主轴系配设轴负荷指示仪的重要性

轴负荷是主机正确操车的主要依据之一 ,若操车人员无法即时掌握轴负荷的变化状态 ,将会产生大量的误操现象 ,导致不必要的经济损失。本文以关键的典型操车为实例 ,阐述了配置输出轴负荷指示仪在主机操作中的重要性 ,以期引起造船技术界的重视。

轴负荷指示仪在船舶主机紧急倒车操作中的作用

船舶紧急制动 ,是船舶航行中为避碰而采取的应急措施。紧急制动成功与否 ,决定于主机操纵的正确程度。本文分析了主机紧急倒车操作中存在的问题及其客观原因 ,阐述了船舶主机紧急倒车手动操作的实质性技术依据与操作要求。笔者认为只有依据船舶实时倒航工况 ,方能做到主机操作的及时与正确 ,确保航行安全。最后 。

火力发电机组汽动引风机带负荷轴振大的原因分析

探讨了火力发电机组汽动引风机带负荷轴振大这一现象,首先,对汽动引风机进行了介绍,并总结了造成负荷轴振大的原因,结合实际提出解决建议;其次,解决汽动引风机带负荷轴振大这一问题,使汽动引风机能够在火力发电机组中长期维持稳定运行。通过对火力发电机组汽动引风机带负荷轴振大现象的分析,以期能够为今后火力发电机组的运行、故障检查等提供支持与参考。

轴系轴承负荷的测量分析与调整

轴系合理校中是将轴系作为弹性连续梁进行计算分析各支承受力情况,并用调整支承位置的方法使支承力合理化。该种分析方法应用于轴系设计,从而更新了轴系设计概念和方法,使轴系运行状况大为改善。目前各船级社基本上都要求查看轴系校中轴承负荷。通过对近海多用途供应船轴系轴承负荷测量、调整进行描述和分析,以供相关专业人员借鉴与参考。

一种船舶轴系负荷测量新技术

传统的船舶轴系负荷测量方法步骤繁琐。我们通过工装的改进和系统的配套升级,开发了一种船舶轴系负荷测量新技术,有效解决了作业劳动强度大、测量效率和精度低、周期长的问题,做到准确和快速地进行船舶轴系负荷测量,达得降本增效的作用。

4900car PCTC船轴系校中探索

轴系校中主要目的是使轴系在各种运行工况下轴系负荷能够合理分布、满足要求。通常这项工作贯穿新造船轴系设计阶段、船台轴系调整安装阶段以及水下轴系调整校中阶段。文章以厦门船舶重工股份有限公司在建4900car PCTC船为例,探讨整个轴系校中过程。

船舶主机误操分析及措施

针对海洋运输船舶存在的主机误操现象,本文从主机实操角度分析了误操发生的因素和原因,揭示了轴负荷显示的意义,并提出了建设性措施与相应对策。

制动灵敏,为何警报灯常亮?

故障现象一辆红旗 CA7220型轿车,在正常行驶中制动警报灯突然亮了起来。司机急忙刹车,制动很灵敏,再试犹然。故障分析与检查经查阅资料,一汽生产的小红旗轿车,针对前轴负荷大(发动机前置、制动时惯性力也较后轴大得多)和前轮通风式制动器易受外界灰尘磨粒侵入而导致前轮制动蹄片磨损快这一特点。

SG1020扭杆式独立悬架前桥

SG1020扭杆式独立悬架前桥,主要用于前轴负荷在一吨以下的汽车上,特点是通过性能好,能提高整车高速行驶时操纵稳定性,提高整车的平顺性,它重量轻,适应性强,能与各种轻型车及改装车相匹配使用。

Complete load transfer behavior of base-grouted bored piles

A field study on the behavior of three destructive piles in soft soils subjected to axial load was presented.All the three piles with different diameters were base-grouted and installed with strain gauges along the piles.The complete load transfer behavior of the base-grouted pile was analyzed using measured results.Moreover,the thresholds of the relative pile-soil displacement for fully mobilizing skin frictions in different soils were investigated,and pile tip displacements needed to fully mobilize tip resistances were analyzed.The results of the full-scale loading tests show that the skin frictions are close to the ultimate values when the pile-soil relative displacements are 1%-3% of pile diameter,and the pile tip displacements needed to fully mobilize the tip resistances are about 1.3%-2.0% of pile diameter.The load transmission curve of the soils around the pile tip corresponds to a softening model when the pile is loaded to failure.

