Dynamic response test method and system for nonlinear structures using virtual signals

Abstract

In a dynamic response test method for a nonlinear structure using a virtual signal provided in the present application, a load is applied to the free end of the nonlinear structure by an actuator according to the target dynamic parameter A(t) of the nonlinear structure, and then an excitation signal is applied to the nonlinear structure to capture the dynamic response of the nonlinear structure. The present application uses a virtual signal to control the actuator to generate a target load to load onto the nonlinear physical structure to simulate target parameters, such as stiffness, damping, and the force under action. Load simulation can be accurately performed through virtual signals, and accurate load simulation can finely control and adjust dynamic parameters such as damping and stiffness to solve the problem of sensitivity to dynamic parameters of nonlinear structures.

Description

Technical Field

[0001] The present application belongs to the technical field of dynamic testing of structures, and in particular, relates to a dynamic response test method and system for nonlinear structures using virtual signals. Background Art

[0002] The unique mechanical properties of nonlinear structures, such as negative stiffness, negative Poisson's ratio, and multistability, make them suitable for applications in vibration isolation and shock protection systems, robotics / actuators, metastructures / metamaterials, and other major structural components. Therefore, nonlinear structures have great potential for application in high-precision fields such as aerospace, military defense, and biomedicine. However, nonlinearity can lead to complex dynamic behavior, which not only affects the normal operation of high-precision equipment but may even cause damage. Therefore, before their application, experimental research on nonlinear structures is necessary to predict their response behavior under different excitation environments.

[0003] Nonlinear structures are extremely sensitive to dynamic parameters, and even small changes can cause dramatic changes in the response. During testing, even subtle changes in the physical elements of the system in which the structure resides, such as the attached load mass, stiffness components, damping elements, and excitation conditions, can lead to changes in the dynamic parameters, causing distorted responses and making it impossible to accurately simulate the dynamic behavior in real-world applications. Summary of the Invention

[0004] The present application provides a dynamic response test method and system for nonlinear structures using virtual signals, which can accurately simulate the dynamic behavior in a real application environment during the test process, and then predict its response behavior under different excitation environments.

[0005] The dynamic response test method of nonlinear structures using virtual signals includes:

[0006] S11: Determine the target load f to be applied to the nonlinear structure according to the current target dynamic parameter A(t) of the nonlinear structure and the current motion state of the nonlinear structure. * (t), according to the target load f * (t) determining the input voltage V(t) of the actuator;

[0007] S12: Collect the output f(t) of the actuator under the input voltage V(t), and determine whether the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * (t) the difference between;

[0008] S13: If the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure * If the difference between the two values ​​is greater than the first allowable error, the input voltage V(t) of the actuator is adjusted;

[0009] S14: Repeat S12 and S13 until the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * The difference between (t) is not greater than the first allowable error;

[0010] The current output f(t) of the actuator is related to the target load f to be applied to the nonlinear structure. * When the difference between the output f(t) and the output f(t-1) of the actuator in the current test is not greater than the first allowable error, compare the output f(t) of the actuator in the current test with the output f(t-1) of the actuator in the previous test;

[0011] S15: If the output f(t) of the actuator in the current trial is greater than the output f(t-1) of the actuator in the previous trial, adjust the target dynamic parameter A(t) in S11 to A(t+1);

[0012] S16: Repeat S11, S12, S13, S14, and S15 until the output f(t) of the actuator in the current test is no greater than the output f(t-1) of the actuator in the previous test; record the target dynamic parameter A(t), the input voltage V(t) of the actuator, and the output f(t) in the current test;

[0013] S2: applying an excitation signal to the nonlinear structure to capture a dynamic response of the nonlinear structure.

[0014] In one embodiment, when capturing the dynamic response of the nonlinear structure in a working scene, the dynamic parameter A* of the nonlinear structure in the working scene is defined in the extended parameter space for discretization, and the target dynamic parameters A(1), A(2)...A(n-1), A(n), A(n+1) of the nonlinear structure are obtained, where A(n-1)<A*,A(n)=A*,A(n+1)> A*;

[0015] In S15, if the output f(t) of the actuator in the current test is greater than the output f(t-1) of the actuator in the previous test, the target dynamic parameter in the current test is adjusted from A(t) to A(t+1), where t=0, 1, 2···n.

