Statistical analysis of cavitation erosion impacts in a vibratory apparatus with copulas

29th IAHR Symposium on Hydraulic Machinery and Systems

Taillon, G.^1 ; Onishi, K.^1 ; Mineshima, T.^1 ; Miyagawa, K.^2

Department of Applied Mechanics, Waseda University, Shinjuku-ku, Tokyo

169-8555, Japan^1

Department of Applied Mechanics and Aerospace Engineering, Waseda University, Shinjuku-ku, Tokyo

169-8555, Japan^2

关键词: Dependence structures;    Exponential family;    Gamma distribution;    Joint distributions;    Kolmogorov-Smirnov test;    Maximum likelihood methods;    Measured parameters;    Pressure amplitudes;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/240/6/062035/pdf
DOI  :  10.1088/1755-1315/240/6/062035

来源: IOP

【 摘 要 】

A method of analysis of cavitation peaks (impact events) using copulas is developed. Impact events, otherwise known as peaks, are defined as maximum in the pressure amplitude applied to a material surface. These impact events were measured using a high speed pressure sensor in a cavitation apparatus based on the ASTM G32 standard. A total of 46180 impacts were measured over 100 realizations of 4ms long recording. First, the impact duration and amplitude's joint marginals are modeled as gamma distribution (part of the exponential family), determined by a Kolmogorov-Smirnov test (KS test). Then, copulas enable the study of the dependence structure of the measured impacts characteristics. The measured parameters are shown to not be independent but instead have a complex, asymmetric dependence structure. There are almost no impacts that have a combination of a high amplitude (>12MPa) and low duration (