WorldWideScience

Sample records for bearing capacity

  1. The ultimate bearing capacity of ice beams

    Directory of Open Access Journals (Sweden)

    Li Liang

    2013-02-01

    Full Text Available It is usually proposed that bearing capacity of the ice beam during its interaction with a sloping hydraulic structure is exhausted when tensile stresses in the beam’s cross-section reach some limit. But besides the tensile stress there is a compressive stress during the interaction with a sloping structure. This can change our estimations of the ultimate bearing capacity and load exerted on the structure. The purpose of the study was to estimate influence of the longitudinal compressive stress on the ice beam’s ultimate bearing capacity. The solution was obtained with the program complex LS-DYNA. Results of the mathematical modeling were compared with data of physical experiments conducted by Sodhi. Good correlation of the results gave possibility to conduct wide numerical experiments and to suggest corrections to the existing methodology.

  2. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  3. Load-Bearing Capacity of Roof Trusses

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Damkilde, Lars; Munch-Andersen, J.

    2004-01-01

    systems such as roof trusses are established and statistical characteristics of the load bearing capacity are determined. The results show that there is a significant increase in the characteristic (nominal) value and a reduction in the coefficient of variation (COV) for typical loads such as permanent...

  4. 24 CFR 3285.202 - Soil classifications and bearing capacity.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Soil classifications and bearing... Soil classifications and bearing capacity. The soil classification and bearing capacity of the soil... bearing capacity must be determined by one or more of the following methods, unless the soil...

  5. Bearing capacity of mixed soil model

    Directory of Open Access Journals (Sweden)

    Mehdi Khodashenas Pelkoo

    2009-01-01

    Full Text Available The main objective of this research is improvement of red soil with addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to assess the behavior of red soil, when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC. Safe bearing capacity of all models, have been calculated to identify best and worst soil mixed model.

  6. Lightweight Aggregate Concrete Components. Load-bearing Capacity

    DEFF Research Database (Denmark)

    Larsen, Henning; Ingholt, N.U.; Goltermann, Per

    1996-01-01

    The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity......The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity...

  7. Lightweight Aggregate Concrete Beams. Load-bearing Capacity

    DEFF Research Database (Denmark)

    Larsen, Henning; Goltermann, Per; Ingholt, N.U.

    1997-01-01

    This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity.......This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity....

  8. The Influence of Time on Bearing Capacity of Driven Piles

    DEFF Research Database (Denmark)

    Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.

    2004-01-01

    In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay......, a regeneration factor appears. The regeneration factor accounts for effects of dissipation of pore pressure due to pile driving and true time effects such as ageing on the ultimate bearing capacity. Normally the factor is 0.4 but in this paper, the influence of the undrained shear strength and time...

  9. Increasing the load bearing capacity of barrel vaults

    NARCIS (Netherlands)

    Kamerling, M.W.

    2011-01-01

    Just after World War II many barrel vaults and domes were built with a structural system, known as Fusée Ceramique. This paper analyses the load bearing capacity of these vaults. Schemes, theories, idealizations and assumptions are analysed, validated and discussed. Methods to increase the load bear

  10. Seismic ultimate bearing capacity of strip footings on slope

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of earthquake forces on ultimate bearing capacity of foundations on sloping ground was studied. A solution to seismic ultimate bearing capacity of strip footings on slope was obtained by utilizing pseudo-static analysis method and taking the effect of intermediate principal stress into consideration. Based on limit equilibrium theory, the formulae for computing static bearing capacity factors, Nq, Nc, Nγ, and dynamic bearing capacity factors, Nqd, Ncd, Nγd, which are associated with surcharge, cohesion and self-weight of soils respectively, were presented. A great number of analysis calculations were carried out to obtain the relationship curves of the static and dynamic bearing capacity factors versus various calculation parameters. The curves can serve as the practical engineering design. The calculation results also show that when the values of horizontal and vertical seismic coefficients are 0.2, the dynamic bearing capacity factors Nqd, Ncd and Nγd, in which the effects of intermediate principal stress are taken into consideration, increase by 4%-42%, 3%-27% and 34%-57%, respectively.

  11. Bearing capacity analysis using the method of characteristics

    Institute of Scientific and Technical Information of China (English)

    Jian-Ping Sun; Zhi-Ye Zhao; Yi-Pik Cheng

    2013-01-01

    Using the method of characteristics,the bearing capacity for a strip footing is analyzed.The method of characteristics leads to an exact true limit load when the calculations of the three terms in the bearing capacity formula are consistent with one collapse mechanism and the soil satisfies the associated flow rule.At the same time,the method of characteristics avoids the assumption of arbitrary slip surfaces,and produces zones within which equilibrium and plastic yield are simultaneously satisfied for given boundary stresses.The exact solution without superposition approximation can still be expressed by Terzaghi's equation of bearing capacity,in which the bearing capacity factor Nyλ is dependent on the dimensionless parameterλand the friction angle φ.The influence of groundwater on the bearing capacity of the shallow strip footing is considered,which indicates that when the groundwater effect is taken into account,the error induced by the superposition approximation can be reduced as compared with dry soil condition.The results are presented in the form of charts which give the modified value (yλcw/Nyλc) of bearing capacity factor.Finally,an approximated analytical expression,which provides results in close agreement with those obtained by numerical analysis in this paper,has been suggested for practical application purposes.

  12. Bearing capacity and mechanical behavior of CFG pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    陈秋南; 赵明华; 周国华; 张主华

    2008-01-01

    CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.

  13. Bearing capacity improvement using micropiles a case study

    OpenAIRE

    Babu, Sivakumar GL; Murthy, Srinivasa BR; Murthy, DSN; Nataraj, MS

    2004-01-01

    Micropiles have been used effectively in many applications of ground improvement to increase the bearing capacity and reduce the settlements particularly in strengthening the existing foundations. Frictional resistance between the surface of the pile and soil and the associated group/network effects of micropiles are considered as the possible mechanism for improvement. This paper deals with a case study in which micropiles of 100 mm diameter and 4 m long have been used to improve the bearing...

  14. Bearing Capacity of Foundations subjected to Impact Loads

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Jakobsen, Kim Parsberg

    1996-01-01

    In the design process for foundations, the bearing capacity calculations are normally restricted to monotonic loads. Even in cases where the impact load is of significance the dynamic aspects are neglected by use of a traditional deterministic ultimate limit state analysis. Nevertheless it is com......In the design process for foundations, the bearing capacity calculations are normally restricted to monotonic loads. Even in cases where the impact load is of significance the dynamic aspects are neglected by use of a traditional deterministic ultimate limit state analysis. Nevertheless...

  15. Bearing capacity evaluation of rubblized concrete pavements

    Directory of Open Access Journals (Sweden)

    González, M.

    2009-03-01

    Full Text Available The paper presents the findings of a research work performed on a real scale concrete pavement project where Rubblizing technology was used for its structural rehabilitation. Rubblizing may be defined as a fracture technique in which a concrete pavement slab is transformed in a granular base with a very high Modulus. This technique, fractures the concrete slab in angular pieces by using a concentrated dynamic load of low amplitude and high frequency. The research work was based on field study on the rehabilitation of 5 km motorway. The structural evaluations where made, before, during and after one year construction. Measurements and site evaluation where made by using DCP, Light Weight Deflectometer and FWD (on top of asphalt layer and excavating inside pits. The structural capacity of the Rubblized layer was evaluated through theoretical analysis. Because of the anisotropic properties of the Rubblized layer the results are presented using AASHTO structural layer coefficient. The structural layer coefficients recommended are between the range of 0.25 and 0.30 for concrete slabs with thickness grater than 220 mm.El trabajo presenta los resultados de un estudio a escala real de la capacidad estructural de un firme de hormigón rehabilitado utilizando la técnica de Rubblizing. La técnica de Rubblizing ha sido traducida como el pulverizado del firme de hormigón pero, es más bien un efecto combinado de trituración y fracturación de la losa de hormigón en todo su espesor para convertir esta en una base granular de alto módulo. Esta tecnica fractura la losa de hormigón en trozos angulares y entrelazados empleando una carga dinámica concentrada, de baja amplitud y alta frecuencia. La investigación se basó en el estudio de la rehabilitación de 5 km de autopista. Los estudios de la capacidad estructural fueron realizados durante, al término y un año después de la construcción. Para las mediciones y evaluaciones de terreno se utilizó, el

  16. The Bearing Capacity of Circular Footings in Sand

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

    2012-01-01

    dependent on the stress level and on the basis of the test results, a non linear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100mm, has been conducted...

  17. Soil bearing capacity under dynamic conditions for the ALWR systems

    International Nuclear Information System (INIS)

    The present work is a part of the studies carried out by ENEL DSR-VDN and ISMES on ALWR systems. From a geotechnical point of view the soil bearing capacity in dynamic stress conditions is of particular interest for the development of the ALWR project. In fact the possible Italian sites are not rocky sites but generally of alluvial kind. This work is a continuation of a previous paper. Here we show the results of the finite element soil-structure analysis and the subsequent bearing capacity analysis with reference to four geotechnical profiles that represent the lower and upper bound of the Italian variability range of data. Some comments are made on the codes of practice, of interest to Italy, the safety factor concept and the possible use of other calculation methods in addition to classical ones. (author)

  18. Bearing Capacity of Mixed Pile with Stiffness Core

    Institute of Scientific and Technical Information of China (English)

    YUE Jianwei; JIANG Xinliang; LING Guangrong

    2006-01-01

    To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core (MPSC), which is formed by inserting a precast reinforced concrete pile (PRCP), in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out.Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained.The load transfer between cement soil and PRCP was analyzed by finite element method (FEM).Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil.The length and the section area on PRCP of an MPSC both have an optimum value.Adopting MPSC is effective in improving the bearing capacity of soft soil ground.

  19. Vertical bearing capacity of pile based on load transfer model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; YANG Ming-hui; ZOU Xin-jun

    2005-01-01

    The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.

  20. Unconventional Bearing Capacity Analysis and Optimization of Multicell Box Girders

    Directory of Open Access Journals (Sweden)

    Jovan Tepic

    2014-01-01

    Full Text Available This study deals with unconventional bearing capacity analysis and the procedure of optimizing a two-cell box girder. The generalized model which enables the local stress-strain analysis of multicell girders was developed based on the principle of cross-sectional decomposition. The applied methodology is verified using the experimental data (Djelosevic et al., 2012 for traditionally formed box girders. The qualitative and quantitative evaluation of results obtained for the two-cell box girder is realized based on comparative analysis using the finite element method (FEM and the ANSYS v12 software. The deflection function obtained by analytical and numerical methods was found consistent provided that the maximum deviation does not exceed 4%. Multicell box girders are rationally designed support structures characterized by much lower susceptibility of their cross-sectional elements to buckling and higher specific capacity than traditionally formed box girders. The developed local stress model is applied for optimizing the cross section of a two-cell box carrier. The author points to the advantages of implementing the model of local stresses in the optimization process and concludes that the technological reserve of bearing capacity amounts to 20% at the same girder weight and constant load conditions.

  1. Bearing Capacity of the Working Platform with Kinematic Method

    Directory of Open Access Journals (Sweden)

    Białek Katarzyna

    2015-03-01

    Full Text Available Bearing capacity of the working platform for heavy tracks was analysed using Distinct Layout Optimization (DLO method. The platform layer constructed from cohesionless soils is resting on weak cohesive subgrade. Different thickness of the platform, its effective angle of internal friction and undrained shear strength of the soft soil were taken into consideration. Kinematic method permits different failure mechanisms to be analyzed. Margin of safety for a given load and subsoil conditions was determined using two approaches: increasing the load or decreasing the shear strength up to failure. The results were compared with solution proposed in BRE recommendations.

  2. Bearing Capacity Analysis Using Meshless Local Petrov-Galerkin Method

    Directory of Open Access Journals (Sweden)

    Mužík Juraj

    2014-05-01

    Full Text Available The paper deals with use of the meshless method for soil bearing capacity analysis. There are many formulations of the meshless methods. The article presents the Meshless Local Petrov-Galerkin method (MLPG - local weak formulation of the equilibrium equations. The main difference between meshless methods and the conventional finite element method (FEM is that meshless shape functions are constructed using randomly scattered set of points without any relation between points. The Heaviside step function is test function used in the meshless implementation presented in the article. Heaviside test function makes weak formulation integral very simple, because only body integral in governing equation is due a body force.

  3. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2015-01-01

    Full Text Available The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain reference value for theoretical research and technical application of the technique.

  4. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    OpenAIRE

    Zhao Feng

    2015-01-01

    The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base pos...

  5. Numerical analysis on bearing capacity of middle pylon caisson foundation of Taizhou Bridge

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Shao Guojian; Hu Feng; Gu Lijun

    2012-01-01

    Because of the computation difficulty of the beating capacity of large underwater caisson foundation on thick overburden layer ground, the geotechnieal software FLAC3D was utilized in the 3D numerical analysis on the bearing capacity of middle pylon foundation. From the computational results, it is concluded that the caisson foundation has a good bearing capacity on thick overburden layer ground and the beating capacity can be improved assuming that the soil near the area of basal comer is reinforced.

  6. Bearing Capacity Analyses for the Great Belt East Bridge Anchor Blocks

    DEFF Research Database (Denmark)

    Sørensen, Carsten Steen; Clausen, Carl J. Frimann; Andersen, Henrik

    1993-01-01

    This paper presents a comparison between different methods of bearing capacity analyses: Upper Bound Method. Limit Equilibrium Analysis and Finite Element Analysis. For the Great Belt East Bridge anchor blocks it was concluded that these methods of calculation agree within 5%. However, for cases...... where the bearing capacity is dominated by frictional materials, much higher differences should be expected....

  7. Effect of lobe profile on the load capacity of 2-lobe journal bearing

    Institute of Scientific and Technical Information of China (English)

    Stanislaw; STRZELECKI

    2001-01-01

    The rotors of turbogenerators operate in 2-lobe journal bearings. These bearings can bedesigned with the same or different profile of upper and bottom lobe, e.g. the upper lobe has cylin-drical and bottom one the offset profile. Shaping the bearing profile this way allows the variation ofstatic and dynamic characteristics of bearing. The static characteristics consist among others theload capacity of bearing which is very important parameter. The paper introduces the results ofcalculations of load capacity of 2-lobe journal bearing characterised by different profiles of upperand bottom lobe. The laminar, adiabatic oil flow in the bearing lubricating gap, parallel orientationof journal and bearing axis as well as the static equilibrium position of journal have been assumed.

  8. Analytical Model for the End-Bearing Capacity of Tapered Piles Using Cavity Expansion Theory

    Directory of Open Access Journals (Sweden)

    Suman Manandhar

    2012-01-01

    Full Text Available On the basis of evidence from model tests on increasing the end-bearing behavior of tapered piles at the load-settlement curve, this paper proposes an analytical spherical cavity expansion theory to evaluate the end-bearing capacity. The angle of tapering is inserted in the proposed model to evaluate the end-bearing capacity. The test results of the proposed model in different types of sands and different relative densities show good effects compared to conventional straight piles. The end-bearing capacity increases with increases in the tapering angle. The paper then propounds a model for prototypes and real-type pile tests which predicts and validates to evaluate the end-bearing capacity.

  9. Improvement of Bearing Capacity of Shallow Foundation on Geogrid Reinforced Silty Clay and Sand

    Directory of Open Access Journals (Sweden)

    P. K. Kolay

    2013-01-01

    Full Text Available The present study investigates the improvement in the bearing capacity of silty clay soil with thin sand layer on top and placing geogrids at different depths. Model tests were performed for a rectangular footing resting on top of the soil to establish the load versus settlement curves of unreinforced and reinforced soil system. The test results focus on the improvement in bearing capacity of silty clay and sand on unreinforced and reinforced soil system in non-dimensional form, that is, BCR. The results show that bearing capacity increases significantly with the increased number of geogrid layers. The bearing capacity for the soil increases with an average of 16.67% using one geogrid layer at interface of soils with equal to 0.667 and the bearing capacity increases with an average of 33.33% while using one geogrid in middle of sand layer with equal to 0.33. The improvement in bearing capacity for sand underlain silty clay maintaining and equal to 0.33; for two, three and four number geogrid layer were 44.44%, 61.11%, 72.22%, respectively. The finding of this research work may be useful to improve the bearing capacity of soil for shallow foundation and pavement design for similar type of soil available elsewhere.

  10. Parametric analysis of thermal effect on hydrostatic slipper bearing capacity of axial piston pump

    Institute of Scientific and Technical Information of China (English)

    汤何胜; 訚耀保; 张阳; 李晶

    2016-01-01

    Hydrostatic slipper was often used in friction bearing design, allowing improvement of the latter’s dynamic behavior. The influence of thermal effect on hydrostatic slipper bearing capacity of axial piston pump was investigated. A set of lumped parameter mathematical models were developed based on energy conservation law of slipper/ swash plate pair. The results show that thermal equilibrium clearance due to solid thermal deformation periodically changes with shaft rotational angle. The slipper bearing capacity increases dramatically with decreasing thermal equilibrium clearance. In order to improve the slipper bearing capacity, length-to-diameter ratio of fixed damper varies from 3.5 to 8.75 and radius ratio of slipper varies from 1.5 to 2.0. In addition, the higher slipper thermal conductivity is useful to improve slipper bearing capability, but the thermal equilibrium clearance is not compromised.

  11. Evaluation of Land Safety Degree of the Tourist Area Based on the Land Comprehensive Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Sun Chao

    2015-09-01

    Full Text Available The regional land safety evaluation indicator system is built based on the land comprehensive bearing capacity in the study and the primary and secondary relationship of the land safety obstacle factors of Mengshan tourist area and influence degree of various obstacle factors on land safety are determined, so as to provide reference for sustainable utilization of land in Mengshan tourist area. The results indicate that: (i The land comprehensive bearing capacity of Mengshan tourist area is at the safety state. Where, the social bearing capacity is at the weak safety state, which is the most critical factor influencing the land bearing capacity of Mengshan tourist area. (ii The traveling and living ratio, the output values of the secondary industry and the tertiary industry of the unit construction land and the land utilization intensity are the key factors influencing the regional safety level.

  12. Bearing Capacity of High Density Polyethylene (HDPE) Reinforced Sand Using Plate Load Test

    OpenAIRE

    Er. Aly K; Prof. Stephen Joseph Nigli

    2015-01-01

    The work presented here is a study to examine the improvement in bearing capacity of coastal sand of Trivandrum, Kerala, India using high density polyethylene (HDPE) /woven fabric as reinforcement in discrete layers. The bearing capacity was evaluated using plate load test. The effect of reinforcement configurations like sheet reinforcement (sanded with adhesive, with adhesive and sheet alone) and strip reinforcement (single and grid pattern) are investigated. The test parameters ...

  13. Improvement of Bearing Capacity of Shallow Foundation on Geogrid Reinforced Silty Clay and Sand

    OpenAIRE

    Kolay, P. K.; Kumar, S; Tiwari, D.

    2013-01-01

    The present study investigates the improvement in the bearing capacity of silty clay soil with thin sand layer on top and placing geogrids at different depths. Model tests were performed for a rectangular footing resting on top of the soil to establish the load versus settlement curves of unreinforced and reinforced soil system. The test results focus on the improvement in bearing capacity of silty clay and sand on unreinforced and reinforced soil system in non-dimensional form, that is, BCR....

  14. Influences of Taper Geometry Modified Oil-Grooves on Load Carrying Capacity of Crosshead Bearings

    Science.gov (United States)

    Kitahara, Tatsumi; Otsubo, Masaru; Nakahara, Daisuke

    The crosshead bearing in large two-stroke diesel engines operates under severe lubrication conditions, because the bearing oscillates within a small angle at a low speed and is always subject to a high downward load. The recent trend towards more compact engines with increased output raises the bearing specific load, thereby causing the lubrication severity to increase significantly. Thus it is very important to improve the load carrying capacity of the crosshead bearing. In the present study, experiments using a dynamically loaded bearing seizure test apparatus were carried out to clarify the influences of the clearance ratio and the oil-groove geometry on the load carrying capacity. The electrical resistance of the oil film was also measured to evaluate the extent of the oil film formation. The major results are: (1) A decrease in the clearance ratio is effective in enhancing squeeze action on the entirety of the bearing pads, thereby improving the load carrying capacity. When the clearance ratio becomes too low, however, the ability to form an adequate wedge film is degraded, causing the load carrying capacity to decrease; (2) A significant improvement in the load carrying capacity can be expected, because incorporating the taper geometry on both sides of the oil-groove promotes a thicker oil film; and (3) A taper geometry with a subtended length of 5 degrees and a taper angle of 0.1 degree produces the maximum load carrying capacity.

  15. Regressive approach for predicting bearing capacity of bored piles from cone penetration test data

    Directory of Open Access Journals (Sweden)

    Iyad S. Alkroosh

    2015-10-01

    Full Text Available In this study, the least square support vector machine (LSSVM algorithm was applied to predicting the bearing capacity of bored piles embedded in sand and mixed soils. Pile geometry and cone penetration test (CPT results were used as input variables for prediction of pile bearing capacity. The data used were collected from the existing literature and consisted of 50 case records. The application of LSSVM was carried out by dividing the data into three sets: a training set for learning the problem and obtaining a relationship between input variables and pile bearing capacity, and testing and validation sets for evaluation of the predictive and generalization ability of the obtained relationship. The predictions of pile bearing capacity by LSSVM were evaluated by comparing with experimental data and with those by traditional CPT-based methods and the gene expression programming (GEP model. It was found that the LSSVM performs well with coefficient of determination, mean, and standard deviation equivalent to 0.99, 1.03, and 0.08, respectively, for the testing set, and 1, 1.04, and 0.11, respectively, for the validation set. The low values of the calculated mean squared error and mean absolute error indicated that the LSSVM was accurate in predicting the pile bearing capacity. The results of comparison also showed that the proposed algorithm predicted the pile bearing capacity more accurately than the traditional methods including the GEP model.

  16. Evaluation of Bearing Capacity of Strip Footing Using Random Layers Concept

    Directory of Open Access Journals (Sweden)

    Kawa Marek

    2015-09-01

    Full Text Available The paper deals with evaluation of bearing capacity of strip foundation on random purely cohesive soil. The approach proposed combines random field theory in the form of random layers with classical limit analysis and Monte Carlo simulation. For given realization of random the bearing capacity of strip footing is evaluated by employing the kinematic approach of yield design theory. The results in the form of histograms for both bearing capacity of footing as well as optimal depth of failure mechanism are obtained for different thickness of random layers. For zero and infinite thickness of random layer the values of depth of failure mechanism as well as bearing capacity assessment are derived in a closed form. Finally based on a sequence of Monte Carlo simulations the bearing capacity of strip footing corresponding to a certain probability of failure is estimated. While the mean value of the foundation bearing capacity increases with the thickness of the random layers, the ultimate load corresponding to a certain probability of failure appears to be a decreasing function of random layers thickness.

  17. Evaluation of Strip Footing Bearing Capacity Built on the Anthropogenic Embankment by Random Finite Element Method

    Science.gov (United States)

    Pieczynska-Kozlowska, Joanna

    2014-05-01

    One of a geotechnical problem in the area of Wroclaw is an anthropogenic embankment layer delaying to the depth of 4-5m, arising as a result of historical incidents. In such a case an assumption of bearing capacity of strip footing might be difficult. The standard solution is to use a deep foundation or foundation soil replacement. However both methods generate significant costs. In the present paper the authors focused their attention on the influence of anthropogenic embankment variability on bearing capacity. Soil parameters were defined on the basis of CPT test and modeled as 2D anisotropic random fields and the assumption of bearing capacity were made according deterministic finite element methods. Many repeated of the different realizations of random fields lead to stable expected value of bearing capacity. The algorithm used to estimate the bearing capacity of strip footing was the random finite element method (e.g. [1]). In traditional approach of bearing capacity the formula proposed by [2] is taken into account. qf = c'Nc + qNq + 0.5γBN- γ (1) where: qf is the ultimate bearing stress, cis the cohesion, qis the overburden load due to foundation embedment, γ is the soil unit weight, Bis the footing width, and Nc, Nq and Nγ are the bearing capacity factors. The method of evaluation the bearing capacity of strip footing based on finite element method incorporate five parameters: Young's modulus (E), Poisson's ratio (ν), dilation angle (ψ), cohesion (c), and friction angle (φ). In the present study E, ν and ψ are held constant while c and φ are randomized. Although the Young's modulus does not affect the bearing capacity it governs the initial elastic response of the soil. Plastic stress redistribution is accomplished using a viscoplastic algorithm merge with an elastic perfectly plastic (Mohr - Coulomb) failure criterion. In this paper a typical finite element mesh was assumed with 8-node elements consist in 50 columns and 20 rows. Footings width B

  18. Analysis of bearing capacity of CA corner wall in AP1000 nuclear power plant

    International Nuclear Information System (INIS)

    Background: The module construction technology is widely used in the AP1000 nuclear power plant. The CA structural module in the containment building is important for the safety of the nuclear power plant, the corner wall of the CA structural is critical under load, so it is important to do research on bearing capacity of CA corner wall. Purpose: Finite element analysis model of the CA comer wall is conducted in the ABAQUS software to study the bearing capacity and the stress/strain state of the CA comer' wall under different load cases. Methods: Finite element analysis model considering the material nonlinearity, contact nonlinearity and geometric nonlinearity conducted in the ABAQUS software is used for the analysis of the CA corner wall. Results: The ultimate bearing capacities of the CA comer wall in different loads are studied, and the study also gets the load-displacement curves. The bearing capacities of CA corner wall under different axial loads are also studied in this paper. The influence of ultimate bearing capacities of CA comer wall is founded out if the steel and concrete work together. Conclusions: When the CA corner wall subjects to the bending load, the failure part of the CA corner wall is the corner core concrete. When the CA corner wall subjects to the shear load, the failure part of the CA corner wall is the straight module wall. The axial load has notable influence on the capacity of CA corner wall. (authors)

  19. Modified Vertical Bearing Capacity for Circular Foundations in Sand Using Reduced Friction Angle

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Barari, Amin; Larsen, Kim André

    2012-01-01

    Recently Bucket foundation as a large cylindrical structure that is open as the base and closed at the top, has attracted much attention in offshore projects. In order to present relationship between vertical bearing capacity of a bucket foundation relative to the corresponding capacity...... of a circular plate, several loading tests on small scale bucket foundations including the circular surface footings are performed at Aalborg University. In current research, the vertical bearing capacity of circular surface footings is investigated using reduced friction angle. It is also presented a linear...

  20. Bearing Capacity Estimation of Bridge Piles Using the Impulse Transient Response Method

    Directory of Open Access Journals (Sweden)

    Meng Ma

    2016-01-01

    Full Text Available A bearing capacity estimation method for bridge piles was developed. In this method, the pulse echo test was used to select the intact piles; the dynamic stiffness was obtained by the impulse transient response test. A total of 680 bridge piles were tested, and their capacities were estimated. Finally, core drilling analysis was used to check the reliability of this method. The results show that, for intact piles, an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles. The core drilling analysis proved that the estimation method was reliable.

  1. Dynamic load testing on the bearing capacity of prestressed tubular concrete piles in soft ground

    Science.gov (United States)

    Yu, Chuang; Liu, Songyu

    2008-11-01

    Dynamic load testing (DLT) is a high strain test method for assessing pile performance. The shaft capacity of a driven PTC (prestressed tubular concrete) pile in marine soft ground will vary with time after installation. The DLT method has been successfully transferred to the testing of prestressed pipe piles in marine soft clay of Lianyungang area in China. DLT is investigated to determine the ultimate bearing capacity of single pile at different period after pile installation. The ultimate bearing capacity of single pile was founded to increase more than 70% during the inventing 3 months, which demonstrate the time effect of rigid pile bearing capacity in marine soft ground. Furthermore, the skin friction and axial force along the pile shaft are presented as well, which present the load transfer mechanism of pipe pile in soft clay. It shows the economy and efficiency of DLT method compared to static load testing method.