[0016] In one embodiment, before S11, the kinetic response test method further comprises:

[0017] S10: Determine the target dynamic parameters A(t), the input voltage V(t) of the actuator, and the target load f(t) applied to the nonlinear structure through static preliminary tests. * (t) The gain relationship between the three, under which the output range of the actuator includes the target load f* (t), the output of the actuator acts on the nonlinear structure so that the dynamic parameters of the nonlinear structure are the target dynamic parameters A(t);

[0018] The gain relationship is used to determine the target load f according to the target dynamic parameter A(t) * (t), according to the target load f * (t) Determine the input voltage V(t) of the actuator.

[0019] In one embodiment, the target load f to be applied to the nonlinear structure is * (t) = Bcos(wt).

[0020] In one embodiment, in S13, if the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure, * (t) is greater than the first allowable error, then according to the current output f(t) of the actuator and the target load f to be applied to the nonlinear structure * The PID algorithm is used to adjust the input voltage V(t) of the actuator based on the difference between the two.

[0021] In one embodiment, in S11, the current motion state of the nonlinear structure is collected after the response of the nonlinear structure is stabilized;

[0022] If the response of the nonlinear structure remains unstable after a certain period of time, the parameters in the PID algorithm are adjusted until the response of the nonlinear structure becomes stable.

[0023] In one embodiment, S2 comprises:

[0024] S21: applying an excitation signal to the nonlinear structure;

[0025] S22: After the response of the nonlinear structure is stabilized, an actual response of the nonlinear structure is collected, and a difference between the actual response of the nonlinear structure and an expected response is determined:

[0026] S23: If the difference between the actual response and the expected response of the nonlinear structure is greater than the allowable error, adjusting the excitation signal applied to the nonlinear structure by adjusting parameters of higher-order harmonic interference terms other than the target fundamental harmonic in the expected response according to the difference between the actual response and the expected response, until the difference between the actual response and the expected response of the nonlinear structure is no greater than a second allowable error;

[0027] S24: If the difference between the actual response of the nonlinear structure and the expected response is not greater than the second allowable error, then determine the difference between the actual response of the current test and the actual response of the previous test:

[0028] S25: If the actual response of the current test is not greater than the actual response of the previous test, adjusting the excitation signal applied to the nonlinear structure by adjusting the parameters of the target fundamental harmonic in the expected response until the actual response of the current test is greater than the actual response of the previous test;

[0029] S26: If the actual response of the current test is not greater than the actual response of the previous test, then record the parameters of the excitation signal applied to the nonlinear structure in the current test and record the current response result, where the current response result is the nonlinear structural dynamic response captured by the test method.

[0030] In one embodiment, in S23, a PID algorithm is used to adjust parameters of higher-order harmonics other than a target fundamental harmonic in the excitation signal applied to the nonlinear structure;

[0031] S21: applying an excitation signal to the nonlinear structure; thereafter,

[0032] If the response of the nonlinear structure remains unstable after a certain period of time, the parameters in the PID algorithm are adjusted until the response of the nonlinear structure becomes stable.

[0033] In one embodiment, in S25, the excitation signal applied to the nonlinear structure is gradually increased by adjusting parameters of a target fundamental harmonic in the desired response;

[0034] The increase in the parameter of the target fundamental harmonic in the expected response is calculated by the continuation method, so as to gradually increase the excitation signal applied to the nonlinear structure.

[0035] The present application also provides a dynamic response test system for a nonlinear structure using a virtual signal, characterized in that the nonlinear structure is placed on a base, and the test system comprises:

[0036] an actuator, wherein an active end of the actuator is connected to a free end of the nonlinear structure;

[0037] an exciter, wherein an active end of the exciter is connected to a designated excitation position of the nonlinear structure;

[0038] an acceleration / force dual-purpose sensor for acquiring the acceleration of the nonlinear structure or the vibration load applied to the nonlinear structure by the exciter; and acquiring the load applied to the free end of the nonlinear structure by the actuator;

[0039] A displacement sensor for acquiring the displacement of the excitation point and the response point of the nonlinear structure;

[0040] The controller outputs signals to the actuator and the vibrator according to the signals from the acceleration / force dual sensor and the displacement sensor and the above-mentioned test method.

