The influence of an elastic uniaxial deformation of a medium-carbon steel on its magnetostriction in the longitudinal and transverse directions

In order to reveal the role of magnetostriction in the formation of a magnetic texture that appears in steels during their elastic deformation, the influence of stresses during uniaxial loading on the behavior of several magnetic characteristics of medium-carbon steel 45 was investigated. The magnetic parameters were measured under the conditions of a closed magnetic circuit with the application of attachable transducers along and across the direction of the applied load. The results of measurements of the hysteresis and magnetostriction properties of the investigated steel were compared. The magnetic parameters that monotonically change with an increase in the applied stresses were established.     

Application of an Eddy-current method for the assessment of stored plastic deformation and residual mechanical properties after cyclic loading of an annealed medium-carbon steel

The effect of cyclic loading of annealed steel 45 during low-cycle fatigue on changes in its electrical characteristics is studied. In the region of both small and mediate strains, an eddy-current transducer signal is found to be highly sensitive to the plastic deformation stored during cyclic loading. Correlations between readings of an eddy-current instrument and the residual mechanical properties of the material after cyclic loading are obtained. The possibility of assessing the residual mechanical properties of the material during its cyclic loading is considered.     

The biomechanical response of spinal cord tissue to uniaxial loading

The spinal cord is an integral component of the spinal column and is prone to physical injury during trauma or more long-term pathological insults. The development of computational models to simulate the cord-column interaction during trauma is important in developing a proper understanding of the injury mechanism. Such models would be invaluable in seeking both preventive strategies that reduce the propensity for injury and identifying specific treatment regimes. However, these developments are hampered by the limited information available on the structural and mechanical properties of this soft tissue owing to the difficulty in handling this material in a cadaveric situation. The purpose of the present paper is to report the rapid deterioration in the quality of the tissues once excised, which provides a further challenge to the successful elucidation of the structural properties of the tissue. In particular, the tangent modulus of the tissue is seen to increase sharply over a period of 72 h.     

The influence of a uniaxial load on the spatio-temporal characteristics of the electromagnetic response during acoustoelectric transformations in dielectric specimens

Preliminary investigations of the influence of the stressed-strained state of a specimen on the parameters of an electric response were performed using a multisensory testing system, which is based on the phenomenon of mechanoelectrical transformations in dielectric structures. The stressed-strained state was provided by uniaxial compression in a press. It was shown that the multi-sensory system is efficient and allows reliable recording of changes in the response parameters even at a relatively small variation in the stressed-strained state of the specimen.     

The influence of metal surface composition on the tribological properties of filled PTFE/steel couples

In this paper, the friction and wear behaviors of filled PTFE/steel couples are studied. The stationary specimen was made of filled PTFE. The rotating specimen, made of steels, underwent various treatments. The experimental results showed that the frictional coefficient and wear rate were low when the surface of the steel specimen contained nitrogen. The structure of the transfer film was examined by X-ray photoelectron spectroscopy (XPS). The transfer film containing nitrogen on the steel surface was thick. The authors consider that the hypothesis of the adhesion of the n–p–n structure may explain the characteristics of the different sliding couples in this paper and might be an important way to improve the friction and wear properties of the filled PTFE/metal sliding couples.     

The influence of experimental conditions on the wear of the metal surface during fretting of steel on polycarbonate

The effects of experimental conditions on the amount of wear of the metal surface during fretting of steel on polycarbonate in laboratory air have been studied within the following limits: amplitude 2–20 μm, frequency 10–120 Hz and normal load 130–830 g. The influence of water vapour on the wear has also been investigated.The polycarbonate induces fretting damage of the steel, with α-Fe₂O₃ particles being transferred from the steel to the polymer surface. After an incubation period during which wear does not take place a running in period occurs during which the rate of wear decreases with the number of cycles, followed by a steady state period, during which the rate of wear remains fairly constant. The length of the incubation period generally increases with decreasing amplitude of slip and with increasing frequency of vibration, while the amount of subsequent wear generally increases with increasing amplitude of slip, with decreasing frequency of vibration and with decreasing applied load within the range studied. It is found that water vapour content has the most significant effect on the amount of wear. In moist oxygen, moist argon and moist nitrogen (relative humidity about 85%) the amount of wear is greater than in laboratory air (relative humidity about 50%), while in dry gases virtually no wear of the metal is observed.     

The influence of polymer composition on the wear of the metal surface during fretting of steel on polymer

The effects of the nature of the polymer on the amount of metal wear during fretting of steel on polymers in laboratory air have been studied under a range of loads (130–330 g), amplitudes (3–10 μm) and frequencies (30–60 Hz).A number of polymers can cause damage to the metal, which takes the form of adhesive transfer of α-Fe₂O₃ particles to the polymer surface. The amount of metal wear depends on the polymer counterface and, under a given set of experimental conditions, increases in the order polytetrafluoroethylene (PTFE) and polyethylene, polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polysulphone, Polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polycarbonate, nylon 66. No metal wear occurs when the counterface is PTFE and only occurs with polyethylene when the amplitude is greater than 7 μm. These differences are explained in terms of the adhesive properties of the polymers, as determined by their surface energetics. Wear of the polymer during fretting takes the form of fibre formation for polysulphone, PVC, polycarbonate, nylon 66 and, to a small extent, polyethylene, while it takes the form of a transfer of a polymer film to the metal for PTFE and PVDF. No polymer wear occurs for PCTFE or PMMA.     