  2. THE CAPACITY OF INTERNATIONAL ORGANIZATIONS TO BEAR INTERNATIONAL RESPONSIBILITY

    OpenAIRE

    Ovidiu-Emilian IVANESCU

    2015-01-01

    The status of international personality is not exclusively reserved for states. In modern days, the international organizations have legal international personality and also have the capacity to be internationally responsible for their conduct. Some particularities of the legal personality of international organizations are decisive in determining their international responsibility. The study will establish the connection between the foundations of the personality and responsibility of an int...

  3. New design equations for estimation of ultimate bearing capacity of shallow foundations resting on rock masses

    Institute of Scientific and Technical Information of China (English)

    Amir H Alavi; Ehsan Sadrossadat

    2016-01-01

    Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehen-sive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations.

  4. Bearing capacity of shell strip footing on reinforced sand

    Directory of Open Access Journals (Sweden)

    W.R. Azzam

    2015-09-01

    Full Text Available In this paper, the ultimate load capacities of shell foundations on unreinforced and reinforced sand were determined by laboratory model tests. A series of loading tests were carried out on model shell footing with and without single layer of reinforcement. The tests were done for shell foundation at different shell embedment depth and subgrade density. The results were compared with those for flat foundations without reinforcement. The model test results were verified using finite element analysis using program PLAXIS. The experimental studies indicated that, the ultimate load capacity of shell footing on reinforced subgrade is higher than those on unreinforced cases and the load settlement curves were significantly modified. The shell foundation over reinforced subgrade can be considered a good method to increase the effective depth of the foundation and decrease the resulting settlement. Also the rupture surface of shell reinforced system was significantly deeper than both normal footing and shell footing without reinforcement. The numerical analysis helps in understanding the deformation behavior of the studied systems and identifies the failure surface of reinforced shell footing.

  5. BEARING CAPACITY OF REINFORCED GRANULAR BEDS ON SOFT NON-HOMOGENEOUS CLAY

    Directory of Open Access Journals (Sweden)

    K. RAJYALAKSHMI

    2011-07-01

    Full Text Available Most naturally deposited clays have induced non-homogeneity. Neglect of this increase of undrained strength would lead to conservative estimate of bearing capacity of foundations laid on top. The two layered foundation bed considered for the study, consists of a layer of dense reinforced granular fill overlying soft nonhomogeneousclay whose undrained strength increases with depth. The paper presents a method developed to estimate the bearing capacity of a strip footing on the surface of a reinforced granular bed over a finite layer of clay whose undrained strength increases linearly with depth, incorporating the contribution of granular fill, thatof soft ground based on the Davis and Booker’s theory and the axial tension in reinforcement. Parametric studies presented quantify the improvement in bearing capacity over that by the conventional Meyerhof’s approach for homogeneous deposit.

  6. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    Directory of Open Access Journals (Sweden)

    Wang Duanduan

    2015-01-01

    Full Text Available Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.

  7. Determining the bearing capacity of soil foundation reinforced by geogrid

    Directory of Open Access Journals (Sweden)

    E.S. Kolosov

    2012-06-01

    Full Text Available The article deals with improving the construction properties of soils due to their reinforcement by geosynthetics, namely the geogrid. Geosynthetics have been widely used in the construction of extended objects: the mound of roads and railways, dams, retaining walls.The article includes a description of the possible destruction of reinforced soil base under load. It is established that the soil reinforcement by geogrids prevents adhesive failure (slip.The definition of carrying capacity of geogrid reinforced foundation is considered in terms of spatial task for the case when the ratio of base length to its width is not more than 5. The solution presented in the form of the equilibrium conditions of active and passive earth pressure.The coefficient of geogrid space work for water-saturated silt and fine sands is derivered. The optimal size and depth of geogrid inception are determined.

  8. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    OpenAIRE

    Wang Duanduan; Wang Longfei; Zhang Lipeng

    2015-01-01

    Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capac...

  9. Reliability Analysis of Bearing Capacity of Large-Diameter Piles under Osterberg Test

    Directory of Open Access Journals (Sweden)

    Lei Nie

    2013-05-01

    Full Text Available This study gives the reliability analysis of bearing capacity of large-diameter piles under osterberg test. The limit state equation of dimensionless random variables is utilized in the reliability analysis of vertical bearing capacity of large-diameter piles based on Osterberg loading tests. And the reliability index and the resistance partial coefficient under the current specifications are calculated using calibration method. The results show: the reliable index of large-diameter piles is correlated with the load effect ratio and is smaller than the ordinary piles; resistance partial coefficient of 1.53 is proper in design of large-diameter piles.

  10. Lower-Bound Calculations of the Bearing Capacity of Eccentrically Loaded Footings in Cohesionless Soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2012-01-01

    Lower-bound calculations based on the finite element method are used to determine the bearing capacity of a strip foundation subjected to a vertical, eccentric load on cohesionless soil with varying surcharges. The soil is assumed perfectly plastic following the Mohr-Coulomb failure criterion. Th...

  11. The Bearing Capacity of Strip Footings in Cohesionless Soil Subject to Eccentric and Inclined Loads

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2014-01-01

    Lower bound calculations based on the finite element method is used to determine the bearing capacity of a strip foundation subjected to an inclined, eccentric load on cohesionless soil with varying surcharges and with friction angles 25, 30 and 35°. The soil is assumed perfectly plastic followin...

  12. Effect of Embedment on the Vertical Bearing Capacity of Bucket Foundations in Clay

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo

    2011-01-01

    the top and applying suction inside the bucket. The hydrostatic pressure difference and the deadweight cause the bucket to penetrate the soil. In the present study, results of an experimental study addressing the effect of embedment (skirt length to the diameter) on the undrained bearing capacity...

  13. Bearing Capacity of Footings on Thin Layer of Sand on Soft Cohesive Soil

    DEFF Research Database (Denmark)

    Philipsen, J.; Sørensen, Carsten S.

    2004-01-01

    This paper contains the results of some numerical calculations performed with the aim to determine the bearing capacities of footings placed on a thin layer of sand underlain by soft cohesive soil. During the last 30-35 years different analytical and empirical calculation methods for this situation...

  14. Influence of Reel Lay on Residual Stress and Ultimate Bearing Capacity of Pipe

    Science.gov (United States)

    Liao, Hongqian; Wang, Liquan

    Reel lay is a fast and cost-effective way to install subsea pipelines. During reel lay, pipe's repeated plastic bending produces residual stress, which has influence on pipe's ultimate bearing capacity. First, the deformation of pipe in reel lay is analyzed, and the cyclic bending stages are simplified for convenience of theoretical research. Based on the finite element method (FEM), the Ramberg-Osgood model is adopted to describe material's mechanical property with kinematic hardening rule, and five bending stages are simulated. Further, the influence of material parameters and geometry parameters on pipe's residual stress is studied. Finally, the effect of residual stress on pipe's external pressure bearing capacity and tensile capacity is analyzed. Some important conclusions can be drawn: (1) the influence of diameter-thick ratio on residual stress is small, and material parameters' effect on the residual stress is large; (2) the influence of residual stress on pipe's external pressure bearing capacity is small, but its influence on tensile capacity is large.

  15. Oil Pocket’s Bearing Capacity Analysis of Liquid Hydrostatic Worktable in Gantry Moving Milling Center

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jianhua; LIANG Yingna; GAO Dianrong

    2014-01-01

    Durning the design process of hydrostatic rotary worktable, the processing and assembly tolerance, (the offset of worktable and the gap of the oil film’s thickness) is ignored. But it will cause that the real bearing of oil pocket deviates from the initial design value, and then the performance of rotary worktable will be reduced significantly. Up to now, no effort is found toward the research of influence of the processing and assembly tolerance on the performance of the rotary worktable. So the hydrostatic oil film is assumed as the elastomer in this paper, and then the bearing capacity of the oil pocket is studied with and without the mass offset of the worktable by taking an expression between the bearing capacity and the oil film’s thickness of the oil pocket as the deform compatibility equation. The influence of the processing tolerance of the oil sealing belt’s gap on the bearing capacity of the oil pocket is analyzed. In the light of the liquid hydrostatic worktable of Gantry Moving Milling Center using on the scene, the oil pocket’s pressure of the worktable is tested using Rotary Worktable Test System under the circumstance of the mass offset of the worktable and the gap tolerance of the oil sealing belt, and then the equivalent offset of worktable, the average pressure of the oil pocket and the actual thickness of the oil film are analyzed respectively. The test results show that the bearing capacity component of the oil pocket caused by G is consistent, and the component caused by M is relative to the position of the oil pocket. When the oil sealing belt’s gap is larger than the theoretical value, the bearing capacity of the oil pocket is smaller than the others;whereas the bearing capacity of the oil pocket is larger than the others. The maximum and minimum equivalent offsets are 0.256 4 mm and 0.047 5 mm, respectively, and the average oil pocket pressure varies from 0.345 MPa to 0.460 MPa, the maximum and minimum value of the actual oil film

  16. Upper and Lower Bound Calculations of the Bearing Capacity of Strip Footings near Slopes in Cohesionless Soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2013-01-01

    The calculation of the bearing capacity of a strip foundation located on the edge of or near a slope is commonly based on the well-known bearing capacity equation applying so called slope factors, and expressions for these factors have been proposed by amongst others Brinch Hansen and Vesic. Thes...

  17. Stålplader gav dobbelt bæreevne (Steel plates doubled the load bearing capacity)

    DEFF Research Database (Denmark)

    Nielsen, Jan Broch

    1999-01-01

    Abstract from an examination of motor road bridge beams reinforced with steel plates on the sides and bottom. The plates doubled the load bearing capacity of the beams.......Abstract from an examination of motor road bridge beams reinforced with steel plates on the sides and bottom. The plates doubled the load bearing capacity of the beams....

  18. Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity.

  19. The effect of manufacturing tolerances on the load carrying capacity of large diameter bearings

    Indian Academy of Sciences (India)

    Starvin M S; Manisekar K

    2015-09-01

    This paper deals with simplified 3D finite element (FE) analysis on the effect of manufacturing tolerances on the load carrying capacity of large diameter bearings based on Hertz theory. The nonlinear connector elements are used to model the rolling elements. This model enables us to evaluate the contact load on the rolling elements with relatively reduced calculation time. FE study has been carried out by allocating tolerance on balls and raceways using Monte Carlo simulation technique. The variation in dimension on balls is taken as per IS 2898-1976. A coding has been developed and employed for Monte Carlo simulation. Using the results of Monte Carlo simulation, tolerance has been assigned to the elements of large diameter bearing. From the results of finite element analysis, it is identified that analysis of large diameter bearing with tolerance on ball and raceway will lead to safe design.

  20. Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

    Directory of Open Access Journals (Sweden)

    Amin Keshavarz

    2016-04-01

    Full Text Available In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided for analysis. Given the footing and rock parameters, the code can calculate the stress characteristics network and obtain the stress distribution under the footing. The seismic effects have been applied as the horizontal and vertical pseudo-static coefficients. The results of this paper are very close to those of the other studies. The seismic bearing capacity of weightless rock masses can be obtained using the proposed equations and graphs without calculating the whole stress characteristics network.

  1. Bearing Capacity and Critical Punch-Through Depth of Spudcan on Sand Overlying Clay

    Institute of Scientific and Technical Information of China (English)

    刘君; 于龙; 周慧; 孔宪京

    2014-01-01

    Spudcan may experience punch-through failure on strong over weak layered soils, such as sand overlying clay. A large deformation finite element method (LDFE) is used to simulate the penetration process of spudcan into sand overlying clay. The sand is simulated by smoothed hyperbolic Mohr-Coulomb model, and the clay is simulated by a simple elasto-plastic model which obeys Tresca yield criterion. According to the LDFE results of a large amount of cases, the effects of the strength, unit weight and thickness of the top sand layer, as well as the effect of the strength of the underlying clay on the spudcan punch-through behavior, are investigated. The critical depth occurring punch-through and the critical bearing capacity are presented in charts. Fitting equations to calculate the critical punch-through depth and the critical bearing capacity are proposed for the convenience of engineering practice.

  2. Comparison of standard penetration test methods on bearing capacity of shallow foundations on sand

    Directory of Open Access Journals (Sweden)

    Scott Bernard Akpila

    2013-03-01

    Full Text Available A comparison of standard penetration test methods on bearing capacity analysis of shallow foundations on sand using analytical methods proposed by Parry, Meyerhof and modified Meyerhof has been carried out. The results showed three bound limits; upper, middle and lower bonds of net allowable bearing capacity, qn(a, values for isolated pad foundations placed on sand. Perry’s method gave higher values followed by the modified Meyerhof’s method and lastly by the Meyerhof’s method. Generally, qn(a showed a decreasing trend as foundation breadth and depth increased. The qn(a of modified Meyerhof’s model can be approximated by applying a factor of safety, FS, of 3.25 on Perry’s model. Similarly, qn(a of Meyerhof’s model can be approximated by applying a factor of safety, FS, of 2.0 on the modified Meyerhof’s model.

  3. Static Indentation Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2012-01-01

    The nickel-rich, binary nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt%), are emerging as viable materials for use in mechanical components like rolling element bearings and gears. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx.100 GPa). These properties result in the potential to endure extremely high indentation loads such as those encountered in bearings, gears and other mechanical components. In such applications, quantifying the load that results in permanent deformation that can affect component performance and life is important. In this paper, the static load capacity is measured by conducting indentation experiments in which 12.7 mm diameter balls made from the ceramic Si3N4 are pressed into highly polished, hardened 60NiTi flat plates. Hertz stress calculations are used to estimate contact stress. The results show that the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.6 microns deep) occurs. This load capacity is approximately twice that of high performance bearing steels suggesting that the potential exists to make highly resilient bearings and components from such materials.

  4. Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

    OpenAIRE

    Amin Keshavarz; Abdoreza Fazeli; Siavosh Sadeghi

    2016-01-01

    In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided...

  5. Static and dynamic bearing capacity of strip footings, under variable repeated loading

    OpenAIRE

    ARVIN, Mohammad Reza; ASKARI, Faradjollah; Farzaneh, Orang

    2012-01-01

    The problem of bearing capacity of strip footings is one of the basic and classical problems of geotechnical engineering. Footings under variable repeated loads are vulnerable to collapse due to accumulation of plastic strains or inadaptation. Unlike common limit state methods, the shakedown method can be applied to investigate the behavior of structures subjected to loads varying and repeating in time. In the present study, shakedown theory is employed to determine the static and dy...

  6. Application of pressuremeter measurements for the prediction of bearing capacity of verticaly loaded piles

    OpenAIRE

    Robas, Alenka

    2007-01-01

    Pressuremeter is an in situ test widely in operation in France, and in the last decade it has won recognition all over the world, as well as in Slovenia. Basically it is used to determinate the soil characteristics needed for the design of foundations. This thesis deals with the calculation of the bearing capacity of the vertically loaded piles using different methods based on pressuremeter measurements. The thesis deals only with buildings on deep foundations and because the u...

  7. Bearing Capacity of High Density Polyethylene (HDPE Reinforced Sand Using Plate Load Test

    Directory of Open Access Journals (Sweden)

    Er. Aly K

    2015-06-01

    Full Text Available The work presented here is a study to examine the improvement in bearing capacity of coastal sand of Trivandrum, Kerala, India using high density polyethylene (HDPE /woven fabric as reinforcement in discrete layers. The bearing capacity was evaluated using plate load test. The effect of reinforcement configurations like sheet reinforcement (sanded with adhesive, with adhesive and sheet alone and strip reinforcement (single and grid pattern are investigated. The test parameters chosen for the present study are, depth of topmost layer of reinforcement layer below footing, compacted density and number of layers of reinforcement etc. From the tests, it has been observed that sheet reinforcement is more effective than sheet sanded with adhesive and strip reinforcements. It is found that the synthetic adhesive gives no binding action at the interface of the reinforcement and soil. But it is to be noted that the sheet with adhesive dried has a marked influence on the bearing capacity especially at lower densities. The strip reinforcements in single pattern is considered to be a favorable choice for minimum reinforcement. The strip reinforcement in single or grid pattern gives sufficient improvement in strength.

  8. Evaluation of safe bearing capacity of soil foundation by using numerical analysis method

    Directory of Open Access Journals (Sweden)

    Abdoullah Namdar

    2014-10-01

    Full Text Available The soil mechanic laboratory results help in accurate soil foundation design and enhancement failure mitigation. The mixing soil design has been used in many geotechnical engineering for soil improvement. In this paper, several types of soil foundations have been made from mixed soil. The bearing capacity of soil foundations by using mixed soil parameters and change footing dimensions have been calculated. 180 footings, placed on 15 soil foundation types have been designed. It is assumed the underground water has not effect to bearing capacity of soil foundation. The results of numerical analysis and mixed soils technique have been combined. The numerical analysis has supported mixed soil design, and introduced an appropriate result for soil foundation design. The effects of mixed soil on depth and width of footing have been compared. The mixed soil design influenced numerical analysis result, and economically, soil foundation design helps to select the appropriate dimensions of footings. The result of numerical analysis supports geotechnical and structural engineering codes, predicts structural stability with different age, natural hazard and prevention as well as it is useful in understanding safe bearing capacity of soil foundation behavior.

  9. The influence of selecting the correlation model on soil parameters and bearing capacity

    Science.gov (United States)

    Pieczynska-Kozlowska, Joanna M.

    2016-04-01

    Consideration of soil spatial variability in the geotechnical design is still marginalized. The design process is based on taking the average parameters, which often results the oversize of geotechnical constructions. This procedure works until there are no geotechnical design problems. In most cases, geotechnical constructions represent a small percentage of the total investment so effects lacking developed of optimization procedures. If the optimization is needed requires the most accurate mapping of the soil. The basic background for statistical interpretation of soil spatially variables are Cone Penetration Tests, which represents variable nature of the soil with depth. Assuming the soil structure as a spatially random variable can be applied by description based on random fields. Field parameters are the probability distribution and correlation model dependent of a scale of fluctuation estimated from CPT. The main goal of this study is to contribute to the understanding on how the choice of correlation model affects random soil properties and for example shallow foundation bearing capacity. The study is particularly focused on scale of fluctuation as related to the reduction of bearing capacity. Scale of fluctuation were estimated using two effective methods: Vanmarcke and Rice. Soil properties were analyzed from 12 Cone Penetration Tests distributed throughout the regions of Świebodzice (Lower Silesia, Poland). While the project was developed in hilly terrain the macrolevelling were taken involving the displacement of native soil mass to form a working platform for shallow foundation. The construction of embankment has been tested by cone resistance tests to determine the parameters for the design. The procedure adopted to this study include the modeling soil variability from the CPT results and calculate the bearing capacity of shallow foundation using random finite element method and different correlation models. The aim of study was to answer questions

  10. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  11. Finite Element Analysis of the Effect on Edge Distance of the Tensile Bearing Capacity of Embedded Hanging Parts

    Directory of Open Access Journals (Sweden)

    Meng Xian Hong

    2016-01-01

    Full Text Available In order to explore the trend of tensile bearing capacity of embedded hanging parts when change the edge distance. Based on the finite element analysis software ABAQUS, the four simulation model was established. The buried depth and strength of concrete remain unchanged, but the edge distance was gradient change. By the load - displacement curve of every model known, the greater the edge distance, the greater the bearing capacity. When the edge distance reaches 1.5 times buried depth, the effect of increasing edge distance for improving the bearing capacity will be impaired.

  12. Hertzian Load-bearing Capacity of Hybrid and Nano-hybrid Resin Composites Stored Dry and Wet

    OpenAIRE

    Farmani S; Orandi S; Sookhakiyan M; Mese A

    2016-01-01

    Statement of Problem: Hertzian indentation test has been proven to be an efficient and reliable alternative upon Vickers hardness test. This method has been used to test dental ceramics, amalgams, glass ionomers and luting cements.There is limited published information about the load-bearing capacity of resin composites using Hertizian indentation test. Objectives: To investigate the load-bearing capacity of hybrid and nano-hybrid resin composites stored dry or wet up to 30 days, using ...

  13. Numerical simulation of the influence of soil core on the bearing capacity of pipe pile

    Directory of Open Access Journals (Sweden)

    G.Ya. Bulatov

    2010-03-01

    Full Text Available The cost of the foundation can be up to 20-30% of the total building cost. Reducing consumption of materials and quality selection of the required characteristics of the pile can reduce both the estimated cost and time of work.In terms of compact construction and the high land prices the most relevant is high-rise building. But it is hard to build in soft ground conditions (for example, in St. Petersburg. The situation is complicated by insufficiently explored methods of selection and design of piles (especially steel-tube piles for specific cases of construction, as well as by the absence of regulatory documents related to the high-performance technology.The article considers the clarification methods for calculating the bearing capacity of tubular steel piles. An additional contribution of soil core to the overall bearing capacity due to accounting an effect of its "natural" selflocking in the cavity of the steel pipe is considered.The conclusions about the effectiveness of the piles, depending on different initial parameters are made.

  14. Experimental research on ultimate bearing capacity of grouted-round-steel-tube N-joint

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wen-zhong; LIU Xu-dong; ZHANG Ge-ming; ZHANG Bo-yi

    2007-01-01

    As an important structural member in self-supporting concrete floor during construction, encased steel truss-concrete composite beam has brilliant prospect in outer-jacketing structures for adding stories or mega frame structures. Compared with encased angle truss, encased round steel tube truss can facilitate layout of itself in column and facilitate layout and anchorage of prestressed reinforcement placed horizontally. N-joint is wildly used in encased steel truss. For cave-in failure easily occurs in hollow steel-tube joint, the idea that the chord is grouted to increase cave-in bearing capacity of hollow tube is proposed. Test results of 8 grouted-roundsteel-tube N-joints from the beginning of loading to failure are reported. Mechanical property and failure mode of this kind of truss joint are analyzed, and the formulas of ultimate bearing capacity of the joint corresponding to different failure modes are established. All these can provide basic data for spreading encased steel truss-concrete composite beam.

  15. Effect of Bearing Capacity of Strip Footing on Reinforced Double Layer Soil System with Fly ash Stabilized Clayey Soil

    Directory of Open Access Journals (Sweden)

    Love Sharma

    2015-08-01

    Full Text Available This research was performed to investigate the effect of bearing capacity of strip footing on geogrid reinforced sand overlay on stabilized expansive soil (i.e. double layer soil system and check the different parameters contributing to their performance using laboratory model tank tests. The parameters investigated in this study include H/B (thickness of top sandy layer to width of footing u/B (location of the 1st layer of reinforcement to width of footing, h/B (vertical spacing between consecutive geogrid layers to width of footing, b/B (length of the geogrid layer to width of footing. The effect of different H/B ratios and geogrid reinforcement N values on the bearing capacity ration (BCR and settlement reduction ratio (SRR were also investigated. The results show that bearing capacity increases significantly with increasing the H/B ratio as well as number of geogrid layers. The bearing capacity for the soil increases with an average of 12.35% using H/B equal to0.5 and the bearing capacity increases with an average of 35.76%, 75.56% & 230.83% while using H/B equal to 1.0, 1.5 & 2.0. It also found that the use of sandy layers over flyash mixed clayey soil has a considerable effect on the bearing capacity characteristics and the use of geogrid layers in the granular overlay has remarkable effect on Bearing capacity ratio (BCR & Settlement reduction ratio (SRR.

  16. Ultimate bearing capacity and settlement of coal pillar sub-strata

    Energy Technology Data Exchange (ETDEWEB)

    Chugh, Y.P.; Pula, O.; Pytel, W.M. (Southern Illinois University, Carbondale, IL (USA). Dept. of Mining Engineering)

    1990-06-01

    This paper develops a rational approach for design of coal pillars under weak floor strata conditions considering ultimate bearing capacity (UBC) as well as pillar settlement. An approximate solution is presented for estimation of UBC for a shallow foundation on a two-layered rock system with consideration of both cohesion ({ital c}) and ({phi}) for both layers. Similarly, deformability underneath a full-size pillar is estimated from deformability calculated from plate loading tests. The effect of adjacent pillars on UBC and deformability of coal pillars in a panel is considered using foundation engineering analysis techniques. The design of pillars based on limiting settlements considers both differential settlements as well as mean settlement of pillar in a panel. An attempt is made to validate the proposed design approach based on field data and observations at an Illinois mine. 37 refs., 12 figs., 1 tab.

  17. Analysis of Bearing Capacity of Suction Bucket Foundation Subjected to Horizontal and Moment Loadings

    Directory of Open Access Journals (Sweden)

    W.U. Ke

    2013-07-01

    Full Text Available The suction bucket foundation is not only supporting the vertical loading such as the sea platform and weight itself, but also subjecting to horizontal and moment loading due to wind and wave. The response of bucket foundation to combined Horizontal (H and Moment (M loading has been studied using 3D finite element analysis Then the proposed method is numerically implemented in the framework of the general-purpose FEM software ABAQUS. Relationship curve between the coefficient of ultimate bearing capacity and displacement is obtained by the application of load-displacement controlled method in homogeneous soft foundation the failure envelope of foundation in the M-H is obtained by the application of swipe testing. The behavior is explained using upper bound plasticity mechanisms suggested by the soil deformation mechanisms observed in the finite element analysis. The numerical results computed by the proposed method will be helpful in engineering practices.

  18. Approximate solution of oil film load-carrying capacity of turbulent journal bearing with couple stress flow

    Science.gov (United States)

    Zhang, Yongfang; Wu, Peng; Guo, Bo; Lü, Yanjun; Liu, Fuxi; Yu, Yingtian

    2015-01-01

    The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half-speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational efforts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, which are suitable for high eccentricity ratios and heavy loads.

  19. Approximate Solution of Oil Film Load-carrying Capacity of Turbulent Journal Bearing with Couple Stress Flow

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yongfang; WU Peng; GUO Bo; L Yanjun; LIU Fuxi; YU Yingtian

    2015-01-01

    The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half-speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational efforts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, which are suitable for high eccentricity ratios and heavy loads.

  20. Development of bearing capacity of fine grained permafrost deposits in western greenland urban areas subject to soil temperature changes

    DEFF Research Database (Denmark)

    Agergaard, Frederik Ancker; Ingeman-Nielsen, Thomas

    2012-01-01

    The bearing capacity of frozen soils is high, compared to non-frozen soils of same composition. Projected climatic warming in the Arctic will increase the soil temperature, thus affecting the bearing capacity and the deformation properties. Western Greenland temperatures are projected to increase...... excess ice free samples. Unfrozen water contents are seen to be directly inversely proportional to the undrained shear strength when both are normalized, which may reduce costs for establishing reliable soil strength parameters. It is suggested that a relation to deformation parameters are investigated...

  1. DESIGN OF STRUCTURAL ELEMENTS IN THE EVENT OF THE PRE-SET RELIABILITY, REGULAR LOAD AND BEARING CAPACITY DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Tamrazyan Ashot Georgievich

    2012-10-01

    Full Text Available Accurate and adequate description of external influences and of the bearing capacity of the structural material requires the employment of the probability theory methods. In this regard, the characteristic that describes the probability of failure-free operation is required. The characteristic of reliability means that the maximum stress caused by the action of the load will not exceed the bearing capacity. In this paper, the author presents a solution to the problem of calculation of structures, namely, the identification of reliability of pre-set design parameters, in particular, cross-sectional dimensions. If the load distribution pattern is available, employment of the regularities of distributed functions make it possible to find the pattern of distribution of maximum stresses over the structure. Similarly, we can proceed to the design of structures of pre-set rigidity, reliability and stability in the case of regular load distribution. We consider the element of design (a monolithic concrete slab, maximum stress S which depends linearly on load q. Within a pre-set period of time, the probability will not exceed the values according to the Poisson law. The analysis demonstrates that the variability of the bearing capacity produces a stronger effect on relative sizes of cross sections of a slab than the variability of loads. It is therefore particularly important to reduce the coefficient of variation of the load capacity. One of the methods contemplates the truncation of the bearing capacity distribution by pre-culling the construction material.

