Effect of repetitive corrugation and straightening on Al and Al-0.25Sc alloy

The improvement in strength of Al and Al-0.2Sc alloys through repetitive corrugation and straightening (RCS) was studied. The RCS was carried out using both single teeth as well as multiple teeth corrugative setup attached to a universal testing machine. The improvement in strength was obtained by measuring the hardness after processing. The rotation of sample by 90° between successive passes resulted in higher hardness values as compared to the simple bending and straightening. The increment in hardness obtained with same number of passes in the case of Al-0.2Sc alloy is more as compared to Al and is possibly due to blocking of dislocations that are introduced during deformation by Al₃Sc precipitates.     

Microstructure alterations at the surface of a heavily corrugated rail with strong ripple formation

The topography, morphology, structure and residual stress state at the surface of a rail with severe longitudinal ripples was characterized using a combination of spectrometry, microscopy, scattering and diffraction methods. The investigations reveal that white etching layers develop at the ripple hills, while the ripple valleys contain a severely plastic deformed layer. While the structure in the ripple valleys remains pearlite, the structure of the white etching layers on top of the ripple hills is nanocrystalline martensite containing cementite particles of a few nanometer size. The microhardness of the white etching layers on top of the ripple hills is about three times higher than the microhardness in the ripple valleys. The microhardness throughout the white etching layer is not homogeneous due to the non-uniform amount of carbon in solute solution and also due to differences in the amount and the size of the fine carbide particles. The whole running surface is under biaxial compressive residual stresses. In the ripple valleys the direction of the principal residual stresses nearly coincides with the longitudinal and the transverse direction on the rail. On the ripple hills the compressive residual stresses due to the martensite formation are significantly higher and the stress state is nearly homogeneous.     

长短边波纹壁高度不同的全密封油浸变压器波纹油箱

本文介绍了两种全密封油浸变压器波纹油箱的结构，并对它们的经济效益和社会效益进行分析。     

Effect of passenger car curving on rail corrugation at a curved track

The paper presents a corrugation calculation model, which considers Kalker's non-Hertzian rolling contact theory to be modified, a material wear model and a vertical and lateral coupling dynamics of a half passenger car and a curved track. The dynamics characters of the curved track model in frequency domain were investigated by the commercial finite element code ANSYS, and some results concerning rail corrugation are presented in this paper. During a passenger car passing a curved track the dynamical performance of the vehicle and track and the initiation and growth of the curved rail corrugation are analyzed with the present corrugation calculation model. In the numerical calculation, two track states are investigated. One is that the track does not have any congenital defect except for the discrete rail support by sleepers. The other is that the track has a lateral dent on the gauge corner of the high rail. The rail corrugations analyzed are attributed to the material wear mechanism. The numerical results obtained indicate that (1) a high passing frequency corrugation initiates on the smooth running surface of the curved rail during the first passing of the passenger car through the curved track without defects; (2) the initial corrugation develops quickly and its passing frequencies change with an increase of passenger car passage; (3) the interaction of the leading wheelset of the bogie and the curved rails causes more severe corrugation and wear on the rail running surface than that of the trailing wheelset of the same bogie; (4) discrete rail support by sleepers is the congenital defect leading to rail corrugation formation.     

Nanoscale Morphology in Tensile Fracture of a Brittle Amorphous Ribbon

The paper reports on the observation of nanoscale morphology on the tensile fracture surface of a brittle amorphous Fe-based ribbon. The formation of nanoscale damage cavity structure is a main characteristic morphology on the fracture surfaces. Approaching the ribbon boundary, these damage cavities assemble and form the nanoscale periodic corrugations, which are neither Wallner lines nor crack front waves. The periodic corrugations result from the interactions between the reflected elastic waves by the boundaries of amorphous ribbon and the stress fields of the crack tip.     

Effect of a scratch on curved rail on initiation and evolution of rail corrugation

The effect of a scratch formed on the running surface of a curved rail, due to the slide of a locomotive wheel, on the formation and evolution of rail corrugation is investigated in detail with numerical methods when a wheelset is steadily and repeatedly curving. In the calculation we consider a combination of Kalker’s rolling contact theory with non-Hertzian to be modified, a linear frictional work model and a vertical dynamics model of railway vehicle coupled with a curved track. Also the influence of different speeds of wheelset curving through the scratch on the development of the corrugation is taken into account. The numerical results indicate that a scratch causes strong contact vibration between the wheel and rail, and initiation and development of rail corrugation under the condition of steady creepage occurring between the wheel and curved rail. The wave-length of the corrugation depends on the speed of wheelset curving and the natural frequencies of the track.     

基于中点弦测模型的钢轨波磨量值估计

针对中点弦测模型无法复原轨道不平顺量值的问题,在分析钢轨波磨及对应的弦测数据后发现两者均具有周期性,在此基础上提出了一种多弦测量并计算钢轨波磨量值的方法。通过采用不同弦长对同一轨道的测量,避免单一中点弦测法中特殊波长幅值增益为零的问题;利用小波变换多分辨率的特点获取了波磨的频率及出现位置,将其应用于轨道波磨量值测算。结果表明,该方法能够从轨道中点弦测数据中发现钢轨波磨,并通过计算复原其原始量值,适合工程中对钢轨波磨的快速检测估计。     

浅析降低铝锭表面波纹的措施

从铝电解铸造铝锭时影响铝锭表面的因素出发，结合现有设备实际状况，阐述了降低铝锭表面波纹的措施，通过设备改造不仅取得很好的应用效果，而且取得很好的经济效益。     

Effect of wall corrugation on indoor sound decay

This paper studies low frequency decay in a rectangular room with the walls replaced by a variety of scattering surfaces. The study is carried out using a numerical approach. The finite-element method is used to model the problem. The results show that certain types of scattering materials have more positive effects on the decay than others. Therefore it is possible to obtain desirable decay for a room by choosing suitable wall corrugations.     

波纹膨胀节失效分析

应用化学分析、金相和电子探针显微分析技术对排气冷却器中波纹膨胀节的失效原因进行了分析。结果表明，波纹膨胀节发生早期失效是由于构件发生应力腐蚀开裂所致。