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A new method for estimating the value of the load factor (the ratio of the additional bolt force to the load) is proposed by introducing the spring constant kpt . The value of kpt is analyzed by using an axisymmetric theory of elasticity. For verification of the proposed method, experiments were carried out to measure the load factor. A fairly good agreement is seen between the analytical and the experimental results. The effects of some factors on the load factor were discussed.

The experiments to loosen bolted joints and joints with double nuts and eccentric nuts were carried out using Junker’s machine and NAS machine. As the results, no loosening was found in the bolted joints with the market-sold eccentric nuts and the conventional nuts in almost all joints were loosened. In addition, in order to know the loosening mechanism, several finite element analyses were performed and reproduced the phenomenon that the bolts were loosened, or the nut rotates, when the repeated transverse loads were applied. Based on this result, the mechanism of the bolt loosening (the nut rotation) is investigated.

This paper dealt with the interface stresses of thin wall box-shaped bolted flanged structures when internal pressure was applied. The flexible flanges were fastened by M8 bolts and nuts with an initial clamping force after being joined with silicone sealant. In the elastic and thermo elastic F.E.A, the effects of bolt pitch distance, bolt positions, flange rigidity and flange thickness were examined. In addition, the effect of the liner thermal expansion coefficient and Young's modulus of the joint in the steady temperature state were also examined. The experimental results were in fairly good agreements with the numerical results. From the results, it was found that the effect of thermal condition is greater than that of internal pressure on the interface stress distributions. In other words, it indicates that thermal conditions are affective on the sealing performance rather than internal pressure application in this case.

Recently, joints combining shrink fit with anaerobic adhesives (bonded shrink fitted joint) have been appeared in order to increase the joint strength. This paper deals with stress analysis and strength estimation of the bonded shrink fitted joints in which the ring is fitted at the end/middle of the hollow shafts subjected to torsion. The stress distributions at the interface of the joints are analyzed using axisymmetric theory of elasticity as a three-body contact problem. The effect of the inner diameter of a shaft, outer diameter, height of and stiffness of the ring on the interface stress distributions are examined in the numerical calculations. It is found that a rupture of adhesive layer initiates from the edge of the interfaces close to the end of the shaft to which a torsional load is applied. The numerical results show more conservative values than the experimental results.

It is important to improve the sealing performance of bolted flanged joints subjected to internal pressure. Recently, bolted joints with flexible flanges of stamped steel have been used in an oil-pan structure of automobile from a lightweight viewpoint. However, it is difficult to improve the sealing performance of flexible bolted flanged joints due to the reduction of the interface pressure. In this paper, a liquid sealant is applied to a box-shaped flexible bolted flanged joints such as oil-pan structures subjected to internal pressure in order to improve the sealing performance. In the experiments, an internal pressure when a leakage occurred was measured in the case where box-shaped bolted flanged joints in which liquid sealant was applied to the interfaces between aluminum flexible flanges (the upper) with thickness of 1 and 3mm and the steel (aluminum) flange with 10mm thickness (the lower) and where the bolt positions are changed.

This paper deals with stress analysis and strength evaluation of bonded shrink fitted joints subjected to torsion. The stress distributions in the adhesive layer of bonded shrink fitted joints are analyzed by using the axisymmetric theory of elasticity when an external torsion is applied to the upper end of shaft. The effect of the outer diameter and the stiffness of rings on the interface stress distributions are clarified by the numerical calculations. Using the interface stress distributions, joint strength is predicted. In addition, joint strength was measured experimentally. It is seen that a rupture of adhesive layer is initiated from the upper edge of the interfaces when a torsion is applied to the upper end of shaft. The numerical result are in fairly good agreement with the experimental results. It is found that the joint strength of bonded shrink fitted joints is greater than that of shrink fitted joints.

Shrink fit has been used commonly for joining the cylindrical components such as shaft and gears. It is noted recently the shrink fitted joint with anaerobic adhesives is adopted in order to improve it's joint strength. In a reliable design of bonded shrink fitted joints, it is necessary to know the contact stress distributions at the interfaces. In this paper, the interface stress distribution of bonded shrink fitted joint under push-off force is analyzed by using axisymmetric theory of elasticity as four-body contact problem. Analogical test is conducted to determine the relationship between the normal stress and the shear stress. Using the interface stress distribution and analogical test results, a method for estimating the joint strength is proposed. In the numerical calculations, the effect of the outer diameter and Young's modulus of the rings and the engagement length on the contact stress distributions at the interfaces are clarified.

It is important to improve the sealing performance of bolted flanged joints subjected to internal pressure. Recently, bolted joints with flexible flanges of stamped steel have been used in an oil-pan structure of automobile from a lightweight viewpoint. However, it is difficult to improve the sealing performance of flexible flanged bolted joints due to the reduction of the interface pressure. In this paper, a liquid sealant is applied to a box-shape flexible flanged bolted joints subjected to internal pressure in order to improve the sealing performance. In the experiments, a leakage is observed when a box-shape flanged joints in which liquid sealants are applied to the interfaces between aluminum flexible flanges with thickness of 1 and 3 mm and the steel (aluminum) flange with 10 mm thickness. Experiments are also conducted on bolted joints with asbestos gaskets. In addition, the effects of the adjacent bolt distance and bolt preload on the sealing performance are examined.