  2. Toward the problem of oil and gas bearing capacity of the East Tom-Kolyvan structural zone (Western Siberia)

    International Nuclear Information System (INIS)

    The vast depression in the east Tom-Kolyvan folded zone (West Siberia) has been identified by the geophysical data. The well which uncovered 4000 m deep profile of the Jurassic and Paleozoic deposits has been drilled. The relevance of the research is the oil/gas-bearing capacity evaluation of the discovered depression in this West Siberia area

  3. Experimental research on the creep behavior and bearing capacity of repeatedly prestressed concrete beam

    Institute of Scientific and Technical Information of China (English)

    SHAO Xudong; LI Lifeng; YANG Jianjun

    2007-01-01

    In the prestress tensioning process of medium or short span prestressed concrete beam bridges,there are always many serious problems,such as the camber of straight beam being too large,curved beam going crosswise,and columns of rigid beam bridge cracking,that can be commonly seen because of its greater additional stress in prestressing.To solve the above problems,a new concept of repeatedly prestressed bridge structure was innovatively proposed in this work.It was proved,through theoretical and experimental comparison between this new structure and the traditional prestressed structure,that the application of repeated prestressing technology can greatly improve the mechanical and deformational performance of the low height beam during construction and long-term use.Furthermore,a kind of computational formula to calculate creep strain and deformation due to repeated prestressing in terms of time t was derived in this paper and the bearing capacity of this new structure has been tested.Finally,the work concludes that there is a bright application prospect for this new structure for medium and short span prestressed beam bridges to control deformations.

  4. Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System

    Science.gov (United States)

    Mukoyama, Shinichi; Matsuoka, Taro; Furukawa, Makoto; Nakao, Kengo; Nagashima, Ken; Ogata, Masafumi; Yamashita, Tomohisa; Hasegawa, Hitoshi; Yoshizawa, Kazuhiro; Arai, Yuuki; Miyazaki, Kazuki; Horiuchi, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pan-cake coils was obtained to a satisfactory force of 39.2 kN (4 tons).

  5. Influence of particles on the loading capacity and the temperature rise of water film in Ultra-high speed hybrid bearing

    Science.gov (United States)

    Zhu, Aibin; Li, Pei; Zhang, Yefan; Chen, Wei; Yuan, Xiaoyang

    2015-04-01

    Ultra-high speed machining technology enables high efficiency, high precision and high integrity of machined surface. Previous researches of hybrid bearing rarely consider influences of solid particles in lubricant and ultra-high speed of hybrid bearing, which cannot be ignored under the high speed and micro-space conditions of ultra-high speed water-lubricated hybrid bearing. Considering the impact of solid particles in lubricant, turbulence and temperature viscosity effects of lubricant, the influences of particles on pressure distribution, loading capacity and the temperature rise of the lubricant film with four-step-cavity ultra-high speed water-lubricated hybrid bearing are presented in the paper. The results show that loading capacity of the hybrid bearing can be affected by changing the viscosity of the lubricant, and large particles can improve the bearing loading capacity higher. The impact of water film temperature rise produced by solid particles in lubricant is related with particle diameter and minimum film thickness. Compared with the soft particles, hard particles cause the more increasing of water film temperature rise and loading capacity. When the speed of hybrid bearing increases, the impact of solid particles on hybrid bearing becomes increasingly apparent, especially for ultra-high speed water-lubricated hybrid bearing. This research presents influences of solid particles on the loading capacity and the temperature rise of water film in ultra-high speed hybrid bearings, the research conclusions provide a new method to evaluate the influence of solid particles in lubricant of ultra-high speed water-lubricated hybrid bearing, which is important to performance calculation of ultra-high speed hybrid bearings, design of filtration system, and safe operation of ultra-high speed hybrid bearings.

  6. Influence of Particles on the Loading Capacity and the Temperature Rise of Water Film in Ultra-high Speed Hybrid Bearing

    Institute of Scientific and Technical Information of China (English)

    ZHU Aibin; LI Pei; ZHANG Yefan; CHEN Wei; YUAN Xiaoyang

    2015-01-01

    Ultra-high speed machining technology enables high efficiency, high precision and high integrity of machined surface. Previous researches of hybrid bearing rarely consider influences of solid particles in lubricant and ultra-high speed of hybrid bearing, which cannot be ignored under the high speed and micro-space conditions of ultra-high speed water-lubricated hybrid bearing. Considering the impact of solid particles in lubricant, turbulence and temperature viscosity effects of lubricant, the influences of particles on pressure distribution, loading capacity and the temperature rise of the lubricant film with four-step-cavity ultra-high speed water-lubricated hybrid bearing are presented in the paper. The results show that loading capacity of the hybrid bearing can be affected by changing the viscosity of the lubricant, and large particles can improve the bearing loading capacity higher. The impact of water film temperature rise produced by solid particles in lubricant is related with particle diameter and minimum film thickness. Compared with the soft particles, hard particles cause the more increasing of water film temperature rise and loading capacity. When the speed of hybrid bearing increases, the impact of solid particles on hybrid bearing becomes increasingly apparent, especially for ultra-high speed water-lubricated hybrid bearing. This research presents influences of solid particles on the loading capacity and the temperature rise of water film in ultra-high speed hybrid bearings, the research conclusions provide a new method to evaluate the influence of solid particles in lubricant of ultra-high speed water-lubricated hybrid bearing, which is important to performance calculation of ultra-high speed hybrid bearings, design of filtration system, and safe operation of ultra-high speed hybrid bearings.

  7. Progressive collapse resisting capacity of reinforced concrete load bearing wall structures

    Institute of Scientific and Technical Information of China (English)

    Alireza Rahai; Alireza Shahin; Farzad Hatami

    2015-01-01

    Reinforced concrete (RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the “load factor” parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.

  8. Hertzian Load-bearing Capacity of Hybrid and Nano-hybrid Resin Composites Stored Dry and Wet

    Directory of Open Access Journals (Sweden)

    Farmani S

    2016-03-01

    Full Text Available Statement of Problem: Hertzian indentation test has been proven to be an efficient and reliable alternative upon Vickers hardness test. This method has been used to test dental ceramics, amalgams, glass ionomers and luting cements.There is limited published information about the load-bearing capacity of resin composites using Hertizian indentation test. Objectives: To investigate the load-bearing capacity of hybrid and nano-hybrid resin composites stored dry or wet up to 30 days, using Hertzian indentation test. Materials and Methods: Three resin composites were used: two nano-hybrids (Filtek Supreme, and Luna and one hybrid, (Rok. A total of 108 disc-shaped specimens (1mm thick x 10 mm diameter were prepared using polyethylene mould. The specimens of each material were randomly divided into 6 groups of 6 (n=6 and stored at 370C either in distilled water or dry for 1, 7 and 30 days. The specimens were tested using Hertzian jig aligned in the universal testing machine. The specimen was placed on the top of a disc-shaped substrate. The load was applied at the center of each specimen and the load at the first crack was recorded. Data were analyzed by ANOVA, Tukey’sand student’s t-test using SPSS version 18.0. Results: Three-way ANOVA showed a significant interaction between all the factors (p = .0001. The load bearing capacity of almost all materials reduced significantly in the wet condition in comparison with the dry condition (p = .0001. After seven days of immersion in distilled water, Filtek Supreme had significantly lower values than those of Rok and Luna, there was no significant differences between materials in the dry condition. Conclusions:In contrast to dry condition, the load-bearing capacity of specimens stored in distilled water decreased significantly over the 30 days of immersion. The load bearing capacity of nano-hybrid composites tested in this study was shown to be comparable with that of the hybrid composite.

  9. Study on Failure Mechanism and Bearing Capacity of Three-Dimensional Rectangular Footing Subjected to Combined Loading

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper presents two kinematic failure mechanisms of three-dimensional rectangular footing resting on homogeneous undrained clay foundation under uniaxial vertical loading and uniaxial moment loading. The failure mechanism under vertical loading comprises a plane strain Prandtl-type mechanism over the central part of the longer side, and the size of the mechanism gradually reduces at the ends of the longer side and over the shorter side as the corner of rectangular footing is being approached where the direction of soil motion remains normal to each corresponding side respectively. The failure mechanism under moment loading comprises a plane strain scoop sliding mechanism over the central part of the longer side, and the radius of scoop sliding mechanism increases linearly at the ends of the longer side. On the basis of the kinematic failure mechanisms mentioned above, the vertical ultimate bearing capacity and the ultimate bearing capacity against moment or moment ultimate bearing capacity are obtained by use of upper bound limit analysis theory. At the same time, numerical analysis results, Skempton's results and Salgado et al.'s results are compared with this upper bound solution. It shows that the presented failure mechanisms and plastic limit analysis predictions are validated. In order to investigate the behaviors of undrained clay foundation beneath the rectangular footing subjected to the combined loadings, numerical analysis is adopted by virtue of the general-purpose FEM software ABAQUS, where the clay is assumed to obey the Mohr-Coulomb yielding criterion. The failure envelope and the ultimate bearing capacity are achieved by the numerical analysis results with the varying aspect ratios from length L to breadth B of the rectangular footing. The failure mechanisms of rectangular footing which are subjected to the combined vertical loading V and horizontal loading H (Vertical loading V and moment loading M, and horizontal loading H and moment loading M

  10. Determination of Load Bearing Capacity for Spatial Joint with Steel Angle Brackets

    Science.gov (United States)

    Sejkot, P.; Ormarsson, S.; Vessby, J.; Kuklík, P.

    2015-11-01

    The design of spatial connections in load bearing timber structures with steel angle brackets has insufficient support in the existing design standards. Therefore, research has been necessary to improve this state of the art. In the current paper an experimental study on two designs of angle brackets is presented and the results from full-scale experiments are compared to numerical and analytical computational models.

  11. Numerical Analyses of Bearing Capacity of Deep-Embedded Large-Diameter Cylindrical Structure on Soft Ground Against Lateral Loads

    Institute of Scientific and Technical Information of China (English)

    LUAN Mao-tian; FAN Qing-lai

    2006-01-01

    Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotropic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill's criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.

  12. Reliability Analysis of Bearing Capacity of Square Footing on Soil with Strength Anisotropy Due to Layered Microstructure

    Directory of Open Access Journals (Sweden)

    Kawa Marek

    2015-12-01

    Full Text Available The paper deals with reliability analysis of square footing on soil with strength anisotropy. The strength of the soil has been described with identified anisotropic strength criterion dedicated to geomaterials with layered microstructure. The analysis assumes dip angle α and azimuth angle β which define direction of lamination of the structure to be random variables with given probability density functions. Bearing capacity being a function of these variables is approximated based on results of deterministic simulations obtained for variety of orientations. The weighted regression method by Kaymaz and McMahon within the framework of Response Surface Method is used for the approximation. As a result of analysis, global factor of safety that corresponds to assumed value of probability of failure is determined. The value of the safety factor denotes the ratio between the value of the design load and the mean value of bearing capacity which is needed to reduce the probability of failure to the acceptable level. The procedure of calculating the factor has been presented for two different cases. In the first case, no information about lamination direction of the soil has been provided and thus all the orientations are assumed to be equally probable (uniform distribution. In the second case, statistical information including mean, variance and assumed probability distribution for both α and β angle is known. For the latter case, using results obtained for few different values of mean of angle α, also the influence of strength anisotropy on the value of global factor of safety is shown.

  13. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    OpenAIRE

    Laura Garach; Mónica López; Francisco Agrela; Javier Ordóñez; Javier Alegre; José Antonio Moya

    2015-01-01

    Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new ceme...

  14. Embedment Effects on the Vertical Bearing Capacity of Offshore Bucket Foundations on Cohesionless Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo; Ghalesari, Abbasali Taghavi;

    2016-01-01

    This paper presents the results from a series of physical modeling and three-dimensional finite 9 element (FE) analyses, which examined the uniaxial vertical capacity of suction caissons for 10 offshore wind turbines. The experiments were carried out in quartz sand and involved monotonic 11 appli...... and FE analyses, new expressions for depth factor of shallow foundations have 15 been validated for embedment ratios (aspect ratios) up to unity, calibrating the fitting parameters 16 by employing data from a range of soil profiles....... application of vertical load. It was found that the drained capacity of suction caissons is 12 dependent on embedment ratio. On the other hand, predictions from conventional semi-empirical 13 depth factors were found to somewhat underestimate when applied to rough foundations. On the 14 basis of the tests...

  15. Embedment Effects on the Vertical Bearing Capacity of Offshore Bucket Foundations on Cohesionless Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo; Ghalesari, Abbasali Taghavi;

    2016-01-01

    application of vertical load. It was found that the drained capacity of suction caissons is 12 dependent on embedment ratio. On the other hand, predictions from conventional semi-empirical 13 depth factors were found to somewhat underestimate when applied to rough foundations. On the 14 basis of the tests...... and FE analyses, new expressions for depth factor of shallow foundations have 15 been validated for embedment ratios (aspect ratios) up to unity, calibrating the fitting parameters 16 by employing data from a range of soil profiles....

  16. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    Directory of Open Access Journals (Sweden)

    Laura Garach

    2015-12-01

    Full Text Available Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

  17. On Bearing Capacity of the Tourism Environment in China%我国旅游环境承载力研究综述

    Institute of Scientific and Technical Information of China (English)

    吴夏楠; 黄倩辉

    2014-01-01

    The development of tourism industry in China shows that the bearing capacity of the tourism environment is a problem for the sustainable development of the tourism industry. The paper systematically reviews the research of theo-retical principles, methods of measurement, practical bearing capacity of the tourism environment in China and the pros-pect of the development trend, which is a summarization of the bearing capacity of tourism environment in China.%文章通过文献法,分别从基础理论、测量方法、实证和发展趋势四个方面,对我国学术界关于旅游环境承载力研究进行了综述。

  18. Methods of calculating the bearing capacity of eccentrically compressed concrete elements and suggestions for its improvement

    Directory of Open Access Journals (Sweden)

    Starishko Ivan Nikolaevich

    2014-03-01

    Full Text Available The proposed calculation method is specific in terms of determining the carrying capacity of eccentrically compressed concrete elements, in contrast to the calculation by error method, as in the existing regulations, where in the result of the calculation is not known what is the limit load the eccentric compression element can withstand. The proposed calculation method, the publication of which is expected in the next issue of the "Vestnik MGSU" the above mentioned shortcomings of the existing calculation methods, as well as the shortcomings listed in this article are eliminated, which results in the higher convergence of theoretical and experimental results of eccentrically compressed concrete elements strength and hence a high reliability of their operation.

  19. Analysis of the Ultimate Bearing Capacity of Oil Field Drilling Masts%在役钻机井架极限承载性能分析

    Institute of Scientific and Technical Information of China (English)

    韩东颖; 周国强; 李子丰

    2005-01-01

    In order to improve the safety of drilling operations, this paper presents a new method for forecasting the ultimate bearing capacity of oil field drilling masts. The method is based on a double nonlinear finite element theory and applies a referential stress method for measuring defects and defacements. The lab mast model was analyzed using the proposed method. The relative error, which was less than 5.0% between the forecast results and the destructive experiment values,verified the correctness of this method. It also forecasts the ultimate bearing capacity for a local drilling mast.

  20. Screw anchor used in closure work and its bearing capacity%堵口用螺旋锚及其承载力

    Institute of Scientific and Technical Information of China (English)

    汪滨; 洪晓林; 陈基成

    2001-01-01

    The bearing capacity mechanism and affecting factors of screw anchors are described. Laboratory experiments show that the anti-lifting force and horizontal bearing capacity of screw anchors are higher than those of steel pipes with the same diameter. Modified screw anchors are suitable to the closure work.%分析了螺旋锚的承载机理和影响其承载力的因素.室内试验表明,螺旋锚的抗拔力和水平承载力优于同杆径的钢管.经改进的螺旋锚适用于堵口抢险工程.

  1. Analysis on Bearing Capacity of Tunnel-Type Anchorage of a Long-Span Suspension Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhu Yu; Wei Jun; Yang Manjuan; Li Hao; Liu Hongqing

    2005-01-01

    Due to complicated rock structure and environment, a prototype test for a tunnel-type anchorage is infeasible. Based on the rock mass parameters from tests, a three-dimensional (3D) elasto-plastic analysis was performed to simulate the influence of the construction procedure of Siduhe bridge with tunnel-type anchorage (TTA) in Hubei Province, China. The surrounding rock and concrete anchorage body were simulated by 8 nodes 3D brick elements. The geostatic state of the complex geometric structure was established with initial data. The in-situ concrete casting of the anchorage body and excavation of the rock mass were simulated by tetrahedral shell elements. The results show that the surrounding rock is in an elastic state under the designed cable force. The numerical overloading analysis indicates that the capacity of the surrounding anchorage is 7 times that of the designed cable force. The failure pattern shows that two anchorage bodies would be pulled out in the end. The maximum shear stress appears 10 m before the back anchorage face. The maximum range influenced by the TTA under ultimate loads is about 16 m.

  2. Least Limiting Water Range and Load Bearing Capacity of Soil under Types of Tractor-Trailers for Mechanical Harvesting of Green Sugarcane

    Directory of Open Access Journals (Sweden)

    Antonio Higino Frederico Pereira

    2015-12-01

    Full Text Available ABSTRACT The expansion of the sugarcane industry in Brazil has intensified the mechanization of agriculture and caused effects on the soil physical quality. The purpose of this study was to evaluate the limiting water range and soil bearing capacity of a Latossolo Vermelho distroférrico típico (Rhodic Hapludox under the influence of different tractor-trailers used in mechanical sugarcane harvesting. The experiment was arranged in a randomized block design with five replications. The treatments consisted of green sugarcane harvesting with: harvester without trailer (T1; harvester with two trailers with a capacity of 10 Mg each (T2; harvester with trailer with a capacity of 20 Mg (T3 and harvester and truck with trailer with a capacity of 20 Mg (10 Mg per compartment (T4. The least limiting water range and soil bearing capacity were evaluated. The transport equipment to remove the harvested sugarcane from the field (trailer at harvest decreased the least limiting water range, reducing the structural soil quality. The truck trailer caused the greatest impact on the soil physical properties studied. The soil load bearing capacity was unaffected by the treatments, since the pressure of the harvester (T1 exceeded the pre-consolidation pressure of the soil.

  3. The influence of framework design on the load-bearing capacity of laboratory-made inlay-retained fibre-reinforced composite fixed dental prostheses

    NARCIS (Netherlands)

    F. Keulemans; L.V.J. Lassilla; S. Garoushi; P.K. Vallittu; C.J. Kleverlaan; A.J. Feilzer

    2009-01-01

    Delamination of the veneering composite is frequently encountered with fibre-reinforced composite (FRC) fixed dental prosthesis (FDPs). The aim of this study is to evaluate the influence of framework design on the load-bearing capacity of laboratory-made three-unit inlay-retained FRC-FDPs. Inlay-ret

  4. 爆炸荷载下桩基竖向动承载力研究%Study on vertical bearing capacity of pile foundation under blast loading

    Institute of Scientific and Technical Information of China (English)

    王后裕; 姚焕忠; 言志信; 张剑寒; 杨进勇

    2013-01-01

    针对地面抗爆工程建设中桩基设计问题,采用动三轴试验、动力有限元方法等手段,开展了爆炸作用下地基土的动力特性及桩基抗爆承载力研究,结果表明桩基竖向极限抗爆承载力为其竖向极限静承载力2倍以上,高于按照现行桩基规范得到的1.25 ~1.5倍范围值,表明将常规抗震设计的办法直接用于抗爆炸冲击荷载的桩基设计时偏保守.%For the problem of pile foundation design of ground protective projects subjected to blast loading,a series of resrearches of dynamic property of soil and bearing capacity of pile under shock waves are carried out by the methods of dynamic triaxial test and dynamic FEM and so on.The result shows that the dynamic bearing capacity of pile is two times greater than that of static bearing capacity and 1.25 ~ 1.5 times greater than that of current pile code method.Therefore it is conservative to estimate the dynamic bearing capacity of pile with current pile code method.

  5. An Investigation on Load Bearing Capacities of Cement and Resin Grouted Rock Bolts Installed in Weak Rocks

    Science.gov (United States)

    Kalyoncu Erguler, Guzide; Abiddin Erguler, Zeynal

    2015-04-01

    Rock bolts have been considered one of indispensable support method to improve load bearing capacity of many underground engineering projects, and thus, various types of them have been developed until now for different purposes. Although mechanically anchored rock bolts can be successfully installed to prevent structurally controlled instabilities in hard rocks, in comparison with cement and resin grouted rock bolts, these types of anchors are not so effective in weak rocks characterized by relatively low mechanical properties. In order to investigate the applicability and to measure relative performance of cement and resin grouted rock bolts into weak and heavily jointed rock mass, a research program mainly consisting of pull-out tests was performed in a metal mine in Turkey. The rock materials excavated in this underground mining were described as basalt, tuff, ore dominated volcanic rocks and dacite. To achieve more representative results for rock materials found in this mining and openings excavated in varied dimensions, the pull-out tests were conducted on rock bolts used in many different locations where more convergences were measured and deformation dependent instability was expected to cause greater engineering problems. It is well known that the capacity of rock bolts depends on the length, diameter and density of the bolt pattern, and so considering the thickness of plastic zone in the studied openings, the length and diameter of rock bolts were taken as 2.4 m. and 25 mm., respectively. The spacing between rows changed between 70 and 180 cm. In this study, totally twenty five pull-out tests were performed to have a general understanding about axial load bearing capacity and support reaction curves of cement and resin grouted rock bolts. When pull load-displacement curves belongs to cement and resin grouted rock bolts were compared with each other, it was determined that cement grouted rock bolts carry more load ranging between 115.6 kN and 127.5 kN with

  6. 拱撑门架承载力试验及有限元分析%EXPERIMENTS AND FEM ANALYSIS FOR BEARING CAPACITY OF ARCH SUPPORT PORTALFRAME

    Institute of Scientific and Technical Information of China (English)

    阎奇武; 黄伟; 杨承惁; 杨棣柔; 陈杰刚

    2012-01-01

    为确定单榀拱撑内门架承载力,进行拱撑门架和MF1219门架承载力非线性有限元分析和拱撑门架承载力试验。利用ANSYS软件建立拱撑门架模型和MF1219门架模型,进行特征值屈曲分析,得到各计算模型的承载力。拱撑门架立杆低端铰接,在两立杆上端或上横杆拱形加强杆两端对应位置处进行分级竖向加载,进行了8榀拱撑门架承载力试验。选择JGJ 128—2010《建筑施工门式钢管脚手架安全技术规范》中门架承载力公式进行了单榀拱撑门架承载力计算,并对门架承载力有限元分析、试验和公式计算结果进行了比较。建议:拱撑门架宜立杆直接受力,拱撑门架立杆受力承载力可采用JGJ 128—2010中5.2.1-8a计算,拱撑门架上端横杆受力承载力折减系数宜取0.3。%In order to determine the bearing capacity of single arch support inner portalframe,experiments on the bearing capacity of single arch support portalframe and nonlinear FEM analysis of the bearing capacity of single arch support portalframe and single MF1219 portalframe were carried out.Models of single arch support portalframe and single MF1219 portalframe were set up using ANSYS software,their eigenvalue buckling analysis was done,and their bearing capacity was obtained.Loading in grades on top ends of two uprights or the corresponding positions of both ends of the arch strengthened rod of single arch support portalframe,in which low ends of two uprights were articulated,8 single arch support portalframes bearing capacity tests were conducted.Different portalframe bearing capacity formula in JGJ 128—2010 Technical Code of Portal Steel Pipe Scalffold for Building Construction was selected,and the single arch support bearing capacity was calculated.After the results of FEM analysis,experiment and calculation of bearing capacity of single portalframe were contrasted,it was proposed that forces should act on top ends of two uprights

  7. Bearing capacity of compressed continuous and perforated thin-walled steel members of C-shaped cold-formed profiles

    Directory of Open Access Journals (Sweden)

    T.V. Nazmeeva

    2013-08-01

    Full Text Available Nowadays there is steady rising demand for thin-walled light-weight steel structures. But the shortage of relevant standards on their design and use taking into account Russian conditions leads to the current situation when thin-walled light-weight steel structures are used according to the recommended guidelines of thin-walled structures’ producers. The author performed numerical and experimental investigations on general stability and bearing capacity of members of different length which are made of C-shaped profile and C-shaped perforated profile. The main aim of the investigations was to receive a reliable engineering methodology of their calculation. The author developed the testing methodology and designed two test beds С-12 (1200mm/20t and В-50 (2200mm/50t to perform the experimental investigation. Numerical solution for stability of thin-walled member made of C-shaped profile was received during the numerical simulation done in PLM Femap 10.1 Nastran. Subsequently the processing of research results will be continued in order to get the corresponding dependences for development of method for calculating thin-walled members under compression.

  8. Comparison of Effects of Using Geosynthetics and Lime Stabilization to Increase Bearing Capacity of Unpaved Road Subgrade

    Directory of Open Access Journals (Sweden)

    Erhan Burak Pancar

    2016-01-01

    Full Text Available So many soil improvement methods have been developed in order to increase bearing capacity of superstructure of the road to be constructed on the soft clayey road base soils, decrease settlements, and increase other strength specifications (CBR, k, MR values, etc.. In this paper, lime stabilization of clayey road base soil with high water content and its improvement with geosynthetics (geocell + geotextile reinforcement and comparisons of these two different improvement methods were made. For this purpose, plate loading experimental comparisons of clayey soil, which had high water content by 10% increasing the optimum water content, were made after it was improved with lime at the rates of 3, 6, and 12%, geotextile reinforcement, geocell reinforcement, geosynthetics reinforcement, and geosynthetics reinforcement + lime stabilization at various rates. It was understood that these improvement methods will not yield sufficient results on clayey soils with high water content on their own, and method of improvement with lime and then reinforcement with geosynthetics yields better results on these types of soils. Only one improvement state among ten different states examined in this study gave the sufficient results for the soil to be used for unpaved roads.

  9. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GigaPascals) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 millimeters diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  10. 滚压成型灌注螺纹桩承载性能研究%Bearing Capacity Behavior of Roll Forming Filling Screw Pile

    Institute of Scientific and Technical Information of China (English)

    徐学燕; 于琳琳; 刘复孝

    2011-01-01

    采用静载荷试验及数值计算相结合的方法进行了螺纹桩承载性能的研究.分析了螺齿宽度、螺距等桩型参数对螺纹桩承载性能的影响,对外径相同的直径桩与螺纹桩的承载性能进行了静载荷对比试验研究.螺纹桩单桩极限承载力较相同桩外径的直型桩极限承载力稍高,螺齿宽度对螺纹桩的极限承载力影响非常明显,随螺齿宽度的增加螺纹桩的极限承载力增大;螺距对极限承载力影响也较为明显,随螺距的减小,螺纹桩的极限承载力增大.螺纹桩在低荷载水平下,桩侧阻力沿桩身均匀发挥,桩端阻力较小,随荷载水平的增大,桩端阻力大幅提高,并提出螺纹桩承载力的计算公式.%Bearing capacity behavior of roll forming filling screw pile (screw pile for short) is investigated through numerical calculation and static load test. The influence of pile-type parameters, such as width of thread tooth and thread pitch, on the ultimate bearing capacity of crew pile is studied; furthermore, the bearing capacity behavior of screw pile and that of pile with the same diameter are compared and analyzed through static load test. The results show that the ultimate bearing capacity of screw pile is a bit higher than that of pile with the same outside diameter; width of thread tooth has a distinct effect on ultimate bearing capacity which increases with the increment of width of thread tooth. When the screw pile is tested under light load, the resistance on pile side is distributed along screw pile, and tip resistance is small, but the resistance rises considerably with load increasing. Besides, the design formula of bearing capacity of screw pile is proposed.

  11. Experimental Study on Uplift Bearing Capacity of Micropiles for Transmission Tower%微型桩杆塔基础上拔试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 陈培; 鲁先龙

    2011-01-01

    Field tests were done to study the uplift bearing mechanism and the uplift design method of micropiles. Study shows that the uplift bearing capacity of single pile is composed of pile weight and lateral friction; the second grouting can increase the uplift bearing capacity of micropiles, calculating the uplift bearing capacity of two-grouting micropiles must consider the effect of the second grouting; the obliquity of inclined piles in the micropile group can be 10°; under uplift load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is minimum; in this experimental condition, the uplift pile group effect coefficient is 0. 7.%通过现场真型试验,对微型桩基础抗拔承载机理及其抗拔承载力计算方法进行了研究.试验研究表明:微型桩单桩抗拔承载力可由桩身自重和桩周侧摩阻力相加组成;二次注浆有利于提升微型桩抗拔承载力,在进行微型桩抗拔承载力计算时应考虑二次注浆的提升作用;群桩基础中布置斜桩可采用10度倾角;由于承台对上拔荷载的重分配,在上拔荷载作用下,角桩承力最大,边桩次之,中桩最小;本次试验条件下,微型桩抗拔群桩效应系数可取0.7进行计算.

