焊接H形截面钢压弯构件计算机程序

用一般手算法选择钢压弯构件截面时，往往要经过多次尺寸调整才能通过强度、整体稳定、局部稳定、刚度几方面的验算。该计算过程既繁又慢，且不易得到最优截面。为改进这一计算过程，本文列出了用电算法验算焊接Ｈ形截面钢压弯构件的计算公式，用ＢＡＳＩＣ语言编写了相应的计算机程序。算例表明，用本文程序设计的构件可比手算法省钢１０％左右。     

高精度细长轴高效数控加工自适应控制系统研究

高精度细长轴在精密机械设备和仪器仪表中使用很多。针对现有加工手段存在工序复杂、精度不易保证、加工效率低下等缺点,提出了基于自适应控制思想的高精度细长轴高效数控加工系统的解决方案。采用该系统可以很方便高效地加工出各种高精度细长轴。在控制好数控随动支架的位移精度和检测系统的精度的前提下,还可以实现超高精度、超长细长轴的高效自动加工。如能实现检测元件测杆的自动开合状态,则可以方便地实现高精度细长阶梯轴的自动加工。     

关于“逆算单元长度法”的改进

本文对原有的“逆算单元长度法”进行了适当的改进,并编制了相应的计算程序.计算表明:改进后的逆算单元长度法计算效率明显提高.同时,本文计算所得的等端弯矩作用下工字形截面和双角钢T形截面的N/N_P-M/M_P相关曲线可供设计参考,具有一定的实用价值.     

工字形截面偏心钢压杆考虑残余应力时的弯扭屈曲

本文以理想弹塑性材料为基础求解弯扭屈曲荷载,取用制订TJ17-74规范所用典型截面,考虑了焰割边钢板焊接工字形截面构件残余应力的影响。应用分支屈曲理论进行分析,将截面分为若干单元,编制了稳定系数φ_1的计算程序,算出了稳定系数φ_1。并将所算得的φ_1值与既有的试验结果和按三角形残余应力分布图形以及无残余应力时所算得的1值进行了对照比较,提出了简化方案。     

细长钢材的在线称量技术

本文介绍了以钢轨为例的细长钢材的在线称量技术方案。对称量设备的工艺布置和结构、称量过程和控制系统、称量仪表系统进行了较为详细的描述。该技术方案适用于成捆的钢轨、钢管、棒村等多种细长物料的称量。     

细长轴车削表面粗糙度实验与分析

为了明确加工状态及切削参数对细长轴类零件切削表面粗糙度的影响规律，通过刀具切削刃与工件表面形貌的几何映射关系，推导轴向截面的轮廓曲线方程，得出不同切削参数下的理论表面粗糙度值；对比分析不同加工状态、切削参数下细长轴切削表面粗糙度数据。结果表明：稳定切削时，细长轴工件的振动以主轴转频及其倍频为主，加工表面粗糙度受进给量影响最大，粗糙度随进给量的增大而增大，工件刚度较大时理论粗糙度与实测结果误差较小；当颤振发生时，工件振动信号中出现与其固有频率接近的高频振动成分，此时粗糙度理论预测结果与实测结果误差较大。理论模型中应充分融合工艺系统的振动信息，可进一步提高预测模型的精度与适用范围。     

带自制跟刀架的振动车削细长轴实验研究

细长轴的车削面临振动和让刀两大核心问题。针对振动问题,研制了拉夹顶尖,将工件受到的压应力变为拉应力,从而克服了压杆稳定极限,并且降低了产生振动的可能性。建立了一端卡盘一端拉夹顶尖装夹形式下的力学模型。针对让刀现象,研制了超声振动车削系统和自制跟刀架。超声振动车削方式通过对刀具附加高频,一定振幅的振动信号,使得车削过程中的切削力,切削热显著降低,并且有优异的抑制振动的效果。自制跟刀架通过微分头的形式实现辅助支撑作用。通过超声振动车削细长轴的实验,证明了自制拉夹顶尖、超声振动车削方式和自制跟刀架的组合在加工细长轴的有效性。     

细长型零件X射线自动检测系统研制

细长型箱体铸件空间孔位多,现有的X射线检测方法工序繁琐、劳动强度大,检测周期难以满足航天产品生产进度要求。为了解决这一问题,设计了基于X射线检测原理的自动化系统,该系统包括检测机械装置系统、控制系统、X射线检测系统。采用该系统对某细长零件进行了试验检测,检测结果满足工艺要求,说明设计的X射线自动检测系统可以高效、可靠地完成试验检测。     

Nonlinear analysis of circular concrete-filled steel tubular short columns under eccentric loading

This paper presents an effective theoretical model for the nonlinear inelastic analysis of circular concrete-filled steel tubular (CFST) short columns under eccentric loading. Accurate material constitutive relationships for normal and high strength concrete confined by either normal or high strength circular steel tubes are incorporated in the theoretical model to account for confinement effects that increase both the strength and ductility of concrete. The predicted ultimate bending strengths and complete moment-curvature responses of circular CFST columns under eccentric loading are compared with existing experimental results to examine the accuracy of the theoretical model developed. The fundamental behavior of circular CFST beam-columns with various diameter-to-thickness ratios, concrete compressive strengths, steel yield strengths, axial load levels and sectional shapes is studied using the verified theoretical model. Based on extensive numerical studies, a new design model for determining the ultimate pure bending strengths of circular CFST beam-columns is proposed. The theoretical model and formulas developed are shown to be effective simulation and design tools for the nonlinear inelastic behavior of circular CFST beam-columns under eccentric loading.     

A united model of diametral error in slender bar turning with a follower rest

Follower rest is an essential accessory for turning machines during the manufacture of slender bar. In order to analyze the effects of the follower rest and other machining conditions on diametral error, a united model is developed for predicting diametral error of slender bar. The proposed model consists of three components: geometric analysis of diametral error, finite element model of workpiece deflection and statistical model of cutting forces. Since there is a coupling between the actual depth of cut and the cutting force, a computer program is developed to determine the coupled depth of cut by using dichotomy. Then, a series of experiments are carried out to verify the prediction accuracy of the proposed model and a good agreement between the predicted and measured data is found. Finally, a series of numerical examples are calculated to analyze some important factors influencing diametral error of slender bar. The results show that the diametral error mainly depends on the location of follower rest, depth of cut and feed rate. But the cutting speed only has a slight effect on the diametral error.