The application of Moire interferometry in the measurement of displacement field and strain field at notch-tip and crack-tip

1991 ◽  
Vol 7 (4) ◽  
pp. 376-382 ◽  
Author(s):  
Han Jinhu ◽  
Mao Tianxiang
Keyword(s):  
Displacement Field ◽  
Strain Field ◽  
Crack Tip ◽  
Moiré Interferometry ◽  
Moire Interferometry ◽  
Notch Tip

A Study of the Deformation Measurement of 3D Displacement Field

2005 ◽  
Vol 295-296 ◽  
pp. 313-318
Author(s):  
S.R. Lee ◽  
Z.S. Luo ◽  
H.S. Chiou ◽  
B.G. Wang ◽  
L.S. Liu
Keyword(s):  
Displacement Field ◽  
Incident Angle ◽  
Vertical Direction ◽  
Moiré Interferometry ◽  
Deformation Measurement ◽  
Measuring Error ◽  
Moire Interferometry ◽  
First Order ◽  
Out Of Plane ◽  
Plane Displacement

With the development of modern engineering such as micro-electro-mechanical system (MEMS) and new material, the deformation measurement of 3D displacement field is required. Moiré interferometry has become common for measuring the deformations of two-dimension in-plane displacement field. To solve the problem of 3D displacement field, a system for measuring the deformations of 3D displacement field is designed. By using this system, we can measure the out-of-plane displacement by appending a set of electronic speckle interference system based on Moiré interferometry system. Adjusting the incident angle of the incident light, the transmitting direction of the first order diffracted wave in a Moiré interferometry system is assigned to deviate with a small angle from the vertical direction of the specimen surface. Thus the first order diffracted wave is separated from the place of the appended interference field. The striated patterns of the deformations of 3D displacement field can be obtained at the same time. These striated patterns are recorded respectively by three CCD cameras and are stored and processed by a computer. The synchronous measuring method brings certain amount of measuring errors into the measurement of in-plane displacement. This measuring error is analyzed in theory. When real-time measurement is not required, this system can be changed into another system in which the in-plane and the out-of-plane displacement field are measured by time sharing to reduce the measuring errors. The theoretical derivation and a part of experimental results for verification are presented.

Using the Multi-Parameter Fracture Mechanics for more Accurate Description of Stress/Displacement Crack Tip Fields

2013 ◽  
Vol 586 ◽  
pp. 237-240 ◽  
Author(s):  
Lucie Šestáková
Keyword(s):  
Stress Distribution ◽  
Fracture Mechanics ◽  
Boundary Conditions ◽  
Displacement Field ◽  
Singular Term ◽  
Crack Tip ◽  
Higher Order ◽  
Precise Description ◽  
Accurate Knowledge ◽  
Higher Order Terms

Most of fracture analyses often require an accurate knowledge of the stress/displacement field over the investigated body. However, this can be sometimes problematic when only one (singular) term of the Williams expansion is considered. Therefore, also other terms should be taken into account. Such an approach, referred to as multi-parameter fracture mechanics is used and investigated in this paper. Its importance for short/long cracks and the influence of different boundary conditions are studied. It has been found out that higher-order terms of the Williams expansion can contribute to more precise description of the stress distribution near the crack tip especially for long cracks. Unfortunately, the dependences obtained from the analyses presented are not unambiguous and it cannot be strictly derived how many of the higher-order terms are sufficient.

Sign in / Sign up

Export Citation Format

Share Document