  12. HRBF500钢筋混凝土柱轴压试验研究%EXPERIMENT ON BEARING CAPACITY OF REINFORCED CONCRETE COLUMN WITH HRBF500

    Institute of Scientific and Technical Information of China (English)

    杨勇新; 赵进阶; 岳清瑞; 廉杰

    2009-01-01

    对7个配置HRBF500级钢筋混凝土柱进行轴压试验,研究不同混凝土强度、配筋率、长细比等参数下构件的破坏形态、承载力.结果表明,配置HRBF500级钢筋混凝土柱的承载力按照目前规范公式计算是可行的.%The experiment on 7 columns with HRBF500 under axial load was done, whose failure mode and bearing capacity subjected to different parameters such as concrete strength, ratio of reinforcement and slenderness ratio have been studied. The results show that the bearing capacity of reinforced concrete short column with HRBF500 is feasible according to the current code.

  13. 大尺寸钢管混凝土柱承载力试验%Bearing Capacity Test of Large Size Concrete Filled Steel Tubular Column

    Institute of Scientific and Technical Information of China (English)

    陈彦江; 李勇; 闫维明; 潘迪

    2011-01-01

    为了探讨大尺寸钢管混凝土柱的初始偏心和开洞插管初始缺陷对其承载力的影响规律,以某钢管混凝土拱桥主拱肋Φ1 200×24 mm钢管为原型,采用1∶2.4,1∶4.8两种几何比例尺分别制作了长径比为3∶1的钢管混凝土柱试件,进行了轴压和偏压试验,并将承载力试验结果与中国现行相关规范的承载力计算结果进行了对比。结果表明:钢管混凝土柱的承载力试验值均大于规范计算值,大尺寸试件和小尺寸试件轴压承载力与规范的比值相差不大,但是大尺寸试件的屈服应力较高,开洞插管的试件由于内插钢管的屈服失效而导致整体试件屈服应力较低;C%In order to study the bearing capacity of large size concrete filled steel tubular(CFST) columns and the influence of initial eccentricity and imperfection of opening hole and insertion pipe on the column,taking a main arch rib Φ1 200×24 mm of a CFST arch bridge as research prototype,authors designed ten CFST column specimens whose draw ratios are 3∶1.According to different scales of 1∶2.4 and 1∶4.8,the axial and eccentric compression tests were carried out,and comparisons on test values and calculated values by several domestic codes for bearing capacity were made.Result shows that test values are all larger than the calculated values for bearing capacity of CFST column,and the ratio of bearing capacity of large size specimen and calculated value is almost same to the ratio of bearing capacity of small size specimen and calculated value.However,yield stress of the large size specimen is larger than that of the small size specimen,and the specimen with opening hole has the smaller yield stress because of the smaller yield stress of the insertion pipe.The calculated values of bearing capacity according to the code CECS 28:90 is closer to the test value,while the safety factor of the bearing capacity calculated by the code DL/T 5085—1999 is the largest

  14. Bearing capacity of solid waste ground reinforced by stone column%用于垃圾土地基加固的碎石桩承载力

    Institute of Scientific and Technical Information of China (English)

    高海; 施建勇; 王蕊

    2011-01-01

    根据现有垃圾土地基碎石桩处理的试验,发现其破坏形式为桩体的侧向鼓胀;假设桩周垃圾土因桩的侧向鼓胀达到朗肯被动破坏状态,且不计地基垃圾土和桩身自重,由桩、桩周垃圾土的极限平衡,可以得到桩的极限承载力理论计算公式;依据已经进行的相关试验和参考资料确定公式中的计算参数,计算出桩的极限承载力;同时进行了桩身重型动力触探试验,可以由贯入击数推求承载力的特征值;经过理论计算与原位试验结果对比分析,两者比较接近.%Based on presented tests of improvement of solid waste ground by stone column, the failure mode of lateral expansion of column body can be found. It is assumed that solid waste surrounding column is in Rankin’s positive limit situation caused by lateral expansion of column body, self weight solid waste and column is neglected, the calculation theory of limit bearing capacity of stone column can be extended on equilibrium of solid waste and column. The limit bear capacity of stone column can be calculated on parameters by complete tests and reference data. The heavy dynamic penetration tests were finished in stone column and the characteristic value of bearing capacity can be recommended on blow count. It is shown that bearing capacities of calculation and field test are close.

  15. Least Limiting Water Range and Load Bearing Capacity of Soil under Types of Tractor-Trailers for Mechanical Harvesting of Green Sugarcane

    OpenAIRE

    Antonio Higino Frederico Pereira; Antonio Carlos Tadeu Vitorino; Eber Augusto Ferreira do Prado; Anderson Cristian Bergamin; Munir Mauad; Heverton Ponce Arantes

    2015-01-01

    ABSTRACT The expansion of the sugarcane industry in Brazil has intensified the mechanization of agriculture and caused effects on the soil physical quality. The purpose of this study was to evaluate the limiting water range and soil bearing capacity of a Latossolo Vermelho distroférrico típico (Rhodic Hapludox) under the influence of different tractor-trailers used in mechanical sugarcane harvesting. The experiment was arranged in a randomized block design with five replications. The treatmen...

  16. Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2 before and after cyclic mechanical loading

    Directory of Open Access Journals (Sweden)

    Marc Philipp Dittmer

    2013-07-01

    Full Text Available Implant-supported screw-retained fixed dental prostheses (FDPs produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. OBJECTIVE: The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. MATERIAL AND METHODS: Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation. One half of the specimens was tested for static load-bearing capacity without any further treatment (control, whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test. All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05. RESULTS: All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control to 7,592 N±901 N (test. The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060. The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. CONCLUSION: The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional

  17. Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading

    Science.gov (United States)

    DITTMER, Marc Philipp; NENSA, Moritz; STIESCH, Meike; KOHORST, Philipp

    2013-01-01

    Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. Objective The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. Material and Methods Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05). Results All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. Conclusion The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo

  18. Calculation of Bearing Capacity of Geosynthetic-encased Stone Columns%加筋碎石桩承载力计算

    Institute of Scientific and Technical Information of China (English)

    赵明华; 陈庆; 张玲; 马缤辉

    2011-01-01

    The bearing mechanism of composite foundation of geosynthetic-encased stone columns was analyzed, and several kinds of failure mode of the composite foundation were investigated. In different failure modes, according to the limit equilibrium theory, a calculation formula of the ultimate bearing capacity of single geosynthetic-encased stone column was proposed. Failure mode 1 is mainly controlled by the tensile strength of geogrid sleeve, and failure mode 2 is controlled by the pile-lateral friction of geosynthetic-encased stone column and the end bearing capacity of common stone column before the damage of swelling deformation. The example of calculation indicates that the (1) bearing capacity of geosynthetic-encased stone column has significantly improved than that of common stone column; (2) the reinforcing depth of geosynthetic-encased stone column and the tensile strength of geogrid sleeve have a best combination for the most rational using of geogrid to improve the bearing capacity of the stone columa At last, the geosynthetic-encased stone columns were applied to treatment of weak subgrade of expressway.%分析了加筋碎石桩复合地基的承载机理,探讨了加筋碎石桩复合地基的几种破坏模式.在不同的破坏模式下根据极限平衡理论导出了加筋碎石桩单桩极限承载力计算公式,破坏模式1主要由格栅套筒抗拉强度控制,破坏模式2由加筋段桩体侧摩阻力和非加筋段桩体鼓胀破坏前向上提供的端承力共同控制.实例计算表明,加筋碎石桩的承载力比普通碎石桩的承载力有显著提高,且加筋碎石桩的加筋深度与格栅抗拉强度之间有最优组合,最合理地利用加筋格栅提高碎石桩承载力,最后将加筋碎石桩应用到了高速公路软基处治中.

  19. 轮胎桩复合地基承载性能研究%Numerical Simulation Research on Bearing Capacity of Rubber Tire Pile Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    王凤池; 高寰; 张明; 董明

    2015-01-01

    In order to improve the utilization of waste tires and the bearing capacity of the composite foundation ,a new type of composite foundation with rubber tire piles was put forward .Based on the laboratory test data ,the bearing capaci-ty of tire pile composite foundation ,stress distribution of soil in the pile and lateral deformation of the pile were analyzed using the simulation software FLAC3D .The results indicate that the better the mechanical properties of the soil around the pile ,the larger the bearing capacity of the tire pile composite foundation .When there is a great difference between the compressive modulus of the soil around the pile and in the pile ,the depth gradually increases with the load .Its effect of foundation reinforcement is better than that of granular material piles .%为提高废弃轮胎的利用率,提高复合地基的承载能力,提出了一种新型复合地基,即轮胎桩复合地基。以室内试验数据为基础,利用 FLAC3D数值模拟软件对承载能力、桩内土体应力分布进行了模拟分析。结果表明:桩周土体的力学性质越好,轮胎桩复合地基的承载力越大。当桩周土体的压缩模量与桩内土体的压缩模量相差较大时,随着荷载的增加影响深度逐渐增大。其加固地基的效果较散体材料桩要好。

  20. Vertical load effect on micropile lateral bearing capacity%既有竖向荷载对微型桩水平承载特性的影响

    Institute of Scientific and Technical Information of China (English)

    陈正; 刘宇; 梅国雄

    2011-01-01

    The field flexible micropile was simulated with finite element software ABAQUS. Because numerical analysis results were in agreement with field measured results, the simulation parameters could be considered to be effective and correct. Considering the micropile under vertical load and lateral load as well, lateral displacement, pile moment, soil lateral resistance, and side friction under lateral load induced by vertical load were analyzed. Anaysis results showed that after construction having completed,the pile in foundation beared more vertical load, that pile had more lateral bearing capacity, the pile lateral bearing capacity increased with the vertical load above in crease in different construction stages.%运用ABAQUS有限元软件,分析了微型桩在既有竖向荷载作用时施加水平荷载,桩体的水平位移、桩身弯矩、土体的横向抗力、侧摩阻力等的变化情况;对比不同既有竖向荷载作用对微型桩水平承载性能的影响.结果表明:竣工后桩基础中分担竖向荷载较大的桩,抵抗水平荷载的能力较强;不同施工阶段,随着上部竖向荷载不断增加,桩抵抗水平侧移的能力增强.

  1. 素混凝土柱极限承载力计算方法%Calculation method of ultimate bearing capacity for plain concrete column

    Institute of Scientific and Technical Information of China (English)

    林上顺; 陈宝春

    2015-01-01

    The tests of ultimate bearing capacity for 19 plain concrete columns were carried out. The reasonable scopes of slenderness and eccentricity of plain concrete columns were proposed. The bearing capacities of test columns were calculated by nonlinear finite element method.A calculation method of ultimate bearing capacity for plain concrete column was presented by theoretical analysis and regression of test data. Calculation result shows that when the slendernesses of test columns are higher than 15 and the eccentricities are 0.3,their failure modes are section tensile failure,which can not play full material performance of compression.When the slendernesses are not higher than 15 and the eccentricities are not higher than 0.3,their failure modes are section compression failure.The mean ratio of calculated values by the finite element method to test values is 0.995,the variance is 0.001 8,so the calculated value fits well with test value,and the finite element method can be used for the parameter analysis of plain concrete column.Based on considering the coupling influence of slenderness and eccentricity on bearing capacity,in the proposed calculation method of ultimate bearing capacity,the mean ratio of calculated values by the proposed method and the finite element method is 0.976,the variance is 0.003,which indicates that the proposed method has high precision and high safety.2 tabs, 17 figs,20 refs.%开展了19根素混凝土柱极限承载力试验,提出了素混凝土柱长细比和偏心率的合理取值范围,采用非线性有限元方法对试验柱承载力进行计算,通过理论分析和试验数据回归,提出了素混凝土柱极限承载力计算方法。计算结果表明:当试验柱长细比大于15与偏心率为0.3时,素混凝土柱的破坏模式为截面受拉破坏,未能充分发挥混凝土以受压为主的材料性能;当试验柱长细比不大于15与偏心率不大于0.3时,其破坏模式为截面受压破

  2. Assessment of nitrogen, phosphorus, and potassium uptake capacity and root growth in mature alternate-bearing pistachio (Pistacia vera) trees.

    Science.gov (United States)

    Rosecrance, R. C.; Weinbaum, S. A.; Brown, P. H.

    1996-01-01

    We examined interrelationships between crop load, nitrogen (N), phosphorus (P), and potassium (K) uptake, and root growth in mature, alternate-bearing pistachio (Pistacia vera L.) trees. Pistachio trees bear heavy (on-year) and light (off-year) fruit crops in alternate years. Uptake and partitioning of N, P, and K among tree parts were determined during (a) spring flush (mid-March to late May), (b) nut fill (late May to early September), and (c) postharvest-leaf senescence (late September to early December). Nutrient uptake occurred primarily during nut fill in both on-year and off-year trees. In on-year trees, N and K uptake increased by 35 and 112%, respectively, during nut fill compared with off-year trees. During this period, nutrients were allocated largely to embryo development in on-year trees and to storage in perennial tissues in off-year trees. Nutrient uptake was negligible between harvest and leaf senescence. Although root growth was reduced during nut fill in on-year trees compared with off-year trees, there was no relationship between root growth and the uptake of N, P or K from the soil. Our data support the hypothesis that sink demand regulates the uptake and distribution of N, P, and K in pistachio trees. PMID:14871788

  3. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  4. 大直径扩底人工挖孔桩承载力研究%Experimental Research on Bearing Capacity of Large-Diameter Belled Pile

    Institute of Scientific and Technical Information of China (English)

    杨砚宗

    2014-01-01

    Based on a practical project in Wuhan, the bearing capacity of large-diameter belled pile has been studied by the limits of rock uniaxial compressive strength and deep plate loading test to determine the carrying capacity value of the bearing layer. We used standardized formulas to evaluate by two sets of test parameters characteristic values of pile capacity, and used static load tests to validate the estimated carrying capacity. The results showed that:the estimated carrying capacity of deep plate loading test, which is significantly greater than the uniaxial compressive strength test, is very similar with static load test. The plate loading test can accurately estimate the single pile loading capability, and that can provide a reliable reference for the design of large-diameter belled pile.%依托武汉某工程实例,对大直径扩底人工挖孔桩承载力进行了研究,通过岩石极限单轴抗压强度室内试验和深层载荷板试验确定持力层的承载力特征值,采用规范提供的计算公式,用两套试验参数对单桩承载力进行预估,并通过现场单桩载荷试验对计算结果进行验证。研究表明:深层载荷板试验参数预估单桩承载力特征值,明显大于岩石极限单轴抗压强度室内试验计算值,且前者与单桩静载荷试验结果更为接近,可准确预估单桩承载力,进而为后续大直径扩底挖孔桩设计提供可靠参考。

  5. 区域经济发展的碳足迹与碳承载力研究%Carbon Footprint and Carbon Bearing Capacity of Regional Economic Development

    Institute of Scientific and Technical Information of China (English)

    顾晓薇; 胥孝川; 王青; 王凤波

    2012-01-01

    Based on the method and indicators oI the ecological tootprint, a mathematical model was developed for calculating the carbon footprint, carbon bearing capacity and carbon efficiency of a regional economy, which was applied to the study on the economic development of Shenyang from 1991 to 2005. The results show that, after 1998, the total carbon footprint of Shenyang increased rapidly at an annual growth rate of 15.2 %, overtaking the GDP growth rate at the same period (13.67 %). In the total carbon footprint, the emissions of fossil-fuel consumption occupy 73 %- 86 %. The carbon bearing capacity of Shenyang was relatively stable in the study period, resulting in a severe carbon overload with the carbon footprint 4 times higher than the carbon bearing capacity in 2005. Furthermore, the carbon efficiency exhibited a decreasing trend after 2000, i.e. the carbon footprint for each unit of economic output showed an increasing trend. It can be seen that, the high economic growth after 2000 was achieved at the cost of the rapid increase in carbon footprint, implying the steering to a low-carbon economy faces a grim challenge.%基于生态足迹方法和指标,构建了反映区域经济发展的碳足迹、碳承载力及碳效率的数学模型,并将其用于沈阳市1991~2005年的经济发展研究.结果显示:沈阳市碳足迹总量在1998年后以15.2%的年增长率快速增加,超过同期的GDP平均增速(13.76%);碳足迹总量中,化石能源消费的排放足迹占73%~86%.沈阳市的碳承载力在研究期相对稳定,导致碳超载情况严重,2005年的碳足迹是碳承载力的4倍.另外,碳效率在2000年后呈下降趋势,即单位经济产出的碳足迹呈上升趋势.可见2000年后经济的快速增长是以碳足迹的高速增加为代价的,这意味着向低碳经济转型面临严峻挑战.

  6. Relationship between pile foundation bearing capacity and its dynamic stiffness%桩基承载力与其动刚度的关系

    Institute of Scientific and Technical Information of China (English)

    刘建磊; 马蒙; 张勇; 缴玉森

    2015-01-01

    为分析桩基承载力与机械阻抗法中动刚度的关系,在同一场地设计了4根相同尺寸的带有不同程度缺陷的模型桩(缩颈桩或断桩),对模型桩进行了机械阻抗法动测和静载试验。建立了桩—土有限元模型,利用模型桩测试数据对有限元模型进行校准,并分析了完整桩在冲击动荷载和静载试验中对主要物理参数的敏感性;同时分析了缩颈、扩颈缺陷对桩基动刚度的影响规律。研究结果表明:对于相同形式、相近地层环境中的桩基,动刚度能很好地反映静力特性;动刚度对影响桩基承载能力的缺陷较为敏感,合理动刚度下限值可以作为桩基承载力的预警值。%In order to investigate the relationship between the bearing capacity of pile foundation and its dynamic stiffness in the impulse transient response method ( T RM ) ,four model piles,with same size but different damage ( necking or breaking) ,were designed in a same test field. Dynamic response was measured with T RM and static load test was performed. A pile-soil finite element model was built,calibrated by model pile tests. Sensitivity of main parameters were analyzed for intact piles under impulse and static loads,and the effect of necking or expanding defects on dynamic stiffness were studied. It revealed that dynamic stiffness reflected the corresponding static characteristics for pile foundations with the same type and located in similar ground environment. Dynamic stiffness is sensitive to the defects which affect the pile bearing capacity,and a reasonable lower bound of dynamic stiffness can be used as a precaution for pile bearing capacity.

  7. Fracture mechanical analyses concerning the load-bearing capacity of dissimilar welds in piping with circumferential cracks

    International Nuclear Information System (INIS)

    In power plants numerous dissimilar welds exist between ferritic and austenitic components. The evaluation of the influence of real or postulated flaws to the load bearing and failure behaviour in the area of dissimilar welded joints, e. g. in piping of the primary circuit of nuclear power plants, is an essential part of the safety assessment of these plants. The fracture assessment of dissimilar welds containing flaws is therefore an important issue of structural integrity considerations. During the past decades several assessment procedures for the evaluation of flaws in welds have been developed mainly based on methods originally developed for homogenous materials. The main difficulties in applying these methods are that they are restricted to two different materials and the very limited experimental evaluation especially by component tests. To improve the general understanding of the influence of flaws in piping systems with dissimilar welds and to have a more reliable basis for the assessment of the fracture behaviour, full scale tests on pipes containing a weld between ferritic and austenitic steel have been performed. The test results of these tests are summarised and used for the evaluation of analytical and numerical assessment procedures. (orig.)

  8. Numerical simulation of bearing capacity of the bored pile in soft rock%软岩钻孔灌注桩承载力的数值模拟

    Institute of Scientific and Technical Information of China (English)

    高长岭; 李荣峰; 柴建峰

    2012-01-01

    如何确定软岩地区钻孔灌注桩的承载力是一个复杂而又亟待解决的问题.本文以南京长江三桥软岩钻孔灌注桩为例,利用数值模拟法(FLAC3D模拟分析),模拟南京长江三桥软岩钻孔灌注桩逐级加载后的受力性状,根据得到的桩周土岩的应力场、位移场及破坏区的分布和扩展,确定软岩钻孔灌注桩的极限承载力.将数值模拟结果和自平衡测试结果进行比较,笔者发现两者吻合较好.%A method for determining the bearing capacity of bored piles in soft rock areas has been a complex problem that should be solved urgently. Taking the bored piles in soft rock of the third bridge over the Yangtze River in Nanjing as an example and using the numerical simulation method (FLAC3D simulation analysis), this paper simulated the force behavior of the bored piles in soft rock of the third bridge over the Yangtze River in Nanjing in the case of step stress test. Based on stress field, displacement field and the distribution and expansion of the failure zone obtained in the soil and rock around the pile, the authors determined the ultimate bearing capacity of the bored pile in soft rock. A comparison with the numerical simulation results and the self-balanced load test results shows that the numerical simulation result agrees well with the self-balanced load test result.

  9. Vulnerability Assessment on Government's Marine Disaster Bearing Capacity%海洋灾害中政府承灾力脆弱性研究

    Institute of Scientific and Technical Information of China (English)

    赵昕; 王晓婷

    2011-01-01

    The information diffusion method can turn a distinct value of the sample point into a fuzzy set, and turn a single point into set-valued sample point. This method is especially applicable to the situation in which marine disaster is non-continuous and sample points are fewer in number. It can dig out the maximum information carried by the data themselves. This paper's study subject is the municipal area. First, an evaluation model of the vulnerability of government's disaster bearing capacity is setup based on the information diffusion principle. And the exceeding probability of a government's disaster bearing coefficient is brought in to evaluate it. Next, the vulnerability made through the hierarchical clustering method is given, taking Shandong province as an erample for an empirical research. Then, the vulnerability of government's marine bearing capacity of the coastal cities in Shandong Province is classified. At the end, a risk map is drawn. The research results show that the vulnerability of government's disaster bearing capacity is the heaviest in the cities of Weihai, Yantai, Dongying and Rizhao; Qingdao and Binzhou are the second; Weifang is the city with the minimum vulnerability of government's disaster bearing capacity. The causes for the difference of vulnerability vary from city to city, mainly in the disaster occur rence probability of each city, the level of economic development, and attention to the disaster. In the long run, the improvement of government's marine disaster bearing capacity depends on minimizing the economic loss of marine disasters and maximum funds preparation to cope with the disaster. All of these can give some reference to the concerned departments at all levels when policies are formulated to improve disaster resistance and reduction capacity.%信息扩散方法可以将一个分明值的样本点变成一个模糊集,把单值点变成集值样本点.这种方法对于海洋灾害呈现的非连续、样本点个数少的

  10. Studies on Geogrid Encased Stone Column of Bearing Capacity%包裹碎石桩承载力分析

    Institute of Scientific and Technical Information of China (English)

    齐云龙; 任海波

    2016-01-01

    The Geogrid encased stone column is the type of encased a stone column with geo-grid.In order to make further study on geogrid encased stone column,a laboratory model study is conduc-ted.The P -s curves is based on the load on the bearing plate and the settlement on the bearing plate.The axial force is obtained by placing sensors in the pile body.From the axial force,the load trans-fer mechanism,the tip resistance and the skin friction are studied.From the experiment results,the geo-grid encased stone column effectively improve the load performance of the soil.The geogrid encased stone column exists pressure mainly within 0.7l (5.6 d)depth during the loading.There is about 40% of the pressure on the pile top at a depth of three times pile diameter;And it is about 20% of the pressure on the pile top at a depth of 5.6 times pile diameter.What's more,it exists pressure at a depth of eight times diameter(pile bottom)when the pressure at plate top larger than 85 kPa.%包裹碎石桩是在碎石桩外包裹一层土工材料制成的一种桩体。为了更好地研究这种桩体的承载力情况,进行室内模型试验。由所加荷载和承压板沉降值得到了承载力-沉降曲线,在桩体内布置土压力盒,实测桩身轴力,研究了包裹碎石桩的荷载传递情况、端阻力和侧摩阻力。通过试验发现包裹碎石桩有效地提高了未加固地基的承载力。包裹碎石桩承受竖向荷载时,主要在桩身0.7 l(5.6 d)(l、d 分别为桩长和桩径)深度范围内存在力的作用;在3 d 深度的应力约为桩顶应力的40%,5.6 d 深度的应力约为桩顶应力的20%,当外部压力大于85 kPa 时,8 d 深度(桩底端)存在应力。

  11. Position Effect of Circumferential Crack Defects on Elbow Pipe Bearing Capacity%周向缺陷位置对弯管承载能力的影响

    Institute of Scientific and Technical Information of China (English)

    万晋; 秦超

    2016-01-01

    Taking elbow pipe as the object of study, the finite element method was adopted to investigate axial stress distribution on the cross section of the elbow pipe and plastic limit load;and the stress distribution there under internal pressure and bending load was summarized, including location of the maximum axial stress and its calculation formulation. Analyzing the position effect of circumferential crack defects on the elbow pipe’ s bearing capacity shows that, as for the elbow pipe with smaller bending radius and bigger diameter-thickness ratio, the circumferential crack defect should be located at the spot of the maximal axial stress so as to deter-mine the elbow’ s bearing capacity and lay the foundation for further study of the plastic ultimate bending mo-ment and improvement of elbow failure assessment.%以弯管为研究对象,采用有限元法对弯管中间横截面应力分布规律和塑性极限载荷进行研究,给出了弯管在内压和弯矩载荷下的应力分布情况,指出了弯矩载荷下弯管中间截面最大轴向应力点位置和计算公式,分析了中间截面上不同位置周向裂纹缺陷对弯管塑性极限弯矩载荷的影响。结果表明,对于弯曲半径比较小,径厚比较大的弯管应将周向裂纹缺陷定位在最大轴向应力点确定弯管弯矩承载能力,为进一步研究弯管塑性极限弯矩,完善弯管失效评定奠定基础。

  12. 预应力管桩承载力抗拔系数试验分析%Test and Analysis of Prestressed Pipe Pile Bearing Capacity Pull-out Coefficient

    Institute of Scientific and Technical Information of China (English)

    陈捷; 周同和; 王会龙

    2015-01-01

    通过两组8台现场静载荷试验的成果分析和已有试验成果的比较,研究了采用静压和锤击施工的预应力管桩(采用PHC)在黏土与粉土中的承载力抗拔系数。结果表明,受到桩端阻力与桩侧阻力相互作用的影响,桩端位于承载力较高的砂层时,预应力管桩承载力抗拔系数较小,桩端位于桩端阻力较小的黏土层时,预应力管桩承载力抗拔系数较大。土层抗拔系数受长径比影响较大,长径比大的桩,上部土层抗拔系数可能较大;长径比较小时,下部土层抗拔系数可能较大。研究成果可供建筑抗浮工程优化设计作为参考。%By the analysis of two groups of eight field static load test results and the comparison of existing test results,we studied the bearing capacity uplift coefficient of PHC Piles whose construction adopts hydrostatic pressure and hammering in clay and silt. The results show that bearing capacity of pile resistance coefficient is little when the bearing capacity of pile tip into the higher sand layer,the bearing capacity of pile resistance coefficient is larger when we put the pile end into the clay layer of smaller pile side resistance due to the influence of pile end resistance of pile side resistance. The aspect ratio has a great influence on the bearing capacity uplift coefficient of soil layer. When the aspect ratio is larger,the bearing capacity uplift coefficient of soil upper layer is greater than the pile of little aspect ratio;the bearing capacity uplift coefficient of soil lower layer may be greater than the upper soil layer when the pile has small aspect ratio;The research results can be used for reference by the building anti-floating engineering optimization design.

