Improved Estimation Method of Component Stiffness for Bolted Joint With Different Elastic Moduli

Abstract This study proposes an improved estimation method of component stiffness for bolted joint with different elastic moduli. Component stiffness can be calculated based on the assumption that the compressive stress field forms a cone with an apex angle γ from a component surface under a bolt head. The component stiffness with different elastic moduli were evaluated, and the elastic modulus ratios of a bolt to components Eb/E1 and Eb/E2 were newly incorporated into equation for calculating the tanγ. The equation of tan γ was investigated changing the combination of materials for bolts and the bolted components using three types of materials of aluminum alloy, titanium alloy and steel. The thickness ratio to outer diameter of bolt head, (t1+t2)/dw, was examined in the range of 0.63 to 5.05. The thickness correction term was also investigated under a thickness ratio range (t1/t2) from 0.14 to 1.0. This study assumed actual displacement and pressure distribution of the component surface under the bolt head to calculate the stiffness more accurately. The component stiffness with the proposed equation of tanγ had an error range of −7.5% to +9.8% compared to the 2D axisymmetric finite element analysis results under a wide range of elastic moduli and thickness ratio conditions.