[0041] In a dynamic response test method of a nonlinear structure using a virtual signal provided in the present application, a static load is applied to the free end of the nonlinear structure by an actuator according to the target dynamic parameter A(t) of the nonlinear structure, and then an excitation signal is applied to the nonlinear structure to capture the dynamic response of the nonlinear structure. The present application uses a virtual signal to control the actuator to generate a target load to load onto the nonlinear physical structure to simulate the force under the action of the target parameters (such as stiffness and damping). Load simulation can be accurately performed through virtual signals, and accurate load simulation can finely control and adjust dynamic parameters such as damping and stiffness to solve the problem of sensitivity of the dynamic parameters of nonlinear structures.

[0042] Based on the above-mentioned inventive concept, the present application also provides a dynamic response test system for nonlinear structures using virtual signals, which integrates excitation, control, signal acquisition, and response processing.

[0043] For further clarity of explanation, various aspects and advantages of the embodiments disclosed in the present application will become apparent in the following description or can be understood through the practice of the embodiments disclosed in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the invention but do not constitute a limitation to the invention.

[0045] Figure 1 This is a control logic diagram of S11, S12, S13, S14, S15, and S16 in the dynamic response test method of a nonlinear structure using a virtual signal provided in Example 1 of the present application;

[0046] Figure 2 The control logic flow chart for capturing the dynamic response of the nonlinear structure provided in Example 2 of the present application;

[0047] Figure 3 The control logic diagram for capturing the dynamic response of the nonlinear structure provided in Example 2 of the present application;

[0048] Figure 4 Schematic diagram of the experimental system for capturing the dynamic response of the nonlinear structure provided in Example 3 of the present application. DETAILED DESCRIPTION

[0049] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0050] Example 1

[0051] This embodiment provides a dynamic response test method for a nonlinear structure using a virtual signal, comprising:

[0052] S11: Determine the target load f to be applied to the nonlinear structure according to the current target dynamic parameter A(t) of the nonlinear structure and the current motion state of the nonlinear structure. * (t), according to the target load f * (t) determining the input voltage V(t) of the actuator;

[0053] The target dynamic parameter A(t) of the nonlinear structure includes the stiffness, damping, etc. of the nonlinear structure. For example, the quasi-zero stiffness shock absorber provided in patent document CN116877613A is a nonlinear structure, and its target dynamic parameter A(t) includes the mass, stiffness, and damping of the load.

[0054] The motion state of the nonlinear structure includes the displacement, velocity and acceleration of the free end of the nonlinear structure, and the displacement, velocity and acceleration of the free end of the nonlinear structure can be collected by a displacement sensor, a velocity sensor and an acceleration sensor;

[0055] S12: Collect the output f(t) of the actuator under the input voltage V(t), and determine whether the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * (t) the difference between;

[0056] S13: If the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure * If the difference between the two values ​​is greater than the first allowable error, the input voltage V(t) of the actuator is adjusted;

[0057] S14: Repeat S12 and S13 until the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * The difference between (t) is not greater than the first allowable error;

[0058] The current output f(t) of the actuator is related to the target load f to be applied to the nonlinear structure. * When the difference between the output f(t) and the output f(t-1) of the actuator in the current test is not greater than the first allowable error, compare the output f(t) of the actuator in the current test with the output f(t-1) of the actuator in the previous test;

[0059] S15: If the output f(t) of the actuator in the current trial is greater than the output f(t-1) of the actuator in the previous trial, adjust the target dynamic parameter A(t) in S11 to A(t+1);

[0060] S16: Repeat S11, S12, S13, S14, and S15 until the output f(t) of the actuator in the current test is no greater than the output f(t-1) of the actuator in the previous test; record the target dynamic parameter A(t), the input voltage V(t) of the actuator, and the output f(t) in the current test;

[0061] S2: applying an excitation signal to the nonlinear structure to capture the dynamic response of the nonlinear structure.

