockwise to one end of the swing arm until the swing arm stops moving and the workpiece to be tested is not damaged, and record the pointer reading as i 1, the lower limit of the torsion angle can be obtained Then, apply external force to one end of the swing arm counterclockwise slowly until the swing arm moves to the limit position and the workpiece to be tested is not damaged, and record the pointer reading as i 2. The upper limit of the torsion angle can be obtained ; From this, the maximum working range of the workpiece to be tested can be obtained as .

[0156] In a second aspect, the present invention provides a measurement system based on a laser pulse force source, which is used to perform the measurement method provided in the first aspect, see Figure 3 to Figure 10 , the measurement system includes:

[0157] A support frame 10, the upper portion of the support frame 10 has a first support end 100 and a second support end 101; illustratively, the upper portion of the support frame 10 is a C-shaped frame for supporting other components and maintaining the stability of the entire system;

[0158] The rotating shaft 11 is disposed between the first supporting end 100 and the second supporting end 101, that is, the central cross section of the rotating shaft 11 is coplanar with the symmetry plane of the first supporting end 100 and the second supporting end 101;

[0159] There are two groups of workpiece clamps 12, and each workpiece clamp 12 coaxially clamps the workpiece to be measured; among them, one end of one group of workpiece clamps 12 is fixedly connected to the first support end 100, and the other end is coaxially fixedly connected to the top end of the rotating shaft 11; one end of the other group of workpiece clamps 12 is fixedly connected to the second support end 101, and the other end is coaxially fixedly connected to the bottom end of the rotating shaft 11; suitable clamps can be selected and designed for different workpieces to be measured.

[0160] See also Figure 3 to Figure 6 As an example, each workpiece clamp 12 includes a coaxially arranged fixed chuck 120 and a dynamic chuck 121, wherein the fixed chuck 120 is tightly connected to the supporting end of the support frame 10, and the dynamic chuck 121 is connected to the end of the rotating shaft 11 and rotates with the rotating shaft 11; there is a small gap between the opposite end faces of the fixed chuck 120 and the dynamic chuck 121 to avoid interference between the two during relative rotation, and the two ends of the workpiece to be measured can be respectively inserted into the gap for clamping and fixing.

[0161] See also Figure 3 to Figure 4 The measuring system further includes: a swing arm 13, which is fixedly connected to the rotating shaft 11 in a symmetrical manner at both ends; as an example, the swing arm 13 is a hollow swing arm, and the hollow design can reduce the moment of inertia of the swing arm 13 and improve the natural frequency and sensitivity of the measuring system; it also includes a calibration beam 14, which is fixedly connected to the rotating shaft 11 in a symmetrical manner at both ends and is located at the upper end or lower end of the swing arm 13 under the working condition of the calibration beam 14; under the working condition of no calibration beam 14, it is removed from the rotating shaft 11; illustratively, the moment of inertia of the calibration beam 14 is known, and it is fixedly connected to the rotating shaft 11 in a symmetrical manner at both ends, and the vibration frequency of the measuring system can be changed by replacing the calibration beam 14; as an example, a threaded hole and a positioning hole are provided in the middle of the rotating shaft 11 for installing the swing arm 13 and the calibration beam 14.

[0162] See also Figure 3 and Figure 7The measurement system also includes two groups of working fluid fixtures 15, each group of working fluid fixtures 15 clamps a working fluid 30; one group of working fluid fixtures 15 is fastened to one end of the swing arm 13, and the other group of working fluid fixtures 15 is fastened to the other end of the swing arm 13; as a possible implementation method, the thickness of the working fluid size is 60μm to 300μm, for example, 60μm, 80μm, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 240μm, 260μm, 280μm, 300μm. As an example, each working fluid fixture 15 includes a fixture base 150, and the fixture base 150 is a stepped plate structure that increases in height from one end fixedly connected to the swing arm 13 to the cantilever end; wherein, a mounting hole 1500 is opened on the step for placing the working fluid 30, and after the working fluid 30 is clamped in the mounting hole 1500, it is fastened in sequence by an annular pre-tightening buckle 1501 and a cover plate 1502.

