CN-121994155-A - Polar region ship crack growth monitoring method

CN121994155ACN 121994155 ACN121994155 ACN 121994155ACN-121994155-A

Abstract

The invention relates to the technical field of crack growth monitoring, in particular to a polar region ship crack growth monitoring method. The method comprises the steps of screening hot spot areas where cracks of a ship body structure are initiated, screening key nodes, monitoring strain data at the key nodes by arranging annular optical fiber sensors at the key nodes, analyzing the monitored data by a crack propagation monitoring system, and providing warning information by dividing safety grades according to different interval sections. The invention improves the monitoring range, accuracy and high efficiency.

Inventors

GU YINGBIN
LIN YI
CHEN LIZHI
GAN JIN
PEI ZHIYONG
HUANG YAO
TIAN MINGQI
SUN JIAN
CHEN QIAO

Assignees

中核海洋核动力发展有限公司

Dates

Publication Date: 20260508
Application Date: 20241107

Claims (10)

1. The polar vessel crack growth monitoring method is characterized by comprising the following steps of: step S1, screening hot spot areas where cracks of a ship body structure are initiated; step S2, screening key nodes; step S3, monitoring strain data at the key node by arranging an annular optical fiber sensor at the key node; And S4, analyzing the monitoring data through a crack propagation monitoring system, dividing safety levels according to different interval sections, and providing warning information.
2. The polar vessel crack growth monitoring method according to claim 1, wherein the step S1 specifically comprises: According to the calculation result of the whole ship stress, combining with the standard hot spot position selection suggestion of a class society, screening out a fatigue hot spot region of the ship structure, carrying out grid refinement on the fatigue hot spot region according to the standard requirement, wherein the grid size of the refined region is smaller than the plate thickness, the grid density of the refined grid region between the fine grid and the coarse grid is stable in transition, and finally determining the hot spot region where cracks of the ship structure occur, wherein the grid size of the refined region is larger than 10 times of the plate thickness and the grid density of the refined grid region between the fine grid and the coarse grid is outwards extended from the hot spot position.
3. The polar vessel crack growth monitoring method according to claim 1, wherein the step S2 specifically comprises: Analyzing the stress response time domain result of the node with larger stress in the hot spot area based on a rain flow counting method, counting to obtain the amplitude and the average value of the stress of the node, correcting the obtained average stress by using a Goodman correction method, selecting a proper wave spectral density function according to the sailing sea state information of the icebreaker, and calculating the power spectral density of the stress of the node; For each short-term sea condition, according to a random process theory, when a narrow-band stable random process of node alternating stress with zero mean value is considered, the stress range obeys Rayleigh distribution, and the probability density is calculated; according to the wave statistical information of the navigation area provided by the wave scatter diagram, the node stress distribution under each short-term sea condition can be further obtained, the wave scatter diagram is selected according to the actual operation route of the ship, and the fatigue accumulated damage value of the node can be obtained through an S-N curve; Calculating the node accumulated damage degree of the ship in the ith sea state and the jth heading based on a spectrum analysis method; Considering bandwidth correction and fatigue damage correction in a low stress range, and obtaining total damage in a node design life period T by using a Miner linear accumulated damage theory; And (3) calculating and screening fatigue life of each node with larger stress in the hot spot area and fatigue damage results under the designed service life based on spectrum analysis, so as to determine key nodes and determine the key nodes as crack expansion monitoring point positions.
4. A polar vessel crack growth monitoring method according to claim 3, wherein the method of calculating the node stress power spectral density is: Sσ(ωH s ,T z ,θ)＝|Hσ(ωθ) 2 Sζ(ωH s ,T Z ) Wherein H σ (ωθ) is a node stress transfer function, ω and θ are frequency and wave direction angle respectively, S σ is a node stress power spectrum density function, H S is sense wave height of a short-term sea state, and T Z is average zero crossing period of the short-term sea state.
5. A polar vessel crack growth monitoring method according to claim 3, wherein the probability density is calculated by: Wherein S is the node stress range, and sigma σ is the standard deviation of the alternating stress process.
6. A polar vessel crack growth monitoring method according to claim 3, wherein the cumulative damage of the vessel in the i-th sea state and j-th heading is as shown in the formula: Wherein T ij is the navigation time of the ith sea state and the jth course, f 0ij is the zero crossing frequency of the stress alternating process in the ith sea state and the jth course, K is the S-N curve parameter, m is the slope reciprocal of S-N, and f Sij (S) is the probability density function of the stress alternating process in the ith sea state and the jth course.
7. A polar vessel crack growth monitoring method according to claim 3, wherein the total damage over the node design life T is: Wherein lambda ij is a bandwidth correction coefficient, mu ij is a fatigue damage correction coefficient in a low stress range, n s is the number of sea states, n H is the divided heading number, p i is the occurrence probability of each sea state, and p j is the occurrence probability of each heading.
8. The polar vessel crack growth monitoring method according to claim 1, wherein in the step S3, the annular optical fiber sensors are arranged around the crack growth path, and annular optical fiber sensors having radii of 5mm, 10mm, 20mm, 50mm and 100mm are respectively arranged centering on the initial crack, and a safety class section is set with a difference in radii of two adjacent annular optical fiber sensors.
9. The polar vessel crack growth monitoring method according to claim 1, wherein in the step S4, the criteria of the safety registration division are: micro cracks of 0-5 mm are a safety range, and conventional monitoring is generally not needed to be treated immediately; 5-50 mm of small cracks are used as early warning ranges, evaluation is immediately carried out, and shutdown and repair are considered; Medium and above cracks greater than 50mm are dangerous areas, suggesting immediate shutdown.
10. The polar vessel crack growth monitoring method of claim 9, wherein for different security levels, different alert and reminder messages are employed: microcracks of 0-5 mm, suggesting routine monitoring, generally without immediate treatment; 5-50 mm of small cracks, prompting to immediately evaluate, and considering to stop and repair; Medium and above cracks greater than 50mm, indicating immediate shutdown.

