Method for determining the wear curve of the crankshaft of the internal combustion engine

Determination of the beginning of the abrasive wear section, the wear curve of machine parts, is an urgent task in the resource diagnostics of the facility, since it is in this «most unreliable» area of operation that the permissible and limiting values of the monitored resource parameter are located, characterizing the serviceability and/or operability of the monitored object. The article presents a method for determining the beginning of the abrasive wear section of the crankshaft wear curve. It is known that its operating periods consist of a running-in stage, a normal operation stage and an abrasive wear stage. To determine the beginning of the abrasive wear curve of the crankshaft parts, to obtain the entire graph of the crankshaft wear curve of the internal combustion engine. Calculate the 1st and 2nd derivatives of this wear curve. Then, knowing this wear curve and its derivatives, we can obtain the functional dependencies of the wear of the machine part, in our case, the wear of the crankshaft, depending on its operating time, namely, the beginning of the section of its abrasive wear. In order to obtain wear, it is necessary –rst of all to construct the wear curve of the tested part. For this purpose, special functions of the MathCad 15.0 programming language were used. These were the regress function (t, y, k), the interp function (s, t. y, t), and the Heaviside function.In the diagnosis, the custom function d/dt was used. Then, knowing the wear curve of the part, and its first and second derivatives, you can determine the beginning of the abrasion section of this part. The constructed resulting wear curve z(t) is obtained as the sum of all the stages of operation — and the running-in of the shaft z1(t), and the stage of its normal operation z2(t), and the stage of its abrasive wear z3(t). The 1st and 1st derivatives of this resulting crankshaft wear curve are obtained, on which all stages of operation of the diagnostic machine are clearly visible. A method has been developed for determining the beginning of the abrasive wear section, the wear curve of the crankshaft of the internal combustion engine, equal to 8 thousand engine hours.