Experimental Assessment of Bolted Single Lap Joint Strength for Laminates in Advanced Composite Materials

This paper presents the bearing strength for laminates in advanced composite materials in bolted joints. Bolted single lap joint tests were experimentally investigated with respect to stabilized and unstabilized lap joints. Stabilized bolted single lap joints refer to joints with out-of-plane rotational constraints. Unstabilized bolted single lap joints refer to joints with absence of out-of-plane deflection constraints. The bearing strength values of laminates in the bolted joint showed that the percentages of ply angle for 0, 45, -45, and 90 degrees were not affected. The bearing strength value in the unstabilized bolted joint was smaller than the bearing strength value in the stabilized bolted joint because of the influence of the out-of-plane behavior. The composite material studied in this paper is a carbon/epoxy unidirectional (UD) tape prepreg cured at $177^{\circ}C(350^{\circ}F)$. In the laminate reference system, the standard angles of 0, 45, -45, and 90 degrees were used for ply orientation within the laminate. A total of 112 bolted single lap joint tests were conducted on specimens from eight distinct laminates. The ASTM-D-5961M standards were adhered to for the stabilized and unstabilized bolted single lap joint tests.

첨단복합재료 적층판의 볼트단일접합 강도 시험적 평가

본 논문에서는 첨단복합재의 볼트단일접합 베어링강도에 대한 시험적 평가 결과를 수록하였다. 볼트단일접합 시험은 stabilized 접합과 unstabilized 접합에 대하여 수행하였다. Stabilized 접합은 접합부 면외회전을 제한하는 접합이다. Unstabilized 접합은 면외변위를 제한하지 않는 접합이다. 볼트 단일접합에서 적층판의 베어링강도 값은 적층판 내 적층각 $0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ 및 $90^{\circ}$ 비율에 영향이 없음을 보여준다. 볼트접합부 면외거동의 영향으로 unstabilized 볼트 단일접합 베어링 강도값이 stabilized 볼트 단일접합 베어링 강도값 보다 작음을 보여주고 있다. 본 논문에 사용된 복합재료는 $177^{\circ}C(350^{\circ}F)$에서 경화되는 Carbon/Epoxy UD Tape 프리프레그이다. 표준각 $0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ 및 $90^{\circ}$ 층으로 적층된 8종류의 적층판에서 총 112개 볼트단일접합 시험시편을 구성하였다. Stabilized 접합과 unstabilized 접합의 시험방법은 ASTM-D-5961M 규정을 사용하였다.