기계구조물 설계시 파손이나 갑작스런 붕괴를 방지하기 위하여 응력집중을 실험적으로 측정해야 할 필요가 있다. 본 연구에서는 중앙에 원형구멍이 있는 외팔보 시편의 응력집중계수를 스트레인 게이지와 광탄성법으로 측정하였다. 스트레인 게이지법에서는 구멍 주위에 3개의 스트레인 게이지를 부착하여 측정된 값으로부터 외삽법을 사용하여 구멍에 인접한 지점에서 최대 변형률을 추정하였다. 광탄성법에서는 두 가지 측정법, 즉 배비넷-솔레일 보상법과 위상이동법을 이용하여 응력분포를 측정하였다. 스트레인 게이지와 광탄성법에 의한 측정값들을 서로 실험오차 이내로 근접하였다.
It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error.