[0062] Since changes in load can alter the static deformation of a nonlinear structure and thus change its dynamic parameters such as stiffness, the test method provided in this embodiment can precisely control and adjust dynamic parameters such as mass and stiffness through accurate load simulation using virtual signals, thereby addressing the issue of sensitive dynamic parameters of nonlinear structures. Based on the aforementioned inventive concept, the test method of this embodiment is proposed. A controlled virtual signal is generated based on the target dynamic parameters, and a controlled continuation method is used to stably approximate the target parameters. The virtual signal controls the actuator to generate a target load that is applied to the nonlinear physical structure to simulate the force under the action of the target parameters (such as stiffness and damping).

[0063] To facilitate understanding of this embodiment, the following description is given: α1, α2, α3, α4 are the target dynamic parameters A(t) (known and set), α2x, α3x n 、 It is the corresponding force formed in the system by the dynamic parameters mass, stiffness and damping. x、 The response of the nonlinear structure collected by the sensor and combined with the target dynamic parameters can be used to obtain the target load α2x, α3x n 、、 Assume f * (t). Since the control system can only output virtual signals, the virtual signal controls the input legal voltage signal V(t) to the actuator to control the actuator output f(t). Therefore, it is necessary to establish the relationship between the virtual signal, the dynamic parameters and the output of the actuator. At this time, the virtual signal is composed of the target dynamic parameters. α2x, That is, f * (t), the voltage signal V(t) is the intermediate physical quantity and also the subsequent extension parameter. Through static preliminary test, A(t), V(t) and f are determined. *(t) to ensure that the output command A(t) brake can output static force f. This gain is used in the above-mentioned dynamic response test. For example, if you need to set the dynamic parameter stiffness α2, enter the parameter value, and the control system will discretize the voltage signal v corresponding to the parameter theory into multiple points, such as 0.1v, 0.2v, 0.3v…1v, 1.1v. The purpose is to avoid the direct output v that may excite the nonlinear system to jump across the target response point. Therefore, the target response is gradually approached through discretization. Each approximation requires waiting for the real feedback f(t) collected by the sensor in the response to be consistent with the target f * (t) is consistent (when using the pid control method, f(t) is consistent with the target f * (t) consistent), then move on to the next discrete point. The discrete points have a margin, that is, they will be discretized to a point greater than the target voltage signal v, such as 1.1V. This is to improve accuracy and find the voltage signal with the output force closest to the target force near the theoretical voltage signal v.

[0064] In order to facilitate understanding of this embodiment, a control logic diagram of S11, S12, S13, S14, S15 and S16 is provided, as shown in FIG. Figure 1 As shown. u1(t) is the virtual control signal applied to the actuator, x(t) is the response displacement of the nonlinear structure, and f * (t) is the target load of the nonlinear structure. No other external excitation is provided in the test. The test is directly affected by the control signal u1(t). The control goal of u1(t) is to transform the force feedback f(t) of the nonlinear structure into the desired target signal f * (t) is minimized.

[0065] Under the inventive concept of using the continuation method to obtain the target parameters, this embodiment provides a preferred implementation method: when capturing the dynamic response of the nonlinear structure in the working scene, the dynamic parameter A* of the nonlinear structure in the working scene is defined in the continuation parameter space for discretization, and the target dynamic parameters A(1), A(2)···A(n-1), A(n), A(n+1) of the nonlinear structure are obtained, wherein A(n-1)<A*,A(n)=A*,A(n+1)> A*;

[0066] In S15, if the output f(t) of the actuator in the current test is greater than the output f(t-1) of the actuator in the previous test, the target dynamic parameter in the current test is adjusted from A(t) to A(t+1), where t=0, 1, 2···n.

[0067] In this embodiment, the target dynamic parameters are gradually increased by the continuation method to achieve the gradual increase of the virtual control signal applied to the nonlinear structure. This iterative process is not performed in real time, but is iterated using the Newton-Raphson algorithm:

[0068] X * =X n +h[X n -X n-1 ]

[0069] in, (X n ,X n-1 ) is the coefficient of the stable response obtained in the last two experiments, and h is the calculation coefficient.

