Experimental method for characterizing relaxation characteristics of bolted joint structure

Abstract

The present invention discloses an experimental method for characterizing relaxation characteristics of a bolted joint structure. The method comprises: constructing a finite element model of a singlebolted joint test piece based on the obtained three-dimensional rough shape of the contact surface of the bolted joint structure; performing static strength analysis on the single bolted jointed testpiece by using ANSYS software, and drawing the deformation curve of the single bolted jointed test piece under load conditions; making a single bolted joint axial test piece and a tangential test piece to analyze the influence law of the axial external load and the outward shear load on the relaxation characteristics of the bolted joint structure; establishing an experiment platform, and through the cyclic load control software, applying a cyclic load with a certain frequency on the single-bolt test piece clamped on the fatigue testing machine; performing the modal test on the single bolted joint test piece by using the LMS vibration system at the same time interval; and extracting a clamp force signal output by a pressure sensor and a stiffness signal in the modal test, and fitting the curve for the clamp force signal and the stiffness signal for comparison. The method disclosed by the present invention provides technical support for the relaxation determination and refastening of thejoint bolts of the key precise complicated components.

Description

technical field [0001] The invention relates to an experimental method for characterizing the relaxation characteristics of a bolt connection structure, which belongs to the technical field of threaded fastener design and intelligent assembly of key precision and complex components in industries such as aerospace, rail transit, and equipment manufacturing. Background technique [0002] Bolt fasteners are widely used in mechanical / civil engineering fields such as aerospace, rail transit, ships, equipment manufacturing, bridges, and construction due to their advantages of strong versatility, convenient assembly and disassembly, and high stability under dynamic loads. Compared with riveting, welding and bonding, its connection structure is often accompanied by self-relaxation phenomenon in vibration, alternating load, impact or high temperature environment, resulting in the decline of assembly quality and processing accuracy of key precision and complex components or equipment m...

AI Technical Summary

Problems solved by technology

Among them, the relaxation mechanism of the bolted connection structure mostly uses the clamping force of the connecting bolt (such as document CN 103630282 A) as a characterization parameter to describe its relaxation characteristics, which changes the original structure of the bolted connection, and the obtained relaxation characteristic curve does not have universal applicability

In addition, there are deficiencies in the existing methods of anti-loosening of connecting bolts at home and abroad, such as frictional anti-loosening (setting spring washers, double nuts, lock washers, fastening nuts, nylon inserts, and chemical glue, etc.) under heavy loads and severe vibrations. Or the reliability is unstable under harsh environmental conditions; mechanical anti-loosening (slotted nuts, cotter pins, stop washers and steel wire series connections, etc.) are limited by the connection structure, making reusability poor; Anti-loosening and spring-type anti-loosening, etc.) have not been widely used in the engineering field due to the complicated manufacturing process and high cost.

The above-mentioned anti-loosening methods are mostly related to the pre-tightening force. When the tightening torque is increased, the probability of breaking and damage to the main body may increase, and the implementation of the anti-loosening method increases the workload and cannot fundamentally solve the problem of the bolt connection structure. slack problem

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