[0163] See also Figure 3 to Figure 4 The measurement system also includes: two groups of lasers 16, one group of lasers 16 is correspondingly set for each group of working fluid fixtures 15, and the laser generated by the laser 16 is used to ablate the working fluid; the two groups of lasers 16 provide instantaneous pulse excitation for the measurement system, and the focusing spot diameter of the laser 16 is relatively small, generally 50μm to 500μm, such as 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, so that the change in the moment of inertia caused by each ablation of the working fluid can be ignored, especially, the calculation error caused by the change in the moment of inertia during similar tests can be ignored. Each time the measurement is performed, it is only necessary to install the two groups of lasers 16 at a fixed position to ablate the working fluid to generate the required laser pulse force, until the working fluid at the position is completely ablated, and then the laser can be moved to a nearby position to ablate the working fluid at the new position and continue to generate the pulse excitation required for measurement. When the working fluid at one end is completely ablated according to the S-shaped scanning path, the working fluid at the other end can be ablated in a similar way. On the one hand, the two sets of symmetrically arranged lasers can significantly increase the number of measurements without the need to frequently replace the ablation working fluid, which can effectively improve the test efficiency; on the other hand, the symmetrical distribution helps to improve the stability of the swing arm and improve the measurement accuracy.

[0164] See also Figure 3The measurement system also includes a system response acquisition device 17, which is arranged at one end of the swing arm 13 and is used to output multiple extreme points and their corresponding extreme values; illustratively, the system response acquisition device 17 is composed of a displacement sensor 170 and a system response acquisition board 171, which is used to collect the system response of the measurement system in real time and output multiple extreme points and their corresponding extreme values. In order to ensure the measurement accuracy, a non-contact displacement sensor that has no effect on the measurement system can be used, such as a capacitive displacement sensor, a laser displacement sensor, an eddy current displacement sensor, an optical fiber displacement sensor, and a laser interferometer.

[0165] See also Figure 3 to Figure 4 The measurement system also includes a damping device 18, which is arranged at the other end of the swing arm 13; as an example, the damping device 18 is an eddy current damper, which includes a damping plate 180 that is fastened to one end of the swing arm 13, and the eddy current damper is composed of a damping plate, a permanent magnet pair, and a mechanism that can be used to adjust the spacing between the permanent magnet pairs. The spacing between the permanent magnet pairs can be changed by the adjustment mechanism, so that a suitable damping coefficient can be provided for the workpiece to be measured with different torsional stiffness coefficients. On the one hand, the eddy current damper can accelerate the swing arm 13 to enter the equilibrium state, shorten the transient process, and improve the measurement efficiency; on the other hand, it can also effectively reduce the influence of environmental noise on the measurement, and improve the signal-to-noise ratio and measurement accuracy.

[0166] See also Figure 8 The measurement system further includes a processor 19, including a storage unit 190 and a calculation unit 191. The storage unit 190 is used to store multiple extreme value points output by the system response acquisition device 17 and the extreme value corresponding to each extreme value point; the calculation unit 191 reads the first m+i Extreme Points , No. i Extreme Points , Number of interval cycles m Calculate the vibration frequency of the measurement system oh d :

[0167] ;

[0168] According to i Extreme Value , No. m+i Extreme Value , Number of interval cycles m Calculate the parameter Λ:

[0169] ,

[0170] Then the logarithmic decay rate factor is calculated based on the parameter Λ a :

[0171] ,

[0172] Finally based on a Calculate the damping ratio of the measurement system g :

[0173] ;

[0174] Based on the vibration frequency of the measuring system oh d and the damping ratio of the measurement system g Calculate the vibration natural frequency of the measurement system with and without the calibration beam oh n1 , oh n0 :

[0175] ;

[0176] The vibration natural frequency of the measuring system under two working conditions: with and without the calibration beam oh n1 , oh n0 and the known moment of inertia of the calibration beam , calculate the sum of the torsional stiffness coefficients of each combination of workpieces to be tested, respectively X , Y and Z ; The torsional stiffness coefficient of each workpiece to be tested is calculated as follows k 1. k 2. k 3:

[0177] ,

[0178] ,

[0179] .

[0180] See also Figure 8 to Figure 10 As a possible implementation, a dial 110 and a pointer 111 are installed on the rotating shaft 11 of the measuring system, and the pointer 111 rotates synchronously with the rotating shaft 11; the calculation unit 191 is also used to obtain the working condition of the uncalibrated crossbeam 14, and the swing arm 13 of the measuring system has an angle of rotation when no external force is applied and the pointer is stable. i 0, slowly apply external force clockwise to one end of the swing arm 13 until the swing arm 13 moves to the limit position and the workpiece to be tested is not damaged. i 1. Based on The calculation unit 191 is also used to obtain the value of the lower limit of the torsion range when an external force is slowly applied counterclockwise to one end of the swing arm 13 until the swing arm 13 moves to the limit position and the workpiece to be tested is not damaged. i 2. Based on Calculate the upper limit of the torsion range.

