Zero-dispersion nonlinear MEMS (micro-electromechanical system) accelerometer for monitoring construction stress of floating fan platform

Abstract

The invention discloses a zero-dispersion nonlinear MEMS accelerometer for monitoring construction stress of a floating fan platform, and belongs to the technical field of ocean engineering structure monitoring. The zero-frequency-dispersion nonlinear MEMS accelerometer comprises a mass block, an amplification beam pair assembly, an electrode system and resonant beams arranged on the two sides of the mass block in a bilateral symmetry mode, and the mass block is connected with the resonant beams through the amplification beam pair assembly. According to the invention, adjustable static nonlinearity is introduced in the capacitance excitation process of the double-end clamped resonant beam, and the adjustable static nonlinearity is matched and counteracted with the geometric nonlinearity of the resonant beam, so that the resonator enters a zero-frequency dispersion working area within a preset excitation range, and therefore, under the working conditions of construction load disturbance, structural vibration amplitude fluctuation and the like, the resonance efficiency of the resonator is improved. Frequency response information related to structural dynamic characteristics can still be stably output, and a high-stability perception basis is provided for inversion analysis of welding residual stress and structural health states.

Description

TECHNICAL FIELD

[0001] The application relates to a zero-frequency dispersion nonlinear MEMS accelerometer for monitoring construction stress of a floating wind turbine platform and belongs to the technical field of ocean engineering structure monitoring. BACKGROUND

[0002] With the continuous development and utilization of deep-sea wind energy resources, floating wind turbine foundation platforms have become an important technical route for the development of deep-sea wind power due to their advantages of adapting to large water depth and complex sea conditions. Compared with traditional fixed foundations, deep-sea floating wind turbine foundation platforms usually have the characteristics of large size, large self-weight, complex structure, large number of connection nodes, and uneven overall stiffness distribution. The construction process involves large-scale component manufacturing, complex welding assembly, multi-process collaborative construction, and large-tonnage lifting operation. The overall construction process is complex and has high technical difficulty.

[0003] During the land construction stage of the floating wind turbine foundation platform, especially during the manufacturing and welding process of key components, the structure inevitably bears the combined action of self-weight load, construction load, and environmental disturbance. During the welding process, complex welding residual stress distribution is formed inside the structure due to local high-temperature heat input and rapid cooling, accompanied by local stiffness changes, microscopic defects, and initial damage. These welding residual stresses and hidden defects not only directly affect the subsequent component assembly accuracy and construction safety, but also may induce fatigue damage propagation in the subsequent service stage coupled with long-term dynamic loads such as wind load and wave load, and even cause structural failure in severe cases.

[0004] Therefore, during the construction stage of the floating wind turbine foundation platform, effective monitoring and evaluation of welding residual stress and structural health status is one of the key technical problems to ensure construction quality, improve construction safety, and achieve controllable construction. Existing welding residual stress detection methods, such as strain gauge testing, ultrasonic testing, or offline non-destructive testing methods, often have complex layout, large interference with construction process, difficulty in achieving continuous monitoring, or insufficient environmental adaptability, which cannot meet the real-time, stability, and reliability monitoring requirements of super-large floating foundation platforms during the construction stage.

[0005] In recent years, indirect monitoring methods based on structural vibration response or elastic wave propagation characteristics have gradually attracted attention. By analyzing the micro-vibration response or elastic wave characteristic changes of the structure after welding under excitation conditions, the residual stress state and structural health condition can be evaluated without directly damaging the structure. However, in the actual construction site environment, due to the large size and mass of the components, strong construction disturbance and complex background vibration, the amplitude of the structural vibration or elastic wave response often fluctuates greatly, and traditional sensors are easily affected by amplitude noise and environmental interference under such non-ideal working conditions, resulting in insufficient stability of feature extraction, which in turn limits the high-precision inversion analysis based on frequency characteristics or phase characteristics.

[0006] MEMS resonant accelerometer has been widely used in vibration and dynamic response monitoring field due to its small size, high sensitivity and easy integration. However, existing MEMS accelerometers usually work in linear or weak nonlinear region, when the excitation amplitude or environmental disturbance increases, the resonant structure is easy to enter nonlinear working state, and obvious frequency dispersion effect occurs, which makes the output frequency highly sensitive to vibration amplitude, resulting in significant decrease of frequency stability. This nonlinear dispersion phenomenon can intensify the conversion of amplitude noise to frequency noise, seriously affecting the stable acquisition of frequency type characteristic quantity, and further restricting its application effect in welding residual stress monitoring and other complex engineering construction scenes.

