Research Of Influence Factors On The Strength Of Single Bolt Joint Of Composite Laminate And Metal Plate

Composite material is an ideal material for light and efficient structure design because of its high strength to density ratio and corrosion resistance.The single bolt single lap joint and single bolt double lap joint of composite laminate and metal plate are studied.The influence of different modeling methods on the finite element model of the structure is analyzed.The influence of various factors on the joint strength is discussed.Static strength loading tests of single bolt and single lap M6 joint of T300-3K/ 0164 composite laminate and metal plate are completed.Three dimensional finite element model of the joint assembly is built.The effects of different bolt modeling methods,different preload methods and different failure criteria on the finite element analysis results are discussed.The tensile strength error of the modified analysis model is 3.10%,which is fit well with experiment results.Static loading strength tests of single bolt and single lap joint of composite laminate and metal plate with different bolt diameters are completed.Three dimensional finite element models of the joint assembly with different bolt diameters are built.The analysis results of tensile strength fit well with experiment results.For the joint assemblies of M4-M8,appropriate tightening torques can increase the strength of the joints by 0.91% to 14.43%.And the critical load for delamination failure under compression can be improved as well.The area of failed matrix decreases with the increase of friction coefficient between the composite laminates and metal plate.The tensile strength of M6 joint increases by 1.95% with friction coefficient of 0.25.The increase of spacer diameter leads to decrease of laminate damage caused by tightening torque and bending effect.The tensile strength of M6 joint increases by 2.85% with the spacer diameter increasing from 8mm to 14 mm.The percentage improvement of 0° laminates leads to significant increase of the joint strength.The strength of M6 joint assembly increases by 129.89% with the percentage improvement of 0° laminates from 25% up to 75%.The surface laminate is usually damaged by the bending effect and tightening torque.It is recommended to apply the 45° laminate on the surface to protect the 0° laminates,which improves the joint strength by 8.69% with 0° laminates percentage of 50%.Static loading strength tests of single bolt and double lap joint of composite laminate and metal plate are completed.Finite element model of the joint assembly is built.The effects of different bolt modeling methods and different preload methods on the finite element analysis results are discussed.The results of different analysis models fit well with those of experiments.The errors of joint strength are about 5.43%-6.19%,and 5.43%-6.19% for tensile deformation.Appropriate tightening torques can increase the joint strength.The strength of M5 joint assembly increases by 1.30% with the increase of tightening torque from 2Nm up to 10 Nm.The tensile deformation and failed area of fiber compression damage and tensile delamination decrease with the increase of tightening torque.