排序方式： 共有52条查询结果，搜索用时 31 毫秒
41.
报导采用管式结构的氯化钙－氨吸附／脱附过程传热特性试验台．试验结果表明ＣａＣｌ２对ＮＨ３的吸附／脱附化学反应对ＣａＣｌ２－ＮＨ３介质的传热机理有较大影响．通过建立相应物理模型对ＣａＣｌ２吸附／脱附过程进行了数值分析 相似文献
42.
A template offshore platform, located in the Bohai Bay of China, has exhibited excessive, unexpected vibration un-der mildly hostile sea conditions, which has affected the normal operation of the platform. Since the structure was de-signed to sustain more severe wave climate, the cause of the excessive vibration has been suspected to originate from other sources. The main objectives of this study are to investigate the causes of the excessive vibration, and to explore possible remedies to solve the problem, In this paper, the vibration behavior of the offshore platform is analyzed by means of finite element (FE) modeling, field measurements and laboratory test. Results of analysis suggest that relative movement and impact between the piles and the jacket legs exist, i. e. the piles and the jacket are not perfectly connected. The discon-nection of the piles and jacket weakens the overall stiffness of the platform, and therefore produces unexpected excessive vibration. In this study, measures for reducing 相似文献
43.
1 .Introduction Large civil engineering structures are exposed to various external loads such as earthquakes ,winds ,traffic and wave loads during their lifetime . The structures may become deteriorated and de-graded withtime in an unexpected way, which m… 相似文献
44.
工业产品设计方案的模糊综合评价方法 总被引：1，自引：0，他引：1
本文根据工业产品的特点，建立了工业产品设计方案评价指标体系──－多级多指标评价体系，且具有模糊的特点．通过引入模糊优选理论，提出了设计方案模糊综合评价方法，并将其应用于除湿机的设计方案评价和选优． 相似文献
45.
大型海洋工程结构一般采用吊装法进行海上安装。随着海洋结构物重量的不断增大以及受到起重船吊装能力的限制,大型海上结构物浮托安装技术正成为海上施工安装的1种新方法,并成功应用于浅海固定式平台大型组块和深海浮式海洋平台的海上安装。本文介绍了海洋平台海上浮托安装的步骤、关键缓冲设备,列举了一些国内外的安装工程实例,指出了浮托法的关键技术,最后针对某工程实例,利用SESAM软件进行浮托法水动力分析。 相似文献
46.
本文从特征值问题出发 ,结合结构系统的有限单元模型并引入单元损伤因子 ,导出了求解单元损伤因子的方程 ,从而可以确定结构的损伤位置和损伤程度。利用简支梁进行了数值模拟 ,建立了简支梁的有限单元模型 ,用不同单元弹性模量的降低来模拟各种不同的损伤工况 ,并对每种工况进行了损伤位置和损伤程度识别 ,数值模拟结果同实际情况吻合很好。 相似文献
47.
Semi-Active Control of Wave-Induced Vibration for Offshore Platforms by Use of MR Damper 总被引：2，自引：0，他引：2
The objective of the present research is to examine the effectiveness of the lateral vibration control of wave-excited re-sponse of offshore platforms with magnelo-rheological (MR) damper, In this study, the offshore platform is simplified to be a single-degree-of-freedom (SDOF) system by extracting the first vibration mode of the struclure. The exlernal 'generalized' wave force is determined with a white noise via a designed filler. A semi-active control method based on optimal control the-ory is proposed considering that the yield stress of the MR damper can be varied continuously within a certain range. The dy-namics of SDOF structure coupled with the MR damper is investigated. Numerical simulation demonstrates that the MR damper with this control strategy can significantly reduce the maximum responses and the root-mean-square (RMS) values. 相似文献
48.
This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper (TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focuses on the energy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplified single-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force is assumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied. Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the Standard deviation of the deck motion but less effective in reducing the maximum response under impact loading. 相似文献
49.
传统的卡箍设计方法是通过建立海洋平台有限元模型并在强度分析基础上提取受损单元处完好时的最大载荷,将此载荷作为卡箍设计的初始条件。而卡箍实际承担的是平台安装上卡箍之后载荷重新分担下相应受损处承受的载荷,一般会比初始设计载荷大。着重研究载荷重新分担对膨胀式自应力灌浆卡箍防滑设计和防撬设计的影响,针对渤海湾中主要承受冰载荷作用的一个典型平台结构,提出了在线单元平台有限元模型上近似模拟卡箍的方法,提取载荷重新分担下的卡箍设计载荷进行了分析。结果表明载荷重新分担对卡箍防滑设计影响较小,但对防撬设计有着显著影响,并对此提出了在螺栓设计时增加螺栓预紧力安全系数的应对措施。 相似文献
50.
针对三维框架结构等复杂大型土木工程结构,研究基于振动测试的结构损伤诊断方法,提出了1种精确、有效的基于交叉模态应变能(CMSE)的结构损伤诊断方法。传统的模态应变能方法是将损伤前后的同阶模态进行比较,而CMSE方法没有这个限制。此方法最大的优点是需要的模态信息数量少——通常一阶模态就足够了,除此之外CMSE方法不要求进行模态的归一化。文中以三维5层的框架结构的有限元模型对新的方法进行了验证。数值模拟中结构的损伤分为2种情况——单个单元损伤和多个单元的损伤。虽然只给出了三维框架结构的示例,但这种新方法同样适用于其他结构。 相似文献