[0007] Therefore, there is an urgent need for a sensing technology scheme that can effectively suppress the frequency dispersion effect under nonlinear working conditions and maintain high frequency stability, so that the sensor can still stably acquire frequency response information closely related to the structural dynamics characteristics under complex working conditions such as welding construction, even if the structural vibration amplitude fluctuates, thereby providing reliable data support for welding residual stress monitoring and structural health condition evaluation during the construction stage of deep-sea floating wind turbine foundation platform. SUMMARY

[0008] The present application aims to solve the problem that resonant MEMS accelerometers in complex engineering construction environment are prone to produce frequency dispersion effect under nonlinear working conditions, resulting in high sensitivity of output frequency to vibration amplitude, and thus difficult to stably characterize the weak elastic response characteristics of structure, and proposes a zero-dispersion nonlinear MEMS accelerometer for floating wind turbine platform construction stress monitoring.

[0009] The accelerometer introduces adjustable electrostatic nonlinearity in the capacitive excitation process of the double-end fixed resonance beam, and matches and offsets the geometric nonlinearity of the resonance beam itself, so that the resonator enters the zero frequency dispersion working area in the preset excitation range, so that the frequency response information related to the structural dynamics characteristics can still be stably output under the working conditions of construction load disturbance, structural vibration amplitude fluctuation and the like, and a high stability sensing basis is provided for the inversion analysis of welding residual stress and structural health state. The application specifically adopts the following technical scheme: the zero frequency dispersion nonlinear MEMS accelerometer for monitoring construction stress of a floating fan platform comprises a mass block, an amplification beam pair assembly, an electrode system, and resonance beams symmetrically arranged on both sides of the mass block, the mass block is connected with the resonance beams through the amplification beam pair assembly; the mass block serves as an inertial sensing unit for sensing the inertial force generated by the jacket during construction and detection, and transmitting the inertial force to the rear-end structure; The amplification beam pair assembly is used for mechanically amplifying the tiny inertial displacement. The electrode system is used for applying excitation voltage.

[0010] As a preferred embodiment, the lower side of the mass block is provided with symmetrically distributed first, second, third and fourth fixed supports, and the mass block is suspended through the first, second, third and fourth fixed supports.

[0011] As a preferred embodiment, the amplification beam pair assembly comprises front and rear symmetrically distributed first and second amplification beam pairs and front and rear symmetrically distributed third and fourth amplification beam pairs.

[0012] As a preferred embodiment, the resonance beam comprises first and second double-end fixed beams symmetrically arranged on both sides of the mass block, one end of the first double-end fixed beam is fixedly connected with a first electrode fixedly combined with the substrate insulating layer, the other end of the first double-end fixed beam is connected with the mass block through the first and second amplification beam pairs and is suspended on the hollow substrate insulating layer; one end of the second double-end fixed beam is fixedly connected with a second electrode fixedly combined with the substrate insulating layer, the other end of the second double-end fixed beam is connected with the mass block through the third and fourth amplification beam pairs and is suspended on the hollow substrate insulating layer.

[0013] As a preferred embodiment, the resonance of the first and second double-end fixed beams is controlled through the electrostatic excitation voltage of the electrode system; the electrode system comprises first, second, third and fourth fixed electrodes, the first and second fixed electrodes are symmetrically arranged on the front and rear sides of the first double-end fixed beam, and the third and fourth fixed electrodes are symmetrically arranged on the front and rear sides of the second double-end fixed beam.

[0014] As a preferred embodiment, the dynamic load from the outside world generates inertial force, and the suspended mass applies the perceived inertial force to the first and second double-end fixed beams through the first, second, third and fourth amplification beam pairs, respectively.