The Axial and Radial Solid Loadings up the CFB-Riser

1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase flow.Several tech-niques have been used during the past decades(Table1).These methods can be classified in two groups,depending on their possible disturbance of the two-

Novel approach for determining the optimal axial preload of a simulating rotary table spindle system

This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.

Finite element analysis of couple effect of soil displacement and axial load on single inclined pile

The couple effect of soil displacement and axial load on the single inclined pile in cases of surcharge load and uniform soil movement is discussed in detail with the methods of full-scale field tests and finite element method. Parametric analyses including the degree of inclination and the distance between soil and pile are carried out herein. When the displacement of soil on the left side and right side of a pile is identical, deformation of a vertical pile and an inclined pile is highly close in both cases of surcharge load and uniform soil movement. When the couple effect of soil displacement and axial load occurs, settlement of an inclined pile is greater than that of a vertical pile under the same axial load, and bearing capacity of an inclined pile is smaller than that of a vertical pile. This is quite different from the case when the inclined pile is not affected by soil displacement. For inclined piles, P-Δ effect of axial load would lead to a large increase in bending moment, however, for the vertical pile, P-Δ effect of axial load can be neglected. Although the direction of inclination of piles is reverse, deformation of piles caused by uniform soil movement is totally the same. For the inclined piles discussed herein, bending moment(-8 m to-17 m under the ground) relies heavily on uniform soil movement and does not change during the process of applying axial load. When the thickness of soil is less than the pile length, the greater the thickness of soil, the larger the bending moment at lower part of the inclined pile. When the thickness of soil is larger than the pile length, bending moment at lower part of the inclined pile is zero.

A new calculation method for axial load capacity of separated concrete-filled steel tubes based on limit equilibrium theory

A new calculation method for axial load capacity of separated concrete-filled steel tubes based on limit equilibrium theory was proposed,which took into account the decrease of confinement effect by steel tube and the non-uniform distribution of ultimate stress in cored concrete.The accuracy of the analytical result is validated through running the numerical result by finite element method (FEM) and experimental data as well.The influences of the key parameters on the load capacity of the concrete-filled steel tube (CFST) was studied,including the separation ratio,concrete compressive strength,and steel strength.The results indicate that the load capacity of the tube increases with concrete strength and steel strength under the separation ratio less than 4%,while decreases with a higher separation ratio improved.

Axial compressive behavior and design method of tubed circular steel reinforced concrete short columns

To study the behavior and design of tubed circular steel reinforced concrete (TCSRC) short column under axial compressive loads, a nonlinear finite element model (FEM) has been developed to simulate this kind of structure. Depending on the FEM results, an elastic-plastic analysis was carried out to clarify the status of steel tube, then a simplified procedure was proposed to predict the compressive axial load strength. The results obtained from this procedure were compared with the test results. It is found that they agree well each other.

Stability of perfect and imperfect cylindrical shells under axial compression and torsion

Stability analyses of perfect and imperfect cylindrical shells under axial compression and torsion were presented. Finite element method for the stability analysis of perfect cylindrical shells was put forward through comparing critical loads and the first buckling modes with those obtained through theoretical analysis. Two typical initial defects, non-circularity and uneven thickness distribution, were studied. Critical loads decline with the increase of non-circularity, which exist in imperfect cylindrical shells under both axial compression and torsion. Non-circularity defect has no effect on the first buckling mode when cylindrical shell is under torsion. Unfortunately, it has a completely different buckling mode when cylindrical shell is under axial compression. Critical loads decline with the increase of thickness defect amplitude, which exist in imperfect cylindrical shells under both axial compression and torsion, too. A greater wave number is conducive to the stability of cylindrical shells. The first buckling mode of imperfect cylindrical shells under torsion maintains its original shape, but it changes with wave number when the cylindrical shell is under axial compression.

