Surface Warpage Measurement of Wood at Elevated Temperature by Shadow Moiré Method

2013 ◽  
Vol 303-306 ◽  
pp. 799-802
Author(s):  
Terry Yuan Fang Chen ◽  
Yu Sheng Chen
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Field Method ◽  
Test Results ◽  
Full Field ◽  
Contact Type ◽  
Shadow Moire ◽  
Shadow Moiré ◽  
Moire Method ◽  
Good Agreement

A full-field method to measure the surface warpage of wood plate at elevated temperature by phase-shifted shadow moiré method is presented. Test of the method on a cypress wood plate is demonstrated. A comparison of the test results at room temperature to the ones obtained by contact type sensor was made. A good agreement between them is shown. Further measurement of the plate warpage at elevated temperature reveals the warping behavior of wood plate.

scholarly journals Computer-automated shadow moiré method and applications for 3D surface profiling

2021 ◽  
Author(s):  
Rui Zhao
Keyword(s):  
Least Square ◽  
Automated System ◽  
Image Subtraction ◽  
Full Field ◽  
Surface Profiling ◽  
Shadow Moire ◽  
Shadow Moiré ◽  
3D Surface ◽  
Measurement Resolution ◽  
Moire Method

Among numerous methods for 3D surface profiling, classic shadow moiré method has been kept as the most popular one due to its full-field feature and low cost. This thesis focuses on a computer-vision shadow moiré method with a scope to improve the measurement resolution, accuracy and efficiency. The computer automation is basically realized through the introduction of a phase-shifting technique that is incorporated with a new multi-grid least-square unwrapping algorithm. The method is enhanced by implementing a few additional image processing techniques. These techniques, when implemented, result in improved measurement accuracy and enable easy applications to irregularly shaped surfaces. The study also proposes a new, automated system calibration approach that is based on a real-time image subtraction. A data normalization process is studied to resolve possible confusions in the presentation of the original data. The verification test results show that the modified shadow moiré technique has achieved the initial goal, in that the measurement resolution now reaches a few percentage of the fringe sensititivity.

scholarly journals Computer-automated shadow moiré method and applications for 3D surface profiling

2021 ◽  
Author(s):  
Rui Zhao
Keyword(s):  
Least Square ◽  
Automated System ◽  
Image Subtraction ◽  
Full Field ◽  
Surface Profiling ◽  
Shadow Moire ◽  
Shadow Moiré ◽  
3D Surface ◽  
Measurement Resolution ◽  
Moire Method

Among numerous methods for 3D surface profiling, classic shadow moiré method has been kept as the most popular one due to its full-field feature and low cost. This thesis focuses on a computer-vision shadow moiré method with a scope to improve the measurement resolution, accuracy and efficiency. The computer automation is basically realized through the introduction of a phase-shifting technique that is incorporated with a new multi-grid least-square unwrapping algorithm. The method is enhanced by implementing a few additional image processing techniques. These techniques, when implemented, result in improved measurement accuracy and enable easy applications to irregularly shaped surfaces. The study also proposes a new, automated system calibration approach that is based on a real-time image subtraction. A data normalization process is studied to resolve possible confusions in the presentation of the original data. The verification test results show that the modified shadow moiré technique has achieved the initial goal, in that the measurement resolution now reaches a few percentage of the fringe sensititivity.

Shadow Moire´ Evaluation of Motherboard Warpage Under Preload CPU Thermal Solutions

2005 ◽  
Author(s):  
Phil Geng ◽  
Robert R. Martinson ◽  
Richard L. Williams ◽  
Michael Mello ◽  
Steve Cho
Keyword(s):  
Elevated Temperature ◽  
Failure Mode ◽  
Room Temperature ◽  
Moire Interferometry ◽  
Heating Stage ◽  
Shadow Moire ◽  
Shadow Moiré ◽  
Creep Effect ◽  
Local Board ◽  
Temperature Correlations

This work investigated the motherboard coplanarity and preload correlation using the shadow moire´ interferometry. Motherboards under three different preloads in the CPU area were examined at room temperature and elevated temperature. Both the global board warpage and the local board warpage around the CPU area were measured for preload and temperature correlations. The measured board coplanarity was correlated to the board preload successfully. The results clearly identified a failure mode from the outlier, which has totally different warpage shape and corresponds to the uneven preload case. Also, the creep effect under preload during heating stage was observed and quantified.

A shadow-moiré method with continuously variable sensitivity

1977 ◽  
Vol 4 (3) ◽  
pp. 157-161 ◽  
Author(s):  
Y.Y. Hung ◽  
C.Y. Liang ◽  
A.J. Durelli ◽  
J.D. Hovanesian
Keyword(s):  
Shadow Moire ◽  
Shadow Moiré ◽  
Variable Sensitivity ◽  
Moire Method

Springback Behavior of an Invar Sheet and Its Perforated Form

2006 ◽  
Vol 505-507 ◽  
pp. 781-786
Author(s):  
Yi Che Lee ◽  
Fuh Kuo Chen
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Test Results ◽  
Bending Tests ◽  
Predicted Values ◽  
Springback Behavior ◽  
Good Agreement

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

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