Energy Separation and Explicit Dynamic Analysis of Low Temperature Impact Toughness of Transmission Tower Material Q420B

To determine the physical significance of the impact toughness parameters and accurately characterize the low temperature impact toughness of transmission tower material Q420 B,the finite element model of Charpy impact test is established on the basis of experiment.The simulation and test results are verified,and the specimen fracture is analyzed by scanning electron microscope.The formation and growth mechanism of the crack are dynamically analyzed.On this basis,energy separation method is used to investigate the effect of low temperature on impact toughness.The results show that the simulation and test results are in good agreement,and the ductile-brittle transition temperature of Q420 B is about-50 ℃.The breaking process of the specimen is divided into the crack formation and propagation.When temperature drops from 20 to-60 ℃,the crack propagation energy decreases from 51.0 to 11.9 J,the crack formation energy reduces from 39.9 to 15.8 J,and the fracture time of the material drops from 1.8 to 0.6 ms.     

基于临空经济视角的航空运输发展策略分析

近年来，中国航空运输业构建了比较系统、完善的航空运输体系，临空经济作为全球民航强国发展区域经济不可或缺的一类途径，受到我国各机场的重视，并且取得了一些成效，但是在具体发展过程中仍旧存在不少问题亟待优化。基于此，本文主要从临空经济视角出发，首先介绍了临空经济的有关概念，并分析我国在该模式下航空运输发展现状和存在的主要问题，最后提出了几点发展策略，以供同行参考。