Nonlinear Model for Lead–Rubber Bearings Including Axial-Load Effects

Existing models for isolation bearings neglect certain aspects of their response behavior. For instance, rubber bearings have been observed to decrease in stiffness with increasing axial load, and soften in the vertical direction at large lateral deformations. The yield strength of lead–rubber bearings has also been observed to vary with axial load, such that a lightly loaded bearing may not achieve its theoretical strength. Models that include these axial-load effects in lead–rubber bearings are developed by extending an existing linear two-spring model to include nonlinear behavior. The nonlinearity includes an empirical equation for the experimentally observed variation of yield strength. For numerical implementation, the bearing forces are found by solving the nonlinear equilibrium and kinematic equations using Newton’s method, and the instantaneous bearing stiffness matrix is formed from the differentials of these equations. The response behavior of the models is confirmed by comparison with experimental data.     

Evaluation of Low-Temperature Test Methods for Elastomeric Bridge Bearings

Elastomeric bearings have had an exemplary performance record over the past 40 years. Recently, increased testing requirements have been imposed that now make the testing of elastomeric bearings one of the major costs in constructing the supports. Currently, four low-temperature tests are required for elastomeric bearings. It is not clear whether all these tests are necessary or in fact even related to the actual performance of an elastomeric bridge bearing since some of these tests have been developed for other materials. Research was undertaken to evaluate the various tests and to determine whether they are important or even related to the performance of the bridge bearing. Tests were conducted on full-size natural rubber and neoprene bearings at low temperature subjected to compressive and shear forces, and factors such as testing speed and thermal conditioning were evaluated. As a result of the research, some test methods and performance requirements were found to have little impact on the bearing behavior, and others were overly conservative.     

Shelf life and in vivo duration. Impacts on performance of tibial bearings

Polyethylene has been used for more than 30 years as an orthopaedic bearing material; however, recently concern has been focused on the early failure of some polyethylene bearings. The damage seen in some bearings has been linked to gamma radiation sterilization performed in an air environment. Gamma sterilization in air has been documented to cause an increase in oxidation and degradation of mechanical properties that continue with time. However, not all retrieved bearings that are gamma sterilized in air exhibit the elevated oxidation and mechanical property degradation that lead to early component failure. Bearings that are gamma sterilized in air oxidize while sitting in inventory before implantation. Shelf oxidation rate was estimated based on analysis of a series of never implanted tibial bearings. This shelf oxidation rate allowed estimation of in vivo oxidation for retrieved tibial bearings of known sterilization date. Bearings with less than 1 year of shelf life after gamma sterilization in air had lower in vivo oxidation and better in vivo performance than did those with longer shelf life before implantation. Shelf time before implantation appears to be a significant factor in the success or failure of bearings that are gamma sterilized in air.     

Three-Dimensional Finite-Element Analysis of High Damping Rubber Bearings

A three-dimensional finite element modeling of high damping rubber bearings is studied. At first, the constitutive model of high damping rubber materials proposed by the writers is formulated in order to derive the constitutive tensor, which is required in the application of the finite element method. Second, a mixed finite-element method consistent with the proposed constitutive model is described. In this method, slightly compressible materials with rate form constitutive models are applied. Then, using the constitutive model and the finite-element method, a three-dimensional finite element model of high damping rubber bearings is constructed. The simulations by the model are found to be in good agreement with the experimental results of the bearing. Finally, complex deformation such as torsional or rotational deformation of the bearing are simulated by the finite-element model, and the design equations for these deformation are proposed on the basis of the simulations or experimental results.     

Tensile Stiffness and Deformation Model of Rubber Isolators in Tension and Tension-Shear States

The tensile stiffness and deformation model of rubber bearings are systemically researched in the paper, a series of basic concepts, such as origin tensile longitudinal elastic modulus, tensile stiffness factor, origin tensile stiffness, offset tension origin stiffness, etc. are suggested corresponding to the theoretical formula and the experimental estimation method. Based on the origin tensile stiffness and offset tension origin stiffness, the deformation calculating theories related to pure tensile state and tension-shear state of isolated bearing are established. The double stiffness model and original stiffness model are proposed to describe the tension properties of rubber isolators after the bearings yield. The vertical tensile stiffness, offset tension origin stiffness, and deformation tests are performed with nature rubber bearings and lead plug rubber bearings to verify the new concepts and computation model of rubber isolators. All test results show that the theories established in the paper are suitable to analyze the tensile stiffness and tensile deformation for rubber isolators.     

