Stress analysis of triangular composite plate containing countersunk bolts and SMA pins

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Stress analysis of triangular composite plate containing countersunk bolts and SMA pins

 

Author: Chan, Kuen-cheong
Title: Stress analysis of triangular composite plate containing countersunk bolts and SMA pins
Degree: Eng.D.
Year: 2008
Subject: Hong Kong Polytechnic University -- Dissertations.
Composite materials -- Testing.
Fibrous composites -- Testing.
Bolts and nuts -- Testing.
Shape memory alloys.
Finite element method.
Department: Dept. of Mechanical Engineering
Pages: xii, 209 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2266112
URI: http://theses.lib.polyu.edu.hk/handle/200/3430
Abstract: Composite materials have been used in civil structure for many years due to their excellent lightweight characteristic and consequent ease of handling. Finite element models have been successfully used to analysis bolted joint in structures, but this takes a considerable amount of time and a high computational cost. The objective of this study is to develop a finite element model for a triangular carbon fibre reinforced composite plate with bolted joints which could be used in construction industry to substitute for steel. The tensile and compressive behaviour of a triangular carbon fibre reinforced composite plate with countersunk bolts was studied. In order to prevent delamination when the carbon fibre composite plate was subjected to the compressive load, SMA pins were inserted around the countersunk hole. The analyses were performed using the three dimensional element in the ANSYS finite element package. Three dimensional and contact elements have been used for simulating the connection between bolt and composite plate. A three dimensional finite element model of the bolted joint has been developed to determine the non-uniform stress distribution through the thickness of the laminate in the vicinity of the hole. The finite element model was developed from rectangular composite strip with holes and then extends to a triangular composite plate with countersunk holes. In additional, a button-shaped SMA was proposed to reinforce the hole to prevent delamiantion when the composite laminate is under compression. In view of the difficulty of inserting of the button-shaped SMA pins in composite laminate, SMA pins with a bifurcated pin head were adopted for reinforcement of the holes in the triangular composite plate. Moreover, countersunk bolts were proposed for the connection of a triangular composite plate to the structure. The study is divided into two parts: First, the carbon fibre reinforced composite strip containing SMA wires or pins is analysed. Second, the countersunk bolted joints are used to connect the triangular carbon fibre reinforced composite plate containing SMA pins is also studied. The results from the numerical study show that stress characteristics of the button-shaped and bifurcated SMA pin models are similar. However, the stresses of the button-shaped pin model are slightly lower than that of the bifurcated pin model. The tensile and compressive stresses, in both the button-shaped and bifurcated pin models, are strongly dependent on the percentage of pre-strain of SMA material. It is also found that the SMA pin method significantly reduced the stress concentration of the composite laminate compared with the SMA wire method, especially in the x-direction.

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