[0181] As an example, the pointer reading at the initial steady-state position of the swing arm is -0.1°. An external force is slowly applied clockwise to one end of the swing arm until the swing arm cannot rotate. At this time, the recorded reading is -12.1°. Therefore, the lower limit of the torsion range of the workpiece to be measured can be obtained as:

[0182] ;

[0183] Then, apply external force to the swing arm counterclockwise until the swing arm cannot rotate. At this time, the recorded reading is 11.2°, so the lower limit of the torsion range of the workpiece to be tested can be obtained as:

[0184] .

[0185] See also Figure 4 As a possible implementation method, the measuring system also includes a limiter 20, which includes a fine-pitch bolt 200 and a limit head 201; wherein, the fine-pitch bolt 200 penetrates the side wall of the support frame 10 and is coaxially connected to the limit head 201, and an adjustable gap is provided between the limit head 201 and the rotating shaft 11; illustratively, the limit head 201 is made of rubber, and the gap between the limit head 201 and the rotating shaft 11 can be adjusted by the fine-pitch bolt 200. With such a configuration, the workpiece to be measured and the measuring system can be protected by limiting an excessive torsion angle, and component damage can be avoided during system movement, component replacement, and workpiece testing.

[0186] In one possible implementation, the measurement system body and the calibration beam are both made of aviation aluminum alloy, and the moment of inertia of the calibration beam is 0.00060577 kg·m 2 The system response acquisition device uses the capaNCDT6230 CS1 capacitive displacement sensor, which has a range of 1 mm, a resolution of 20 nm, and a sampling frequency of 1041.67 Hz, which can realize real-time acquisition of system response. The semiconductor laser is used to ablate the working fluid to generate the required pulse excitation, with a pulse width of 200 μs and a power density of 5×10 6 W / cm 2The spot diameter is about 100μm. The working fluid used is GAP energetic material with a thickness of about 70μm. Under the action of laser irradiation, a small amount of GAP will melt, vaporize and ionize in a very short time, forming a high-speed back-spraying plasma plume. The generated instantaneous pulse will act on the swing arm of the measurement system, causing the measurement system to vibrate freely with damping. Three Riverhawk 5006-800 flexure pivots are selected as the workpieces to be measured, and their reference torsional stiffness coefficients are all 0.0045N·m / rad.

[0187] See also Figure 11 , the displacement sensor can be used to obtain the system response with and without the calibration beam caused by the laser pulse when the 1# and 2# combination working conditions are used. According to the system response without the calibration beam, the first and sixth extreme points correspond to 11.16s and 17.12s; while the first and sixth extreme points correspond to 444.9μm~423.2μm and 429.9μm~423.2μm. According to formulas (13) and (17), the natural frequency of the measurement system without the calibration beam can be obtained as:

[0188] rad / s

[0189] Accordingly, it can be obtained that when there is a calibration beam system response, the first and sixth extreme points correspond to 14.95s and 21.46s; and the first and sixth extreme values ​​correspond to 671.8μm~644.9μm and 654.8μm~644.9μm, and then the natural frequency of the measurement system with a calibration beam can be obtained as:

[0190] rad / s

[0191] According to formula (20), the torsional stiffness coefficient corresponding to the 1# and 2# combined working conditions can be obtained as:

[0192] N·m / rad

[0193] See also Figure 12 Similarly, the displacement sensor can be used to obtain the system response with and without the calibration beam caused by the laser pulse when the 1# and 3# combination conditions are met. The torsional stiffness coefficient corresponding to the 1# and 3# combination conditions can be obtained by the same calculation method:

[0194] N·m / rad

[0195] See also Figure 13Furthermore, the displacement sensor can be used to obtain the system response with and without the calibration beam caused by the laser pulse when the 2# and 3# combined working conditions are used. The torsional stiffness coefficient corresponding to the 2# and 3# combined working conditions can be obtained by the same calculation method:

[0196] N·m / rad

[0197] According to formula (22), the torsional stiffness coefficients of the 1#, 2# and 3# workpieces to be tested are:

[0198] N·m / rad

[0199] N·m / rad

[0200] N·m / rad

[0201] Finally, by comparing with the reference value of the torsional stiffness coefficient of 0.0045 N·m / rad, the relative errors of the above measured values ​​are 8.889%, 2.222% and 4.444%, respectively. It can be seen that this embodiment is not only convenient and efficient to use, but also has high measurement accuracy.