[0015] As a preferred embodiment, the first and second capacitor plates extending from the middle of the first double-end fixed beam are connected to the first and second fixed electrodes, respectively, and the third and fourth capacitor plates extending from the middle of the second double-end fixed beam are connected to the third and fourth fixed electrodes, respectively, to excite the bending vibration of the first and second double-end fixed beams by electrostatic force; by controlling the electrostatic force applied to the first, second, third and fourth fixed electrodes, the first and second double-end fixed beams generate corresponding electrostatic soft spring nonlinear effects, and work in the zero dispersion region, respectively.

[0016] As a preferred embodiment, the zero dispersion nonlinear MEMS accelerometer further comprises an anti-interference control method, comprising the following steps: Step SS1: simultaneously loading a direct current bias voltage V dc and an alternating excitation voltage V ac on the electrode system; the direct current bias voltage V dc1 and the direct current bias voltage V dc2 are symmetrically loaded on the first and second electrode pairs, and the excitation voltage on the first and second fixed electrodes is the direct current bias voltage V dc1 , and the excitation voltage on the first fixed electrode is the alternating voltage V ac1 ; Step SS2: generating "electrostatic soft spring effect" by using electric field force; the electrostatic force F and the displacement X have a nonlinear relationship; the electrode system is applied with excitation voltage and the sensor formed by the zero dispersion nonlinear MEMS accelerometer detects the frequency signal; Step SS3: adjusting the voltage parameter V ac so that the nonlinear term in the electrostatic force and the geometric nonlinear term of the first double-end fixed beam itself are offset; based on the symmetric loading method, the excitation voltage on the third and fourth fixed electrodes is the direct current bias voltage V dc2 , and the excitation voltage on the third fixed electrode is the alternating voltage V ac2 ; Step SS4: by adjusting the size of the excitation voltage, so that the third order nonlinear term and the geometric nonlinear term of the double-end fixed beam itself offset, so that the amplitude-frequency response skeleton line of the first double-end fixed beam and the second double-end fixed beam produces linear characteristics in a certain range, the response amplitude and frequency are independent, so that the MEMS accelerometer works in the zero dispersion region; when the two terms are offset in step SS3, the system enters the "zero dispersion region", at this time, the output frequency omega of the sensor composed of the zero dispersion nonlinear MEMS accelerometer is decoupled from the vibration amplitude A, and a constant output is realized.

[0017] As a preferred embodiment, step SS3 specifically comprises: loading a DC bias voltage on the first fixed electrode and the second fixed electrode as the excitation voltage, and loading a DC bias voltage on the third fixed electrode and the fourth fixed electrode as the excitation voltage; loading an AC voltage on the first fixed electrode as the excitation voltage, and loading an AC voltage on the third fixed electrode as the excitation voltage to generate an electrostatic force; by controlling the AC voltage and, the nonlinear term in the electrostatic force and the geometric nonlinear term of the first double-end fixed beam itself are offset.

[0018] As a preferred embodiment, the zero dispersion nonlinear MEMS accelerometer is packaged in a high-humidity and high-salt resistant metal shell and attached to a key stress node of a jacket, and the key stress node is a K-type / T-type node; when performing welding residual stress elastic wave detection in a complex environment, the zero dispersion nonlinear MEMS accelerometer automatically works in the zero dispersion mode, and outputs a frequency signal without drift.