  13. 非埋式桩板结构路基承载机制%Bearing capacity mechanism of non-embedded pile-plank structure subgrade

    Institute of Scientific and Technical Information of China (English)

    苏谦; 王武斌; 白皓; 廖超; 赵伟

    2012-01-01

    Sensor components were disposed at the typical section of test subgrade, and the bearing capacity mechanism of non-embedded pile-plank structure in deep collapsible loess foundations was studied by long-term observation. The pile-soil interaction was considered, the concept of comprehensive rotation stiffness was introduced based on the principle of equal stiffness, the vertical and horizontal plane models of the subgrade were installed, and the deformation and mechanical characteristic of the structure were analyzed. Measured result shows that the test value of structural main reinforcement stress agree well with the theoretical calculation value, the difference is about 10%-30~//00, and the maximum reinforcement stress of 60. 60 MPa appears at the cross section of joist. Pile side earth bears about 95% of total load, and no negative friction is produced. The load transfer law of the structure is different from that of traditional subgrade, load can be transferred to deeper bearing layer by pile foundation, which improves the stress state of soft soil section. Half a year, after the laying completion of track construction, the largest accumulated settlement of top surface for bearing plank occurs at the cross section of mid-span, which is 1.0 mm, and meets the requirement of settlement control. 1 tab, 12 figs, 15 refs.%为了研究深厚湿陷性黄土地基非埋式桩板结构路基的承载机制,选取试验段典型断面进行元器件布置与长期观测;考虑桩土相互作用,依据等刚度的原则引入综合转动刚度的概念,建立了纵、横向平面分析模型,对非埋式桩板结构的受力与变形特性进行测试分析。实测结果表明:结构主筋应力测试值与理论值相差10%~30%,吻合较好,最大值出现在托梁支座断面上侧,为60.60MPa;桩侧土体承受约95%的荷载,且未产生负摩阻力;桩板结构的荷载传递规律与传统路基不同,桩基将荷载传递到更

  14. Comparison of Design Bearing Capacity and Site Static Load Test of the Cast-in-place Piles in Caohe Aqueduct%漕河渡槽灌注桩承载力与静载试验比较

    Institute of Scientific and Technical Information of China (English)

    杨胜慧

    2013-01-01

    The cast-in-place piles foundation is adopted in the Caohe aqueduct body. There is 0.5 meter of the piles foun-dation entering into the weak weathered rock, the bearing capacity of the piles foundation is calculated according to point bearing pile . The static load test is adopted to check the the bearing capacity of the cast-in-place pile foundation, the test results show that the bearing capacity of pile foundation in Caohe aqueduct meet the design requirements.%漕河渡槽槽身段采用灌注桩基础,桩基进入弱风化岩石0.5m,按纯端承桩计算桩基承载力。采用桩基静载试验检测桩基承载力,试验结果表明,漕河渡槽桩基承载力达到设计要求。

  15. Shear Bearing Capacity of Ultra-High Performance Concrete Shear Wall%超高性能混凝土剪力墙抗剪承载力分析

    Institute of Scientific and Technical Information of China (English)

    钟益东; 童小龙; 甘文举

    2015-01-01

    This paper uses nonlinear finite element analysis upon the basic behavior of Ultra -high performance concrete shear wall subjected to monodirectional lateral load, and studies the effect of axial load ratio, shear span ratio, the ratio of hidden column longitudinal, the volumetric ratio of hidden column and the ratio of web reinforcement on the shear bearing capacity. The research shows that: the bearing capacity of UHPC shear wall is high; the displacement ductility of UHPC shear wall is well. With the increased of axial load ratio, the bearing capacity is first increased and then decreased, the ductility drop significantly, so axial load ratio should be strictly controlled; With the shear span ratio increased, the destruction of morphological change and the bearing capacity increase; With the ratio of hidden column longitudinal increasing, the bearing capacity increase; the volumetric ratio of hidden column, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement effect on bearing capacity are not very obvious.%对超高性能混凝土UHPC(Ultra-High Performance Concrete)剪力墙在单向水平荷载作用下的受力过程进行了非线性有限元分析。重点分析了轴压比、剪跨比、暗柱纵筋配筋率、暗柱箍筋配箍率、分布钢筋配筋率等因素对UHPC剪力墙抗剪承载力的影响。结果表明: UHPC混凝土剪力墙抗剪承载力高,延性较好,值得在工程领域应用。随着轴压比的增大,承载力先增大后减小,延性大幅下降,应该严格控制轴压比;随着剪跨比增大,破坏形态发生变化,承载力减小;随着暗柱纵筋配筋率的增大,承载力增大;暗柱箍筋体积配箍率及分布钢筋的增大对承载力的影响不很明显。

  16. 起重吊钩极限承载力试验%Experimental Study of the Ultimate Bearing Capacity of a Lifting Hook

    Institute of Scientific and Technical Information of China (English)

    沈超明; 李旭东; 杨绘峰

    2013-01-01

    The ultimate bearing capacity and safety factor of a large lifting hook was determined by the methods of model test and finite element simulation in the present paper.First,larger stress points,known as dangerous points,are obtained by the method of finite element and mechanical analysis.The similarity relation between the real object and model of lifting hook under the concentrated force was derived based on the model test theory.Then a hook model at a ratio of 4:1 to the original hook was manufactured for different loading tests.Synchronous measurement of the strain of dangerous points was made by using electric resistance strain gauges to get the load which made the model to yield.Finally,the actual ultimate strength and the safety factor of the lifting hook was obtained according to similarity relation.The test results indicate that the lifting hook is safe at the rated condition with a safety factor 1.14 and the proposed method can efficiently determine the actual ultimate bearing capacity of the large lifting hook for its safety and reliability.%利用模型试验与数值计算相结合的方法,测定了某大型起重吊钩的极限承载力及其安全系数.首先,通过有限元计算及力学分析得出其在额定工况下的应力较大点,即危险点;然后应用模型试验理论推导了静态集中力作用下吊钩实物与模型的相似关系,并对按4∶1的比例制作的吊钩模型进行等量逐级加载试验,同时利用电阻应变法对吊钩模型上危险点的应变进行同步测量,计算得到吊钩模型出现局部屈服时的载荷,从而根据相似关系确定了该起重吊钩的实际极限承载力和安全系数.试验结果表明,该起重吊钩在额定工况下是安全的,其安全系数约为1.14;提出的方法可以有效测定大型吊钩的实际极限承载力,以确保大型起重吊钩的安全可靠.

  17. Study on ultimate bearing capacity of hybrid girder%多钢种混用工字钢梁抗弯极限承载力研究

    Institute of Scientific and Technical Information of China (English)

    王鹏飞; 杨晓明; 李海峰

    2012-01-01

    According to the theory of flexural-torsional buckling,25 monosymmetrical I-shaped hybrid girders with 25 top flange strengthened and ordinary girders were modeled by the finite element method.Moreover,the differences between hybrid girders and ordinary girders were critically analysed from the aspects of the ultimate bearing capacity and failure modes.The formula of critical moment was summarised by the regression analysis.The results of this research indicated that the collocation of steel would be significantly optimized and the project cost would be dramatically reduced by rationally applying hybrid girders.%以受弯构件弯扭屈曲理论作为理论基础,对25根上翼缘加强型单轴对称混用工字钢梁及相同跨径与截面尺寸的匀质钢梁进行极限承载力有限元计算,研究多钢种混用钢梁同匀质钢梁在破坏模式、极限承载力等方面的差异性.对有限元计算结果进行回归分析,得出了可用于设计的临界弯矩计算公式.研究结果表明,合理采用混用钢梁的构造理念,可以在满足承载力要求的同时优化钢材搭配,降低工程造价,做到物尽其用.

  18. Research on Appraiser Coefficient of Bearing Capacity of Reinforced Concrete Eccentric Compres ison Member%钢筋砼偏心受压构件承载力鉴定系数研究

    Institute of Scientific and Technical Information of China (English)

    林宏伟

    2015-01-01

    In 'stand for appraiser of reliability of civil buildings '( GB50292-1999 ) , for the safety appraiser of member on bearing capaci-ty, the appraiser coefficient of bearing capacity is identified as the ratio of component resistance and action effects , then the rating of bear-ing capacity can be carried out .But for eccentric compression members , as the bending moment and axial force are related , not a single in-dicator , so determination of the appraiser coefficient is rather difficult .Based on the theory of Nu -Mu bearing capacity envelope curve , the formulas of non-seismic and seismic symmetrical reinforcement eccentric compression member are derived respectively .A new type of appraiser coefficient of bearing capacity is proposed in this paper .In the end, the method is applied on an actual project , and some useful conclusions are obtained for reference .%《民用建筑可靠性鉴定标准》( GB50292-1999)构件的安全性按承载能力评定时,采用抗力与作用效应之比作为承载力鉴定系数,并由此进行评级。但对于偏心受压构件,由于抗力项中弯矩与轴力是相关的,不是单一的指标,从而导致鉴定系数的确定存在困难。本文根据偏压构件Nu-Mu承载力包络曲线理论,推导了对称配筋情况下的非抗震和抗震时的相关公式,并提出了鉴定系数的一种表达方式。最后,本文将该方法应用于工程实例,并得出了一些有益结论供参考。

  19. 对独立基础加防水板地基承载力修正分析%The correction analysis on independent foundation plus waterproof board foundation bearing capacity

    Institute of Scientific and Technical Information of China (English)

    刘正伟; 冯鑫

    2014-01-01

    依据相关规范对地下车库或地下室常用的独立基础加防水板的基础形式进行了分析,指出独立基础地基承载力特征值可以用规范规定修正后的数值加防水板所抵抗的净水头压力值作为地基承载力最终的特征值。%This paper analyzed the commonly used independent foundation plus waterproof board foundation to underground garage or basement according to relevant norms, pointed out the independent foundation bearing capacity characteristic value could as the foundation bearing capacity final characteristic value using the value modified by specification plus clear water head pressure value resistance of waterproof board clear water.

  20. Calculation of axially bearing capacity of a batter pile based on mechanism of deformation compatibility%基于变形协调的斜桩轴向承载力计算方法

    Institute of Scientific and Technical Information of China (English)

    张麒蛰; 卓卫东; 范立础

    2013-01-01

    In order to obtain the axial bearing capacity of a batter pile , the calculation formula for the axially bearing capacity of a batter pile was deduced based on the non-uniform distribution char-acteristics of the friction resistance around the batter pile shaft and the mechanism of pile -soil deformation compatibility .The results calculated by the proposed formula and the method given by the design code of pile were compared to explore the influence of the factors , such as pile inclina-tion, diameter, length and utmost friction resistance around pile shaft , on axial bearing capacity. The calculated results showed that the value of the pile axially bearing capacity calculated by the proposed formula decreased with the increase of pile inclination .For different pile diameters , the pile axially bearing capacity was 7%smaller than that calculated by the code's formula.The shorter of the pile length or the lesser of the utmost friction resistance of the pile was , the smaller bearing capacity calculated by the code's formula was than the values calculated by the proposed formula . Finally , with the increase of the pile length or utmost friction resistance , the value of bearing capaci-ty calculated by this proposed formula was greater than the value calculated by the code's formula. The proposed formula also takes into account of the influence of pile inclination and the mechanism of pile-soil deformation compatibility .It can be a reference to calculate axial bearing capacity of bat-ter piles.%为进一步研究斜桩轴向承载力计算方法,基于斜桩的桩周摩阻力不均匀分布的特性和桩-土受力变形协调的原则,推导了斜桩轴向承载力计算公式,通过对比本文公式与规范公式的计算结果,揭示了桩身倾角、桩径、桩长和桩侧极限摩阻力等因素对斜桩轴向容许承载力的影响规律。结果表明:鉴于规范公式未考虑斜桩桩身倾角对承载力的影响,本文公式计算得

  1. A Study on the Testing of Shear Bearing Capacity of Reinforced Small Concrete Block Shear Walls%配筋砼小砌块剪力墙的抗剪性能

    Institute of Scientific and Technical Information of China (English)

    邱战洪; 赵成文; 陈兆才

    2001-01-01

    在进行七片混凝土小砌块剪力墙试验研究的基础上,分析了在低周反复水平荷载作用下,剪跨比和水平配筋率对试件破坏形态和抗剪承载力的影响,并提出了混凝土小砌块剪力墙的抗剪承载力建议计算公式.%On the basis of the analysis of and experiment on the reinforced masonry shear walls under fixed vertical load, the destruction procedures of shear walls and the relation of shear bearing capacities and shear span ration, reinforced ration are analyzed. The shear bearing capacity calculating formula is presented.

  2. 长春新开河流域粘性土地基承载力研究%Study on Bearing Capacity of Changchun Xinkai River Basin of Clay Foundation

    Institute of Scientific and Technical Information of China (English)

    刘汉蒙; 孙广利

    2015-01-01

    Changchun Xinkai river basin soil is encountered in recent years in the construction of soil. Be regarded as common soil, determined by the empirical method of bearing capacity is big, affect the engineering safety. This paper uses the method of test and laboratory soil test load test in situ determination of bearing capacity of Chang-chun Xinkai river basin of cohesive soilfoundation. The value and natural void ratio, liquid index and compression modulus of foundation bearing capacity characteristics of relationship. Summarized according to the experience for-mula to determine bearing capacity of Changchun Xinkai river basin soil compression modulus of soil testindex, pro-vide the reference for the geotechnical engineering survey.%长春新开河流域粘性土是近年来工程建设中新遇到的土层。将其视为一般粘性土,按经验方法确定的承载力偏大,影响工程安全。本文采用载荷试验原位测试和室内土工试验方法确定长春新开河流域粘性土的地基承载力。研究了地基承载力特征值与天然孔隙比、液性指数和压缩模量的关系,总结出根据室内土工试验指标压缩模量确定长春新开河流域粘性土地基承载力的经验公式,为今后岩土工程勘察工作提供参考。

  3. 浅析挤扩多盘桩单桩竖向抗拔承载力%ANALYSISON THE PUSH-EXTEND MULTI-UNDER-REAMED PILE BEARING CAPACITY OF SINGLE PILE PULLED ON VERTICAL LOADS

    Institute of Scientific and Technical Information of China (English)

    任佳佳; 钱永梅; 尹新生

    2012-01-01

    通过研究挤扩多盘桩的现有抗拔承载力计算方法,提出利用传统模式来计算挤扩多盘桩的抗拔承载力的不足之处,并根据挤扩多盘桩在竖向拔力作用下的土体的破坏特征和桩的受力机理,提出最新的挤扩多盘桩抗拔承载力的计算模式,为该型桩的设计应用提供可靠的理论依据。%By studying the existing calculation method of pulled out of the bearing capacity of the push-extend multi-under- reamed pile, this article put forward deficiencies of the traditional mode to calculate the bearing capacity of the push-extend multi-under-reamed pile, and according to the push-extend multi-under-reamed pile under vertical pull force the characteristics of the soil destruction and working mechanism of pile, put forward the newest calculation method of pulled out of the bearing capacity of the push-extend multi-under-reamed pile, the reliable theory basis will influence the application of the expansion multiple disk pile.

  4. Laboratory Study on Load-Bearing Capacity of Micropiles by Using Different Construction Methods%成桩方式对微型桩承载力影响的室内试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 鲁先龙; 满银

    2012-01-01

    Micropiles can be constructed by pressure grouting method or concreting method. In this paper, laboratory tests about load-bearing capacity of micropiles by using different construction methods were done. Study shows that the pressure grouting can increase vertical load-bearing capacity of micropiles, when calculating the vertical capacity of two-grouting micropiles the effect of the second grouting should be considered; micropiles used in transmission line should be made by two-grouting technology to ensure the quality of micropiles; the influence of pressure grouting on horizontal load-bearing capacity of micropiles is up to the nature of the upper soil layer, calculating the horizontal capacity of micropiles doesn't consider the effect of pressure grouting.%微型桩可采用投石注浆法或者直接灌注细石混凝土法成桩.结合室内试验,对不同成桩方式对微型桩承载力的影响进行了研究.研究表明:压力注浆能够提高微型桩的竖向承载力,在进行微型桩竖向承载力计算时应考虑二次注浆的提升效果;为保证微型桩成桩质量,应用于输电线路工程的微型桩应进行二次注浆;压力注浆对微型桩水平承载力的影响因上部土层性质而易,在进行微型桩水平承载力计算时不考虑压力注浆的影响.

  5. Experimental study on design method of horizontal bearing capacity of micropiles for transmission tower%微型桩杆塔基础水平承载力计算方法研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 盛孝芳; 曲勇

    2013-01-01

    Field tests are done to study the horizontal design method of micropiles for transmission tower. Study shows; the calculating of horizontal bearing capacity of single micropile is suitable to determine by horizontal allowable displacement, the value of " m" can be calculated by the test results, which can be used to calculate the horizontal bearing capacity of single micropile; the horizontal bearing capacity of micropile group is the product of the horizontal bearing capacity of single micropile, the number of single pile and the horizontal pile group effect coefficient, which is product of pile interact coefficient and pile top restrict coefficient. If the reasonable design parameters were chozen,the horizontal bearing capacity of micropile foundation could be designed preliminarily.%通过现场原型试验,对微型桩杆塔基础的水平承载力计算方法进行研究,研究表明:应用于输电线路工程的微型桩基础,微型桩单桩一般采用水平允许位移控制确定其水平承载力设计值,可采用现场试验结果反算得到m值,进而进行单桩水平承载力设计值的计算;微型桩群桩水平承载力可通过单桩水平承载力乘以桩数和水平群桩效应系数得到,水平群桩效应系数只考虑桩的互相影响效应和桩顶约束效应.只要选用合理的设计参数,可采用本文提供的设计方法进行微型桩杆塔基础水平承载力的初步设计.

  6. 多种加固方法应用于双曲拱桥主拱圈的提载加固%Reinforcement for Improving Bearing Capacity of A Double Arch Bridge Main Arch by Strengthen Methods

    Institute of Scientific and Technical Information of China (English)

    黄伟; 申波; 薛守宝; 梁影

    2012-01-01

    In this paper, reinforcement for improving the bearing capacity of a double arch bridge is studied. Based on the test results of a double-arched bridge of Anshun in Guizhou province, the strengthening program of the main arch is proposed. At the section of arch feet, the moment bearing capacity is improved by enlarged upper edge concrete and lower edge concrete of the section, the section is changed to box section. At the other section of the arch, the negative moment bearing capacity is improved by enlarged upper edge concrete of the section, and the positive moment bearing capacity is improved. For the deficiencies of the positive moment bearing capacity, the bonding steel plate is recommended at the arch rib of the other section. The results show that the reinforcement methods can improve load level of the bridge effectively. The construction of the bridge is convenient and can satisfy the design goals.%针对双曲拱桥的提载加固,基于贵州省安顺市木浪河大桥的检测结果,提出了在主拱圈的拱脚上缘增大截面、下缘增大截面改造为箱形断面,以提高拱脚抵抗负弯矩、正弯矩的承载能力;对其它截面采用拱背增大截面以提高抵抗负弯矩的承载能力,相应也提高了抵抗正弯矩的承载能力;对正弯矩承载能力不足的截面,采用粘贴钢板的加固方法.结果表明:采用这种提载加固的设计方法,达到了提高荷载等级的目的,同时方便施工,便于达到加固效果.

  7. Experimental study on enhancing bearing capacity of marine soft soil foundation with cement-mixing piles%水泥土搅拌桩增强海相软土地基承载力的试验研究

    Institute of Scientific and Technical Information of China (English)

    吕田丰

    2015-01-01

    为了研究本地区海相软土地基采用水泥土搅拌桩进行加固技术,提高海相软土地基承载力的可行性。选取了本地区典型的海相软土场地,采用水泥土搅拌桩对软土地基进行加固,利用浅层平板载荷试验和复合地基载荷试验的方法,对海相软土加固前后的地基承载能力进行了比较分析。结果表明,利用水泥土搅拌桩对海相软土地基进行加固,可以有效地增强海相软土地基承载力。%In order to study the feasibility of improving bearing capacity of marine soft soil foundation through the technique of reinforcing local marine soft soil foundation with cement-mixing piles,we select typical marine soft soil site and reinforce the soft soil foundation with cement-mixing piles.Through super-ficial plate loading test and composite foundation loading test,we conduct comparative analysis on the bear-ing capacities of marine soft soil foundation before and after the reinforcement.Results show that reinfor-cing marine soft soil foundation with cement-mixing piles can improve the bearing capacity effectively.

  8. Laminated and pasting CFRP composite strengthening RC beam bending bearing capacity experimental study%叠合与粘贴CFRP复合加固RC简支梁的抗弯承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李红霞; 郭艳芹; 张雷顺

    2013-01-01

    通过分析叠合与粘贴CFRP复合加固RC简支梁承载力的两大主要影响因素,运用现有计算方法推导得出复合加固RC梁的抗弯承载力计算公式,试验发现:仅粘贴CFRP加固RC梁,虽能有效提高构件承载力,但由于下部受拉储备充足而使上部受压储备相对不足,使构件发生类似超筋梁的脆性破坏,其极限承载力明显低于上部同时有叠合层的RC梁.试验比较发现:所用计算方法得出的计算值与试验值相比偏小,计算公式偏于保守.%Through the analysis of laminated composite of RC beams strengthened with bonded CFRP bearing force of the two major influencing factors, using the existing calculation method of composite strengthening RC beam is derived the formula to calculate the bending bearing capacity, test found that: only paste CFRP strengthened RC beams, can effectively improve the bearing capacity of members, but due to the lower tensile reserves and the upper compression reserve is relatively insufficient, make a component similar over-reinforced beam brittle failure, its ultimate bearing capacity was significantly lower than the upper part while the laminated layer of RC beam. Test comparison showed that:this method calculated value compared with experiment data is small,conservative calculation formula.

  9. Bearing system

    Science.gov (United States)

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  10. 单桩竖向抗拔承载力离心模型试验研究%Centrifugal Model Test on the Vertical Uplift Bearing Capacity of Single Pile

    Institute of Scientific and Technical Information of China (English)

    任国峰; 徐光明; 顾行文

    2012-01-01

    To assist the design of pile foundation of an offshore wind farm, centrifuge modeling is performed to determine the uplift bearing capacity of single ultra-long steel pipe-pile of large diameter by which the wind turbine foundation is constituted. Curve of load versus displacement ( Q-S curve) deducted from the results of centrifuge model test are compared with that from prototype uplift capacity test. The effect of loading manner and loading rate on the ultimate uplift bearing capacity is discussed. It is shown by comparison that the value of ultimate uplift bearing capacity of single pile from centrifuge test is greater than that obtained from prototype test. As higher rate usually mobilizes higher strength, a higher loading rate in the centrifuge model test is regarded as the cause of the difference between two test results.%结合某海上风电场桩基工程中的大直径超长钢管桩抗拔承载力研究,利用离心模拟技术,初步推求得出荷载-位移的关系曲线(即Q-S曲线),并与现场抗拔试验成果得出的Q-S曲线进行了比较,分析两者加载方式和加载速率的不同对Q-S曲线的影响.结果发现,上拔力的加载速率较快,求得的单桩抗拔极限承载力偏高.

  11. Bearing capacity calculation of flexural members strengthened with CFRP%粘贴碳纤维加固受弯构件的抗弯承载力计算

    Institute of Scientific and Technical Information of China (English)

    张章; 吴锋; 周国然

    2015-01-01

    The bearing capacity formula of flexural members strengthened with CFRP and the material strength coefficient are proposed in this paper. Combined with experimental data, we obtained the calculation method to improvement coefficient, which can be used to simply calculate the bearing capacity. The bending capacity test of PHC pipe pile strengthened with CFRP was developed. The test results show that the calculation formula for beams strengthened with CFRP also can be used to calculate the bearing capacity of pipe piles strengthened with CFRP.%首先提出碳纤维加固受弯构件承载力计算公式,并提出碳纤维加固材料强度系数,结合收集到的粘贴碳纤维加固梁承载力试验数据,建立碳纤维加固钢筋混凝土梁的抗弯承载力提高系数计算公式,实现粘贴碳纤维加固梁的简化计算。开展了粘贴碳纤维加固预应力高强度混凝土(PHC)管桩抗弯承载力试验。试验结果表明,提出的碳纤维加固梁承载力计算公式也可用于碳纤维加固混凝土管桩承载力的计算。

  12. Experimental Research on Compressive Bearing Capacity of Micropiles Foundation in Silt Ground%粉土地基微型桩基础抗压承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 李晋珍; 田宇

    2012-01-01

    Using micropiles foundation can bring great economic and social benefit in silt ground. Through the field tests, the bearing behavior of micropiles foundation was studied under compressive loads. The results show that the bearing ratio of soil is greater than 6. 9% , soil capacity can be considered properly when calculating the compressive bearing capacity of micropiles foundation. On this basis, the compressive stability calculation methods of micropiles foundation are studied.%在粉土地基中采用微型桩基础具有较大的经济和社会效益.通过现场真型试验,对微型桩基础在下压荷载作用下的承力性状进行了研究,研究表明:对于本次试验,在下压极限荷载作用下承台底部土体承载比例≥6.9%,在进行微型桩基础承载力计算时可适当考虑承台底部土体承力.在此基础上,对微型桩基础的下压稳定计算方法进行了分析.

  13. Calculation of bearing capacity of socketed pile in extremely soft medium weathered rock%极软质中风化岩嵌岩桩承载力计算方法探讨

    Institute of Scientific and Technical Information of China (English)

    宋兰芳; 卢永昌

    2009-01-01

    对软质中风化岩嵌岩桩承载力,目前规范尚无明确的计算方法,实际工程按JTJ285-2000计算的承载力与高应变实测承载力相差较大,其计算方法已不再适用.结合2个实际工程,对极软质中风化岩(饱和单轴抗压强度标准值小于5 MPa)嵌岩桩承载力计算方法进行探讨,提出合理的计算方法.%For the embedding pile bearing capacity in very soft medium weathered rocks, there are no clearly regulated calculation methods in current codes. In accordance with the rules of "Design and Construction Codes for Port Engineering" the calculated results of the bearing capacity show large deviations against the actually measured result by high strain test, therefore, its ealeulation method is not applicable anymore. On the basis of practices in two projects, this article carried out a preliminary study on the calculation method of embedding pipe bearing eapacity in extremely soft medium weathered rock (with saturated uniaxial compressive strength less than 5 Mpa) .