Φ280×4轧机四联箱振动原因分析及措施

对四联箱振动异常机理进行了分析。连接轴结构中虚约束多,造成倾角过大,转动时不平衡附加负荷引起四联箱振动超常。通过改变连接轴花键结构、简化连接轴设计,改变了连接轴传统使用方法,减振效果显著,四联箱轴承寿命提高3倍以上。

Combined torsional buckling of double-walled carbon nanotubes with axial load in the multi-field coupled condition

The present study has theoretically investigated the combined torsional buckling of double-walled carbon nanotubes (DWCNTs) with axial load in the multi-field coupled condition. The effects of torsion, axial load, thermal-electrical change, surrounding elastic medium and the Van der Waals forces are all taken into consideration. The governing equation of buckling for CNTs subjected to thermo-electro-mechanical loadings has been established based on an elastic shell model of continuum mechanics. Reasonable simplifications are made to get the explicit expression of the critical buckling shear stress of DWCNTs, and numerical experiments are conducted for further research. It is shown that under certain electric and temperature field the critical buckling shear stress of DWCNTs only depends on the wave number of buckling modes. On the other hand, all the related impact factors have enormous influence on the critical buckling shear stress under a certain buckling mode. The critical buckling shear stress changes linearly with the axial-to-shear stress ratio, as well as the thermal and electric change. Axial compression tends to make DWCNTs unstable, while axial tension benefits the buckling stability. The critical buckling shear stress is directly proportional to the applied voltage. At room or lower temperature, the critical shear stress for infinitesimal buckling increases as the temperature change increases, while it decreases at a higher temperature. The conclusions are useful for the design of nano-structures related to the buckling stability of DWCNTs.

Deformation analysis of an incompressible composite cylindrical tube subjected to end axial loads and internal constraint

In this paper,the problem of axially symmetric deformation is examined for a composite cylindrical tube under equal axial loads acting on its two ends,where the tube is composed of two different incompressible neo-Hookean materials.Significantly,the implicit analytical solutions describing the deformation of the tube are proposed.Numerical simulations are given to further illustrate the qualitative properties of the solutions and some meaningful conclusions are obtained.In the tension case,with the increasing axial loads or with the decreasing ratio of shear moduli of the outer and the inner materials,it is proved that the tube will shrink more along the radial direction and will extend more along the axial direction.Under either tension or compression,the deformation along the axial direction is obvious near the two ends of the tube,while in the rest,the change is relatively small.Similarly,for a large domain of the middle part,the axial elongation is almost constant;however,the variation is very fast near the two ends.In addition,the absolute value of the axial displacement increases gradually from the central cross-section of the tube and achieves the maximum at the two endpoints.

The Effect of Variable Stator on Performance of a Highly Loaded Tandem Axial Flow Compressor Stage

Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds. Considering the high aerodynamic load effects and structural concerns in the design process, it is possible to obtain higher pressure ratios compared to conventional compressors. However, it must be noted that imposing higher aerodynamic loads results in higher loss coemcients and deteriorates the overall performance. To avoid the loss increase, the boundary layer quality must be studied carefully over the blade suction surface. Employment of advanced shaped airfoils （like CDAs）, slotted blades or other boundary layer control methods has helped the de- signers to use higher aerodynamic loads on compressor blades. Tandem cascade is a passive boundary layer control method, which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads. In fact, the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade＇s suction side. Also, in compari- son to the single blade stators, tandem variable stators have more degrees of freedom, and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance. In the current study, a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage. Following, this design is numerically investigated using a CFD code and the stage characteristic map is reported. Also, the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed. To validate the CFD method, another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.