[0202] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0203] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for measuring torsion parameters, characterized in that: The measurement method is implemented by a measurement system based on a laser pulse force source; the measurement system comprises: A support frame, wherein the upper portion of the support frame has a first support end and a second support end; A rotating shaft, the rotating shaft is arranged in the middle of the first supporting end and the second supporting end, that is, the central cross section of the rotating shaft is coplanar with the symmetry plane of the first supporting end and the second supporting end; Two groups of workpiece clamps, each of which coaxially clamps a workpiece to be measured; wherein one end of the workpiece clamp of one group is fixedly connected to the first support end, and the other end is coaxially fixedly connected to the top end of the rotating shaft; one end of the workpiece clamp of the other group is fixedly connected to the second support end, and the other end is coaxially fixedly connected to the bottom end of the rotating shaft; A swing arm, wherein the swing arm is fixedly connected to the rotating shaft in a symmetrical manner at both ends; The calibration beam is fixedly connected to the rotating shaft in a symmetrical manner at both ends when the calibration beam is present, and is located at the upper end or the lower end of the swing arm; when the calibration beam is not present, the calibration beam is removed from the rotating shaft; Two groups of working fluid clamps, each group of the working fluid clamps clamps a working fluid; one group of the working fluid clamps is fastened to one end of the swing arm, and the other group of the working fluid clamps is fastened to the other end of the swing arm; Two groups of lasers, one group of lasers is set corresponding to each group of working fluid fixtures, and the laser light generated by the lasers is used to ablate the working fluid; A system response acquisition device, the system response acquisition device is arranged at one end of the swing arm, and is used to output a plurality of extreme value points and their corresponding extreme values; A damping device, wherein the damping device is arranged at the other end of the swing arm; The torsion parameter includes a torsion stiffness coefficient; and the method for measuring the torsion stiffness coefficient includes the following steps: S10. Configure three workpieces to be tested, two by two to form a combination of three workpieces to be tested; S11. Each workpiece combination to be measured is symmetrically clamped in a workpiece fixture configured in the measurement system; S12. The vibration natural frequency of the measuring system under two working conditions: with and without the calibration beam ω n1 , ω n0 and the known moment of inertia of the calibration beam 1. 0, calculate the sum of the torsional stiffness coefficients of each combination of the workpieces to be tested, respectively X , Y and Z ; S13. Calculate the torsional stiffness coefficient of each workpiece to be tested by the following method: k 1. k 2. k 3: ， ， 。 2. The method for measuring torsion parameters according to claim 1, characterized in that: Vibration natural frequency of the measuring system with and without calibration beam ω n1 , ω n0 They are calculated by the following formula: ； in, ω n for ω n1 , ω n0 Universal expressions; ω d To measure the vibration frequency of the system; ζ is the damping ratio of the measurement system.

3. The method for measuring torsion parameters according to claim 2, characterized in that: Measuring the vibration frequency of a system ω d Calculated by the following formula: ； in, m is the number of vibration cycle intervals; The output of the system response acquisition device configured for the measurement system is m+i extreme points; The output of the acquisition device configured for the measurement system i An extreme point.

4. The method for measuring torsion parameters according to claim 2, characterized in that: Measuring the damping ratio of a system ζ Calculated by the following formula: ， ， ， in, The output of the system response acquisition device configured for the measurement system is i extreme values; The output of the acquisition device configured for the measurement system m+i extreme values, Λ represents logarithmic reduction, a Represents the logarithmic decay rate factor.

5. The method for measuring torsion parameters according to claim 1, characterized in that: The sum of the torsional stiffness coefficients of each combination of the workpieces to be tested is calculated using the following formula: ， in, k for X , Y and Z Express.

6. The method for measuring torsion parameters according to claim 1, characterized in that: The measuring system has a dial and a pointer installed on the rotating shaft, and the pointer rotates synchronously with the rotating shaft; the torsion parameter also includes a torsion angle range ,in, Determined by: Under the working condition without the calibration beam, the swing arm of the measuring system has no external force and the pointer is stable. The pointer reading from the dial is θ 0; Slowly apply external force clockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged, and the pointer reading on the dial is θ 1, ; Determine by the following method: slowly apply external force counterclockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be measured is not damaged, and read the pointer reading from the dial as θ 2, .