提高振动筛轴承润滑质量延长轴承工作寿命

针对烧结矿生产线中的振动筛轴承使用寿命过短的现象,通过对润滑脂的粘度、极压性和使用温度以及轴承温度监测记录的分析,找到一种大幅延长轴承寿命的方法。     

Vertical Stiffness and Deformation Analysis Models of Rubber Isolators in Compression and Compression-Shear States

The vertical stiffness and deformation theories of rubber isolators in compression and compression-shear states are systemically researched in the paper, a series of basic concepts, such as origin compression stiffness, origin compression longitudinal elastic modulus, offset vertical stiffness, etc. are suggested with corresponding theoretical formula and experimental estimation method. Based on the basic concepts and newly suggested calculating theories, the deformation calculating theory related to pure compression state and compression-shear state of isolating bearing is established. The vertical stiffness, offset vertical stiffness and deformation tests are performed with nature rubber bearings and lead plug rubber bearings total 16 original specimens to verify the new concepts and computation model of rubber isolators. All test results show that the theories established in the paper are suitable for analyzing the vertical stiffness and deformation of rubber isolators.     

POROUS METAL BEARINGS

Abstract

To facilitate the proper application of porous metal bearings, engineers demand a reliable method of predicting bearing performance in order that they may check the suitability of their designs. The responsibility of meeting that demand lies with the powder-metallurgy industry as much as with the many industries that use porous metal bearings. Most of the factors that determine the performance characteristics of these bearings are sensitive to temperature, and the method proposed in this paper commences with techniques for determining the temperature rise and hence the running temperature of the bearing. The temperature rise is obtained from the power loss at the bearing and the heat dissipation of the assembly. It is not possible to calculate these without knowing the bearing dimensions, and even if the dimensions are known the power loss cannot be calculated directly because this depends upon the oil viscosity and running clearance, both of which are dependent on the temperature. However, guidance curves are given for oil viscosity and clearance, which can be used in an iterative design process that converges rapidly towards the required solution. Having predicted the running temperature, assistance is given on methods of predicting the life of the bearing according to the quality and quantity of the oil at that temperature.     

时效处理对Cr20Ni32AlTi合金室温冲击性能的影响

 研究了铁镍基耐热耐蚀合金Cr20Ni32AlTi在1150℃、15min固溶处理并经450~850℃、05~5h的时效处理后室温冲击性能的变化规律。结果表明,450℃时效冲击性能最好。随时效温度升高,时效时间延长,冲击性能下降。450~850℃时效时,在合金晶界上有碳化物M23C6析出,且随温度增加和时间延长,析出增加。850℃时冲击功最低,此时碳化物M23C6析出相呈连续颗粒状析出,布满整个晶界。且观察到一些部位碳化物M23C6析出相形成薄膜,冲击时因基体变形而脆断成条块状。     

淬火工艺对铜沉淀强化UHS钢组织性能的影响

 超高强度钢不仅可以降低海洋装备本身质量，而且节约能源，但这类钢应用过程中要求具有良好的强韧性匹配，而淬火工艺显著影响其后续的相变和性能。采用Thermo Calc软件、光学显微镜、扫描电镜以及透射电镜等研究了淬火工艺对低碳(w(C)<0.05%)铜沉淀硬化超高强海工钢组织性能的影响。结果表明，910 ℃淬火、450 ℃时效处理后峰值硬度达到386HV，700 ℃时效后空冷可得到部分二次马氏体组织，峰值硬度为357HV。525 ℃以下时效，富铜相析出的平均半径约为5 nm，产生较高的强化增量。820~910 ℃淬火，随着淬火温度降低，细小的(Nb，Ti)C粒子能够有效抑制奥氏体晶粒的长大，细化晶粒和马氏体板条块，同时基体中小角度界面密度增加，强韧性提高。其中820 ℃淬火强度最高达到1 109 MPa，-80 ℃ V型冲击功为91 J。     

630～650℃超超临界参数锅炉受热面管备选材料建议

基于630℃二次再热机组受热面管候选新材料Sanicro25、C-HRA-5、SP2215进行了综合性能分析研究,包括化学成分、微观组织、力学性能、高温时效后的冲击性能、抗蒸汽氧化性、耐腐蚀性和经济性等,并与目前应用于600～620℃机组的传统Super304H和HR3C钢进行比对,结果表明3种新型材料综合性能更为优异...     

