• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.11a
• /
• pp.29-29
• /
• 1997

각광 받는 구조재료인 섬유강화 복합적층재에 대한 기계적 체결 거동은 본질적인 재료의 이방성에 의해서 파단강도가 파단 모우드와 매우 밀접한 관련을 갖는 것으로 알려져 있다. 따라서, 복합적층판 체결부의 정밀 구조 설계에서는 단순화에 따른 오차를 줄이고 정밀해에 의한 설계 및 해석이 요청된다. 특히, 층간응력 성분을 무시할 수 없는 두께를 갖는 복합적층 판의 기계적 체결부 해석이나 실제 구조물의 체결부에서 발생하는 굽힘이나 비틀림과 같은 하중 상태를 묘사하기 위해서도 정밀한 3차원 응력 해석은 필요하다. 하지만, 지금까지 기계적 체결부의 거동에 관한 연구는 층간응력 성분들을 어느정도 무시할 수 있는 얇은 평판에 대한 2차원 응력해석에 주로 국한되어 왔으며, 일부 수행된 체결부에 대한 3차원 응력 해석의 경우 여러 단점을 갖는 3차원 연속체 요소에 의한 유한요소 해석이 수행되었을 뿐이다.본 연구는 층간응력 성분들을 무시할 수 없는 두께를 갖는 복합적층판의 기계적 체결부 해석에 지금까지 사용되어온 3차원 연속체 요소에 의한 유한요소 방법이 갖는 단점들을 개선한 Layerwise 유한요소법을 이용하여 3차원 응력해석을 수행하였다. 특히, 선형상보성원리에 근거한 최적설계 기법을 응용하여, 기계적 체결시 핀과 적층판의 홀 사이에 발생하는 하중 전달 과정을 모사하고, 접촉력에 의한 홀 주위의 복잡하고 국부적인 응력 집중현상을 규명하여본다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.9
• /
• pp.49-56
• /
• 2004

With the wide application of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joint have become a very important research area because they are often the weakest areas in composite structures. In this paper, the linear finite element analyses in which the pin of the composite joint was assumed to be the frictionless rigid body were performed and predict the strength of the mechanically fastened composite joint using the failure area index method. By the failure area index method, the strength of the mechanically fastened composite joint which has the specimen of different shape, hole size and stacking sequence could be predicted within 12.2%.

• Composites Research
• /
• v.15 no.4
• /
• pp.9-16
• /
• 2002

With the wide application of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joint have become a very important research area because they are often the weakest areas in composite structures. In this paper, the failure area index method to predict the strength of the mechanically fastened composite joint which has the same stacking sequence was suggested and evaluated. By the suggested failure area index method, the strength of the mechanically fastened composite joint could be predicted within 6.03％.

• Composites Research
• /
• v.18 no.5
• /
• pp.9-14
• /
• 2005

The design of composite joint is a very important research area because they are often the weakest areas in composite structures. In this paper, the failure load of the mechanically fastened composite joint with the clamping force was predicted by the failure area index method. By the suggested failure area index method, the strength of the mechanically fastened composite joint could be predicted within $22.5\%$ when the clamping force was applied to the composite joint.

• Composites Research
• /
• v.21 no.4
• /
• pp.22-28
• /
• 2008

The composite joint has become an important research area because the structural efficiency of a structure with a joint is determined by its joints rather than by its basic structure since the joints are often the weakest areas in composite structures. In this paper, the strengths of adhesive joints consisting of metal and composites were predicted and tested by the maximum strain theory and damage zone theory. Nonlinear finite element analyses of adhesive Joints considering the material nonlinearity of the adhesive layer were performed. From the tests and analyses, the strengths of the adhesive joints could be predicted to within 22.2% using the damage zone ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.1
• /
• pp.21-29
• /
• 2017

In this paper, the total procedure for composite laminate mechanical joint (ASTM D5961 Proc. A, B) from fixture design to test analysis was showed. Composite laminate mechanical joints were analyzed using the FEM(Finite Element Method) and compared to test results. A progressive failure analysis was applied to FEM to analyze the failure behavior of test specimens. Three failure theories - maximum stress, maximum strain, and Tsai-Wu were applied to FEM to predict test failure load. General parameters for composite laminate joints were reviewed and the differences of bearing strength were compared with major parameters.

• Composites Research
• /
• v.27 no.6
• /
• pp.213-218
• /
• 2014

This paper predicted the strength of mechanical joint of composites under bending load by means of the characteristic curve method. The method has been employed only for tensile and compression load conditions, but in this study, this method was extended to the bending load condition. For the finite element analysis (FEA), the nonlinear analysis was conducted considering the contact and friction effects between composite material and pin. The failure strength and mode on characteristic curve were evaluate with Tsai-Wu failure theory. To validate the results of FEA, the experiments were conducted to find out the failure load by applying bending moment on the composite specimens. The results showed reasonable agreements with theoretical results. These results lead to a conclusion that the characteristic curve method can be applied to predict the bending strength of mechanical joint of composites.

• Composites Research
• /
• v.16 no.5
• /
• pp.1-6
• /
• 2003

As the use of composites has become popular in recent years, the design of the composite joints has become a very important research area because the structural efficiency of the composite structure is determined by its joints, not by its basic structures. In this paper, presented comparisons of numerical results by the FAI(Failure area index) method[9] and measured data for a various geometric shapes and stacking sequence justify the validity of the FAI method. The FAI method is shown to produce very favorable comparisons with measured failure loads of mechanically fastened composite joints with the difference well within 9.96% for all II cases investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.3
• /
• pp.194-200
• /
• 2013

In this paper, the results of composite laminate mechanical joints test(ASTM D5961) are compared with the theoretical strength calculations and FEM analysis results. To calculate the S.C.F.(stress concentration factor) on joint strength, equations on metallic and composite materials in ASM Handbook used and compared with experimental results. The difference of joint strength are compared by geometrical parameters and joining types(single/double lap joint). In FEM analysis, to find efficient FEM model on composite laminate mechanical joint, several FEM models are compared with experimental test results.

• Composites Research
• /
• v.30 no.4
• /
• pp.229-234
• /
• 2017

Generally, joints are the weakest part in the composite structures. Composite joints can be classified into adhesive joints and mechanical joints, and mechanical joints are mainly used in areas less sensitive to environmental conditions. In this paper, the failure loads of composite mechanical joints with five different stacking angles are tested and predicted. Finite element analysis of mechanical joints were performed and failure loads were predicted by the FAI(Failure Area Index) method using Tsai-Wu and Yamada-Sun failure criteria, and the predicted failure loads were compared with experimental results. From the experiment and analysis, the failure loads of the mechanical joints were decreased as the ratio of 0 degree layer was low and they could be predicted within 13.03% using the FAI method and Yamada-Sun failure criteria.