7. A measurement system based on a laser pulse force source, characterized in that: Used to perform the measurement method according to any one of claims 1 to 6; the measurement system comprises: A support frame, wherein the upper portion of the support frame has a first support end and a second support end; A rotating shaft, the rotating shaft is arranged in the middle of the first supporting end and the second supporting end, that is, the central cross section of the rotating shaft is coplanar with the symmetry plane of the first supporting end and the second supporting end; Two groups of workpiece clamps, each of which coaxially clamps a workpiece to be measured; wherein one end of the workpiece clamp of one group is fixedly connected to the first support end, and the other end is coaxially fixedly connected to the top end of the rotating shaft; one end of the workpiece clamp of the other group is fixedly connected to the second support end, and the other end is coaxially fixedly connected to the bottom end of the rotating shaft; A swing arm, wherein the swing arm is fixedly connected to the rotating shaft in a symmetrical manner at both ends; The calibration beam is fixedly connected to the rotating shaft in a symmetrical manner at both ends when the calibration beam is present, and is located at the upper end or the lower end of the swing arm; when the calibration beam is not present, the calibration beam is removed from the rotating shaft; Two groups of working fluid clamps, each group of the working fluid clamps clamps a working fluid; one group of the working fluid clamps is fastened to one end of the swing arm, and the other group of the working fluid clamps is fastened to the other end of the swing arm; Two groups of lasers, one group of lasers is set corresponding to each group of working fluid fixtures, and the laser light generated by the lasers is used to ablate the working fluid; A system response acquisition device, the system response acquisition device is arranged at one end of the swing arm, and is used to output a plurality of extreme value points and their corresponding extreme values; A damping device, wherein the damping device is arranged at the other end of the swing arm; The processor comprises a storage unit and a calculation unit, wherein the storage unit is used to store a plurality of extreme value points output by the system response acquisition device and the extreme value corresponding to each extreme value point; the calculation unit reads the first m+i Extreme Points , No. i Extreme Points , Number of interval cycles m Calculate the vibration frequency of the measurement system ω d According to i Extreme Value , No. m+i Extreme Value , Number of interval cycles m Calculate the parameter Λ, and then calculate the logarithmic decay rate factor based on the parameter Λ a , and finally based on a Calculate the damping ratio of the measurement system ζ ; Based on the vibration frequency of the measuring system ω d and the damping ratio of the measurement system ζ Calculate the vibration natural frequency of the measurement system with and without the calibration beam ω n1 , ω n0 ; According to the vibration natural frequency of the measuring system under two working conditions with and without the calibration beam ω n1 , ω n0 and the known moment of inertia of the calibration beam 1. 0, calculate the sum of the torsional stiffness coefficients of each combination of the workpieces to be tested, respectively X , Y and Z ; The torsional stiffness coefficient of each workpiece to be tested is calculated as follows k 1. k 2. k 3: ， ， 。 8. The laser pulse force source-based measurement system according to claim 7, characterized in that: The measuring system has a dial and a pointer installed on the rotating shaft, and the pointer rotates synchronously with the rotating shaft; the calculation unit is also used to obtain the working condition without the calibration beam, and the angle of rotation of the swing arm of the measuring system when no external force is applied and the pointer is stable θ 0, slowly apply external force clockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. θ 1. Based on Calculate and obtain the lower limit value of the torsion range; The calculation unit is also used to obtain the time when an external force is slowly applied counterclockwise to one end of the swing arm until the swing arm moves to the limit position and the workpiece to be tested is not damaged. θ 2. Based on Calculate the upper limit of the torsion range.

9. The measurement system based on a laser pulse force source according to claim 7, characterized in that: The thickness of the working medium is 60 μm to 300 μm; the diameter of the laser focusing spot is 50 μm to 500 μm.

10. The measurement system based on laser pulse force source according to claim 7, characterized in that: The measuring system further comprises a stopper, and the stopper comprises a fine-pitch bolt and a stopper head; wherein the fine-pitch bolt penetrates through the side wall of the support frame and is coaxially connected to the stopper head, and an adjustable gap is provided between the stopper head and the rotating shaft; and / or, The swing arm is a hollow swing arm; and / or, Each of the workpiece clamps comprises a coaxially arranged fixed chuck and a movable chuck, wherein the fixed chuck is tightly connected to the supporting end of the support frame, and the movable chuck is connected to the end of the rotating shaft and rotates with the rotating shaft; the two ends of the workpiece to be measured are respectively inserted into the end faces of the fixed chuck and the movable chuck against each other; and / or, Each of the working medium fixtures comprises a fixture base, and the fixture base is a step plate structure with increasing height from one end fixed to the swing arm to the cantilever end; wherein a mounting hole is provided on the step for placing the working medium, and after the working medium is clamped in the mounting hole, it is fastened by a ring-shaped pre-tightening buckle and a cover plate in sequence; and / or, The damping device is an eddy current damper, which includes a damping sheet that is tightly connected to one end of the swing arm.

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