[0019] The beneficial effects achieved by the present application are: 1. The present application aims at the problem that the resonant MEMS accelerometer in the complex engineering construction environment is prone to produce frequency dispersion effect under nonlinear working conditions, leading to that the output frequency is highly sensitive to the vibration amplitude, and it is difficult to stably characterize the weak elastic response characteristics of the structure. A MEMS accelerometer based on zero dispersion nonlinear regulation mechanism is proposed. The accelerometer introduces adjustable electrostatic nonlinearity in the capacitive excitation process of the double-end fixed beam resonant beam, and matches and offsets the geometric nonlinearity of the resonant beam itself, so that the resonator enters the zero dispersion working area within the preset excitation range. Therefore, under the working conditions such as construction load disturbance and structure vibration amplitude fluctuation, the frequency response information related to the structure dynamics characteristics can still be stably output, providing a high stability sensing basis for the inversion analysis of welding residual stress and structure health state; 2. High measurement stability in extreme environment: under severe working conditions such as typhoon and huge wave (large amplitude excitation), the error of traditional sensors will rise sharply, while the present application can maintain "zero dispersion", the frequency stability is improved by more than 3 times, and the data is ensured not to be lost at critical moment; 3. Effectively reduce the false alarm rate: the present application can distinguish "environmental interference induced frequency shift" and "structure damage induced frequency shift" from the physical layer, and avoid false alarm of structure failure due to excessive wind and wave; 4. High sensitivity and wide dynamic range: the present application combines lever amplification mechanism and zero dispersion control, which can capture weak vibration and withstand extreme sea conditions without distortion. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the overall hardware structure schematic diagram of the zero dispersion nonlinear MEMS accelerometer for floating type wind turbine platform construction stress monitoring of the present application; Figure 2 is the schematic diagram of the output frequency omega and the vibration amplitude A of the present application, wherein the fixed direct current bias voltage V dc1 is 8V, and the alternating voltage V ac1 is changed from 100mV to 400mV. It can be observed that the amplitude-frequency response of the device has shown nonlinear characteristics at the initial 100mV; after increasing to 300mV, it can be obviously observed that the skeleton line of the nonlinear amplitude-frequency curve is biased to the right; when increasing to 360mV-400mV, the skeleton line shows a vertical upward trend with the increase of excitation. In this range, the response frequency of the device is irrelevant to the amplitude (vibration energy), and it enters the zero dispersion region; Figure 3 is the schematic diagram of the zero dispersion region of the present application. The MEMS accelerometer works in the zero dispersion region. In this working region, the response of the first double-end fixed beam 11 and the second double-end fixed beam 12 suppresses the conversion of amplitude noise to frequency noise, and suppresses the corresponding phase noise. Taking Allan variance as the index of frequency stability, it can be observed that the frequency stability is improved by more than 3 times; Figure 3It can be seen that its frequency stability is three times better than that of the linear case.

[0021] The markings in the diagram mean: 11-First double-ended fixed beam, 12-Second double-ended fixed beam; 21-First amplifying beam pair, 22-Second amplifying beam pair, 23-Third amplifying beam pair, 24-Fourth amplifying beam pair; 31-First fixed electrode, 32-Second fixed electrode, 33-Third fixed electrode, 34-Fourth fixed electrode; 41-First electrode, 42-Second electrode; 51-First fixed support, 52-Second fixed support, 53-Third fixed support, 54-Fourth fixed support; 61-First capacitor plate, 62-Second capacitor plate; 71-Third capacitor plate, 72-Fourth capacitor plate; 8-Mass block. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0023] Example 1: As Figure 1 As shown, the present invention proposes a zero-dispersion nonlinear MEMS accelerometer for stress monitoring during the construction of a floating wind turbine platform, comprising a mass block 8, an amplification beam pair assembly, an electrode system, and resonant beams symmetrically arranged on both sides of the mass block 8. The mass block 8 is connected to the resonant beams through the amplification beam pair assembly. Mass block 8 serves as an inertial sensing unit, used to sense the inertial force generated during the construction and inspection of the jacket structure, and to transmit the inertial force to the back-end structure. The magnifying beam assembly is used to mechanically amplify minute inertial displacements; The electrode system is used to apply the excitation voltage.

[0024] Optionally, a first fixed support 51, a second fixed support 52, a third fixed support 53, and a fourth fixed support 54 are symmetrically distributed below the mass block 8, and the mass block 8 is suspended by the first fixed support 51, the second fixed support 52, the third fixed support 53, and the fourth fixed support 54.

[0025] Optionally, the amplifying beam pair assembly includes a first amplifying beam pair 21 and a second amplifying beam pair 22 symmetrically distributed front to back, a third amplifying beam pair 23 and a fourth amplifying beam pair 24 symmetrically distributed front to back.

[0026] Optionally, the resonant beam comprises a first double-end fixed beam 11 and a second double-end fixed beam 12 symmetrically arranged on both sides of the mass block 8, one end of the first double-end fixed beam 11 is fixedly connected with the first electrode 41 fixedly combined with the substrate insulating layer, the other end of the first double-end fixed beam 11 is connected with the mass block 8 through the first amplification beam pair 21 and the second amplification beam pair 22 and is suspended on the hollow substrate insulating layer; one end of the second double-end fixed beam 12 is fixedly connected with the second electrode 42 fixedly combined with the substrate insulating layer, the other end of the second double-end fixed beam 12 is connected with the mass block 8 through the third amplification beam pair 23 and the fourth amplification beam pair 24 and is suspended on the hollow substrate insulating layer.

