基于模态应变能和BP神经网络的混凝土框架结构损伤识别

采用模态应变能变化率和BP神经网络的两步损伤识别方法,对钢筋混凝土框架结构进行损伤识别研究.首先,利用单元的模态应变能变化率作为结构损伤定位因子,运用通用有限元ANSYS的APDL语言编制程序,计算模态应变能变化率;然后,利用BP神经网络进行损伤程度识别.该方法将二者优点相结合,并克服了单纯利用模态应变能难以准确计算损伤程度以及单纯利用BP神经网络样本巨大的困难.数值仿真结果表明,该方法适用于框架结构的损伤识别.     

内置光纤光栅传感器的智能缆索

采用特制光纤光栅应变传感器,将其埋植于缆索的连接筒部位的外层钢丝上、以实现对缆索整体索力的测量。通过独特的传感器封装结构设计、特制的机械连接固定方式、埋植过程中的可靠操作工艺,有效地保证了光纤光栅的存活率;有效地保证了传感器在大应力状态下测试的长期可靠性、稳定性。内置光纤光栅传感器的智能缆索工艺在长约400 m的253丝实索上进行了验证。经过有效的工艺验证及试验结果,智能索制作工艺方案可靠,传感器成活率高。研发的智能缆索可实现对整索索力进行在线监测,满足大型桥梁健康监测要求。     

基于FWD荷载作用的路面力学指标分析

FWD落锤式弯沉仪在路面检测中已经被越来越多地采用。路面结构层厚度及材料的力学性能对于检测结果有着极其重要的影响。基于正交理论,提出具有代表性的试验方案,并通过各组试验的计算结果,分析路面结构参数的变化对于FWD动荷载作用下路面力学性能的影响,对我国FWD检测指标体系的形成具有重要的参考意义。     

组织和氢对15MnVNq钢焊接热应变脆化的影响

本文对15MnVNq钢进行热处理及电解渗氢后,用三点弯曲方法对不同取向、不同组织的热应变脆化进行了研究,认为加工硬化促进了钢中C、N扩散集聚,从而导致其脆化;Z向试样的热应变脆化倾向明显高于y向试样;淬火组织比其它组织的热应变脆化倾向大;氢使热应变材料进一步脆化;条片状夹杂物起到预制缺口的作用,特别能使淬火状态的热应变脆化大大提高。     

Recent progress on wave induced loading measurements in warships

Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form.     

Full scale measurements at magnus

The environmental and structural monitoring system on Magnus tower was designed making use of experience from previous monitoring systems on West Sole, Forties and Buchan. The paper describes the measuring systems adopted together with their calibration procedures and independent checks.

The major results in terms of environmental conditions and platform response are discussed. They are compared with the Forties results and standard design procedures. Deterministic and spectral extreme conditions are considered. Where applicable, comparisons are made with other published results.

Finally, the principal conclusions of the measurement programme are presented and discussed. These refer particularly to structural dynamics, coefficients for the Morison equation and appropriate methods of application of wave loading to a deep water structure.     

钻孔法测定焊接残余应力时的塑性释放应变

用钻孔法测定焊接残余应力时，孔边塑性变形对测量精度有很大影响，本文对孔边屈服过程进行了研究，克服了以往在误差修正方法中的缺点，确定了塑性释放应变εｐ与主应力σｉ、σ２和主方向角β的函数关系，用以修正孔边塑性变形引起的测量误差，使得在二维应力状态下的测量误差降至２％以下。     

金属材料在非对称非比例应变路径循环加载下的塑性行为

本文对42CrMoA高强度合金钢进行了具有不同平均应变的非比例拉压—扭转循环加载试验,研究平均应变对应力响应的影响。试验结果表明,在非对称应变循环下,材料的应力响应与平均应变无关。因此,在循环塑性本构模型的建立中,应该考虑这一试验现象。     

有织构TiC渗层内三维宏观应力梯度分布的研究

本文在综合研究前人理论的基础上,提出用侧倾装置的 H 晶面法或多重因子晶面法,根据所测晶面的 X 线弹性常数来测定有织构的 TiC 渗层内三维宏观内应力及三维宏观加权平均内应力梯度分布和精确测定无应力的2θ_0。本法可适用于测定各种渗层、涂层材料表面薄层内外的三维宏观内应力梯度分布。