Necking of Q&P steel during uniaxial tensile test with the aid of DIC technique

A lot of research has been focused on the necking process during the plastic deformation of sheet metals, but the localized necking is rarely distinguished form diffused necking by experiments, due to the limit of measurement equipment and method. Quenching and Partitioning (Q&P) steel is a 3rd generation advanced high strength steel (AHSS). Its good combination of high strength and ductility ensures potential application in automobile industry. Uniaxial tensile tests of QP980 steel sheet at five strain rates are performed to investigate the necking process and the effect of strain rate on necking behavior of Q&P steel. Digital image correlation (DIC) method is applied during tensile tests, and evolutions of major strain, minor strain and normal strain distributions along gauge section of the tensile specimens are obtained. The diffused and localized necking strains are determined according to SWIFT necking theory and HILL necking theory respectively. The test results indicate that with the increasing of strain rate in the investigated range, the diffused necking strain decreases from 0.152 to 0.120 and localized necking strain decreases from 0.245 to 0.137. Meanwhile, the difference of the two strains decreases form 0.096 to 0.017. Thus it can be concluded that strain rate has an influence on both necking strains during the deformation of QP980 steel sheet. Diffused and localized necking strains are determined by uniaxial tensile tests with the aid of DIC technique and the effect of strain rate on necking strains is evaluated.     

载荷作用次数和强度退化对SSI模型的影响

在考虑循环载荷作用下强度随使用时间不断退化时,研究了应力-强度干涉模型下的可靠性统计推断问题,给出了一个考虑载荷作用次数应力-强度退化干涉失效模型.应用应力-强度干涉可靠性分析模型进行实例分析计算,结果与实验值符合很好,说明所提出新模型是合理有效的,更符合实际情况.     

Cu含量对耐海水腐蚀不锈钢组织与性能的影响

借助XRD、SEM等研究了0％～0．8％的Cu对20Cr-18Ni-6Mo-0．2Mn-0．8V-0．1Si耐海水腐蚀不锈试验钢力学性能的影响。结果表明：当Cu为0．3％时,抗拉强度（σb）为642Mpa;度（HRB）为93．28,延伸率（δ）为27．1％,其综合力学性能最优。     

工作载荷对旋转叶片固有振动特性的影响研究

根据飞行中的工作状态建立某旋转叶片的振动模型,利用结构有限元方法进行模态分析,通过对比分析法分别研究了气动载荷和离心载荷对叶片固有振动特性的影响。确定了不同载荷组合下的各阶固有频率,给出叶片的共振-转速特性,并分析了转速对振型的影响,为叶片试验与分析提供依据。     

Mn含量对耐海水腐蚀不锈钢组织与性能的影响

借助XRD、SEM等研究了0%~0.6%的Mn对00Cr20Ni18Mo6V0.8Si 0.1耐海水腐蚀不锈试验钢力学性能的影响。结果表明:当Mn为0.2%时,抗拉强度(σb)最大为583MPa;延伸率(δ)最大为23.3%,硬度随Mn含量的增高也略微上升,但变化不是很明显。     

The influence of stress concentration on creep rupture at non-stationary loading

A method is given for the calculation of creep rupture strength of parts containing stress concentrations. The creep theory takes account of the damage and anisotropy of materials. which arise during deformation. For the example of a plane specimen with a notch, results of calculations are compared with experimental data. The results of an investigation into the creep strength of the fir-tree root of a turbine blade at non-stationary loading is given.     

Prediction of necking of high strength steel tubes during hydroforming—multi-axial loading

This article studies tubular hydroforming of high strength low alloy (HSLA) and dual phase (DP600) straight tubes under the action of end feeding loads. Experiments demonstrate that higher end feed loads enhance the formability of the tubes and increase the internal fluid pressure for onset of necking and bursting. Because of the action of the internal pressure and the axial compressive load, the onset of localization (necking) is due to a complex three-dimensional state of stress. Using free expansion experiments, approximate upper and lower bound strain-based forming limit curves are determined for the tube materials. These limit curves, in turn, are used to derive upper and lower bound extended stress-based forming limit curves [Simha et al., Prediction of necking in tubular hydroforming using an extended stress-based FLC. Transactions of the ASME Journal of Engineering Materials and Technology 2007;129(1): 36-47]. In conjunction with finite element computations that use solid elements to model the tube, these stress-based limit curves are used to predict upper and lower bound necking pressures under the action of end feed loading. These predictions of necking pressures, when an appropriate coefficient of tube-die friction is used, are found to bracket the experimentally measured necking pressures. Computations using plane stress shell elements to model the tubes are shown to give erroneous results, since the plane stress approximation is not valid when tubes are hydroformed in a die.     

The effect of the anisotropy of magnetic properties of electrical steel on magnetic losses in power transformer cores

The distribution of the magnetic flux in the zone of rod contacts is investigated using the model of transformer cores. The effect of the anisotropy of magnetic characteristics of steel on magnetic losses and the transformer building factor is demonstrated. A method for estimation and forecasting of the building factor value is proposed. The investigation was performed using anisotropic electric steel of the 3408–3409 grades manufactured at OOO VIZ-STAL’.