内部爆炸加载条件下圆柱钢壳的动态断裂

在内部爆炸冲击波载荷作用下,爆炸容器的动态断裂是进行爆炸容器安全评估和失效分析的基础。为了研究爆炸容器的动态断裂特征,进行圆柱钢壳在中心装药的爆炸加载实验,采用非线性动力有限元分析程序LS-DYNA分析圆柱钢壳的弹塑性动力响应,研究圆柱钢壳的宏观变形和断口的宏观、细观形貌,分析圆柱钢壳的断裂模式及断裂机理。结果表明,圆柱钢壳纵向断口具有微孔聚集型剪切韧窝断裂特征,呈现出微孔聚集型剪切韧性断裂模式。内部爆炸冲击波加载下圆柱钢壳因径向膨胀发生动态塑性变形,产生剪切带,由于剪切带的软化效应而成为优先断裂通道,剪切带和环向拉应力的共同作用是形成微孔聚集型剪切韧窝断裂这种混合韧性断裂模式的原因。     

电铁牵引负荷对电网运行造成的影响及其解决措施

阐述电铁牵引供电系统的原理,分析电铁牵引负荷的特点,研究电铁负荷对电力系统运行的影响及对设备的危害,并从技术上和管理上提出解决措施。     

Beurteilungskriterien für sicherheitstechnische Prüfungen

Methods are presented which enable one to assess and compare the hazard potentials of different technical installations without the necessity of a detailed technical plant analysis. The basis is the energy content of the installation. In the case that energies with different impact mechanisms, e.g., pressure and heat, are to be compared, the probit method is used. In addition, the expected frequency of occurrence is included in the assessment. This is an approach which is already used in neighboring countries. It is foreseeable that it will gain importance in Germany as well. In the case of elevators the predator‐prey model is used to analyze the time series of accidents. The influence of errors in inspection and maintenance is put into evidence by comparison with the SIL classification.     

人工神经网络在钢筋混凝土试验研究中的应用

本文用人工神经网络方法研究钢筋混凝土双向偏心受压构件的强度计算，采用ＢＰ算法，建立了一个四层网络，探讨了单元设置，学习率、指数衰减系数选取的具体方法。     

直立锁缝屋面系统风致破坏全过程研究

直立锁缝屋面系统广泛应用于厂房、车站、体育场馆等大型建筑中,但由于自重轻、柔性大,在强风作用下很容易发生局部损伤及整体破坏,探讨这类屋面系统的风致破坏模式和失效机理,以便提出有效的抗风措施很有必要.本文进行了足尺试验并结合精细有限元方法,对直立锁缝屋面系统在风荷载作用下的变形发展,直到局部屈曲,再到最终破坏的全过程进行...     

单层网壳结构在简单荷载下动力稳定分析

根据网壳结构的动力稳定判别准则，采用精确的空间梁单元切线刚度矩形式及大转角理论，通过二个典型算例，分别考查在突加阶跃荷载，简谐荷载及三角形脉冲荷载作用下，单层网壳结构的动力稳定性能，并得到了一些主要结论。     

Composite Repair in Wind Turbine Blades: An Overview

Renewable energy sources such as wind energy—together with energy-efficient technologies—are essential to meet global energy demands and address climate change. Fiber-reinforced polymer composites, with their superior structural properties (e.g., high stiffness-to-weight) that allow lightweight and robust designs, play a significant part in the design and manufacture of modern wind turbines, especially turbine blades, for demanding service conditions. However, with the current global growth in onshore/offshore wind farm installations (with total global capacity of ～282 GW by the end of 2012) and trend in wind turbine design (～7–8 MW turbine capacity with ～70–80 m blade length for offshore installations), one of the challenges that the wind energy industry faces with composite turbine blades is the aspect of structural maintenance and repair. Although wind turbines are typically designed for a service life of about 20 years, robust structural maintenance and repair procedures are essential to ensure the structural integrity of wind turbines and prevent catastrophic failures. Wind blades are damaged due to demanding mechanical loads (e.g., static and fatigue), environmental conditions (e.g., temperature and humidity) and also manufacturing defects. If material damage is not extensive, structural repair is the only viable option to restore strength since replacing the entire blade is not cost-effective, especially for larger blades. Composite repairs (e.g., external and scarf patches) can be used to restore damaged laminate/sandwich regions in wind blades. With composite materials in the spar (～30–80 mm thick glass/carbon fiber laminates) and aerodynamic shells (sandwich sections with thin glass fiber skins and thick foam/wood as core), it is important to have reliable and cost-effective structural repair procedures to restore damaged wind blades. However, compared to aerospace bonded repairs, structural repair procedures in wind blades are not as well developed and thus face several challenges. In this regard, the area of composite repair in wind blades is broadly reviewed to provide an overview as well as identify associated challenges.     

导管架式采油平台的确定性波浪响应分析

文章介绍了用SACS软件进行导管架平台确定性波浪动力响应的分析方法和分析步骤,并对比波浪动力响应荷载和波浪静力荷载对平台产生的基底剪力,计算出波浪动力响应的放大系数．以期为百米水深左右导管架平台的设计提供简化计算的思路和概念上的认识。     

正交实验法薄壁压杆截面稳定性的优化

针对薄壁结构在工程中失稳破坏的问题,采用ANSYS软件对薄壁压杆双重非线性稳定进行分析,以薄壁压杆工字形截面尺寸为稳定极限载荷的影响因子,通过正交实验方法设计实验,得到了各个因子影响的显著性。翼缘宽度对稳定极限载荷的影响最大,翼缘厚度次之。最后依据多元线性回归原理建立了薄壁压杆稳定数学模型并对截面进行了优化设计,稳定极限载荷提高了30％。     

对地方电网小水电自励磁判断方法的探讨

结合理论研究和仿真分析,探讨地方电网内小水电自励磁判断方法的合理性。研究发电机甩负荷机电过程对自励磁的影响,发现发电机减速释放功率可能导致系统产生极大的暂态自励磁过电压;研究地方电网内有功负荷对发电机自励磁判据的影响,发现地方电网有功负荷的存在将降低等值串联容抗 ,使系统更容易满足自励磁条件。最后通过一个仿真实例对提出的观点进行佐证。本研究对含有小电厂的地方电网自励磁的准确判断具有参考借鉴意义。