改型GH4133A合金长期时效的性能稳定性研究

对经过标准热处理改型GH4133A合金,在650、700和750℃进行长时间的时效处理,测量其室温拉伸和冲击性能、硬度、400℃拉伸性能和在750℃/343 MPa条件下持久性能.结果表明:在650℃和700℃下时效时,合金的性能变化规律一致,性能具有良好的稳定性.而在750℃时效时,合金的室温拉伸和400℃拉伸性能在时效500 h以前保持稳定,500 h以后随时效时间的增长而下降;合金的室温冲击性能在时效300 h以前保持稳定,300 h后下降;合金在750℃/343 MPa条件下,在时效600 h以前,持久性能寿命很稳定,基本保持在100 h左右,时效600 h以后的持久寿命迅速下降.     

Effect of aging conditions on the leaching of mechanically activated pyrite and sphalerite

The leaching of mechanically activated pyrite and sphalerite exposed to nitrogen (99.999 vol pct) or air at ambient temperature or 573 K was investigated. The results indicate that at the same leaching time, the iron-leaching ratio of mechanically activated pyrite or sphalerite aged in nitrogen at both ambient temperature and 573 K decreases slightly with increasing aging time and remains constant after a certain aging period. The iron-leaching ratio of mechanically activated pyrite exposed to ambient air varies with the exposure period. But, at the same leaching time, the zinc-leaching ratio of mechanically activated sphalerite aged at ambient temperature does not change with the aging atmosphere. The structures of mechanically activated pyrite and sphalerite after being aged were determined. The specific granulometric surface area of mechanically activated pyrite and sphalerite decreases with increasing aging time, but keeps constant after a certain aging period. The X-ray diffraction patterns of mechanically activated pyrites aged in nitrogen do not change with aging time; neither do the X-ray diffraction patterns of mechanically activated sphalerites aged either in air or in nitrogen. For mechanically activated pyrite exposed to ambient air for 3 and 6 months, new phases were found. The lattice distortion and the elemental sulfur content of pyrite and sphalerite mechanically activated in nitrogen were also investigated. The results indicate that the elemental sulfur content of mechanically activated pyrite rises noticeably, and its lattice distortion (ε) rises slightly, with increasing grinding time. The elemental sulfur content of mechanically activated sphalerite remains constant at 0.5 mg elemental sulfur per gram of sphalerite, and its lattice-distortion ratio increases apparently with increasing grinding time. These observations provide further evidence for our opinion that the formation of dangling bonds on the surface of mechanically activated pyrites and the lattice distortion on the surface of mechanically activated sphalerites may mainly result in the enhancement of hydrometallurgical process for corresponding sulfide minerals.     

Force-Deformation Behavior of Isolation Bearings

The isolation bearings are widely used in earthquake prone areas to protect the structure from seismic forces. The isolation bearing consists of an isolator to increase the natural period of the structure away from the high-energy periods of the earthquake, and a damper to absorb energy in order to reduce the seismic force. The most common isolation bearings used are lead–rubber bearings. They combine the function of isolation and energy dissipation in a single compact unit, giving structural support, horizontal flexibility, damping, and a centering force in a single unit. The relation between the horizontal force and horizontal displacement of the isolation bearings is nonlinear; to calculate the stiffness and the damping constant, which correspond to effective design displacement, the nonlinear behavior is expressed by bilinear behavior. This technical note presents new relations to calculate yield force, horizontal displacement, and damping.     

进口短应力轧机的改进措施

韶钢从意大利达涅利公司进口的短应力轧机在生产使用过程中存在一些问题，如轧机辊缝难以调整，齿套消耗严重，干油管道不通，轧辊轴承烧坏频繁，轧机摇晃幅度大等，针对这些问题进行了故障和设计分析，并提出了一些改进措施，将轧机丝杆的迷宫式密封改成羊毛毡整体式密封，加大轧机齿套与薄壁套之间的配合过盈量，强化轧辊轴承座及轧辊轴承的备件质量监督管理，将干油管路直径变成原来的5倍，将轧辊两头的组合胶垫改用一种特殊材料，从而获得年节约备件费57万元。     

长期时效对低碳Ni-Cr-W-Mo耐热合金组织和力学性能的影响

 研究了长期时效对低碳Ni-Cr-W-Mo耐热合金组织和力学性能的影响。结果表明,长期时效后低碳Ni-Cr-W-Mo耐热合金存在3种析出相：M6C型初生碳化物相、二次M23C6型碳化物相和μ相;其中M6C型初生碳化物相存在于供应态和时效态。因为合金含碳量低,所以合金在750℃时效超过200h和在900℃时效超过100h时,就析出μ相。合金在750℃时效至1000h时,随着时效时间的延长,合金硬度值不断增加;而合金在900℃时效至1000h时,随着时效时间的延长,合金硬度值首先增加至最大值,随后合金硬度值随着时效时间的延长而降低;这是因为二次M23C6型碳化物析出形态在时效过程中发生了变化。合金时效前后的室温拉伸性能数据证实微量μ相对合金室温拉伸影响很小。     

