Analytical prediction of composite beams response in fire situations

In this paper an extension of the method of the Fourier series expansion to the fire analysis of composite beams is presented. In particular the extension concerns the introduction of the temperature dependent interaction of all the components: steel beams, concrete slab and steel connectors. These last are considered of finite stiffness, and a proper account is given to the combined effect of thermal degradation of the properties, and stress amplification caused by the differential thermal expansion across the interface.The proposed method compares very well with some experimental fire tests of simply supported and framed composite beams. Due to its relative simplicity and speed, it can be used for design purposes in evaluating the critical temperature in terms of critical deflection. Finally we recall that the method is capable of dealing with every type of fastening distribution, such as discontinuous or variable length.     

地面遥控可调弯接头的设计

钻进过程中,为实现定向控制目标,发明了地面遥控可调弯接头,它通过改变钻井液排量来使上、下花键轴在花键筒内上下滑动,由于各花键齿端部形状的特点,这一滑动会导致上、下花键筒之间发生转动,又由于上、下花键筒的转动轴线与它们的外表面不平行,就会使它们之间出现需要的各种弯角,从而在地面就能改变井下弯接头的结构弯角,满足定向控制技术的需要。整个调节过程花费时间很少,因此可节约钻井成本。     

静载荷和疲劳载荷作用下 C/Al 正交层压板的力学响应

本文讨论静载荷及疲劳载荷作用下 C/Al 正交层压板的力学响应,并考虑损伤过程中的临界现象,以此作为结构设计准则的基础。对静载荷作用的情况:(1)90°铺层的门槛应变ε_(FPF)随着约束程度增加而增加,而且开裂后的行为也受约束程度的影响。(2)经历加载-卸载再重新加载至断裂的过程后,初始试样存在一个剩余永久变形,其损伤状态可以用刚度的变化来表征;而疲劳试样在加载-卸载过程中刚度变化很小,反映其损伤达到一个稳定的状态。对疲劳载荷作用的情况:(1)对于给定的应力比 R,试样会趋于与它所承受的 S_(max)最大值相应的 SDS 状态。循环应力范围的不断增大,会引起基体损伤的增加,从而重新建立新的饱和损伤状态。(2)对于每一损伤状态均有一对应的循环应变范围 Δε。在 SDS 状态下,Δε保持不变。(3)以刚度下降为损伤参数对 C/Al 层压板进行了降级应力分析,并由此来预计在ΔS_(sh)以下,层压板不会发生疲劳损伤累积。     

空间柔性机械臂三维动力学数值仿真

本文应用ｄ＇Ａｌｅｍｂｅｒｔ－Ｌａｇｒａｎｇｅ原理，对由基座、（ｎ－１）个柔性连杆及端部负载组成，相互用柱铰连接的柔性链式多体系统进行建模；对在空间技术中，具有一刚杆，两柔杆加上刚性负载所组成的三维机械臂系统，采用Ｇｅａｒ算法进行数值仿真。仿真结果比较符合实际，从而在柔性多体系统的数学模型为刚性常微分方程的情况下，为解决其数值仿真问题，特别是三维问题的数值仿真取得了进展。     

Frequency response function of magnetic bearings using high-temperature superconductor

A high-temperature superconductor YBa₂Cu₃O_7-x with strong pinning force has allowed stable magnetic suspension with no control to be developed. Two types of superconducting magnetic bearings (SMB) using YBCO and permanent magnet were assembled. The two types are radial and axial. The dynamic stiffness of each SMB as it was cooled down under a magnetic field by liquid nitrogen was measured both radially and axially. As a result, it was found that the spring constants of these SMBs were almost as large as a practically desirable value; however, their damping coefficients were lower than the practical level. These findings are useful as one of the data bases for development of an optimum SMB design to support the weight of rotors in an axial direction.     

羊皮服装革的弯曲应力松弛性能及其与(手感)弹性之关系研究

本文研究了羊皮服装革的弯曲应力衰减性能。对应力衰减常数（αｂ）及其与羊皮服装革手感弹性的关系进行了讨论。结果表明：αｂ与革的手感弹性相关。αｂ值定量反映出革的手感弹性优劣。     

单线循环客运索道设计参数研讨(续三)

论证客运索道设计中的几个重要参数,建立抱索器钳口夹紧力计算公式,第一次给出钳口夹紧力与钢索金属断面积的比值,并进行了钢索弯曲应力计算公式的推导.     

矫直状态下钢管弹塑性变形区的研究

根据钢管矫直时的变形规律，通过对矫直中钢管的力学状态及矫直前后的状态参数分析，建立了一种适于现场应用的确定钢管弹、塑性变形区的新方法。     

70推土机主离合器分离杆螺栓失效分析

主离合器分离杆螺栓是一个重要安全件，使用中经常发生断裂。经过失效分析确定断裂原因是由其配件引起。提高配件的冷加工质量及改进结构，可解决分离杆螺栓的断裂问题。     

铝塑复合板用铝带材工艺控制要点简析

铝塑复合板用铝带材是我公司的主要产品。本文主要介绍该产品实际生产中遇到的主要问题（板形、表面质量、折弯性能）及相应的解决措施。