Research on the dynamic response of connecting rod bearing bush wear of reciprocating machine under variable working conditions

As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the bearing and the abnormal vibration of the body.Based on the characteristics of poor lubrication state and complex force of connecting rod small head bearing, a mixed lubrication model considering oil groove feed was established, and the dynamic simulation of the reciprocating compressor model with lubricated bearings was carried out;considering different speeds and gas load conditions, the law of the impact of the eigenvalues changing with working conditions was explored.The fault simulation experiment was carried out by selecting representative working conditions, which verified the correctness of the simulation method.The study found that two contact collisions between the pin and the bearing bush occurred in one cycle, the collision impact was more severe under the wear fault, and the existence of the gap made the dynamic response more sensitive to the change of working conditions.This research provides ideas for the location and feature extraction of fault symptom signal angular segments in the process of complex measured signal processing.

Research on mechanical wear life feature fusion prediction method based on temporal pattern attention mechanism

In order to solve the problem of low prediction accuracy when only vibration or oil signal is used to predict the remaining life of gear wear,a gear wear life feature fusion prediction method based on temporal pattern attention mechanism is proposed.Firstly,deep residual shrinkage network(DRSN)is used to extract the features of the original vibration time series signals with low signal-tonoise ratio,and the vibration features associated with gear wear evolution are obtained.Secondly,the extracted vibration features and the oil monitoring data that can intuitively reflect the wear process information are jointly input into the bi-directional long short-term memory neural network based on temporal pattern attention mechanism(TPA-BiLSTM),the complex nonlinear relationship between vibration features,oil features and gear wear process evolution is further explored to improve the prediction accuracy.The gear life cycle dynamic response and wear process signals are obtained based on the gear numerical simulation model,and the feasibility of the proposed method is verified.Finally,the proposed method is applied to the residual life prediction of gear on a test bench,and the comparison between different methods proved the validity of the proposed method.

升温速率对Al-Si-Cu合金在热震过程中的表面演变行为及机理影响

为探明铝制活塞在爆燃等非稳态热环境中材料表面初始损伤机制,本研究通过调整加热环境,对经T6热处理的铸造Al-Si-Cu合金进行了从室温到450℃温度区间不同升温速率的热震试验研究。通过热震过程中粗糙度、硬度、形貌、组织、物相以及元素分布等对表面演变行为进行表征。结果显示,随着升温速率的增加,粗糙度和硬度均呈现先增后减的演变规律。微结构和相分析表明,在升温速率增加过程中,固态相变和高温氧化与持续增强的热应力协同作用导致了上述演变行为。

铸造Al-Si-Cu活塞合金在热暴露过程中表面粗糙度的演变

将T6热处理后的Al-Si-Cu活塞合金在400~550°C不同温度的电阻炉中热暴露2 h,借助表面粗糙度仪;金相和扫描电镜以及XRD等分析手段研究了合金在热暴露过程中表面粗糙度和微观组织结构的演变规律。实验结果表明:合金的表面粗糙度和质量随着热暴露温度的升高而增加,当热暴露温度低于500°C时,增长速率较慢;当热暴露温度高于500°C时,增长速率急剧升高。合金表面粗糙度的演变与热暴露过程中合金的相变和氧化密切相关。

Tribological performance and scuffing behaviors of several automobile piston rings mating with chrome-plated cylinder liner

The friction and wear properties,as well as the scuffing resistance,of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated.Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating(GDC)and diamond-like coating(DLC).The results indicated that the DLC coating had outstanding tribological properties(small coefficient of friction and wear loss)at 150°C,while the GDC coating exhibited better performance at an elevated temperature(240°C).The DLC coating had a better scuffing resistance;no material adhesion occurred for 70 min under the unlubricated condition.The interrupted wear behaviors revealed that the scuffing process of the GDC coating involved the consumption of lubricant oil with relatively stable wear,a reduction in the friction force,and the occurrence of scuffing,in sequence.In contrast,although the friction force also increased after a short period of weak friction,no scuffing was observed.This is attributed to the formation of a mixed oxide and graphitic C tribolayer.