超长聚合物基复合材料油管力学性能的有限元计算

随着新疆塔里木油田钻井深度的不断攀升,其地壳内部岩浆的化学成分更加复杂,采油油管的长度要求也不断提高,因此对油管的耐腐蚀性能和力学性能提出了越来越高的要求。传统的金属油管由于强度不足,耐腐蚀性能差而无法满足深井采油的需求。非金属聚合物基复合材料油管因具有可调节的力学性能及高的耐磨抗蚀性能而逐渐获得青睐。另外,井深的提高迫切需要超长的聚合物基复合材料油管,然而其力学性能却很难从实验上进行测量。因此采用有限元模拟计算开展油管力学性能的优化计算与预测具有十分重要意义。本文针对10,000米超长非金属聚合物基复合材料油管,采用一维线性单元技术Pipe288,开展油管力学性能的优化与计算,实现了10,000米超长非金属聚合物基复合材料油管力学性能的计算。本文首先根据多尺度协同增强复合材料油管的结构特点,建立了一维线性单元的力学模型,利用ANSYS软件,基于Pipe288单元,建立了10,000米超长非金属聚合物基复合材料油管的有限元模型,分析了油管在不同的工况下的应力、应变和变形的分布规律,探讨了油管的力学性能和可靠性的影响因素,验证了本文的模型和方法的准确性和有效性。

Development and test of hydraulic driven remote transporter

To solve the problems of the traditional orchard conveyor,such as inflexible steering,a complex structure,poor stability and no power grid coverage,a remote-controlled rail conveyor powered by hydraulic pressure for mountainous orchards was designed and manufactured.Climbing stress analysis was carried out on a full-load trailer to obtain the maximum traction force,which met the requirement of the climbing slope of the transport mechanism.The key components of the conveyor were developed,such as the hydraulic transmission,the control system,safety protection devices,limiting devices,the throttle and decompression actuator,the counterweight tension and the battery.Through the theoretical calculations of key components,an orchard conveyor powered by diesel and hydraulic pressure was designed.Finally,the working performance of the transporter was tested through functionality,driving speed,system pressure and remote-controlled tests.The test results showed that the climbing angle of the transporter can reach 50°,the uphill load can reach 840 kg,the downhill load can reach 1100 kg,and the average running speed is 0.77 m/s;the driving speed ranges from 0.29 m/s to 1.08 m/s,and the system pressure ranges from 3.2 MPa to 10 MPa.The driving speed and system pressure are significantly affected by the load,and the remote control distance can reach 455 m.The technical specifications of the transporter meet all the design requirements,and the problem of stable operation of the transporter without power grid coverage has been addressed.The research results can well meet the practical application requirements of mountain orchard transportation without power grid coverage and provide theoretical reference for the design of key components of mountain orchard transportation machinery.

Optimized design of the power consumption test of mountain orchard transporters

In order to study the influence rule of various factors on the operating power consumption of the traction orchard transporter and realize the optimal design of the operation power consumption of the transporter,according to the traditional experience and the existing research foundation,the monorail transporter test bench was designed and built on the basis of the whole structure and operation characteristics of the transporter.Taking the motor frequency,track gradient and load as the investigation factors,and the driving shaft power,shaft power transmission and mechanical efficiency as the evaluation indices,the orthogonal test was conducted,and the range analysis of the influence effect was carried out according to the test results.The primary and secondary orders of the influence of various factors were obtained that motor frequency was greater than track gradient and track gradient was greater than load.According to the orthogonal test results,the second-order response surface method was used to establish the optimization model of the power consumption of the transporter,and the model was verified on the test bench.The results showed that the relative error between the model optimization value and the test value based on the response surface power optimization model was less than 10%,which indicated that the power optimization model had satisfactory performance.The research can provide a reference for the orchard conveyor to choose the parameter combination which can save power consumption and the motor that matches power consumption.

Pre‑rainy Season Rainstorms in South China—Risk Perception of the 11 April 2019 Rainstorm in Shenzhen City

With the acceleration of urbanization in South China, rainstorms and floods are threatening the safety of people in urban areas. The 11 April 2019(4·11 hereafter)rainstorm in Shenzhen City was a typical pre-rainy season rainstorm that caused great damage, yet such pre-rainy season events have not attracted sufficient attention in research.Risk perception of the public may indirectly affect their disaster preparedness, which is important for disaster management. In this study, we conducted a questionnaire survey that considered demographic factors and the level of risk perception, knowledge of risk, impact of the 4·11 rainstorm event on public risk perception, and degree of trust in the government. We used a two-factor model of risk perception to evaluate the factors that influenced public risk perception of the 4·11 rainstorm in Shenzhen. The main conclusions are: The 4·11 rainstorm improved public awareness of both risk and impact through the medium term, but the public’s perceived low probability of disaster occurrence and lack of knowledge of the pre-rainy season rainstorm phenomenon led to serious losses during this event. Although the public has high trust in the Shenzhen government, the management of rainstorm disasters in the pre-rainy season needs to be further improved.