Optical Measurement Methods

 

Optical Microscope Observation

Principle: The material surface is directly observed with an optical microscope, and the morphological details of the cracks can be clearly seen. By regularly observing the same position and comparing the changes in the size of the cracks such as length and width, the crack propagation can be monitored. The magnification of an optical microscope generally ranges from several times to 2000 times, and an appropriate magnification can be selected according to the size of the cracks to be observed.

Application Scenarios: It is commonly used in laboratory studies of the micro - crack propagation of materials. For example, in materials science research, the crack propagation in the microstructure of metal or ceramic materials is observed to analyze the relationship between crack propagation and the material microstructure.

Digital Image Correlation (DIC) Method

Principle: A random speckle pattern is made on the material surface. By taking images of the material surface during the loading process and using digital image - processing technology to analyze the displacement changes of the speckle pattern, the full - field strain distribution on the material surface can be obtained. Based on the principle that crack propagation will cause strain concentration, the strain change at the crack tip can be monitored through the DIC technology, and then the crack propagation can be evaluated.

Application Scenarios: It is more widely used in the mechanical property testing of composite structures. For example, in the fatigue test of wind - turbine blades (mostly made of composite materials), the DIC method is used to monitor the strain changes during the crack propagation on the blade surface.

 

 

Steel standard: ABS,LR,DNV,BV,GL,CCS,KR,NK,RINA

Main application:Shipbuilding steel plates are mainly used to contribute hull of ships and the cranes of break bulker and vessels in low temperature oceans.

Rolling range: Thickness*Width*Length 3-450mm*1220-4200mm*5000-18000mm

 

 

Other Methods

 

Acoustic Emission Detection (AE)

Principle: Elastic waves, that is, acoustic emission signals, will be released during the generation and propagation of cracks in materials. By installing acoustic emission sensors on the material surface to receive these signals and analyzing the characteristics of the signals (such as amplitude, frequency, energy, etc.), the location where the cracks are generated and the extent of propagation can be determined. The frequency range of acoustic emission signals is relatively wide, ranging from dozens of kHz to several MHz.

Application Scenarios: It is used to real - time monitor the crack propagation of large - scale structures (such as bridges, large - scale pressure vessels, etc.) during operation. For example, in the bridge structural health monitoring system, acoustic emission sensors can real - time capture the signals sent out by the crack propagation inside the bridge structure and provide a basis for timely maintenance.

Finite Element Simulation Analysis

Principle: Based on the mechanical property parameters of materials, the geometric shape of the structure, and the boundary conditions, a numerical model of the structure is established using finite - element software. Cracks are preset in the model, and through simulating the loading process, parameters such as the stress - intensity factor and strain - energy release rate at the crack tip are calculated to predict the direction and rate of crack propagation.

Application Scenarios: In the engineering design stage, crack - propagation analysis is carried out for complex structures (such as automobile collision structural parts, aircraft landing gears, etc.) to optimize the design and improve the safety and reliability of the structure.

 

 

 

BV D420 Steel Plate

 

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