[0070] Through static preliminary test, determine A(t), V(t) and f * (t) to ensure that the output command A(t) brake can output the static force f. This gain is used in the above-mentioned dynamic response test. Therefore, in this embodiment, before S11, the dynamic response test method also includes:

[0071] S10: Determine the target dynamic parameters A(t), the input voltage V(t) of the actuator, and the target load f(t) applied to the nonlinear structure through static preliminary tests. * (t) The gain relationship between the three, under which the output range of the actuator includes the target load f * (t), the output of the actuator acts on the nonlinear structure so that the dynamic parameters of the nonlinear structure are the target dynamic parameters A(t);

[0072] The gain relationship is used to determine the target load f according to the target dynamic parameter A(t) * (t), according to the target load f * (t) Determine the input voltage V(t) of the actuator.

[0073] In practical applications, since nonlinear structures may vibrate due to the influence of the external environment, in order to fully simulate the working scenario of the nonlinear structure, in this embodiment, the target load f to be applied to the nonlinear structure is * (t) = Bcos(wt).

[0074] In S13, if the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure, * (t) is greater than the first allowable error, then according to the current output f(t) of the actuator and the target load f to be applied to the nonlinear structure *The PID algorithm is used to adjust the input voltage V(t) of the actuator based on the difference between the two.

[0075] The current output f(t) of the actuator is compared with the target load f to be applied to the nonlinear structure. * The mean square error of the (t) differences characterizes the difference between the actual load and the expected load of the nonlinear structure.

[0076] In S11, after the response of the nonlinear structure is stabilized, the current motion state of the nonlinear structure is collected;

[0077] If the response of the nonlinear structure remains unstable after a certain period of time, the parameters in the PID algorithm are adjusted until the response of the nonlinear structure becomes stable.

[0078] Example 2

[0079] This embodiment provides a specific implementation of "S2: applying an excitation signal to the nonlinear structure to capture the dynamic response of the nonlinear structure" in Embodiment 1.

[0080] Reference Figure 2 S2: applying an excitation signal to the nonlinear structure to capture the dynamic response of the nonlinear structure, including:

[0081] S21: applying an excitation signal u(t) to the nonlinear structure;

[0082] S22: After the response of the nonlinear structure is stable, the actual response x(t) of the nonlinear structure is collected, and the actual response x(t) of the nonlinear structure is compared with the expected response x(t). * The difference between (t):

[0083] S23: If the difference between the actual response and the expected response of the nonlinear structure is greater than the allowable error, adjusting the excitation signal applied to the nonlinear structure by adjusting parameters of higher-order harmonic interference terms other than the target fundamental harmonic in the expected response according to the difference between the actual response and the expected response, until the difference between the actual response and the expected response of the nonlinear structure is no greater than a second allowable error;

[0084] No other external excitation is provided in the experiment. The experiment is directly affected by the excitation signal u(t), and the goal of u(t) is to compare the actual response x(t) with the expected response x * Minimizing the difference e(t) between the two frequencies (t) results in an excitation of the shaker output containing only the target fundamental harmonic.

[0085] The actual response x(t) and the expected response x * (t) can be written as:

[0086]

[0087] The excitation signal u(y) can be considered to be composed of fundamental harmonics and higher-order harmonic components:

[0088]

[0089] Where t is time, ω is the fundamental harmonic frequency, j is the harmonic multiple, m is the maximum harmonic multiple of the test concern, s is the specified maximum fundamental harmonic multiple, A0, are constant values, A j , They are the corresponding coefficients of j times cosine harmonics, respectively B j , They are the corresponding coefficients of j times the sine harmonic amount.

[0090] The fundamental harmonic component is the target excitation (either single harmonic or multi-harmonic) applied to the nonlinear structure. Higher-order harmonics are unavoidable additional terms in the excitation response control and must be eliminated to achieve the same excitation environment as an open-loop harmonic excitation test.

