A Study on Dynamic Response and Diagnosis Method of the Wear on Connecting Rod Bush
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TECHNICAL ARTICLE—PEER-REVIEWED
A Study on Dynamic Response and Diagnosis Method of the Wear on Connecting Rod Bush Zhinong Jiang . Zhiwei Mao . Yidan Zhang . Jinjie Zhang
Submitted: 11 January 2017 / in revised form: 2 June 2017 Ó ASM International 2017
Abstract Wear is a typical failure form for mechanical parts of a reciprocating compressor. The clearance of a connecting rod bearing will exceed the normal value due to the wear caused by poor lubrication or abnormal loads. Wear on the small-end bush of a connecting rod (SEBCR) in a reciprocating compressor is still a hard work to be monitored and diagnosed. In this paper, we focus on the study of the dynamic response and diagnosis method on wear fault of SEBCR based on the dynamic simulation and vibration signal analysis. A rigid-flexible coupling model of a connecting rod has been built, and the connecting rod is treated as a flexible body. The clearance between the crosshead pin and the small-end bush of a connecting rod is taken into account. The simulation results show that abnormal clearance will affect the dynamic characteristic significantly, and high acceleration impacts will occur at the reversal points of the crosshead pin. Based on the dynamic response and signal feature extraction, a new diagnosis method calculating the amplitude and change rate of average vibration energy per crank angle to detect the wear fault is proposed. The experiment results on a reciprocating compressor show that the vibration of the compressor crosshead is consistent with numerical simulation results, and the method is capable of detecting the wear fault in real time. Research presented in this paper is significant in providing tools for diagnosing wear fault of reciprocating compressors.
Z. Jiang Z. Mao Y. Zhang J. Zhang (&) Diagnosis and Self-Recovering Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China e-mail: [email protected]
Keywords Reciprocating compressor Connecting rod Dynamic characteristic Feature extraction Wear fault List of symbols c Radial clearance Rb Radius of bearing Rj Radius of neck journal e Deviation degree of center e Eccentricity Fn Normal contact force K Contact stiffness d Damping coefficient d Depth of relative penetration Relative impact velocity d_ vc Cylinder volume xp Displacement of piston Ti The absolute temperature of the gas in cylinder c The polytropic index of the air gas m_ vi Mass flow rates in the suction process Cdz The variable coefficient qc Density of the air in cylinder L The number of samples in one crank angle Dei Change rate of average vibration energy per crank angle rb, rj Material properties vz Poisson’s coefficient Ez Young’s modulus Ff Friction force fmax Maximum friction forces l(v) Friction coefficient ls Static friction coefficient ld Dynamic friction coefficient v s, v d Threshold velocities pc Gas pressure
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J Fail. Anal. and Preven.
sc Tc pi m_ vd bz Afz si ei LD, LB
Piston cross-sectional area Temperature Absolute pressure of the gas in cylinder Mas
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