CN-121996877-A - Bolt pretightening force calculation method based on porosity

CN121996877ACN 121996877 ACN121996877 ACN 121996877ACN-121996877-A

Abstract

The invention discloses a bolt pretightening force calculation method based on porosity, which is characterized in that a relation formula between contact resistance and bolt pretightening force is established based on porosity, contact resistance can be measured by arranging electrodes at two ends of an interface, and pretightening force of a bolt is calculated by combining easily obtained same batch of material parameters.

Inventors

TA WURUI
ZHANG WANGLONG
ZHANG HAIYANG

Assignees

兰州大学

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (2)

1. The method for calculating the bolt pretightening force based on the porosity is characterized by comprising the following steps of: S1, measuring or calculating the contact resistance of the bolt and the connecting piece through an instrument on the contact interface of the bolt Minimum effective contact area radius of bolt and connector Maximum value of effective contact area radius of bolt and connecting piece Initial porosity of the interface of the connection when not pressed Initial interfacial layer thickness when the connector interface is not under compression Initial void ratio of interface layer of connector Characteristic pressure of porosity Compression modulus of connector material Conductivity of connector material ; S2, substituting the parameters obtained in the step S1 into a bolt pretightening force calculation model to calculate the bolt pretightening force, wherein the bolt pretightening force calculation model is as follows: ; in the formula, For the pre-tightening force of the bolts, To contact the interface layer thickness after the interface is pressed, For the equivalent conductivity to be the same, In order for the real contact area to be a real contact area, In the event of an interface pressure, The coefficient is taken as follows: , For nominal contact area by The calculation results show that, in the formula, And the effective contact area radius is obtained by measurement according to the contact resistance measuring point position.
2. The porosity-based bolt pretension calculation method according to claim 1, wherein the contact resistance is measured by measuring And effective contact area radius The calculated bolt pretightening force Is a contact resistance Bolt pretightening force at measuring point, when measuring whole bolt pretightening force, contact resistance of bolt and connecting piece The method is calculated by a numerical integration method, and comprises the following steps: S21, calculating total conductance at the contact interface of the bolt and the connecting piece: In which, in the process, For total conductance at the contact interface of the bolt and the connector, For porosity after the interface of the connection is pressed, it is calculated by the following formula: ; S22, cause Thereby calculating the integrated function of the total conductance in step S21 as: ; S23, calculating total conductance by adopting a trapezoidal method, wherein the total conductance is as follows: Wherein N is the total division layer number of the integration domain, i is the layer number, The radius of the effective contact area is divided into the radius of the ith layer after N layers on average, The radius of the (i+1) th layer after dividing the radius of the effective contact area into N layers on average, The radius of the effective contact area is divided into N layers on average, and then the radius interval between adjacent layers is divided, that is, ; S24, calculating the contact resistance by the following formula: 。

Description

Bolt pretightening force calculation method based on porosity Technical Field The invention belongs to the technical field of structural part connection, and particularly relates to a bolt pretightening force calculation method based on porosity. Background The bolts are matched with nuts through threads to firmly connect a plurality of parts into a whole, so that structural stability and safety are ensured, in equipment such as valves, pipelines and the like, the bolts compress the sealing surfaces through pretightening force to prevent medium leakage, which is a key factor for ensuring the tightness of the system, and the bolts also need to bear various loads such as internal pressure, vibration, temperature change and the like, so that long-term stable operation of the equipment is ensured. The current mainstream bolt pretightening force calculation and detection method comprises a method for measuring stress by adopting a resistance strain gauge, and mainly comprises two measuring modes of a measuring bolt and an annular gasket at present, wherein the measuring bolt is a sensor for directly replacing the existing bolt and directly measuring the pretightening force of the bolt, so that the pretightening force of the bolt can be accurately measured, and the pretightening force can be accurately measured to kilogram, but the methods all need to replace the bolt, and the measurement is complicated. Disclosure of Invention The invention aims to provide a bolt pretightening force calculating method based on porosity so as to solve the problems of the background technology. In order to achieve the purpose, the invention provides a bolt pretightening force calculation method based on porosity, which is characterized by comprising the following steps: S1, measuring the contact resistance of the bolt and the connecting piece by an instrument on the contact interface of the bolt to obtain the following parameters Minimum effective contact area radius of bolt and connectorMaximum value of effective contact area radius of bolt and connecting pieceInitial porosity of the interface of the connection when not pressedInitial interfacial layer thickness when the connector interface is not under compressionInitial void ratio of interface layer of connectorCharacteristic pressure of porosityCompression modulus of connector materialConductivity of connector material; S2, substituting the parameters obtained in the step S1 into a bolt pretightening force calculation model to calculate the bolt pretightening force, wherein the bolt pretightening force calculation model is as follows: ; in the formula, For the pre-tightening force of the bolts,To contact the interface layer thickness after the interface is pressed,For the equivalent conductivity to be the same,In order for the real contact area to be a real contact area,In the event of an interface pressure,The coefficient is taken as follows:, For nominal contact area by The calculation results show that, in the formula,And the effective contact area radius is obtained by measurement according to the contact resistance measuring point position. Further, by measuring contact resistanceAnd the bolt pretightening force obtained by calculating the radius of the effective contact areaIs a contact resistanceBolt pretightening force at measuring point, when the pretightening force of the whole bolt is required to be measured, contact resistance between the bolt and the connecting pieceThe method is calculated by a numerical integration method, and comprises the following steps: S21, calculating total conductance at the contact interface of the bolt and the connecting piece: In which, in the process, For total conductance at the contact interface of the bolt and the connector,Porosity after being pressed for the interface of the connecting piece; S22, cause Thereby calculating the integrated function of the total conductance in step S21 as: ; S23, calculating total conductance by adopting a trapezoidal method, wherein the total conductance is as follows: Wherein N is the total division layer number of the integration domain, i is the layer number, The radius of the effective contact area is divided into the radius of the ith layer after N layers on average,The radius of the (i+1) th layer after dividing the radius of the effective contact area into N layers on average,The radius of the effective contact area is divided into N layers on average, and then the radius interval between adjacent layers is divided, that is,; S24, calculating the contact resistance by the following formula:。 Compared with the prior art, the invention has the beneficial effects that: According to the method, a relation formula between the contact resistance and the bolt pretightening force is established based on the porosity, and the contact resistance can be measured by arranging the electrodes at the two ends of the interface, so that the pretightening force of the bolt is calculated, compared with the ex