[0091] S24: If the difference between the actual response of the nonlinear structure and the expected response is not greater than the second allowable error, then determine the difference between the actual response of the current test and the actual response of the previous test:

[0092] S25: If the actual response of the current test is not greater than the actual response of the previous test, adjusting the excitation signal applied to the nonlinear structure by adjusting the parameters of the target fundamental harmonic in the expected response until the actual response of the current test is greater than the actual response of the previous test;

[0093] S26: If the actual response of the current test is not greater than the actual response of the previous test, then record the parameters of the excitation signal applied to the nonlinear structure in the current test and record the current response result, where the current response result is the nonlinear structural dynamic response captured by the test method.

[0094] Adjusting the excitation signal applied to the nonlinear structure, ie, changing the initial conditions, can capture all possible stable / unstable responses.

[0095] In this embodiment, the PID algorithm is used in S23 to adjust the parameters of the high-order harmonics in the desired signal until the high-order harmonics in the excitation signal are eliminated.

[0096] After applying an excitation signal to the nonlinear structure, if the response of the nonlinear structure remains unstable after a certain period of time, the control parameters in the PID algorithm are adjusted until the response of the nonlinear structure stabilizes.

[0097] In a specific implementation, the excitation signal applied to the nonlinear structure is gradually increased by adjusting the parameters of the target fundamental harmonics in the desired response. In this embodiment, the increase in the parameters of the target fundamental harmonics in the desired response is calculated by the continuation method to achieve the gradual increase of the excitation signal applied to the nonlinear structure. Each iteration of the continuation method algorithm corrects the fundamental harmonic parameters in the desired signal. This process is equivalent to changing the initial conditions, thereby capturing all possible stable / unstable responses. This iterative process is not performed in real time, but is iterated using the Newton-Raphson algorithm:

[0098] X * =X n +h[X n -X n-1 ]

[0099] in, (X n , X n-1 ) is the coefficient of the stable response obtained in the last two experiments, and h is the calculation coefficient.

[0100] Initial values ​​of parameters of the excitation signal applied to the nonlinear structure are set according to requirements.

[0101] The difference between the actual response of the nonlinear structure and the expected response is characterized by the mean square error between the high-order harmonic response in the actual response of the nonlinear structure and the expected response. Figure 1 in, |U| ∞ is the mean square error between the high-order harmonic response and the target, and δ is the allowable error.

[0102] Considering that linear open-loop control methods commonly used in linear system research, such as sinusoidal swept frequency excitation, can only capture stable responses but cannot capture unstable responses, this affects the accurate capture of nonlinear system responses. Therefore, in this embodiment, a method for capturing the dynamic response of a nonlinear structure is provided based on a control continuation method combined with an FFT multiharmonic balance method. An excitation signal is applied to the nonlinear structure. Based on the difference between the actual response and the expected response, the excitation signal applied to the nonlinear structure is adjusted by adjusting the parameters of the higher-order harmonic interference terms other than the target fundamental harmonic in the expected response until the difference between the actual response and the expected response is no greater than the allowable error. The excitation signal applied to the nonlinear structure is then gradually increased by adjusting the parameters of the target fundamental harmonic in the expected response until the actual response of the current test is greater than the actual response of the previous test. The maximum actual response is the dynamic response of the nonlinear structure captured by this test method. In this test method, the control signal is continuously iterated to capture all possible stable and unstable responses. This can stimulate and capture all possible stable / unstable responses at different frequencies and amplitudes, and establish the corresponding relationship between the excitation conditions (frequency, amplitude, initial conditions) and nonlinear dynamic behaviors.

[0103] The experimental idea is to capture the nonlinear structural dynamic response based on the control-based continuation method (CBC). The numerical continuation method is applied to nonlinear structural tests. An outer loop controller based on continuation is set outside the PID controller to continuously iterate the target signal, such as Figure 3 As shown in Figure 2), it is possible to capture all possible stable and unstable responses in a “non-intrusive” control manner and conduct bifurcation studies on the results.

[0104] In order to facilitate understanding of this embodiment, a control logic diagram is provided, such as Figure 3 shown. Figure 3 In the equation, u(t) is the voltage signal applied to the exciter, x(t) is the response displacement of the nonlinear structure, and x * (t) is the target excitation signal. No other external excitation is provided in the experiment. The experiment is directly affected by the control signal u(t). The control target of u(t) is to transform x(t) and x * (t) is minimized.