Description

Polar region ship crack growth monitoring method Technical Field The invention relates to the technical field of crack growth monitoring, in particular to a polar region ship crack growth monitoring method. Background The icebreaker is impacted by sea random wave action and ice, the hull structure generates alternating stress, and fatigue crack initiation and propagation are easy to occur at the local stress concentration position. In recent years, research on fatigue crack growth is one of hot spots of structural health monitoring, and methods for structural health monitoring can be classified into active monitoring and passive monitoring from signal sources. Active monitoring structural health monitoring is achieved by applying an excitation signal to the structure and analyzing a structural response signal received by the sensor. The equipment of the active Lamb wave technology is relatively simple, and the long-distance large-area detection of the plate structure can be realized. Although active monitoring methods have many applications in crack growth monitoring, continuous monitoring is difficult. Passive methods refer to methods that continuously monitor certain parameters of the structure as the crack grows, including acoustic emission signals, strain, thermal energy, and the like. Wherein the strain of the structure is affected by crack propagation, is relatively easy to monitor, and can be continuously monitored. Because the condition of crack propagation of the structure is complex, the fault characteristics are difficult to accurately obtain by adopting a single sensor in the state monitoring and fault diagnosis, and the reliability is low. Disclosure of Invention The invention aims to solve the technical problem of providing a polar region ship crack propagation-based monitoring method, which improves the monitoring range, accuracy and high efficiency. The invention provides a polar region ship crack growth monitoring method, which comprises the following steps: step S1, screening hot spot areas where cracks of a ship body structure are initiated; step S2, screening key nodes; step S3, monitoring strain data at the key node by arranging an annular optical fiber sensor at the key node; And S4, analyzing the monitoring data through a crack propagation monitoring system, dividing safety levels according to different interval sections, and providing warning information. The step S1 specifically comprises the following steps: According to the calculation result of the whole ship stress, combining with the standard hot spot position selection suggestion of a class society, screening out a fatigue hot spot region of the ship structure, carrying out grid refinement on the fatigue hot spot region according to the standard requirement, wherein the grid size of the refined region is smaller than the plate thickness, the grid density of the refined grid region between the fine grid and the coarse grid is stable in transition, and finally determining the hot spot region where cracks of the ship structure occur, wherein the grid size of the refined region is larger than 10 times of the plate thickness and the grid density of the refined grid region between the fine grid and the coarse grid is outwards extended from the hot spot position. The step S2 specifically comprises the following steps: Analyzing the stress response time domain result of the node with larger stress in the hot spot area based on a rain flow counting method, counting to obtain the amplitude and the average value of the stress of the node, correcting the obtained average stress by using a Goodman correction method, selecting a proper wave spectral density function according to the sailing sea state information of the icebreaker, and calculating the power spectral density of the stress of the node; For each short-term sea condition, according to a random process theory, when a narrow-band stable random process of node alternating stress with zero mean value is considered, the stress range obeys Rayleigh distribution, and the probability density is calculated; according to the wave statistical information of the navigation area provided by the wave scatter diagram, the node stress distribution under each short-term sea condition can be further obtained, the wave scatter diagram is selected according to the actual operation route of the ship, and the fatigue accumulated damage value of the node can be obtained through an S-N curve; Calculating the node accumulated damage degree of the ship in the ith sea state and the jth heading based on a spectrum analysis method; Considering bandwidth correction and fatigue damage correction in a low stress range, and obtaining total damage in a node design life period T by using a Miner linear accumulated damage theory; And (3) calculating and screening fatigue life of each node with larger stress in the hot spot area and fatigue damage results under the designed service life based on spectrum analysis,