Abstract: Aiming at characterizing the load of earthmoving machinery under non-stationary random cyclic conditions for design and tests of its components， a parameterized model was proposed. In order to study the multi-way valve in the hydraulic excavator， the outlet pressure at valve port was decomposed into random term and trend term by wavelet transform. The stationary random term was described by “random term function” using the estimation of power spectral density， and the non-stationary trend term was expressed by “trend term function” using the function to fit with condition-variables. Then the two functions were combined to generate “cyclic condition load function”. Comparisons between simulated and test data prove that this function can accurately reconstruct random character in multi-way valve under non-stationary random cyclic conditions. The results also indicate that the modeling method will be an applicative reference for realizing the parametric expression of non-stationary random load with cyclic features in engineering application.

Key words: cyclic condition load, hydraulic excavator, multi-way valve, overall test, parameterized model