  14. 大直径钻孔灌注桩的竖向承载性能%Vertical bearing capacity of large-diameter bored pile

    Institute of Scientific and Technical Information of China (English)

    刘念武; 龚晓南; 俞峰

    2015-01-01

    T he self‐balancing test w as conducted on tw o 2 .2 m diameter drilled piles in order to analyze the bearing capacity of large diameter bored piles .The test results were compared with in‐situ test results . Results show that the change of load‐displacement of pile with post‐grouting is slower than pile without post‐grouting .The end resistance reached the limit state when pile tip displacements approached 20 mm (1% D ,D is the pile diameter) .The side resistance increased firstly and maintained a stable trend with the increase of pile‐soil relative displacement .The critical displacement was 1 .5‐3 .0 mm .Post‐grouting can improve the side resistance over a certain depth from the pile tip ,and the improvement in round gravel mixed pebble bed is 18 percent . Resistive loads up and dow n the side of the load cell is different and transformation coefficient is 0 .92 and 0 .91 , respectively . Side resistance and undrained vane‐shear strength has a linear relationship and has a better goodness of fit .The ultimate side resistance of round gravel mixed can be estimated by dynamic sounding (63 .5 kg) hits .%为了分析大直径钻孔灌注桩的承载性能,对2根直径分别为2.2m的钻孔灌注桩开展自平衡试验,将试验结果与原位测试结果进行对比分析.通过对测试结果的分析发现,注浆后荷载箱的向上及向下荷载‐位移曲线的变化更加缓慢,当桩端位移为20 mm(1% D ,其中 D为桩径)左右时,端阻达到极限状态,未注浆桩和注浆桩的极限端阻分别为2834、3561 kPa .桩身侧阻随着桩土相对位移的增大呈先增大后保持稳定的趋势,淤泥质粉土层、黏土夹粉砂层、圆砾混卵石层的侧阻在桩土相对位移为1.5~3.0mm时达到稳定.注浆能够提高桩端以上一定深度的桩身侧阻,圆砾混卵石层中侧阻的提高幅度约为18%.荷载箱上下的侧阻随位移的变化模式不同,未注浆桩

  15. 不同土质情况下机械连接竹节桩的承载力对比分析%Comparative Analysis on Bearing Capacity of Mechanical-connection Bamboo Joint Pile in Different Soil Conditions

    Institute of Scientific and Technical Information of China (English)

    施卫力; 杨成斌

    2015-01-01

    Mechanical‐connection bamboo joint pile has been used in different soil conditions and showed significant effect . In this paper , we carried out contrast test analysis of the mechanical connection bamboo pile with the conventional pipe pile in different soil vertical ultimate bearing capacity and anti pulling capacity .. T he results show that the bearing capacity of composite pile mechanical connection in different soil conditions is obviously higher than that of the conventional pipe .%机械连接竹节桩已在不同土质工程中得到应用且效果显著。本文将机械连接竹节桩与传统管桩在不同土质中的竖向极限承载力和抗拔承载力分别进行了对比性试验分析。结果表明,在不同土质情况下机械连接竹节桩的承载力比传统管桩有明显的提高。

  16. Application of Finite Element Method in Calculating the Bearing Capacity of Pile Boots%有限元法在桩靴承载力计算中的应用

    Institute of Scientific and Technical Information of China (English)

    王楠; 朱龙海; 姜胜辉; 胡日军; 徐永臣

    2014-01-01

    Pitching pile of self elevating drilling platform is a dynamic process of continu-ous plastic damage of foundation soils in the pile shoe loads .When the ultimate bearing capacity of foundation equals to the load on pile boots ,the pile pitching is completed . Because the classical theory of limit bearing capacity of soil mechanics has made assump-tions to the sliding surface hidden in the soil body ,the damage process occurring inside the soil could not be analyzed efficiently .For this reason ,the finite element method (FEM ) is used to simulate the pile pitching process ,by w hich the failure mechanism of foundation soils and the stress-strain of subsoil body under a middle load are obtained . By comparing with the ultimate bearing capacity calculated by using different theoretical formulae ,the factors influencing the ultimate bearing capacity of foundation soils are analyzed .T he results reveal that the larger the B/H ratio is ,the easier the plastic dam-age occurs in the underlying soft stratum .As a result ,the ultimate bearing capacity re-duces obviously .When the value of B/H is less than 0 .286 ,the influence of the under-lying soft stratum on the ultimate bearing capacity of foundation soils can be ignored .%自升式钻井平台插桩是地基土在桩靴荷载作用下发生连续的塑性破坏的动态过程,当地基极限承载力等于桩靴荷载时插桩完成。经典土力学极限承载力理论对土体潜在滑动面做了假设,无法有效分析土体内部的破坏过程。本研究应用有限元法(FEM )对插桩过程进行了模拟,得到地基土的破坏机制以及中间荷载下土体的应力、应变情况,通过和各理论公式计算的极限承载力进行对比分析,分析影响地基极限承载力的因素。研究表明,基础宽度与硬土层厚度的比值 B/H越大,下卧软土层越容易发生塑性破坏,极限承载力明显下降,当B/H<0.286时,可以忽略下卧软土层对地基承载力的影响。

  17. GFRP套管钢筋-钢骨混凝土短柱轴压承载力研究%Analysis on the axial ultimate bearing capacities of GFRP tubed short columns filled with steel-reinforced concrete

    Institute of Scientific and Technical Information of China (English)

    王娟; 赵均海; 朱倩; 孙珊珊; 刘朝

    2012-01-01

    In order to investigate the axial ultimate bearing capacities of GFRP tubed short columns filled with steel-reinforced concrete,the twin shear unified strength theory was carried out to analyze the strength of core-concrete and steel.Considering the enhanced role of GFRP tube and reinforcement comprehensively,the formula on the axial ultimate bearing capacities of GFRP tubed short columns filled with steel-reinforced concrete was proposed.By the comparison with the results calculated by the formulas and the test results,it shows a good accordance.On the basis of these works,several factors which may have effects on the bearing capacities were analyzed,such as tension-compression strength ratio,ratio of reinforcement,strength of concrete and thickness of tube.%应用双剪统一强度理论分析轴心受压GFRP套管钢筋-钢骨混凝土短柱的核心混凝土及钢骨的强度,通过综合考虑GFRP套管及钢筋对核心混凝土强度的增强作用,推导出了GFRP套管钢筋-钢骨混凝土短柱轴压承载力公式,将该公式计算结果与相应文献试验结果及已有公式计算结果进行了对比,结果吻合良好。在此基础上分析了材料拉压比、配筋率、混凝土强度及套管厚度对极限承载力的影响。

  18. Experimental study on uplift bearing capacity of micropiles by concreting method%灌注细石混凝土微型桩基础上拔试验研究

    Institute of Scientific and Technical Information of China (English)

    苏荣臻; 童瑞铭; 杨文智

    2012-01-01

    The field tests are carried out to study the uplift hearing mechanism and the uplift design method of micropiles by concreting method. The study shows: in this testing condition, the uplift hearing capacity of single pile is composed of the pile weight and the lateral friction ; under uplift load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is the minimum; the limit uplift bearing capacity of pile group could be obtained from the product of the limit bearing capacity of single pile, the pile number and the effect coefficient of the pile group, in the testing condition, the uplift effect coefficient of the pile group is 0.75.%通过现场真型试验,对灌注细石混凝土微型桩基础抗拔承栽机理及其抗拔承载力计算方法进行了研究。试验表明:在本次试验条件下,微型桩单桩抗拔承载力可由桩身自重和桩周侧摩阻力相加组成;由于承台对上拔荷载的重分配,在上拔荷栽作用下,角桩承力最大,边桩次之,中桩最小;微型桩群桩抗拔极限承载力可以通过单桩抗拔极限承载力乘以桩数和群桩效应系数计算得到.本次试验条件下.微型桩抗拔群桩效应系数选取0.75讲行计算.

  19. 输电塔K 节点极限承载力影响因素分析%Analysis on Influence Factor on Ultimate Bearing Capacity of K Node of Power Transmission Tower

    Institute of Scientific and Technical Information of China (English)

    陈加宝; 雷俊方

    2015-01-01

    In order to study characteristics of nodes of power transmission steel tube tower and steel tube angle combined tow-er,finite element software ANSYS was used to establish a 3D entity model of K node of power transmission steel tube angle combined tower. Influence on ultimate bearing capacity of K node by three failure modes of K node,length and thickness of steel angle and length of node plate was analyzed. The results indicates that ultimate bearing capacity of K node of power transmission steel tube angle combined tower obviously increases with increase of thickness of node plate and steel angle. Secondly,thickness of the steel angle is not suitable to be less than 1 0 mm in design. Influence on ultimate bearing capacity of K node by length of node plate and steel angle is small.%为研究输电钢管塔及钢管角钢组合塔节点的特性,采用有限元软件 ANSYS 建立输电钢管角钢组合塔 K节点三维实体模型,分析K节点的三种破坏模式以及角钢长度、角钢厚度和节点板长度对 K 节点极限承载力的影响。结果表明:输电钢管角钢组合塔K节点的极限承载力随着节点板和角钢厚度的增加而显著增大,在设计时角钢厚度不宜小于10 mm;输电塔K节点的极限承载力受节点板长度、角钢长度的影响较小。

  20. The bearing capacity research for slender reinforced high strength concrete columns under eccentric compression loading%钢筋高强混凝土偏压中长柱承载力研究

    Institute of Scientific and Technical Information of China (English)

    杨荣华; 焦俊婷

    2015-01-01

    The bearing capacity was researched for slender reinforced high strength concrete ( RHC ) columns under eccentric compression loading .Based on the element model of beam -column when considering material nonlinearity and geometric nonlinearity , the computer program was given about nonlinearity analysis for RHC structures .Then main affecting factors were researched , such as slen-derness ratio , relative eccentricity , concrete strength , and longitudinal reinforcement ratio .The influ-encing order of these factors was relative eccentricity , slenderness ratio , longitudinal reinforcement ra-tio , and concrete strength , on the bearing capacity for slender RHC columns under eccentric compres-sion loading.As last, the design formula of the bearing capacity was given for slender RHC columns under eccentric compression loading by using the regression statistics method , this would offer design reference .%基于考虑材料非线性和几何非线性耦合梁柱单元模型,采用编制的钢筋高强混凝土结构非线性数值分析程序,分析钢筋高强混凝土偏压中长柱极限承载力主要影响因素有长细比、相对偏心距、混凝土强度、纵筋配筋率等。研究钢筋高强混凝土偏压中长柱极限承载力对各主要影响因素的敏感性,依次为相对偏心距、长细比、纵筋配筋率和混凝土强度。通过回归给出钢筋高强混凝土偏压中长柱极限承载力的计算公式,为实际工程应用提供计算参考。

  1. Practical calculation method of stability bearing capacity of shuttle-shaped steel lattice columns with bending moment%考虑弯矩作用梭形格构柱稳定承载力实用算法研究

    Institute of Scientific and Technical Information of China (English)

    田伟; 干钢

    2013-01-01

    以大型通用软件ANSYS为平台,研究以轴力为主、同时考虑弯矩作用的梭形格构柱的稳定承载能力.通过对不同高度和长细比的梭形格构柱进行非线性稳定计算和参数分析,提出了梭形格构柱稳定承载力的实用计算方法:以弹性特征值为基础计算梭形格构柱的等效长细比,并利用弯矩系数对等效长细比进行修正,得到修正长细比后即可通过查表的方式得到梭形格构柱稳定承载力.%The stability bearing capacity of shuttle-shaped steel lattice columns subject to combined axial force and bending moment is explored through general software ANSYS.Through nonlinear stability analysis and parameter analysis of shuttleshaped steel lattice columns with various heights and slenderness ratios,a practical calculation method is proposed to calculate stability bearing capacity of shuttle-shaped steel lattice columns with bending moment:equal slenderness ratio based on elastic buckling eigenvalues is present; moment ratio is then proposed to modify slenderness ratio,and the ratio can be used to get the stability bearing capacity of shuttle-shaped steel lattice columns through tables.

  2. 关于有黏结强度增强体复合地基承载力深度修正的讨论%DISCUSSION ON DEPTH MODIFICATION OF COHESIVE PILE COMPOSITE FOUNDATION BEARING CAPACITY

    Institute of Scientific and Technical Information of China (English)

    吴迈; 侯伟明; 王恩远

    2014-01-01

    Depth modification of the bearing capacity of a composite foundation involves project safety and investment.Due to lacking research and unified understanding in that issue , and based on the regulations of Technical Code for Ground Treatment of Buildings (JGJ 79—2012) and related points of view in The Understanding and Use of the Technical Code ( JGJ 79—2012 ) , the substance of depth modification of cohesive-pile composite foundation was analyzed and , two methods to predict the modified bearing capacity of pile and soil between piles were deduced .The suitability of the two methods was testified by an example , the principle and method to revise the bearing capacity were also presented .%复合地基承载力深度修正问题,事关工程的安全和投资。但目前对这一问题的研究不足,认识并不统一。基于JGJ 79—2012《建筑地基处理技术规范》的规定和《建筑地基处理技术规范理解与应用》(按JGJ 79—2012)的观点,辨析有黏结强度增强体复合地基承载力深度修正的实质,导出考虑深度修正的桩身和桩间土承载力的两种计算方法。结合算例对该两种方法的适用性予以验证,最后提出有黏结强度增强体复合地基承载力深度修正的原则和方法。

  3. Diagonal sectional bearing capacity of steel fiber concrete coupling beams under low frequency cyclic load%低周反复荷载下钢筋钢纤维混凝土连梁的斜截面承载力

    Institute of Scientific and Technical Information of China (English)

    赵军; 马鑫; 高丹盈

    2012-01-01

    The experiment was carried out on the shear performance of 5 steel fiber reinforced concrete coupling beams and 1 common reinforced concrete coupling beam under low cyclic load. The effects of steel fibers on the cracks and failure modes of reinforced concrete coupling beams were studied. The changing laws of diagonal section bearing capacity of steel fiber reinforced concrete coupling beams with mixed fiber content were analyzed. Based on the calculating method for the diagonal section bearing capacity of common reinforced concrete coupling beam, the calculating method for the diagonal section bearing capacity of reinforced concrete coupling beam with steel fibers was put forward. Comparative results show that the calculated values agree well with test ones.%通过低周反复荷载下5个钢筋钢纤维混凝土连梁和1个普通钢筋混凝土连梁的抗剪性能试验,研究了钢纤维对钢筋混凝土连梁裂缝和破坏形态的影响,探讨了钢筋钢纤维混凝土连梁的斜截面承载力随钢纤维掺量的变化规律,结合普通钢筋混凝土连梁斜截面承载力的计算方法,提出了钢筋钢纤维混凝土连梁斜截面承载力的计算公式,比较结果表明,计算值和试验值吻合较好.

  4. 粒料桩复合地基承载力发挥值试验研究%Experimental Study on Efficiency Factor of Bearing Capacity of Granular Pile Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    轩勇; 刘军勇

    2013-01-01

    结合实体公路工程,通过现场试验段土压力监测,计算复合地基承载力发挥值;结合破坏模式,对其复合地基承载力发挥值进行分析.研究结果表明:粒料桩复合地基按照土体先破坏计算的复合地基承载力发挥值,接近现场载荷试验结果,复合地基承载力可通过桩墩间土压力进行计算确定;不论是强夯置换砾石墩还是振动砾石桩,其破坏形式是桩(墩)间土先破坏引起的整个复合地基的破坏.%Combining with substantial highway engineering,efficiency factor of bearing capacity of composite foundation was calculated through soil pressure monitoring at the section for site test and,with failure mode,it was analyzed as well.The study result shows that for granular pile composite foundation,the efficiency factor of bearing capacity calculated in terms of earth mass failure taken place first is close to the result of on-site load test and the bearing capacity may be calculated through soil pressure between piles/piers.In addition,the failure mode is such that the whole composite foundation is destroyed in the event that the soil between piles (piers) is destructed at first,regardless of dynamic replacement gravel pier or vibration gravel pile.

  5. CFRP加固混凝土梁抗弯极限承载力计算方法%Calculating Method of Bending Ultimate Bearing Capacity of CFRP Reinforced Concrete Beam

    Institute of Scientific and Technical Information of China (English)

    林巧吟

    2009-01-01

    The article studies the destroyed form and ultimate status of carbon fiber material strengthened steel reinforced concrete bending members, and puts forward a practical calculation method for the front sectional bending bearing capacity, which can provide the reference for the practical engineering design.%该文对碳纤维材料补强加固钢筋混凝土抗弯构件的破坏形态和极限状态进行了研究,提出了正截面受弯承载力的实用计算方法,可为实际工程设计提供参考.

  6. 灰土挤密复合地基桩体极限承载力统一解%Unified solution of ultimate bearing capacity of piles in lime-soil composite foundation

    Institute of Scientific and Technical Information of China (English)

    赵均海; 崔莹; 张常光; 孙珊珊

    2013-01-01

    As the values of theoretical calculation for ultimate bearing capacity of piles are quite different from the actual measured values, with the unified strength theory and considering the compatibility condition between piles and soil, the theoretical calculation formula for ultimate bearing capacity of piles has been put forward involving the following factors such as regarding the soil around single pile reinforced area as a long thick-walled cylinder and considering the lateral ultimate binding pressure which soil can exert on pile. Furthermore, the influence factors such as intermediate principal stress, the length of pile and the internal friction angle of lime-soil pile are illustrated according with an actual project and the values calculated by the formula are in good accordance with the actual measured values of ultimate bearing capacity of piles. The results show that the intermediate principal stress has great impact on the lateral ultimate binding pressure which soil can exert on piles. The solution with consideration of the intermediate principal stress has the positive effect on the ultimate strength of soil. And the value of ultimate bearing capacity of piles increases with the increase of the length of piles or with the increase of the internal friction angle of lime-soil.%针对目前灰土挤密复合地基桩体极限承载力理论计算值与实测标准值存在较大差异的问题,将单桩加固区的土体视为一定深度的长厚壁圆筒,基于统一强度理论和桩土变形协调条件,推导了桩孔极限内压下的灰土桩极限承载力统一解.讨论中间主应力、桩长和内摩擦角对灰土桩极限承载力的影响特性,并将理论公式计算值与实测标准值进行了对比,吻合较好.研究结果表明:中间主应力对土体所能提供的侧向极限约束力有较大影响;考虑中间主应力影响对岩土材料的强度发挥有着积极作用;增加桩长和灰土的内摩擦角,灰土桩极限承载力相应提高.

  7. ANALYSIS ON THE DETERMINAION OF VERTICAL LOAD-BEARING CAPACITY OF SINGLE PILE WITH NEW AND OLD REGULATIONS%浅析新、旧规范单桩竖向承载力的确定

    Institute of Scientific and Technical Information of China (English)

    姬立君; 李爱群; 赵恩山

    2001-01-01

    通过桩基础新、旧规范对比的论述,指出了在以静压法确定单桩承载力时,旧规范存在着的不足及新规范具有的优点。%By comparison with new and old regulations of pile foundation, the paper points out faults of old regulations and advantages of new regulations when static pressure method is used to determine load-bearing capacity of single pile.

  8. 时间对复合地基桩间土承载力的影响研究%Study about influence of time on bearing capacity of soil between piles in composite foundation

    Institute of Scientific and Technical Information of China (English)

    张军平; 刘涛; 吴宗璋

    2013-01-01

      结合青藏铁路西格段增建二线工程碎石桩复合地基工程实例,通过重型动力触探试验和桩间土承载力计算分析,研究了复合地基桩间土承载力随软土固结时间提高的特性,得到了动力触探曲线随时间变化的规律;理论分析了地基处理后瞬时桩间土承载力与处理前地基承载力的关系,得到了时间对桩间土承载力影响的规律,给碎石桩复合地基的处理效果提供评价依据,为碎石桩复合地基上层的路基施工提供科学指导。%In accordance to the project of gravel pile composite foundation in the double tracking project in Xining-Golmud section of Qinghai-Tibet Railway,and computational analyses of heavy dynamic penetration test and the bearing capacity of soil between piles,this paper studies the time characteristics of bearing capacity of soil between piles in composite foundation increasing with the soft soil consolidation,and gets the regulation that dynamic penetration curves change with time and the feature that soil between piles increases with time as well. Besides,in theory,this paper elaborates on the relation between momentary bearing capacities of soil between piles after and before soil foundation process,and gets influence mechanism of time on bearing capacity of soil between piles. At last,this study provides the evaluation basis for the processing treatment of gravel pile composite foundation and scientific guidance for roadbed construction of the upper layer of gravel pile composite foundation.

  9. Experimental study on the pressure bearing capacity of recycled concrete hollow block masonry walls%再生混凝土小型空心砌块墙体受压承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    郭樟根; 孙伟民; 沈丹; 刘佳亮

    2011-01-01

    An experimental study on the pressure bearing capacity of recycled concrete hollow block masonry walls was presented in this paper. The failure characteristic and mechanism, ultimate bearing capacity of recycled concrete hollow block masonry walls were analyzed. The results of the test show that the compression failure process of recycled concrete hollow block wall are similar to ordinary concrete hollow block walls, which is divided into three stages: elastic stage, crack development stage and the destruction phase. The pressure bearing capacity of specimens were calculated according to formula in masonry structure design code( GB50003 -2001 ). The calculating results are to be less than the experimental result,so that the pressure bearing capacity of recycled concrete hollow block walls can be calculated according to building code. The research results can provide reference for engineering applications of the recycled concrete hollow block.%对4片再生混凝土小型空心砌块墙体进行了轴心和偏心竖向荷载作用下的试验研究,分析了再生棍凝土小型空心砌块墙体在竖向荷载作用下的受力全过程及破坏形态.再生骨料掺人量为75%,再生混凝土小型空心砌块强度等级达到MU7.5.研究结果表明,再生混凝土小型空心砌块墙体在竖向荷载作用下的破环全过程和普通混凝土空心砌块墙体基本相似.受力全过程分为三个阶段;弹性阶段、裂缝发展阶段以及破坏阶段.墙体的偏心受压承载力小于轴心受压承载力.按GB50003-2001公式计算得到的墙体受压承载力小于试验结果,通过对试验数据的回归分析,再生混凝土砌体承载力的计算可参照中有关砌体受压承载力的计算公式.研究成果,可供再生混凝土小型空心砌块的工程应用参考.

  10. Study of working mechanism and bearing capacity behavior of bucket foundation for offshore wind turbine%海上风电机组筒型基础工作及承载特性研究

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Compared with traditional offshore foundation structure, bucket foundations which are large cylindrical structures open at the base and close at the top may realize economical advantages over traditional driven piles due to the speed of installation, elimination of the pile driving process, and reduction in quantities and material costs. Though bucket foundation is a new foundation type for offshore wind turbine, there have no standards for bucket foundation designing up to now. In designing the bucket foundation, the simplified limit equilibrium method is usually adopted, in which the soil inside the bucket and the skirt of the bucket are assumed to form a whole foundation. But this method cannot reflect the working mechanism of the internal soil. Based on a foundation of offshore wind turbine in Fujian, adopting the finite element software ABAQUS, the three-dimensional numerical analysis is performed to simulate the working mechanism and evaluate the bearing capacity behavior of bucket foundation. According to the bearing capacity of offshore wind turbine, the simplified model and models with or without compartments are established with the considering of the compartments effect. According to calculation results, the bearing characteristic of the bucket foundation is different from the simplified limit equilibrium method that the internal soil of the foundation yields first in the loading process. The difference leads the simplified limit equilibrium method will over estimate the bearing capacity of bucket foundation. In addition, the error of the bearing capacity calculated by the simplified limit equilibrium method is estimated. The suggestion about the bearing capacity of bucket foundation has reference value to project designer.%  筒型基础是一种新型的海上风电基础,由于其具有减少工程量、节省投资、缩短施工时间、可重复使用等优点,在某些领域正在逐步替代桩基和重力式基础。目

  11. Stable bearing capacity coculation of greenhouse structures considering skin effect of covering material%考虑覆盖材料蒙皮效应的温室结构稳定承载力计算

    Institute of Scientific and Technical Information of China (English)

    丁敏; 李密密; 施旭栋; 张鹏; 蒋秀根

    2016-01-01

    The greenhouse is a kind of agriculture production building facilities. It should bear all kinds of loads, including the loads induced by gravity, improper operation, and live loads, such as wind load and snow load. At the present time, a large number of research studies on greenhouse have focused on illumination, temperature, gas and humidity, whereas there are few researches published on greenhouse structures, especially on greenhouse structure design theory taking the supporting role of covering materials into account. It is necessary to carry out the research on space robustness of greenhouse structure by bringing the design work condition into correspondence with the actual work condition. Then three types of greenhouse including Huabei-type greenhouse, venlo greenhouse and sunlight greenhouse, were chosen to be prototypes, and the numerical simulations on the overall collapse process of single hinged frame, whole frame structure, whole frame structure with plate glass covering, whole frame structure with PC board covering, and whole frame structure with membrane covering under windstorm and snowstorm were carried out by using finite element analysis software ANSYS with consideration of geometric imperfections, material nonlinearity and geometric large deformation. The collapse modes of greenhouse structure and the corresponding load-displacement curves were obtained. The stable bearing capacity and the space robustness of greenhouse structures were analyzed under three typical weather disasters. At the same time their ultimate load coefficient and stable bearing capacity coefficient were provided. The results showed that buckling failure mode happens easily for greenhouse structure under vertical snow load, the whole structure bearing capacity was higher for greenhouse structure under horizontal wind load considering skin effect of covering material. It was due to more compression-flexure members existing in greenhouse structure under vertical snow load than

  12. 平板静载荷试验确定地基承载力在某工程中的应用%Application of Plate Static Load Test to Determine the Bearing Capacity of Foundation in a Project

    Institute of Scientific and Technical Information of China (English)

    郑兴富

    2012-01-01

    某新建高层住宅楼工程设计拟采用浅层强风化绿泥石片岩作为天然基础持力层,为确定地基承载力特征值,选用了平板静载荷试验(慢速维持荷载法)对地基进行了检测工作。对检测过程进行了介绍,并结合该场地的地质环境特征,对该场地的承载力特征值及变形模量提出建议。%A new high -rise residential building project is designed to adopt shallow strongly weathered chlo- rite schist as a natural foundation bearing stratum. In order to determine the characteristic value of the bearing ca- pacity of foundation, a plate static load test ( slow sustaining load method) is selected to detect the foundation. De- tection process is described, combined with the characteristics of the geological environment of the site, recommen- dations are proposed for the bearing capacity characteristic value and deformation modulus of the site.

  13. 按沉陷深度控制的深海沉积物承载力分析方法%Analysis on Deep-sea Sediments' Bearing Capacity Controlled by Subsidence Depth

    Institute of Scientific and Technical Information of China (English)

    曹喜仁; 蔡永; 曹文贵; 王江营

    2011-01-01

    The subsidence depth of mining equipment and the bearing capacity of deep-sea sediments are important to the design of mining equipment. In this paper, firstly, the subsidence depth model of mining equipment was proposed by using the limit balance theory, according to the deep-sea sediments' physical properties, subsidence, bearing mechanism, and its shear strength changing with depth. Secondly, the bearing capacity of deep-sea sediments is closely related to the subsidence depth of mining equipment. The deep-sea sediment bearing capacity method controlled by subsidence depth was presented on the basis of the subsidence depth model. Finally, the case study and indoor simulation test indicate that the model proposed is reasonable and feasible.%采运设备沉陷深度和深海沉积物承载能力是大洋资源采运设备设计的重要依据.首先从研究深海沉积物物理力学性质特点及其沉陷与承载机理入手,针对深海沉积物抗剪强度随深度变化的特征,利用极限平衡理论建立了采运设备沉陷深度分析模型;其次,考虑到深海沉积物承载能力与采运设备沉陷深度的相关性,在采运设备沉陷深度分析模型研究基础上,采用按沉陷深度控制深海沉积物承载能力的思想,提出了按采运设备沉陷深度控制的深海沉积物承栽能力分析方法;最后,通过实例分析与室内模拟试验,验证了本文模型的合理性与可行性.

  14. The application of plate loading test in the experiment of bearing capacity of foundation soil%平板载荷试验在强夯地基土承载力检测中的应用

    Institute of Scientific and Technical Information of China (English)

    马青峰; 辛淑珍; 刘文兴

    2015-01-01

    This paper introduced the using plate loading test method for the experiment of bearing capacity of foundation soil after dynamic compaction, analyzed by the plate loading test of a new project in Inner Mongolia, and the use of static load test and analysis system JYC software to deal with test data, mainly discussed test principle, test points, determination of characteristic value of bearing capacity of the plate loading test, further analysis illustrated the applicability of plate loading test.%本文介绍了地基土在强夯作用之后运用平板载荷试验方法进行地基土承载力检测的试验,通过对内蒙古某新建工程实例的平板载荷试验进行分析,利用静载荷测试分析系统JYC软件对试验数据进行处理,重点讨论了平板荷载试验的试验原理、试验要点、承载力特征值的确定等内容,进一步分析说明了平板荷载试验的适用性。

  15. 混凝土小型砌块墙体抗剪承载力灰色关联分析%Grey Correlation Analysis of Shear Bearing Capacity on Small Concrete Block Wall

    Institute of Scientific and Technical Information of China (English)

    谢成新

    2001-01-01

    The shear bearing capacity on the small concrete block wall are analyed by grey system theory as well as the correlation factors.The analysis result shows that the first factor that influences the shear bearing capacity on the concrete block wall is pressure resistance strength of wall f,height and width ratio h/b and normal pressure N,the shear span ratio λ has the least influence.%应用灰色系统理论,对混凝土小型砌块墙体抗剪承载力及其关联因素进行关联度分析。结果表明,对混凝土小型砌块墙体抗剪承载能力影响最大的是砌体抗压强度f,其次是墙体的高宽比h/b、垂直压力N,影响最小的是剪跨比λ。

  16. Load-bearing Capacity Analysis Method for Explosive Bolt on Launch Vehicle%运载火箭爆炸螺栓承载能力分析方法

    Institute of Scientific and Technical Information of China (English)

    杨帆; 张希; 章凌; 曾杜娟; 郑卫东

    2015-01-01

    The transverse unlocking plane of fairing in launch vehicle is usually connected by explosive bolts. The empirical formula used for calculating explosive bolt strength is rash without considering local deformation effect. In this paper, finite-element method was adopted to stimulate the local deformation of explosive bolt which disclosed the mechanism of local deformation of explosive bolt. A method for calculating explosive bolt load-bearing capacity was proposed. By comparing with finite-element calculation results, the revised method can enhance the calculating precision of explosive bolt load-bearing capacity significantly.%运载火箭的整流罩横向解锁面一般采用爆炸螺栓连接,目前针对爆炸螺栓强度计算采用的是经验算法,由于没有考虑局部变形效应往往偏于冒进.采用有限元方法对爆炸螺栓的局部变形进行详细的仿真,揭示了爆炸螺栓结构的局部变形机理,并提出一种计算爆炸螺栓承载能力的方法,通过与有限元计算结果的对比,修正后的方法能够大幅提高爆炸螺栓承载力的计算精度.