[0027] Optionally, the resonance of the first double-end fixed beam 11 and the second double-end fixed beam 12 is excited by electrostatic excitation voltage control of the electrode system. The electrode system comprises a first fixed electrode 31, a second fixed electrode 32, a third fixed electrode 33 and a fourth fixed electrode 34, the first fixed electrode 31 and the second fixed electrode 32 are symmetrically arranged on the front and back sides of the first double-end fixed beam 11, and the third fixed electrode 33 and the fourth fixed electrode 34 are symmetrically arranged on the front and back sides of the second double-end fixed beam 12.

[0028] Optionally, the dynamic load from the outside world generates an inertial force, and the suspended mass block 8 applies the sensed inertial force to the first double-end fixed beam 11 and the second double-end fixed beam 12 through the first amplification beam pair 21, the second amplification beam pair 22, the third amplification beam pair 23 and the fourth amplification beam pair 24, respectively.

[0029] Optionally, the first capacitor plate 61 and the second capacitor plate 62 extending from the middle of the first double-end fixed beam 11 to both sides are respectively connected with the first fixed electrode 31 and the second fixed electrode 32, and the third capacitor plate 71 and the fourth capacitor plate 72 extending from the middle of the second double-end fixed beam 12 to both sides are respectively connected with the third fixed electrode 33 and the fourth fixed electrode 34, so as to excite the bending direction vibration of the first double-end fixed beam 11 and the second double-end fixed beam 12 by the action of electrostatic force; by controlling the electrostatic force applied to the first fixed electrode 31, the second fixed electrode 32, the third fixed electrode 33 and the fourth fixed electrode 34, the first double-end fixed beam 11 and the second double-end fixed beam 12 generate corresponding electrostatic soft spring nonlinear effects, so as to work in the zero dispersion area, respectively.

[0030] Optionally, the zero dispersion nonlinear MEMS accelerometer further comprises an anti-interference control method, comprising the following steps: Step SS1: simultaneously loading a direct current bias voltage V dc and an alternating excitation voltage V ac on the electrode system; the direct current bias voltage V dc1 and the direct current bias voltage V dc2Symmetrically load on the first electrode pair and the second electrode pair, load the excitation voltage on the first fixed electrode 31 and the second fixed electrode 32 as a direct current bias voltage V dc1 , load the excitation voltage on the first fixed electrode 31 as an alternating current voltage V ac1 ; Step SS2: generate "electrostatic soft spring effect" by using electric field force, the electrostatic force F and the displacement X are nonlinear relationship; the electrode system is applied to the excitation voltage and the sensor composed of the zero dispersion nonlinear MEMS accelerometer detects the frequency signal; Step SS3: adjust the voltage parameter V ac , so that the nonlinear term in the electrostatic force and the geometric nonlinear term of the first double-end fixed beam 11 itself are offset; based on the symmetric loading mode, the same reasoning can be obtained that the excitation voltage is loaded on the third fixed electrode 33 and the fourth fixed electrode 34 as a direct current bias voltage V dc2 , load the excitation voltage on the third fixed electrode 33 as an alternating current voltage V ac2 ; Step SS4: by adjusting the size of the excitation voltage, so that the third-order nonlinear term and the geometric nonlinear term of the double-end fixed beam itself are offset, so that the amplitude-frequency response skeleton line of the first double-end fixed beam 11 and the second double-end fixed beam 12 produces linear characteristics in a certain range, the response amplitude and the frequency are independent, so that the MEMS accelerometer works in the zero dispersion region; when the two terms are offset in step SS3, the system enters the "zero dispersion region", at this time, the output frequency omega of the sensor composed of the zero dispersion nonlinear MEMS accelerometer is decoupled from the vibration amplitude A, and constant output is realized.

