• Proceedings of the KSME Conference
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• 2004.11a
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• pp.772-776
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• 2004

The paper describes the quantitative determination of out-of-plane displacement from result of Shearogrpahy, which can measure the first-order partial derivative of out-of-plane displacement directly. However, the differential sensitivity of Shearography is related to the amount of shearing, which is manually adjustable in optical interferometer and affects the quantitative determination. The relationship between those is inspected by comparing ESPI with Shearography. From the result, the amount of shearing plays a modulation factor of out-of-plane displacement and small amount of shearing gives good agreement with out-of-plane displacement.

• Current Optics and Photonics
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• v.7 no.6
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• pp.692-700
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• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.726-732
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• 2012

Pipe and Pressure Vessels that is used in power plant and chemical industry have many Internal Defects that is corrosion caused by the flow of fluid. These Internal Defects that have possibility of explosion are very dangerous because it can not see from the outside. This days many companys using NDT method to find an Internal Defect. Most of the NDT methods have limitations that are constraint of shape and materials. But Sheargoraphy have many advantages compared conventional NDT method. It has very fast measuring speed, non-destructive and non contacting measurement. As well as it hasn't constraint of shape and materials. As a paper on the analysis of measurement of error, the important factors were the Shearing Amount and pressure, and discovered measurement of the Internal Defect of the object by using shearography. The optimal Shearing Amount and pressure was discovered and utilized.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1493-1499
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• 2004

This paper describes the speckle shearing interferometry, a non-destructive optical method, for quantitative estimation of void defect and monitoring separation defect inside of a pneumatic tire. Previous shearing interferometry has not supplied quantitative result of inside defect, due to effective factors. In the study, factors related to the details of an inside defect are classified and optimized with pipeline simulator. The size and the shape of defect can be estimated accurately to find a critical point and also is closely related with shearing direction. The technique is applied for quantitative estimation of defects inside of a pneumatic tire. The actual traveling tire is monitored to reveal the cause of separation and the starting points. And also unknown void defects on tread are inspected and the size and shape of defects are estimated which has good agreement with the result of visual inspection.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.687-694
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• 2018

To investigate the crushing behaviour of coarse granular materials, a specifically designed, large-scale simple shear apparatus with eight-staged shearing rings was developed. A series of monotonic simple shear tests were conducted on two kinds of coarse granular materials under different vertical stresses and large shear strains. The evolution of the particle breakage during the compression and simple shearing processes was investigated. The results show that the amount of particle breakage is related to the particle hardness and the state of the stresses. The amount of particle breakage is greater for softer granular materials and increases with increasing vertical stresses. Particle breakage may tend towards a critical value during both the compression and the shearing processes. Particle breakage mainly occurs during the processes of confined compression and contraction.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.298-303
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• 2003

In recent years, shearogrpahy has significantly improved capabilities in the areas of unbond and separation detection in tires. Although shearography has many advantages for qualitative evaluation, the technique remains the problem of quantitative analysis of inside defects, because shearography needs several effective factors including the amount of shearing, shearing direction and induced load, which exist as barrier for the quantitative analysis of inside defects. Since the factors are highly dependent on inspectors skill and also affect the in-situ workability. The factors were optimized and the size of cracks inside of pipeline and tire has been quantitatively determined.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.122-129
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• 2006

Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.47-52
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• 2007

Punching, blanking, trimming and slitting are widely used in shearing processes in sheet metal forming of automotive parts. In this paper the effects of clearance, cutting angle and tool sharpness on the formation of burr were investigated by experimental method in shearing processes of steel sheets, SPCEN and SPRC35E. The amount of burr and the shapes of burr were different between two kinds of steel sheets. It has been shown that the cutting angle of the shearing blade had no effects on the height of burr when the clearance was below the 10% of the steel sheet thickness, and also that the height and shape of burr were not affected by the cutting angle when the wear of shearing blade was below the 10% of the steel sheet thickness. It was known that there had been existing the critical clearance of 10 to 15% for the tested steel sheet, SPCEN and SPRC35E.

• Transactions of Materials Processing
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• v.23 no.8
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• pp.501-506
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• 2014

Progressive shearing with blanking dies is commonly employed to produce large quantities of tiny sheet metal electronic parts. Sheet metal pins, which are narrow and long, that are sheared with a progressive die set are often twisted. The twist in the sheet metal pins, which usually occurs in the final shearing operation, generally decreases with increasing blank holding force. The blank holding forces in all shearing operations are not the same because of different shearing positions and areas. In the current study, the optimal layout of the springs in a progressive die set to minimize the twist of the sheet metal pin is proposed. In order to find the holding force acting on the tiny narrow blanks produced with the proposed springs during the shearing process, the equivalent area method is used in the structural analysis. The shearing of the sheet-metal pin was simulated to compute the twist angle associated with the blank holding force. The constraint condition satisfying the pre-set blank holding force from the previous shearing operations was imposed. A design of experiments (DOE) was numerically implemented by analyzing the progressive die structure and by simulating the shearing process. From the meta-model created from the experimental results and by using a quadratic response surface method (PQRSM), the optimal layout of the springs was determined. The twist of sheet metal pin associated with the optimal layout of the springs found in the current study was compared with that of an existing progressive die to obtain a minimal amount of twist.

• Design & Manufacturing
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• v.17 no.1
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• pp.13-19
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• 2023

Blanking processing is one of the shear processing method in which the cut part becomes a product and piercing processing is a press molding process in which the cut part is discarded as a scrap. The shear angle of the punch used for blanking is determined by conditions such as the characteristics of the shear material, shear thickness and shear length. The shear angle of a punch is an important factor in determining the size of the shear load, the life of the shear punch, the deformation of the shear product and the quality of burrs In this study, blanking punches applied with four types of shear angles (i.e., 0°, 0°23", 0°46", 0°69") to the blanking punches of bracket products used in practical work were manufactured and tested. In the blanking experiment, the remaining variables except for the shear angle were the same. Experiments show that the product has the least amount of deformation in blanking punches with a shear angle equal to the material thickness, i.e., 0°46"..