  17. Determining the pile bearing capacity by the curve match method of high strain dynamic testing%确定基桩承载力的高应变实测曲线拟合法

    Institute of Scientific and Technical Information of China (English)

    王秉宇; 崔建波; 王士杰; 孙东岭

    2012-01-01

    采用高应变实测曲线拟合法确定基桩承载力及桩侧摩阻力的分布,通过基桩承载力动、静试验结果的对比,分析了高应变实测曲线拟合法的测试精度和可靠性,探究了高应变动测法确定基桩承载力的误差来源及因由,为合理确定桩基工程设计参数提供可靠保证.%This essay will determine, the bearing capacity of the pile and shaft resistance by the curve match method of high strain dynamic testing. By the pile of bearing capacity of the contrast between the testing results of static loading and dynamic high strain, analyses the reliability and surveying precision of the curve match method and exdores the error sources and reason, which reasonably determine the pile foundation engineering of design parameters.

  18. 火灾后型钢混凝土轴压柱剩余承载力试验%EXPERIMENTAL STUDY ON RESIDUAL LOAD BEARING CAPACITY OF SRC COLUMNS UNDER AXIAL FORCE AFTER EXPOSURE TO FIRE

    Institute of Scientific and Technical Information of China (English)

    李俊华; 赵银海; 唐跃锋; 刘明哲

    2012-01-01

    进行了5个火灾后型钢混凝土柱轴心压力作用下的试验,研究长细比、混凝土强度对构件破坏形态和剩余承载能力的影响.试验结果表明,火灾后型钢混凝土轴心受压柱在荷载作用下的破坏形态与常温下基本相同,试件破坏时其内部核心型钢依然完好,不会发生局部屈曲现象.混凝土强度和长细比是影响型钢混凝土轴心受压柱火灾后承载能力的两个重要因素,当长细比相差不太大的情况下,混凝土强度高的试件,其火灾后极限承载力相对较高;在混凝土强度大致相当的情况下,随着长细比的增大,火灾后试件的极限承载力降低.利用YB规程和JGJ规程方法,对所有试件常温下的极限承载力进行了计算,结果表明在该文的试验条件下得到的火灾后型钢混凝土轴心受压柱承载能力的试验值与常温下承载力计算结果的比值在62%~71%之间,经历火灾作用后型钢混凝土轴心受压柱承载能力显著降低,火灾后的剩余承载力水平平均为常温下承载力水平的67%.%This paper provided five test data pertaining to the residual load bearing capacity of steel reinforced concrete (SRC) columns after exposure to fire. Two parameters, that is, slenderness ratio and concrete strength are mainly taken into consideration. Test results show that the failure pattern of SRC columns under an axial pressure force after exposure to fire is basically the same with that at room temperature. When the specimens are destroyed, the internal core steels are still fine, having no local buckling phenomena. Concrete strength and the slendemess ratio are two important factors that affect the strength of SRC columns under an axial pressure force after exposure to fire. For the specimens of about the same slenderness ratios, the higher concrete strength they are, the higher ultimate bearing capacity they have. In the condition of roughly the same concrete strength, the ultimate

  19. LATERAL BEARING CAPACITY OF HIGH SHEAR WALL WITH STEEL FIBER REINFORCED CONCRETE IN BOUNDARY ELEMENTS%钢纤维增强边缘构件混凝土高剪力墙抗侧承载力分析

    Institute of Scientific and Technical Information of China (English)

    楚留声; 赵军; 王卫仑; 李明杰

    2016-01-01

    Based on the idea of partial reinforcement, a method that using steel fiber reinforced concrete in boundary elements of high wall was proposed according to the construction difficulty and complex stress state of boundary elements.Combined with the test results, the applicability of the finite element numerical analysis was verified, and the influences on the lateral bearing capacity of this kind of shear wall from different steel fiber volume ratios and axial load ratio were studied, to which a comparative analysis of accordingly lateral bearing capacity of overall steel fiber reinforced concrete shear wall was then conducted.Results showed that the lateral bearing capacity was best when the steel fiber volume ratio in reinforced concrete of boundary elements was between 1.5% and 2%, with a maximum increase of 45.1%.Compared with the overall steel fiber reinforced concrete shear wall, the high shear wall with steel fiber reinforced concrete only in boundary elements does not reduce excess capacity, while has great economic advantage.%基于“部分增强”的思想,针对剪力墙边缘构件受力复杂、施工困难的特点,提出在高剪力墙边缘构件中采用钢纤维局部增强的方法。结合试验结果,验证了有限元数值分析的适用性,研究了钢纤维体积率和轴压比对钢纤维增强边缘构件混凝土高剪力墙抗侧承载力的影响,并与整体钢纤维混凝土剪力墙相应的抗侧承载力进行对比分析。结果表明:边缘构件钢纤维体积率为1.5%~2%时,对剪力墙承载力增强效果最强,最大提高幅度达45.1%。相对于整体钢纤维混凝土剪力墙,仅边缘构件采用钢纤维增强的剪力墙在未降低过多承载力的情况下,具有较好的经济优势。

  20. Bearing Capacity of Composite Columns of Waste Tires Filled with Granular Material%内填散体材料废弃轮胎叠合体承载能力研究

    Institute of Scientific and Technical Information of China (English)

    王凤池; 高寰; 张倍川; 徐云龙

    2016-01-01

    为提高废弃轮胎在土木工程上的利用率 ,提出利用废弃轮胎环箍约束散体材料 ,形成具有良好载荷能力的叠合体.通过竖向载荷试验 ,测得不同因素对叠合体承载能力和变形特点的影响情况.分析出叠合体的承载力主要与填充材料的性质和轮胎的直径有关 ,实验表明叠合体的承载力与内摩擦角或轮胎的直径呈正相关关系 ,当后者增大时 ,前者也随之增大 ;当叠合体内填充不同的材料时 ,它的横向变形量沿高度分布情况也不同 ,即变形特点与填充材料有关 ;旧轮胎能够提供相当大的环向约束力 ,给出了横向约束力和横向位移的计算公式 ,具有较好的计算精度 ;该叠合体能够承受很大的上部载荷 ,其颗粒材料的抗剪强度和轮胎的环向约束能力被充分发挥.%The treatment of waste tires is gaining more and more attention .In order to improve the utilization of waste tires in civil engineering ,composite column of waste tires was proposed which was used to constrain the granular material thus had good bearing capacity .By vertical loading tests ,effects of various factors on the bearing capacity and deforma-tion properties of composite columns were studied .The bearing capacity was related with diameter of tires and natures of filling material closely .With the increase of the internal friction angle and the tire diameter ,the bearing capacity of com-posite columns increase as well .Deformation features of composite columns relate to the filling material .Different filling materials lead to different distribution of lateral deformation along the height .Waste tires can provide considerable circu-lar confining force ,calculation formula for lateral binding and transverse displacement was given which has higher calcu-lation accuracy .The results showed that the composite columns filling with granular material could play the roles of shear strength of granular material and the confining

  1. 海上风电桩基础竖向承载力循环弱化简化分析%Simplified analysis of cyclic degradation of axial bearing capacity for offshore wind turbine pile foundations

    Institute of Scientific and Technical Information of China (English)

    刘莹; 黄茂松; 李帅

    2013-01-01

    提出了一个考虑循环衰减作用的软黏土弹塑性损伤弱化模型,在此模型基础上建立了一个基于剪切位移法的单桩竖向承载力简化计算方法,并利用大型有限元软件进行了不同循环荷载水平下单桩竖向承载力的计算。为了证明简化方法的准确性与有效性,将计算结果与有限元计算结果进行对比,二者的吻合度较高。先期循环荷载能引起单桩竖向承载力弱化,并且弱化程度随先期循环荷载水平的增加而增加。最后将简化方法应用于某海上风电场桩基础承载力的计算中,结果表明,提出的简化方法可应用于实际工程问题的分析。%A modified undrained elastic-plastic model considering the cyclic degradation of clay soil is proposed. Based on this model, a simplified analysis procedure based on shear displacement method is presented. Numerical simulations for axial bearing capacity of single pile are conducted by commercially available finite element software at different cyclic load levels. The results calculated by this simplified analysis have a good consistency and effectiveness with the results from finite element analysis. The axial bearing capacity of single pile will be degraded after resisting cyclic loading, and the degradation will be greater as the increase of cyclic loading levels. As an example, the axial bearing capacities of pile foundation of an offshore wind farm are studied with the application of the proposed simplified analysis method. The proposed simplified calculation method will serve as a useful tool for engineering design.

  2. The Inspection and Appraiser for the Bearing Capacity of Beam-column Joint of the Hotel%某酒店框架梁柱节点承载力的检测鉴定

    Institute of Scientific and Technical Information of China (English)

    王丽敏; 宋雄彬

    2012-01-01

    Because separating column and beam-slab exist certain difficulty, accustomed to utilize unified the strength of floor concrete to pouring in joint construction. If the concrete strength grades of column and beam have large difference, the concrete strength of joint area can" t meet the design requirements, bearing capacity of beam- column joint whether or not satisfied the requirements cause the most attention to engineers. In this paper, we take the inspection and appraiser for the bearing capacity of beam-column joint of the hotel as an example, based on consulting some domestic and foreign experience concerning this subject, introducing the concept of " discount strength " of the joint area, to solve the problem of the strength concrete value ,giving more accurate result of bearing capacity of beam-column joint, providing a certain reference action for similar appraisal work.%由于柱与梁板之间的分隔存在一定难度,施工中习惯于在节点区统一采用楼盖的混凝土强度进行浇注,此时若柱、梁的混凝土强度等级相差较大,就将造成节点区混凝土强度达不到设计要求,节点区的承载力是否能满足要求成为工程技术人员最关心的问题。本文以某酒店框架节点承载力检测鉴定为例,在参考国内外相关经验的基础上,引入节点区混凝土“折算强度”的概念,较好地解决了节点区混凝土强度的取值问题,较准确地鉴定了节点的承载能力,为相关类似检测鉴定工作提供了参考。

  3. 轴向荷载对斜桩水平承载特性影响试验及理论研究%Test and theoretical research on influence of axial load on lateral bearing capacity of batter piles

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      斜群桩受水平荷载作用时,群桩中的基桩受到径向荷载、轴向荷载和弯矩的共同作用。为研究轴向荷载对斜桩水平承载特性的影响,完成了3根单桩以及1组1×2斜桩的大尺寸模型试验。试验结果表明:轴向拉力作用会降低斜桩的水平刚度和极限承载力;而轴向压力作用则会使其水平刚度和极限承载力提高。基于桩侧浅层土体楔形破坏假定,推导了考虑轴向荷载影响的斜桩水平极限土抗力计算公式,提出了桩侧土抗力的p-y曲线方法,并通过模型试验及现场试验验证其合理性。%When batter pile group are under lateral load, the foundation piles in pile group are subjected to radial load, axial load and bending moment. In order to study the influence of axial load on lateral bearing capacity of batter piles, large-scale model tests of three single piles and a 1×2 batter pile group have been conducted in a larger soil tank. It is found that the upward axial force on the pile top decreases the lateral stiffness and the lateral ultimate bearing capacity of batter pile; while the downward axial force enhances the horizontal stiffness and the lateral ultimate bearing capacity of batter pile. Based on the assumption of wedge failure of the shallow soil around piles, considering the influence of axial load on piles, a formula for calculating the lateral ultimate resistance force of soil is deduced. Then, a p-y curve method for resistance force of soil around piles is proposed. Finally, the formula and the proposed p-y curve method for batter pile are verified by model tests and field tests.

  4. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  5. Fracture mechanical analyses concerning the load-bearing capacity of dissimilar welds in piping with circumferential cracks; Bruchmechanische Untersuchungen zum Tragvermoegen von Rohrleitungen mit Umfangsrissen in Mischschweissnaehten

    Energy Technology Data Exchange (ETDEWEB)

    Schuett, T.; Hoffmann, M.; Schuler, X.; Stumpfrock, L. [Materialpruefungsanstalt (MPA), Univ. Stuttgart, Stuttgart (Germany)

    2007-07-01

    In power plants numerous dissimilar welds exist between ferritic and austenitic components. The evaluation of the influence of real or postulated flaws to the load bearing and failure behaviour in the area of dissimilar welded joints, e. g. in piping of the primary circuit of nuclear power plants, is an essential part of the safety assessment of these plants. The fracture assessment of dissimilar welds containing flaws is therefore an important issue of structural integrity considerations. During the past decades several assessment procedures for the evaluation of flaws in welds have been developed mainly based on methods originally developed for homogenous materials. The main difficulties in applying these methods are that they are restricted to two different materials and the very limited experimental evaluation especially by component tests. To improve the general understanding of the influence of flaws in piping systems with dissimilar welds and to have a more reliable basis for the assessment of the fracture behaviour, full scale tests on pipes containing a weld between ferritic and austenitic steel have been performed. The test results of these tests are summarised and used for the evaluation of analytical and numerical assessment procedures. (orig.)

  6. 土工合成材料加筋地基承载力的可靠度分析%Reliability Analysis of Bearing Capacity of Foundation Reinforced with Geosynthetics

    Institute of Scientific and Technical Information of China (English)

    张晓君

    2001-01-01

    首先选用土工合成材料加筋地基承载力的极限状态方程,对随机变量的概率模型进行了分析,最后结合工程实例,采用优化方法进行了复合地基可靠度的计算.%Firstlythe state equation of bearing capacity of foundation reinforced with geosynthetics was Constructed .Secondlythe probabilistic models of parameters treated as stochastic variables were analyzed. Finallyusing a case historythe reliability of composite foundation was calculated by way of microsoft Excel 2000 solver.

  7. 几何缺陷影响下的CFRP-方钢管极限承载力解析解%ANALYTICAL SOLUTIONS ON ULTIMATE BEARING CAPACITY OF A SQUARE CFRP-STEEL TUBE MEMBER WITH INITIAL IMPERFECTION

    Institute of Scientific and Technical Information of China (English)

    钮鹏; 金春福

    2015-01-01

    Based on Je(z)ek method for computing the elastic-plastic buckling of the member under axial compressive loads and the bending moments,and considering the initial imperfection,the analytical expressions are derived for calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for a square steel tube member with flange outsides wrapped by carbon fibre.Using the elastic-plastic finite element method and the theory of nonlinear buckling,the impact by initial geometric imperfections on the square steel tube member wrapped by carbon fibre is analyzed and the numerical solutions for ultimate bearing capacity are obtained.By comparing with the values of the finite element method (FEM),it shows that the analytical method proposed is valid.The calculation results show that when the value of moment is given,only the ultimate bearing capacity of the member reinforced by the carbon fiber among the three member always keeps a higher figure.When the given moment is small,the ultimate bearing capacity of a bare steel member is higher than that of a steel member reinforced by the carbon fiber with the initial geometric imperfection.When the value of the bending moment increases gradually,the ultimate bearing capacity of the former reduces faster than the latter.%该文利用计算压弯钢构件弹塑性失稳的Je(z)ek法,推导了受轴心压弯外力作用下具有初始几何缺陷且翼缘两侧分别粘贴碳纤维片后的方钢管构件失稳时极限荷载的计算公式.通过采用数值分析法,结合非线性屈曲理论,进行了受初始几何缺陷影响的碳纤维增强方钢管构件的屈曲分析,并得到极限承载力的数值解.将数值分析结果与Je(z)ek法得到的解析解进行比对,可以发现两种计算结果吻合的较好.由计算结果可知,当给定弯矩值时,三种构件当中碳纤维增强后的构件极限承载力始终保持较高数值.给定弯矩较小时,裸钢构件的极限承载

  8. 大跨钢桁拱钢-混组合桥面板极限承载力试验%Experiment on Ultimate Bearing Capacity of Steel and Concrete Composite Deck Slab of Long Span Steel Truss Arch Bridge

    Institute of Scientific and Technical Information of China (English)

    卢彭真; 赵人达; 任剑

    2012-01-01

    To assess the ultimate bearing capacity of the steel-concrete composite deck slab subject to highway load, ultimate bearing capacity tests were carried out. According to Saint Venant Principle, by taking the part steel-concrete deck slab in column area with positive and negative bending moments as finite element models of the actual bridge, the study focused on the ultimate bearing capacity of the steel-concrete deck slab in column area with positive and negative bending moments for 2 composite deck slab specimens (model A and model B). The results show that tensile failure has occurred in the concrete slab of model A. The upper and lower flange plates of I beam, web plate and longitudinal reinforcement have not yielded under ultimate load, but steel bottom plate, PBL and lateral reinforcement have yielded before failure. The failure load of model A is 1 750 kN. As for model B, concrete slab has compression failure, PBL has yielded before failure, and the failure load of model B is 2 200 kN. Research results provide reference for design calculation of the ultimate bearing capacity of steel-concrete composite deck slab.%为评估钢一混组合桥面板结构在公路荷栽作用下的极限承载力,对其进行极限承载力性能试验研究。根据圣维南原理,选取正负双向弯矩受力的立柱区部分桥面板作为实桥的有限元分析模型,并试验制作了2个等尺模型试件A和B,用于考察钢一混组合桥面板正负双向弯矩区的极限承载力性能。试验结果表明:模型A混凝土板被拉坏,工.字钢上下翼缘板、腹板以及纵向钢筋始终未屈服,PBL、钢底板以及横向钢筋均在破坏之前屈服,模型A的破坏荷载为1750kN;模型B混凝土板被压坏,PBL在破坏之前屈服,模型B的破坏荷载为2200kN。研究结果可为钢一混组合桥面板极限承栽能力设计计算提供参考。

  9. Calculation method of bearing capacity of the concrete floor when walking crane%混凝土楼板上行走吊机时楼板承载能力计算方法

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    为了简化施工过程,节约施工成本,阐述了利用通用有限元分析软件对楼板承载力计算的方法,以保证在不加固原有混凝土楼板时,吊机等机械设备可以直接安全可靠的在混凝土楼板上进行行走和吊装构件等工作。%In order to simplify the construction process and save the construction cost,describes the calculation method of bearing capacity of slabs using finite element analysis software,ensure the machines can be directly safety running and lifting components on unreinforced concrete floor.

  10. 基于贝塔分布的抗拔桩承载力可靠度分析%Reliability analysis of bearing capacity for anti-uplift piles based on Beta distribution

    Institute of Scientific and Technical Information of China (English)

    徐志军; 郑俊杰; 边晓亚; 赵文艺

    2012-01-01

    The bearing capacities of 12 anti-uplift piles were collected,and the probability distribution of partial factor(the ratio of the measured values of bear capacity of anti-uplift piles and their corresponding calculated values) was fitted utilizing Beta distribution.The results through the K-S test indicate that the fitting accuracy employing Beta distribution is better than employing normal distribution,lognormal distribution and extreme value I distribution.The results from calculation of reliability indices based on Monte Carlo simulation method show that the mean of partial factor,loading combinations,loading ratios and factors of safety have significant influence on reliability indices,while the reliability index is insensitive to coefficient of variation of partial factor.Finally,the resistance factors of anti-uplift piles were given according to load and resistance factor design method.%以12根抗拔桩承载力为研究对象,利用4参数的贝塔分布拟合出抗拔桩承载力试计比(承载力实测值和计算值的比)的概率分布.通过K-S检验法检验指出:贝塔分布的拟合精度优于常见的正态分布、对数正态分布和极值I型分布.利用蒙特卡罗法计算出抗拔桩承载力的可靠度指标,计算结果表明:承载力试计比的均值、荷载组合、荷载比和安全系数对可靠度有显著的影响.最后利用荷载抗力系数设计法给出了抗拔桩的抗力系数.

  11. Theoretical solution for time effect of shaft bearing capacity of single pile in soft soils%软土中单桩桩侧承载力时效性理论解

    Institute of Scientific and Technical Information of China (English)

    曹权; 施建勇; 雷国辉; 艾英钵; 陈鸿

    2011-01-01

    以有效应力原理为基础,结合考虑应变软化、桩径和弹性区孔压分布等因素的桩周土固结解,推导出软土中单桩桩侧承载力时效性的理论解.与传统桩的承载力时效性简化分析方法不同,该理论解不仅考虑了多土层地基中各土层刚度指数的差异对固结过程的影响,还考虑了各土层因固结系数不同对孔压消散速率的影响.通过现场不同间歇期的单桩载荷试验测试结果验证了其合理性.%Based on the theory of effective stress, consolidation solution around the pile which is taken into account the influence of strain softening, magnitude of pile radius and range of excess pore water pressure, a theoretical relationship about time-effect of bearing capacity of single pile is developed, which can be used to predict the variation of shaft bearing capacity of a jacked-in pile with time in saturated soft clay. Different from the traditional way, the effect of different stiffness indices and different consolidation coefficients on the consolidation process in varied clays and highly stratified deposits are considered in the new consolidation solution. Besides, the rationality of the solution is verified by the pile load tests in different time periods after installation.

  12. Autosizing Control Panel for Needle Bearing

    Directory of Open Access Journals (Sweden)

    Prof.A.R.Wadhekar,

    2016-02-01

    Full Text Available A needle roller bearing is a bearing which uses small cylindrical rollers. Bearings are used to reduce friction of any rotating surface. Needle bearings have a large surface in contact with the bearing outer surfaces as compared to ball bearings. There is less added clearance(Diameter of the shaft and the diameter of the bearing are different so they are much compact. The structure consists of a needle cage which contains the needle rollersthemselves and an outer race (The housing itself. Radial bearings are cylindrical and they use rollers parallel to the axis of the shaft. Radial pattern of needle are being used by thrust needles. Complement bearings have solid inner as well as outer rings and rib-guided cylindrical rollers. The bearings have the largest number of rolling elements and also have extremely high radial load carrying capacity and are suitable for compact designs.Needle roller bearings have relatively small diameter cylindrical rolling elements whose length is much larger than their diameter. As compared to other types of rolling bearings, needle roller bearings possess a small cross-sectional height and significant load-bearing capacity and rigidity relative to their volume. Also, because the inertial force acting on them is limited, needle bearings are an ideal choice for applications with oscillating motion. These bearings also work well in compact and lightweight machine designs and they serve as a ready replacement for sliding bearings. Needle bearings features are great rigidity, smaller cross-section, higher loadcarrying capacity, and has lower inertia forces that facilitate to size and weight reductions in machinery. Needle bearings are designed to stand in oscillation, performwell under any conditions, and interchange with the sliding of bearings.

  13. 轮胎碎片加筋砂土路基承载力试验%Tyre Pieces of Reinforced Sand Subgrade Bearing Capacity Test

    Institute of Scientific and Technical Information of China (English)

    李丽华; 刘毅; 肖衡林; 崔飞龙; 任增乐; 高萌

    2016-01-01

    废旧轮胎碎片与砂土混合使用,可以有效提高路基承载力,减小路基不均匀沉降。为了深入研究废旧轮胎碎片加筋路基工作机理,通过室内模型试验,利用数字照相无标点变形测量系统,结合地基土压力分布和 P-S 曲线,研究了废旧轮胎碎片加筋路基的加筋机理和破坏模式,研究结果表明,轮胎碎片加筋使土体位移场产生了显著的变化,有效的限制了路基浅部土体的水平位移,轮胎碎片含量为5%时,加筋效果较优。%Scrap tire chips mixed with sand,can effectively improve the subgrade bearing capaci﹣ty,reduce differential settlement of subgrade.In order to study fragments of scrap tires working mechanism of reinforced embankment.Through model tests,the use of digital photography without punctuation de﹣formation measurement system.Combined with soil pressure distribution and P -S curve.Study the rein﹣forcement mechanism of scrap tires and debris reinforced embankment failure mode.The results show,tyre pieces of reinforcement to displacement field of soil produced a significant change and effective limits the roadbed shallow soil horizontal displacement.When the tire debris content is 5%,subgrade has the best effect of reinforcement.

  14. 输电线路沙漠地区偏心装配式基础的承载性能研究%RESEARCH ON BEARING CAPACITY OF ECCENTRIC ASSEMBLY FOUNDATION OF TRANSMISSION LINE IN DESERT AREA

    Institute of Scientific and Technical Information of China (English)

    侯鹏翔; 郑卫锋; 李维

    2016-01-01

    On geogrid reinforced aeolian sand ground in Ningxia, a full-scale in-site comparison experiments of the uplift bearing capacity for eccentric assembly foundation were tested under uplift loading and uplift combined with horizontal loadings.Both the site conditions and the load tests were recorded comprehensively, allowing for a thorough evaluation of the loading-displacement behavior.Based on the displacement of top plane of foundaiton and the soil reaction forces, the mechanism of the the eccentric assembly foundation on reinforced aeolian sand ground was obtained.Through taking geogrid reinforcement and eccentric structure measures, the bearing performance of assembly foundation was significantly improved, which could improve its anti-horizontal bearing capacity and did not reduce the uplift performance.The test result provided useful evidence for its practice in transmission line projects in aeolian sand.%在宁夏毛乌素加筋风积沙地基中开展偏心装配式基础在单上拔、上拔与水平力组合工况下的现场对比试验,通过监测其顶部荷载位移曲线、地表竖向位移及基础底板土压力数据,分析偏心装配式基础的抗拔承载机理。试验表明:采用增强地基稳定的加筋和设置基础偏心的结构措施,可显著改善装配式基础的受力性能,在提高其抗水平承载性能的同时不降低其抗拔性能,为沙漠地区输电线路工程中应用装配式基础提供了试验数据。

  15. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  16. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  17. 预应力墩基础的抗倾覆承载力研究%Research on the Anti-overturning Bearing Capacity of Wind Turbine Prestressed Pier Foundation

    Institute of Scientific and Technical Information of China (English)

    郭敏; 申超

    2013-01-01

    随着风电机组容量的逐渐增大,传统风电机组基础形式已经不能满足使用要求,必须要在传统基础上进行创新。预应力墩基础预应力墩基础作为一种新型基础,在适用范围、安全性能以及建造成本上具有一定优势。该文通过研究预应力墩基础的抗倾覆验算方法,为计算这种新型基础的抗倾覆承载力探索一种快速、合理的方法。%As the gradually increasing of wind turbine capacity, traditional wind turbine foundation type can no longer meet the operating requirements. It is necessary to make innovation based on the traditional foundations. As a new type of wind turbine foundation, the prestressed pier foundation has advantages on the application range, safety performance and construction costs. Tis paper researched and explored a fast and reasonable method for computing the anti-overturning bearing capacity of wind turbine prestressed pier foundation through studying several calculation methods.

  18. 灌注桩钢筋笼长度对承载力的影响%The bearing capacity of pile length of reinforcing cage of inlfuence

    Institute of Scientific and Technical Information of China (English)

    王东; 马青龙; 王德庆

    2015-01-01

    The uplift pile for foundation under pulling force is a common practice of engineering. In some deep underground engineering, the bored piles can provide higher pull-out force, reinforced concrete pile and the soil is a good way to combine, make the uplift capacity of pile with good performance. But in actual project, the contractor to save costs, fail to execute the works in accordance with the drawings, to reduce the length of reinforcing cage, brings to the engineering quality hidden trouble.%抗拔桩来承担基础承受的上拔力是工程界常见的做法.在一些较深的地下工程中,钻孔灌注桩能提供较高的抗拔力,钢筋混凝土桩身与土层可以很好地结合 ,使这种桩具有良好的抗拔性能.但在实际工程中,施工方为节约成本,未能按照图纸施工,减少钢筋笼的长度,给工程质量带来隐患.