[0105] Example 3

[0106] This embodiment provides a dynamic response test system for nonlinear structures using virtual signals, referring to Figure 4 , the nonlinear structure 2 is placed on a base, and the test system comprises:

[0107] An actuator 3, wherein an active end of the actuator 3 is connected to a free end of the nonlinear structure 2;

[0108] Exciter 1, the active end of the exciter 1 is connected to the designated excitation position of the nonlinear structure 2, and can output vibration at a set frequency and amplitude;

[0109] The acceleration / force dual-purpose sensor obtains the acceleration of the nonlinear structure 2 or the vibration load applied by the exciter 1 to the nonlinear structure 2; and obtains the load applied by the actuator 3 to the free end of the nonlinear structure 2;

[0110] Displacement sensor, to obtain the displacement of the excitation point and the response point of the nonlinear structure 2;

[0111] The controller 6 outputs signals to the actuator 3 and the exciter 1 according to the signals of the acceleration / force dual sensor and the displacement sensor and the test method provided in Examples 1 and 2. The program carrying the test method is stored and run by the computer 7.

[0112] The response point is determined by the tester and is usually located at the location of maximum response of the structure.

[0113] The dynamic response test system further comprises:

[0114] The power amplifier 5 is used to amplify the excitation signal sent by the controller 6 to the exciter 1 and the actuator 3 and output the amplified excitation signal to the exciter 1 and the actuator 3 .

[0115] and a signal conditioner 4 for amplifying and processing digital signals.

[0116] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present technical solution 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 technical solution.

[0117] In this technical solution, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this technical solution based on specific circumstances.

[0118] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present technical solution. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0119] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A dynamic response test method for a nonlinear structure using a virtual signal, characterized in that: Include: S11: Determine the target load f to be applied to the nonlinear structure according to the current target dynamic parameter A(t) of the nonlinear structure and the current motion state of the nonlinear structure. * (t), according to the target load f * (t) determining the input voltage V(t) of the actuator; S12: Collect the output f(t) of the actuator under the input voltage V(t), and determine whether the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * (t) the difference between; S13: If the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure * If the difference between the two values ​​is greater than the first allowable error, the input voltage V(t) of the actuator is adjusted; S14: Repeat S12 and S13 until the current output f(t) of the actuator is consistent with the target load f to be applied to the nonlinear structure. * The difference between (t) is not greater than the first allowable error; The current output f(t) of the actuator is related to the target load f to be applied to the nonlinear structure. * When the difference between the output f(t) and the output f(t-1) of the actuator in the current test is not greater than the first allowable error, compare the output f(t) of the actuator in the current test with the output f(t-1) of the actuator in the previous test; S15: If the output f(t) of the actuator in the current trial is greater than the output f(t-1) of the actuator in the previous trial, adjust the target dynamic parameter A(t) in S11 to A(t+1); S16: Repeat S11, S12, S13, S14, and S15 until the output f(t) of the actuator in the current test is no greater than the output f(t-1) of the actuator in the previous test; record the target dynamic parameter A(t), the input voltage V(t) of the actuator, and the output f(t) in the current test; S2: applying an excitation signal to the nonlinear structure to capture a dynamic response of the nonlinear structure.

2. The dynamic response test method according to claim 1, characterized in that: When capturing the dynamic response of the nonlinear structure in the working scene, the dynamic parameter A* of the nonlinear structure in the working scene is defined in the extended parameter space for discretization, and the target dynamic parameters A(1), A(2)···A(n-1), A(n), A(n+1) of the nonlinear structure are obtained, where A(n-1)<A*,A(n)=A*,A(n+1)> A*; In S15, if the output f(t) of the actuator in the current test is greater than the output f(t-1) of the actuator in the previous test, the target dynamic parameter in the current test is adjusted from A(t) to A(t+1), where t=0, 1, 2···n.