Directional Effects of Shear Combined with Compression on Bridge Elastomeric Bearings

Elastomeric bearings are widely used in bridge supports to accommodate thermal and other movements. The study presented in this paper extends an earlier investigation of two-dimensional bearing performance to three dimensions. Large-deformation rubber hyperelasticity is reviewed and a theoretical model is described with the steel-reinforced bearing subjected to compression in the direction through the thickness followed by shear in various lateral directions, including bridge longitudinal and transverse directions. Computations are carried out using the general-purpose, finite-element analysis computer program, ABAQUS. Conclusions are drawn regarding the effects of shear direction on bearing behavior.     

Influence of Reaction-Induced Phase Decomposition to Dispersion of Samariam Acrylic Acid (Sm (AA)3 ) in Rubber and Shielding Property of Sm(AA) 3/NR Composites

According to radiation protection theory, the radiation shielding properties of composites are closely related to dispersion condition of radiation absorbing materials in matrix. The more equably radiation-shielding materials dispersed in the matrix, the better the composites' shielding properties are. Rare earth ions have preferably absorbing ability for radiation due to their special electronic structures. From our early work, we know Sm(AA) 3 has good radiationabsorbing ability and excellent compatibility with polymer matrix. Furthermore, Sm (AA) 3 has double key structures which can in-situ react with polymer matrix in vulcanization process. This in-situ reaction can also help Sm(AA) 3 disperse better in the matrix. Based on these, we studied a new method to prepare Sm( AA)3/NR( nature rubber) composites( NR used as matrix), in which Sm(AA)3 dispersed very equably with tiny particle size. Both sulfur and peroxide exist in the system as crosslinking agent. The vulcanization process occurred at the temperature of 110℃ first and a certain degree crosslinking network formed in this stage, which we called pre-vulcanization process in this paper. In this stage sulfur was used as the crosslinking agent. Then continued the vulcanization process at higher temperature(170℃). The peroxide was used as crosslinking agent in this stage. According to reaction-induced phase decomposition mechanism, we studied the phase decomposition changing mode of Sm(AA) 3 in NR matrix of different crosslinking degrees. We also studied the influence of different degrees of pre-vulcanization to the dispersion condition of Sm (AA) 3 in NR matrix. The crystal-fusion status of both Sm(AA) 3 powder and Sm(AA) 3 in cured rubber were observed by DSC (Differential Scanning Calorimetry) and XRD (X-rays Diffraction). The dispersion condition of Sm(AA) 3 in cured rubber was observed by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscope).The studyresults show different degrees of pre-vulcanization have different effect on the in-situ reaction at high temperature (170℃), which influences the dispersion condition of Sm( AA)3 in NR matrix and the composites' final radiationshielding properties directly.     

固溶温度对新型无钻马氏体时效钢00Nil4Cr3Mo3Ti 冲击性能的影响

研究了固溶温度750～1050℃对00Ni14Cr3Mo3Ti新型马氏体时效钢冲击性能和硬度的影响,并用扫描电镜观察试验钢冲击断口的形貌和固溶态显微组织。试验结果表明,钢的固溶温度低于900℃时,随着固溶温度的升高,基体中未溶的Laves相逐渐溶解,固溶态和510℃ 5 h时效态的冲击性能均随着固溶温度的上升而提高;固溶温度高于900℃,固溶态冲击性能随着固溶温度的上升而提高,该钢固溶态冲击功由900℃的215J增加至1050℃固溶的226J,但时效态冲击性能随着固溶温度上升而降低,510 5h时效钢的冲击功由900℃最大值62J降至1050℃固溶的25J。     

烧结含油轴承

烧结含油轴承的金属结构中含有众多的相互连通的开孔，轴承中的孔隙容积约为10％－40％。这个孔隙容只可用来贮存流体润滑剂，流体润滑剂是在轴承的制造过程中含浸于其中的，在大多数应用中，是由轴承自身含的润滑剂进行润滑的。这份报告介绍了烧结含油轴承的概况和著者在烧结含油轴承方面近50年研究经历，并对烧结含油轴承的改进提出了一些建议。