Stress relaxation in radial interference-fit bolted-type connections
In modern airplanes design, radial interference-fit bolted-type connections are widely used as an effective means of increasing life of an airframe. Due to the assembly in the vicinity of the hole of the connected elements, i.e. package, of aluminum alloys, a stress field is formed, stresses exceeding the yield strength of the material. For such materials, at stresses close to the yield strength even at a temperature of 20±3 °C, creep strains arise, which after a few hundred hours reach values that commensurate with elastic strains. As a result of this, a noticeable decrease in stresses in the connection occurs. Within the research, we studied the effect of the creep process on the redistribution of stresses in the aluminum alloy package after a steel bolt was pressed into it. We used one of the technical creep theories — flow theory. A single-row bolted-type connection with various values of the nominal radial interference was considered. The calculations were performed numerically by the finite element method using the ANSYS Academic application package. Graphs of changes in the main stresses over time (up to 2400 hours), as well as the dependences of equivalent stresses and contact pressure on the nominal interference (up to 1.2%) are given.
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