[0031] Optionally, step SS3 specifically includes: loading the excitation voltage on the first fixed electrode 31 and the second fixed electrode 32 as a direct current bias voltage, loading the excitation voltage on the third fixed electrode 33 and the fourth fixed electrode 34 as a direct current bias voltage; load the excitation voltage on the first fixed electrode 31 as an alternating current voltage, load the excitation voltage on the third fixed electrode 33 as an alternating current voltage, generate electrostatic force; by controlling the alternating current voltage and, the nonlinear term in the electrostatic force and the geometric nonlinear term of the first double-end fixed beam 11 itself are offset.

[0032] Optionally, the zero dispersion nonlinear MEMS accelerometer is packaged in a high-humidity and high-salt resistant metal shell and attached to a key stress node of a jacket, the key stress node is a K-type / T-type node; when welding residual stress elastic wave detection is carried out in a complex environment, the anti-nonlinear interference MEMS vibration monitoring device automatically works in the zero dispersion mode, and outputs a frequency signal without drift.

[0033] The core of the present application is: 1. Specific application scene combination: protect the device is specially used for vibration monitoring of deep sea engineering structure (such as booster station, jacket), especially for the monitoring application of K type / T type pipe joint in extreme sea conditions. 2. "Zero dispersion" anti-interference control mechanism: a method for actively canceling the mechanical nonlinearity caused by environmental load (large amplitude) by adjusting the AC / DC voltage ratio on the electrode to generate electrostatic nonlinearity. The focus is: use this method to eliminate the frequency drift error caused by wave impact. 3. Specific MEMS topology: the symmetric double-end fixed beam + amplification beam pair assembly composed of the first double-end fixed beam 11 and the second double-end fixed beam 12, and the parallel capacitor plate and fixed electrode excitation structure composed of the lever amplification mechanism + electrode system. This structure is the physical basis for realizing the above-mentioned nonlinear cancellation.

[0034] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code.

[0035] The present application is described with reference to flowcharts and / or block diagrams according to the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that carries out the functions specified in one or more flows and / or blocks. These computer program instructions can also be stored in a computer-readable memory that can cause the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that carries out the functions specified in one or more flows and / or blocks. These computer program instructions can also be loaded into a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a device for implementing the functions specified in the flowcharts and / or block diagrams.Figure 1 one or more processes and / or functions specified in one or more blocks ​ one or more blocks or any combination thereof.

[0036] It should be noted that the above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not limit the technical solutions of the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application. Any modification or equivalent replacement, which does not depart from the spirit and scope of the present application, should be covered in the protection scope of the claims of the present application.

Claims

1. A zero-frequency dispersion non-linear MEMS accelerometer for floating wind turbine platform construction stress monitoring, characterized by, The quality block (8), an amplification beam pair assembly, an electrode system, and resonant beams symmetrically arranged on both sides of the quality block (8) are provided. The quality block (8) is used as an inertial sensing unit to sense the inertial force generated in the construction detection process of the jacket platform and transmit the inertial force to the rear-end structure. The amplification beam pair assembly is used for mechanical amplification of the tiny inertial displacement. The electrode system is used for applying excitation voltage.

2. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 1, wherein, The quality block (8) is suspended by the first fixed support (51), the second fixed support (52), the third fixed support (53), and the fourth fixed support (54).

3. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 1, wherein, The amplification beam pair assembly includes the first amplification beam pair (21) and the second amplification beam pair (22) symmetrically arranged front and back, and the third amplification beam pair (23) and the fourth amplification beam pair (24) symmetrically arranged front and back.

4. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 3, wherein, The resonant beams include the first double-end fixed beam (11) and the second double-end fixed beam (12) symmetrically arranged on both sides of the quality block (8).

5. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 4, wherein, The first double-end fixed beam (11) is fixedly connected to the first electrode (41) fixed to the substrate insulation layer, and the other end of the first double-end fixed beam (11) is connected to the quality block (8) through the first amplification beam pair (21) and the second amplification beam pair (22) and suspended on the hollow substrate insulation layer.

6. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 5, wherein, The second double-end fixed beam (12) is fixedly connected to the second electrode (42) fixed to the substrate insulation layer, and the other end of the second double-end fixed beam (12) is connected to the quality block (8) through the third amplification beam pair (23) and the fourth amplification beam pair (24) and suspended on the hollow substrate insulation layer. The resonances of the first double-end fixed beam (11) and the second double-end fixed beam (12) are excited by electrostatic excitation voltage control of the electrode system. The first fixed electrode (31) and the second fixed electrode (32) are symmetrically arranged on the front and back of the first double-end fixed beam (11), and the third fixed electrode (33) and the fourth fixed electrode (34) are symmetrically arranged on the front and back of the second double-end fixed beam (12). The inertial force generated by the dynamic load of the external environment is applied to the first double-end fixed beam (11) and the second double-end fixed beam (12) through the first amplification beam pair (21), the second amplification beam pair (22), and the third amplification beam pair (23) and the fourth amplification beam pair (24).

7. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 5, wherein, The first and second capacitor plates (61, 62) extending to both sides in the middle of the first double-end fixed beam (11) are connected with the first and second fixed electrodes (31, 32) respectively, the third and fourth capacitor plates (71, 72) extending to both sides in the middle of the second double-end fixed beam (12) are connected with the third and fourth fixed electrodes (33, 34) respectively, the bending direction vibration of the first and second double-end fixed beams (11, 12) is excited by the electrostatic force, and the first and second double-end fixed beams (11, 12) generate corresponding electrostatic soft spring nonlinear effects by controlling the electrostatic force applied on the first, second, third and fourth fixed electrodes (31, 32, 33, 34) to work in the zero dispersion region respectively.

8. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 1, wherein, The zero dispersion nonlinear MEMS accelerometer further comprises an anti-interference control method, comprising the following steps: Step SS1: simultaneously loading a DC bias voltage V dc and an AC excitation voltage V ac on the electrode system; loading the DC bias voltage V dc1 and the DC bias voltage V dc2 symmetrically on the first electrode pair and the second electrode pair, loading the excitation voltage as the DC bias voltage V dc1 on the first fixed electrode (31) and the second fixed electrode (32), and loading the excitation voltage as the AC voltage V ac1 on the first fixed electrode (31); In step SS2, the "electrostatic soft spring effect" is generated by using the electric field force, the electrostatic force F has a nonlinear relationship with the displacement X, the electrode system is applied with an excitation voltage, and the sensor formed by the zero dispersion nonlinear MEMS accelerometer detects the frequency signal; Step SS3: adjusting the voltage parameter V ac , the nonlinear term in the electrostatic force is counteracted by the geometric nonlinear term of the first double-end clamped beam (11) itself; based on the symmetric loading mode, by the same reasoning, the excitation voltage loaded on the third fixed electrode (33) and the fourth fixed electrode (34) is a direct current bias voltage V dc2 , the excitation voltage loaded on the third fixed electrode (33) is an alternating voltage V ac2 ; In step SS4, the third-order nonlinear term and the geometric nonlinear term of the double-end fixed beam itself are offset by adjusting the size of the excitation voltage, the amplitude-frequency response skeleton line of the first and second double-end fixed beams (11, 12) has linear characteristics in a certain range, the response amplitude and the frequency are independent, the MEMS accelerometer works in the zero dispersion region, when the two terms are offset in step SS3, the system enters the "zero dispersion region", at this time, the output frequency omega of the sensor formed by the zero dispersion nonlinear MEMS accelerometer is decoupled from the vibration amplitude A, and constant output is realized.

9. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 8, wherein, In step SS3, the excitation voltage applied on the first and second fixed electrodes (31, 32) is a direct current bias voltage, the excitation voltage applied on the third and fourth fixed electrodes (33, 34) is a direct current bias voltage, the excitation voltage applied on the first fixed electrode (31) is an alternating current voltage, the excitation voltage applied on the third fixed electrode (33) is an alternating current voltage, and the electrostatic force is generated; the nonlinear term in the electrostatic force and the geometric nonlinear term of the first double-end fixed beam (11) itself are offset by controlling the alternating current voltage.

10. The zero-gauss nonlinear MEMS accelerometer for offshore wind turbine platform construction stress monitoring according to claim 8, wherein, The zero dispersion nonlinear MEMS accelerometer is packaged in a metal shell resistant to high humidity and high salt, and is attached to a key stress node of a jacket, the key stress node is a K-type / T-type node, when the welding residual stress elastic wave detection is carried out in a complex environment, the zero dispersion nonlinear MEMS accelerometer automatically works in the zero dispersion mode, and outputs a frequency signal without drift.

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