焦炭塔鼓胀变形分析与安全评定

对发生明显鼓胀变形的焦炭塔进行了表面检查、筒壁厚度测量、X-射线检测(RT)、渗透检测(PT)、硬度测定、机械性能测试、化学成分分析、金相分析。并按照GB150—89《钢制压力容器》国家标准中有关低中压薄壁容器的规定,对其筒壁厚度、筒壁应力、许用操作压力进行了校核。检测和分析结果表明,筒体的最大鼓胀量已达到260 mm;材质显微组织发生了中度球化,其球化级别为4级。但在筒壁厚度、筒壁应力、以及最大允许操作压力方面都有很大的安全裕度。该焦炭塔完全可以在严格遵守规定的操作条件下,监控使用一个检修周期(即3 a)。     

Effects of surface deformation and crack closure on fatigue crack propagation after overloading and underloading

In the case of a negative baseline stress ratio, the fatigue crack growth rate can actually accelerate after a tensile overload. This crack propagation behavior is related to the local bulging of the specimen in the thickness direction during compression and the resultant tensile residual stress distribution at the crack tip. In the present investigation, the effects of a single tensile overload as well as the effects of a tensile overload followed immediately by a compressive underload on subsequent fatigue crack growth were investigated. The extent of crack opening displacement influences the magnitude of residual stress as well as the crack-tip opening level, and consequently, the subsequent rate of fatigue crack propagation.     

等边双圆锥台壳体内环约束胀形的实验研究

针对等边双圆锥台壳体在自由胀形过程中,赤道环焊缝处由于纬向压应力而产生失稳起皱现象,提出在壳体内加圆环的约束胀形工艺,实验证明了壳体内侧加约束圆环后成形过程中没有起皱现象发生。     

影响板料胀形性能的参数的研究

本文利用有限元数值模拟方法对影响板料胀形性能的参数进行了研究,并得出了各参数对板料胀形性能影响程度的规律。     

Experimental and numerical study on formability in tube bulging: A comparison between hydroforming and rubber pad forming

Flexible-die forming methods such as hydroforming (HF) and rubber pad forming (RPF) allow producing a variety of complex tubular components that are difficult to fabricate by means of conventional forming. In this paper, firstly, in the bulging of a tube with oil pressure using numerical approach, weld-seam was modeled as a mechanical defect and non-homogeneity factor was calibrated by experimental observations and Vickers micro-hardness testing. Forming limit diagram (FLD), as well as effective plastic displacement factor, was utilized to estimate the initiation and evolution of damage, respectively. Then, with the aim of achieving a defect-free part in RPF process, the effect of lubricating conditions was experimentally and numerically examined. The sound parts were obtained using nylon and drawing oil, respectively, at the tube/rubber and the tube/die interaction surfaces. The results represented that by utilizing the accurate non-homogeneity factor, the numerical method can closely predict the damage in both processes. Also, it was indicated that due to friction in RPF versus HF, the tube was pushed into the bulged zone and the strain path tended to the left side of FLD; therefore, the formability of tube was meaningfully improved.     

方舱复合叠层板高温力学性能研究

对由双层3A21-H24δ1.5mm铝合金板与硬质聚氨酯泡沫通过高强度粘接剂粘接制成的方舱复合叠层板进行了日照试验条件下高温力学性能研究.采用有限元计算和应力应变测试进行了分析,结果显示,复合叠层板在96±8℃温度应力作用下,泡沫上方铝蒙皮的应力大约在l10MPa以下,而且该处应力大于骨架上蒙皮的应力,泡沫的尺寸大小对...     

南京龙脖子段包山式城墙鼓胀的数值分析

南京明城墙作为世界上目前残存规模最大的古城墙，其文物保护价值不言而喻。鼓胀作为一种常见损伤类型对城墙的危害极大，鼓胀主要是由温度、降雨等因素作用引起的。结合龙脖子段城墙，对温度和降雨的影响机理进行简化，考虑温度变化，并将降雨简化为复合墙体强度指标的下降及雨水渗入砖土接触面所产生的附加水压力的影响，采用非线性有限元软件A...     

伴有胀形时拉深高度的分析与计算

板料拉伸伴有胀形存在时，产品的成形高度应是拉深变形和局部变薄的变形共同决定的。本文分析和验证了两种变形量，导出了总成形高度的计算公式，给出了实验曲线。对生产有一定的指导意义。     

板坯连铸机分节式支承导辊的刚度分析

分节式导辊是８０年代出现的连铸机新结构，具有刚性好和能有效控制铸坯鼓变形的特点，已在连铸机辊列设计中得到推广应用。本文中对串心杆式支承导辊的结构及分节数对铸坯鼓肝变形的影响作了分析，从力学机理上证明了采用分节式导辊的合理性。     

井巷底鼓变形防治工程实践

通过对李雅庄矿＋355大巷底鼓变形原因分析以及＋355大巷底鼓变形防治的工程实践,提出了软岩巷道的底鼓变形防治措施.