3. The dynamic response test method according to claim 2, characterized in that: Before S11, the dynamic response test method further includes: S10: Determine the target dynamic parameters A(t), the input voltage V(t) of the actuator, and the target load f(t) applied to the nonlinear structure through static preliminary tests. * (t) The gain relationship between the three, under which the output range of the actuator includes the target load f * (t), the output of the actuator acts on the nonlinear structure so that the dynamic parameters of the nonlinear structure are the target dynamic parameters A(t); The gain relationship is used to determine the target load f according to the target dynamic parameter A(t) * (t), according to the target load f * (t) Determine the input voltage V(t) of the actuator.

4. The dynamic response test method according to claim 3, characterized in that: The target load f to be applied to the nonlinear structure * (t) = Bcos(wt).

5. The dynamic response test method according to claim 4, characterized in that: In S13, if the current output f(t) of the actuator is equal to the target load f to be applied to the nonlinear structure, * (t) is greater than the first allowable error, then according to the current output f(t) of the actuator and the target load f to be applied to the nonlinear structure * The PID algorithm is used to adjust the input voltage V(t) of the actuator based on the difference between the two.

6. The dynamic response test method according to claim 5, characterized in that: In S11, after the response of the nonlinear structure is stabilized, the current motion state of the nonlinear structure is collected; If the response of the nonlinear structure remains unstable after a certain period of time, the parameters in the PID algorithm are adjusted until the response of the nonlinear structure becomes stable.

7. The dynamic response test method according to claim 1, characterized in that: S2 contains: S21: applying an excitation signal to the nonlinear structure; S22: After the response of the nonlinear structure is stabilized, an actual response of the nonlinear structure is collected, and a difference between the actual response of the nonlinear structure and an expected response is determined: S23: If the difference between the actual response and the expected response of the nonlinear structure is greater than the allowable error, adjusting the excitation signal applied to the nonlinear structure by adjusting parameters of higher-order harmonic interference terms other than the target fundamental harmonic in the expected response according to the difference between the actual response and the expected response, until the difference between the actual response and the expected response of the nonlinear structure is no greater than a second allowable error; S24: If the difference between the actual response of the nonlinear structure and the expected response is not greater than the second allowable error, then determine the difference between the actual response of the current test and the actual response of the previous test: S25: If the actual response of the current test is not greater than the actual response of the previous test, adjusting the excitation signal applied to the nonlinear structure by adjusting the parameters of the target fundamental harmonic in the expected response until the actual response of the current test is greater than the actual response of the previous test; S26: If the actual response of the current test is not greater than the actual response of the previous test, then record the parameters of the excitation signal applied to the nonlinear structure in the current test and record the current response result, where the current response result is the nonlinear structural dynamic response captured by the test method.

8. The dynamic response test method according to claim 7, characterized in that: In S23, a PID algorithm is used to adjust parameters of higher-order harmonics other than the target fundamental harmonic in the excitation signal applied to the nonlinear structure; S21: applying an excitation signal to the nonlinear structure; thereafter, If the response of the nonlinear structure remains unstable after a certain period of time, the parameters in the PID algorithm are adjusted until the response of the nonlinear structure becomes stable.

9. The dynamic response test method according to claim 7, characterized in that: In S25, the excitation signal applied to the nonlinear structure is gradually increased by adjusting parameters of a target fundamental harmonic in the desired response; The increase in the parameter of the target fundamental harmonic in the expected response is calculated by the continuation method, so as to gradually increase the excitation signal applied to the nonlinear structure.

10. A dynamic response test system for nonlinear structures using virtual signals, characterized in that: The nonlinear structure is placed on a base, and the test system comprises: an actuator, wherein an active end of the actuator is connected to a free end of the nonlinear structure; an exciter, wherein an active end of the exciter is connected to a designated excitation position of the nonlinear structure; an acceleration / force dual-purpose sensor for acquiring the acceleration of the nonlinear structure or the vibration load applied to the nonlinear structure by the exciter; obtaining a load applied by the actuator to the free end of the nonlinear structure; A displacement sensor for acquiring the displacement of the excitation point and the response point of the nonlinear structure; A controller outputs signals to the actuator and the vibrator according to the signals of the acceleration / force dual-purpose sensor and the displacement sensor and the test method according to any one of claims 1 to 9.

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