Experimental determination of the main load factor of threaded connection of connecting rod head with oblique connector

According to the methodology developed earlier the experimental-calculated investigations of a determination of the stresses in the rod bolts of connecting rods with an oblique connector when the bolt was tightened, and after loading the connecting rod with an external load were conducted. The main point of an investigation’s methodology of the stress-strain state of connecting rod bolts is in that on the outer circumference of the bolt body at some distance from each other strain gauges are glued. The coordinates of the measurement points must be precisely defined in a rectangular coordinate system, and one of the coordinates along the z-axis is taken by the stresses in the cross section of the bolt body. The simplest formulas for calculations have been obtained if the strain gauges are glued along the circumference 120 ° from each other. According to the average value for all three indications of strain gauges determines the tensile stress. As shown by the result of experimental investigations during the tightening process the body of connecting rod experiences tensile and bending stresses. It’s known that when installation shells in the crank head of the connecting rod, their length exceeds the length of the saddle by the protrusion amount. Because of the protrusion of the shell the entire load during tightening the bolts falls on the shell and it is applied eccentrically. However even after a deformation of the shell around the perimeter, the force on bolt is transmitted through the average radius of the thread. When the external force of the connecting rod is applied to the rod bolt only a part of the load is transferred, it’s equal to the product of this force by the coefficient of the main load. After experimental determination the stress in the connecting rod bolts, as well as the force in each of the bolts with the oblique connector, the main load of the connecting rod is determined by the experiment-calculated investigation.