# 광탄성 위상이동법을 이용한 순수굽힘보 시편의 재료 응력 프린지 상수 측정

• Liu, Guan Yong (Dept. of Mechanical Engineering, Graduate College, Kunsan Nat'l Univ.) ;
• Kim, Myung Soo (Dept. of Electronic Engineering, Kunsan Nat'l Univ.) ;
• Baek, Tae Hyun (School of Mechanical and Automotive Engineering, Kunsan Nat'l Univ.)
• 류관용 (군산대학교 대학원 기계공학과) ;
• 김명수 (군산대학교 전자공학과) ;
• 백태현 (군산대학교 기계자동차공학부)
• Accepted : 2014.09.11
• Published : 2014.12.01
• 106 7

#### Abstract

In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant can be obtained using a simple tension specimen and/or a circular disk under diametric compression. In these methods, there is generally a need to apply numerous loads to the specimen in response to the relationship of the fringe order. Then, the least squares method is used to obtain the material constant. In this paper, the fringe orders that appear on a four-point bending specimen are used to determine the fringe constant. This method requires four photoelastic fringes obtained from a circular polariscope by rotating the analyzer to 0, ${\pi}/4$, ${\pi}/2$, and $3{\pi}/4$ radians. Using the four-point bending specimen to determine the material stress fringe constant has an advantage because measurements can be made at different locations by applying a constant load. The stress fringe constant measured with this method is within the range suggested by the manufacturer of the photoelastic material.

#### Keywords

Photoelasticity;Material Fringe Constant;Phase Shifting Method;Isochromatic Fringe;Pure Bending

#### Acknowledgement

Supported by : 한국연구재단

#### References

1. Dally, J. W. and Riley, W. F., 1991, Experimental Stress Analysis, 3rd Ed., McGraw-Hill, Inc., pp. 441-444.
2. Burger, C. P., 1993, "Chapter 5 Photoelasticity in Handbook on Experimental Mechanics," 2nd Ed., Edited by A. S. Kobayashi, Society for Experimental Mechanics, Inc., Bethel, Connecticut, pp. 165-266.
3. Sharples Stress Engineers Ltd. Unit 29, Old Mill Industrial Est., School Lane, Bamber Bridge, Preston, Lancs, U. K. PR5 6SY.
4. Cloud, G. L., 1995, Optical Methods of Engineering Analysis, Cambridge University Press, pp. 57-76.
5. Asundi, A., 1993, "Phase Shifting in Photoelasticity," Experimental Techniques, Vol. 7, No. 1, pp. 19-23.
6. Baek, T. H., Kim, M. S. and Cho, S. H., 2005, "Measurement of Isochromatic Fringe Distribution of a TV Glass Panel by Use of Photoelastic 4-step Phase Shifting Method," Journal of the Korean Society for Nondestructive Testing, Vol. 25, No. 1, pp. pp. 1-8.
7. Baek, T. H. and Lee, J. C., 1994, "Development of Image Processing Technique for Photoelastic Fringe Analysis," Trans. of KSME, Vol. 18, No. 10, pp. 2577-2584.
8. Baek, T. H., 1993, "Development Image Processing Technique for Photoelastic Isochromatic Fringe Sharpening," Journal of the Korean Precision Engineering, Vol. 10, No. 3, pp. 220-230.
9. ANSYS 14, www.ansys.com, ANSYS, Inc.