  19. Method for analyzing cyclic bearing capacity of suction anchor with taut mooring system using cyclic strengths%利用循环强度分析张紧式吸力锚循环承载力的方法

    Institute of Scientific and Technical Information of China (English)

    王建华; 李书兆; 周杨锐; 刘晶磊

    2012-01-01

    A limiting equilibrium method for calculating cyclic bearing capacities of suction anchors in soft clays using undrained cyclic shear strength of soft clays was developed based on the failure mode of suction anchors with inclined loads at the optimal loading point. Effects of average shear stresses due to average mooring loads on cyclic shear strengths of soft clays and cyclic bearing capacities of suction anchors were considered for the method. In order to verify its feasibility, a large number of model tests of suction anchors with combined average and cyclic mooring loads were conducted associated with different test parameters. The displacement criterion to failure at the loading point associated with the vertical pullout failure mode was determined based on test results. Cyclic bearing capacities of model tests with different parameters were determined based on the criterion. Cyclic bearing capacities associated with different model tests were further calculated by limiting equilibrium analyses using the relationship determined by undrained cyclic triaxial tests between normalized cyclic strengths and normalized average stresses and measuring shear strengths of model test strata. Comparison between calculating and testing results show that calculating results larger than testing results for the vertical pullout failure mode of suction anchors with taut mooring system. The average difference between them is 1.9%. Most of differences are not more than 10%. Therefore, it is appropriate that the calculating result is decreased 10% if the cyclic bearing capacity associated with the vertical pullout failure mode is calculated using the method for suction caissons with taut mooring system in soft clays.%按照在最佳系泊点受倾斜荷载作用的张紧式吸力锚的破坏机制,建议了利用软土不排水循环剪切强度计算软土中吸力锚循环承载力的极限平衡分析方法.该方法考虑了平均系泊荷载在土中引起的平均剪应力

  20. 玻璃钢锚环承载性能的有限元分析%Finite Element Analysis of Bearing Capacity of Glass Fiber Reinforced Plastics Anchor Ring

    Institute of Scientific and Technical Information of China (English)

    刘建月; 崔小朝; 刘伟婧; 郑亚东

    2016-01-01

    通过 ABAQUS 有限元分析软件建立了连续玻璃纤维缠绕的聚酯树脂基玻璃钢锚环的有限元计算模型,对玻璃钢锚环与金属夹片、钢绞线配合使用的支护系统进行了加载分析。通过改变玻璃钢锚环的半锥角,研究了玻璃钢锚环与夹片的锥角搭配对锚具承载性能的影响。计算分析表明,在300 kN载荷作用下,计算模型中锚环纤维方向承载性能良好;轴对称面内最大主应力集中在锚环与夹片接触面附近,此处小范围基体开裂对锚环承载性能影响不大;锚环对称面内剪应力大面积超出基体强度极限,是影响锚环承载性能的主要因素。当夹片半锥角为7°时,玻璃钢锚环半锥角为6.3°~6.5°能改善锚环的应力分布状态,提高锚具的承载能力。%This paper established a finite element calculation model of continuous glass fiber winding and polyester resin GFRP anchor ring with ABAQUS,which conducted a loading analysis on the supporting system consisting of GFRP anchor ring,metal clip and steel strand.A research was made on the influence on the loading capacity of an-chor ring by changing the match of taper angles of GFRP anchor ring and clip.According to the calculation analy-sis,the anchor ring of the calculation model has a good bearing capacity in fiber direction under the load of 300 kN;in the symmetrical plane,the maximum principal stress is concentrated nearby the contact face between anchor ring and clip,and the crack of resin in small scale has small influence on the anchor ring bearing capacity;in sym-metrical plane,a large area of shearing stress of anchor ring surpassing resin ultimate stress is the main factor which can influence the loading capacity of anchor ring.When the half taper angle of clip is 7°and that of GFRP anchor ring is 6.3°~6.5°,the stress distribution and loading capacity of anchor ring can be well improved.

  1. Stability Theoretical Analysis of the Bearing Capacity of Frame Scaffolding with Steel Tubes%门式钢管脚手架承载力的稳定理论分析

    Institute of Scientific and Technical Information of China (English)

    刘希月; 杨建军; 王元清

    2013-01-01

    对脚手架这种临时结构重要性的忽视以及对新型脚手架的性能研究不够,是导致脚手架倒塌事故频发的主要原因之一.为了对新型门式钢管脚手架的承载性能有充分的认识,保证其安全性,保护国家财产和人民生命安全,有必要对新型门式钢管脚手架进行科学的试验研究和理论分析,为其推广提供一定的理论参考.本文在对由两种新型门架(MF0817,MF1017)组成的三步六跨门式钢管脚手架受力性能进行试验研究的基础上,利用钢框架稳定分析理论,考虑半刚性节点作用,修正转角位移方程,对三组不同搭设情况下的脚手架承载力进行稳定理论分析,推出了门式钢管脚手架在不同搭设情况下的立杆计算长度系数的计算公式,分析结果表明立杆杆端约束条件对结果影响较大,可利用转角位移法求得反映脚手架中其他杆件对立杆约束程度的计算长度系数,并将理论分析结果与相应的试验值比较,验证了理论分析方法的正确性.%The neglect of the importance for scaffoldings as temporary structures, and the lack of study for the scaffoldings of new types are the main factors that lead the collapse accidents of scaffoldings have occurred frequently. In order to get full understanding of the bearing capacity of frame scaffolding with steel tubes that are new types and ensure the safety of those new type scaffoldings, it is necessary to conduct research scientifically about them. Based on the experimental study of the three bays-six floors full scale scaffoldings which are composed of two new type portals( MF0817,MF1017) , the paper applied the stability theory of steel frames, modified the slope-deflection equation, considering the effect of semi-rigid joints, conducted theoretical analysis of the bearing capacity of the three frame scaffoldings that are constructed in different conditions, and derived the formulation of the effective length factor of

  2. Experimental study and numerical analysis of the bearing capacity of KT-shaped RHS joints%KT形RHS加强节点承载力试验研究与数值分析

    Institute of Scientific and Technical Information of China (English)

    余志祥; 吴昊; 闫雁军; 赵世春; 张贵海

    2011-01-01

    KT-shaped rectangular hollow section (RHS) joints are widely used in the steel structure of the East Railway Passenger Station of Hohhot. The mechanical behavior of two local strengthening treatments is studied, from the aspects of bearing capacity, technics and economy. Model tests and numerical analysis are adopted to analyze the differences in statics behavior between the outer sleeve and inner stiffening strengthening measures. The nonlinear N-R algorithm is employed by introducing the Low-Speed Dynamics Damping Factor. In view of the yield and rupture failure of material,the explicit damage characteristics are simulated by using the implicit algorithm given by ADINA. The real joints are simplified in the experiment. One specimen without any strengthening treatment and two strengthened specimens are designed, considering the related mechanics. Static tests are conducted on the three specimens with a 1:2 scale model.The influences of the two strengthening measures on quality control, bearing capacity and failure mode are analyzed,which indicate that the outer sleeve strengthening treatment with better technics can improve the bearing capacity and the stiffness of the joint significantly.%结合呼和浩特火车东站站房钢结构工程,针对其高频度使用的矩管KT形RHS节点,从受力、工艺和经济性出发,综合阐述了节点局部构造加强方式的工艺力学性能差异.采用模型试验和数值计算结合的方法,分析弦杆外套和弦杆内加劲两种强化方式的静力力学行为差异,数值分析采用引入Low-Speed Dynamics Damping Factor的非线性N-R方法,考虑材料屈服与破裂失效,基于Adina的隐式算法模拟模型的显式破坏特征.对节点进行抽象简化处理,综合考虑工艺力学性能,设计3组不同构造的KT形RHS节点,进行1:2缩尺比例静力加载试验.分析两种强化方式对其质量控制、承载能力、破坏形态的影响,并与无任何加强措施的构件结构进

  3. CALCULATION OF BEARING CAPACITY OF ECCENTRICALLY LOADED CONCRETE-FILLED GFRP TUBULAR LONG COLUMNS%玻璃纤维增强套管钢筋混凝土组合柱偏压承载力计算

    Institute of Scientific and Technical Information of China (English)

    关宏波; 王清湘

    2012-01-01

    A total of 15 concrete-filled glass fiber reinforced polymer(GFRP) tubular columns were tested and the specimens were divided into two groups.One group consisted of 6 specimens considering the eccentricity changes,the other consisted of 9 specimens considering the slenderness ratio changes.The test results showed that the eccentricity and slenderness ratio had great influence on mechanical properties of the concrete-filled GFRP tubular columns.With the increase of eccentricity,the destruction configuration of test specimens took place transformation from compression to tension failure gradually,and with the increasing of the slenderness ratio,the failure form of specimens changed from material damage to the instability destruction.The ultimate bearing capacity also decreased with the increasing of the eccentricity and slenderness ratio,but the amplitude of reducing slowed down.Based on the test data statistical regression,the reduction coefficient of the slenderness ratio and eccentricity of composite columns was obtained,and then the bearing capacity calculation formula of the axis pressure long columns and the eccentric-loaded columns was derived.The calculated results were compared with the experimental results,which showed a good agreement.These indicated that the proposed bearing capacity formula of the composite columns had a certain practical significance.%对9根不同长细比和6根不同偏心距的玻璃纤维增强(GFRP)套管钢筋混凝土组合柱进行试验研究。试验结果显示:偏心距和长细比对GFRP套管钢筋混凝土组合柱的力学性能有很大的影响。随着偏心距的增大,试件的破坏形态逐渐由压缩破坏向拉伸破坏转变;随长细比的增大,试件的破坏形态则由材料破坏向失稳破坏过渡。试件的极限承载力亦随偏心距和长细比的增大而降低,但降低的幅度变缓。在试验的基础上,对试验数据进行统计回归,得到GFRP套管钢筋混凝土组合柱的

  4. Debonding bearing capacity calculation of RC beam flexural strengthened with high strength steel wire mesh%高强钢绞线网抗弯加固RC梁剥离承载力计算

    Institute of Scientific and Technical Information of China (English)

    黄华; 刘伯权; 贺拴海; 吴涛; 潘元

    2012-01-01

    In order to research the debonding failure of reinforced concrete (RC) beam flexural strengthened with high strength stainless steel wire mesh, the debonding failure in the anchorage area of strengthened beam plategend was taken as research object, Smith-Teng model was revised to calculate the debonding failure of beam strengthened with fiber reinforced plastics(FRP) or bonding steel based on anchorage tests at the plate-end of 8 strengthened RC beams. The calculation model of debonding bearing capacity at the plate-end of beam strengthened with high strength steel wire mesh was established. The debonding failure at the middle part of strengthened beam was taken as research object, the middle part between two nearby flexural cracks of RC beam was regarded as arithmetic element, the stress condition of steel wire mesh was analyzed, and the calculation models of bonding shear stress and debonding normal stress at the middle part of strengthened beam were deduced. The debonding criteria at the middle part of strengthened beam were proposed, and the models were validated. Analysis result indicates that the upper limit of the calculation model of debonding bearing capacity at plate-end equals 0.57, it is in accordance with test result. The difference between the value calculated by the model of debonding bearing capacity at the middle part and test result is approximately3.77%, so the calculation model is feasible. 2 tabs, 5 figs, 16 refs.%为分析高强不锈钢绞线网加固的钢筋混凝土梁抗弯剥离破坏,以加固梁端部锚固区域的剥离破坏为研究对象,以8根钢筋混凝土加固梁端部锚固试验为基础,对计算FRP加目梁和粘贴钢板加固梁端部剥离破坏的Smith和Teng模型进行修正,建立适合高强钢绞线网加固技术的端部剥离承栽力计算模型。以加固梁中部的剥离破坏为研究对象,取加固梁跨中部位两弯曲裂缝之间的部分为计算单元,分析钢绞线网的受力状

  5. Test Research on Vertical Bearing Capacity of Bored Pile Reinforced by High Pressure Jet Grouting%旋喷加固灌注桩竖向抗压承载性能试验研究

    Institute of Scientific and Technical Information of China (English)

    于宝来

    2015-01-01

    In the reconstruction and restoration project , the ground treatment which improves the bearing capacity of bored pile can obtain much more economic benefit and engineering efficiency .However, relatively less research has been carried out on the combined application of ground treatment and bored pile .Based on the data of in-situ static load tests , the laws of load-displacement curve , internal force , and soil friction resistance of single pile were discussed .The test results show that the load transfer mechanism of bored piles is the same each other .The vertical bearing capacity of bored pile reinforced by high pressure jet grouting is significantly im-proved, and the displacement is less under the same load .The skin friction resistance is enhanced by high pres-sure jet grouting .The effect of high pressure jet grouting reinforcement to shallow soil is larger than that to deep soil, and the skin friction resistance of silty soil grows larger than that of clay soil .%城市建筑改造和修复工程发展迅速,钻孔灌注桩和地基处理的联合应用能有效地解决施工条件限制和承载力的要求,提高经济效益和工程效率。目前二者联合应用的实例和研究相对较少。通过现场试验,对高压旋喷地基处理前后相同规格的钻孔灌注桩进行荷载试验,对比分析旋喷处理前后灌注桩的荷载-沉降曲线、极限承载力及桩侧摩阻力分布等规律。结果表明,旋喷加固前后灌注桩竖向荷载传递规律相似;旋喷加固后灌注桩的竖向极限承载力提高,相同荷载下沉降降低;高压旋喷提高了土体侧摩阻力,旋喷对浅层土的加固效果高于深层土,对粉土侧摩阻力的提高效果要高于黏性土。

  6. 有机玻璃与不锈钢连接节点承载性能试验研究%Experimental research on bearing capacity of joint of acrylic and stainless steel

    Institute of Scientific and Technical Information of China (English)

    王综轶; 王元清; 杜新喜; 周燕; 衡月昆; 宗亮

    2016-01-01

    In order to achieve the feasible joint for the Jiangmen neutrino detector, an approach to connect acrylic and stainless steel is proposed.Three joint specimens were manufactured considering the different forms of stainless steel fastener.The ultimate bearing capacity and the mechanical be-havior under the long-term load of joint specimens are experimentally investigated.Modeling and a-nalysis of the joint specimens are carried out by using the ABAQUS finite element software.The re-sults show that the creep of acrylic is obvious under the long-term load and the joint failure is brittle at the ultimate load.The ultimate bearing capacities of joint specimens are at least twice as large as the design load.The maximum measured stress on acrylic is 8.467 MPa.In the process of joint specimens, the common polymerization of acrylic and stainless steel should be avoided for preventing initial defects caused by the deformation difference.Meanwhile, the requirements of temperature and illumination should be satisfied.%为了得到满足江门中微子探测器结构使用要求的连接节点,设计了一种有机玻璃与不锈钢的连接方式,根据不锈钢紧固件形式的不同,加工了3个节点试件.通过试验考察了节点试件的极限承载力及其在长期荷载作用下的受力性能,并利用ABAQUS有限元软件对节点试件进行建模分析.结果表明:有机玻璃在长期受力时会发生明显的蠕变,节点试件在极限荷载作用下为脆性破坏;节点试件的极限承载力都能达到设计荷载的2倍以上;有机玻璃上测点的最大应力为8.467 MPa.节点试件的加工过程中应避免不锈钢与有机玻璃的共同聚合,防止因变形差异而产生的初始缺陷,并且应满足温度和光照的要求.

  7. 冷弯薄壁型钢拼合截面柱轴压承载力计算%Calculation Method for Bearing Capacity of Cold-formed Steel Built-up Columns Under Axial Compression

    Institute of Scientific and Technical Information of China (English)

    周绪红; 李喆; 刘永健; 石宇

    2012-01-01

    In order to investigate bearing capacity of cold-formed steel built-up columns under axial compression, authors used ANSYS finite element program to analyze the cold-formed steel built-up columns at home and abroad. Compared with experimental results, the validity of the finite element method (FEM) was verified. Furthermore, a detailed parametric study by FEM was carried out to mainly determine the influence of cross-section form, cross-section dimension and slenderness ratio of component for the built-up effect. The simplified calculation method to the bearing capacity of cold-formed steel built-up columns under axial compression was extracted. The analytical results show that with the increase of the slenderness ratio, the built-up effect improves. As for these columns connected with screws through web, when width-thickness ratio of flange is certain, with the increase of width-height ratio of cross-section, the integrity of the built-up web increases, which leads the built-up effect to strengthen. But the influences of different areas of cross-sections are not so obvious.%为了研究冷弯薄壁型钢拼合截面柱的轴压承载力,对各国有关冷弯薄壁型钢拼合截面柱的轴压试验进行了ANSYS有限元模拟分析,有限元计算结果与试验结果吻合良好,从而验证了有限元方法的正确性.采用有限元方法分析了构件截面形式、截面尺寸以及长细比对冷弯薄壁型钢拼合截面柱拼合效应的影响,提出了冷弯薄壁型钢拼合截面柱轴压承载力的简化计算方法.分析结果表明:随着长细比的增大,拼合截面柱的拼合效应随之增大.对于主要通过螺钉将腹板进行拼合的构件,当翼缘宽厚比一定时,随着截面宽高比的增大,腹板拼合的整体性增强,从而使拼合效应增大,而截面面积的改变对拼合效应的影响则不是很明显.

  8. Influential Study on Wave Loading to Vertical Bearing Capacity of Wharf Pile Foundation%波浪荷载对码头桩基竖向承载力的影响研究

    Institute of Scientific and Technical Information of China (English)

    袁伟; 闫澍旺; 赵亮

    2011-01-01

    The soil around pile foundation in the wharf will suffer from strength reduction under the cycle wave loading conditions, which would further influence the vertical bearing capacity of the pile foundation. Through the indoor dynamic biaxial GDS to simulate' the cycle wave loading and apply these loads to the soil sample of Tianjin port, the strength reduction laws of soil under the dynamic cycle loads in different depths are obtained. Next, with the help of ABAQUS, combining the working loads with cycle wave loading on the pile foundation, the distribution laws of soil dynamic stress around the pile are analyzed. After synthesizing the dynamic biaxial test, the final results are obtained, which show the soil suffered from strength reduction spreads to the depth up to 5 m, the maximum strength reduction rate nearby soil can reach 85.3 % and the vertical bearing capacity of wharf pile foundation reduction rate is 5.73 % .%码头桩基在波浪循环荷载的长期作用下,桩周一定范围的土体会出现强度弱化,进而会一定程度的影响基桩竖向承载力.该文首先通过室内GDS动态三轴仪对天津港码头地基土样作用模拟的波浪循环荷载,研究不同深度土体受到不同幅值的循环动应力荷载作用后其强度的折减规律.然后通过ABAQUS有限元软件计算模拟码头桩基在上部既有结构相互作用的同时,桩身上部受波浪循环荷载,桩周土动应力的分布规律.结合室内动三轴试验结果,计算得到该码头桩基在波浪循环荷载作用下桩周土体弱化的影响深度约为5m,桩周土体的强度折减率最大达到85.3%,码头桩基竖向承载力的折减率为5.73%.

  9. 加筋高性能砂浆加固RC梁抗弯性能及承载力计算%Flexural Behavior and Bearing Capacity Calculation of RC Beams Strengthened with Reinforced High Performance Mortar

    Institute of Scientific and Technical Information of China (English)

    潘元; 黄华; 刘伯权; 付国

    2012-01-01

    For achieving consensus of views about the flexural behavior of the beams strengthened with reinforced high performance mortar, based on the domestic experimental study on 95 strengthened RC beams, the flexural behavior and failure mechanism of these strengthened beams were analyzed. The formulas of the flexural bearing capacity, the flexural rigidity, and the crack width were proposed, with considering the influence of first load, secondary load, the magnitude of sustained load, quantity and style of the reinforcement, and concrete strength. The calculated values were compared with tested values. The results indicate that the reinforcement included high strength stainless steel strand, reinforcing mesh and steel wire mesh. Their mechanical performances were significantly different, but the flexural behavior and failure mechanism of these beams strengthened with the reinforcement were the same. So the uniform formula could be used to calculate the bearing capacity of these strengthened beams. The calculated values are consistent with that of the experiments and the formula can be used in actual practice.%为统一中国对加筋高性能砂浆加固RC梁抗弯性能的认识,以中国学者所做95根加筋高性能砂浆加固的钢筋混凝土梁抗弯性能试验研究为基础,分析加固粱的受力性能和破坏机理,在此基础上考虑一次受力、二次受力、持载程度、加固筋类型、加固筋数量、混凝土强度等级等因素影响,建立加固梁抗弯承载力计算公式、刚度计算公式和裂缝宽度计算公式,并与试验数据进行了对比。结果表明:该加固技术采用高强钢绞线、钢筋网、钢丝网作为受力材料,虽然三者受力性能存在显著差异,但加固构件力学性能和破坏机理相似,可按统一计算公式进行承载力设计;公式计算值与试验结果符合良好,可用于实际工程计算。

  10. 高强钢筋RPC简支梁抗剪承载力及延性研究%RESEARCH ON SHEAR BEARING CAPACITY AND DUCTILITY OF HIGH STRENGTH REINFORCED RPC BEAM

    Institute of Scientific and Technical Information of China (English)

    金凌志; 李月霞; 祁凯能; 何培

    2015-01-01

    By the shear experiment of 6 high strength reinforced reactive powder concrete beams,we analyzed the factors influencing the beam's damage pattern,shear capacity and shear ductility.The research shows that the shear span ratio,stirrup ratio and longitudinal reinforcement ratio are the key factors of high strength reinforced reactive powder concrete beams,among them the shear span ratio has the most significant influence;with the increase of longitudinal reinforcement ratio,the capacity and inclined crack angle of beams without stirrups increase,and the shear capacity decreases,but the inclined crack angle of beams with stirrups does not change obviously under the condition of suitable shear span ratio;improving the longitudinal reinforcement ratio can not only enhance the shear bearing capacity of the beam,but also effectively improve the shear ductility.%通过6根高强钢筋活性粉末混凝土简支梁的抗剪试验,得到了不同因素对梁的破坏形态、抗剪承载力及其剪切延性的影响规律.研究表明:剪跨比、配箍率和纵筋率是影响高强钢筋活性粉末混凝土简支梁抗剪性能的主要因素,其中剪跨比影响最大;在适宜的剪跨比条件下,随着纵筋率的提高,无腹筋梁的承载力与斜裂缝倾角增大,剪切延性降低,但有腹筋梁的斜裂缝倾角变化不太明显;提高配箍率不仅可以增强梁的抗剪承载力,而且能够有效改善其剪切延性.

  11. X型钢管相贯节点抗弯极限承载力的影响因素分析%Analysis of Influencing Factors on Ultimate Flexural Bearing Capacity of X-shaped Steel Tubular Joints

    Institute of Scientific and Technical Information of China (English)

    廖贤

    2011-01-01

    To solve the design problem of the tube joints in the design of steel pipe structure,influences of β(β is ratio of branch pipe diameter and the main pipe diameter)and γ(γ is ratio of main pipe diameter and the main pipe Wall thickness) on ultimate flexural capacity of the X-shaped steel tubular joints were analyzed by establishing a finite element model in finite element programmer of ANSYS for X-shaped steel tubular joints which used a three-dimensional and four-joint elastic-plastic shell 181 elements and ideal elastic-plastic materials.Impact rules of various factors on ultimate flexural bearing capacity of X-shaped steel tubular joints were given.%为解决钢管结构设计中相贯节点设计问题,采用三维四节点弹塑性壳单元shell 181单元和理想弹塑性材料在ANSYS有限元程序中建立X型钢管相贯节点的有限元模型,分析了支管直径与主管直径比β、主管直径与壁厚比γ对X型钢管节点的极限抗弯承载力的影响,并给出各影响因素对X型钢管相贯节点抗弯极限承载力的影响规律.

  12. 薄膜承载力及其对日光温室结构稳定性能的影响%Load-bearing capacity of films and its effect on structure stability of Chinese solar greenhouse

    Institute of Scientific and Technical Information of China (English)

    丁敏; 施旭栋; 李密密; 剧锦三; 蒋秀根

    2013-01-01

    of film thickness, film span, film pre-tension and load on load-bearing capacity of the single film was analyzed. At the same time, three computation models of solar greenhouse structures, including single hinged arch structure, whole frame structure without film, and whole frame structure with film, were made. The overall failure process and space coefficient of solar greenhouse structure were obtained. The effect of tensioned film on the solar greenhouse structure stability was discussed with parameters such as film thickness, film elastic modulus and film pre-tension changing. The results showed that film dimension and thickness are the main factors affecting its load-bearing properties, and the ratio of film length to film width should also be considered appropriately. Film at 0.2mm thick can prevent disaster caused by extra heavy hail. Tension film was used in favor of wind resistance for solar greenhouse structures, but is not effective for snow resistance. The space coefficient of solar greenhouse structures is least effected by film elastic modulus in all analyzed parameters. The ultimate bearing capacity of the whole frame structure without film is higher than that of the single hinged arch structure under wind and snow loads. The reason is that the stiffness out of plane is enhanced by purelines. Film also plays an important role on improving the ultimate load bearing capacity of greenhouse structures. The fruits are useful to the wind, snow and hail resistant design of solar greenhouse structure covered film.

  13. Discussion on bearing capacity of water resources in Guangxi from economic and social water consumption status%从经济社会用水状况浅析广西水资源承载能力

    Institute of Scientific and Technical Information of China (English)

    何素明; 农卫红

    2013-01-01

    Based on the current status of economic and social water consumption in Guangxi as shown by the water census results,the authors analyze the water use efficiency and the existing problem;discuss the bearing capacity of water resources in Guangxi from the requirements of building a moderately well-off society and implementing the most stringent water resource administration system;and put forward suggestions for supporting economic and so-cial development in Guangxi.%从广西水利普查经济社会用水现状情况,分析用水效率、存在问题;从全面建成小康社会、实行最严格水资源管理制度要求,分析广西水资源承载能力,提出支撑广西经济社会发展的对策与建议。

  14. Study on the bearing capacity of the capital city of the transfer of rural labor force employment%省会城市的农村劳动力转移就业承载能力研究

    Institute of Scientific and Technical Information of China (English)

    唐莉; 高焕才; 李通

    2013-01-01

    Along with the city to speed up the process,the increase of urban population,the rapid expansion of city size,increasing consumption of resources,environmental pollution,the city's comprehensive carrying capacity bottleneck constraints on labor mobility gradually,especially provincial capital city is relatively developed economy.Therefore,the relationship between the number of sustainable development and how to coordinate the provincial capital city and the labor force bearing,has become the focus of social concern.%  随着城市化进程的加快、城镇人口的增加、城市规模的迅速扩张,资源消耗不断增多,环境污染日益加重,城市综合承载力对劳动力流动的瓶颈约束作用逐渐凸显,尤其经济相对发达的省会城市。因此,如何协调省会城市的可持续发展与劳动力承载数量之间的关系,便成为当今社会各界普遍关注的焦点。

  15. The Relationship Research between the Structural Bearing Capacity of Roof and the Thickness of Planting Soil%屋顶绿化结构承载力与种植土厚度的关系研究

    Institute of Scientific and Technical Information of China (English)

    于素英

    2015-01-01

    In order to make the roof greening achieve "practical,economical,safe",the article made respectively research of the three corresponding relationships between the design value of live load on roof structure,planting soil density and soil thickness,then gave the effective method to improve the bearing capacity of roof greening in order to increase the thickness of soil without the structural reinforcement.%为使屋顶绿化做到"实用、经济、安全",分别对屋顶结构承载力、绿化种植土进行研究,给出了屋顶结构活荷载设计值与种植土密度、覆土厚度三方的对应关系,并给出在不进行结构加固的前提下,提高屋顶绿化承载能力的有效方法.

  16. Research On Bearing Capacity Of Micropile Groups Arranged Inclined Piles By Numerical Simulation%斜桩布置对微型桩群桩承载力影响的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    吴开辉

    2015-01-01

    采用plaxis有限元软件,对三组设置斜桩的微型桩群桩进行数值计算分析,分析结果显示,布置斜桩时,群桩的抗压、抗拔以及水平承载力相比于未设置斜桩情况均有一定程度的提高,进一步分析,斜桩的设置对2×2群桩的提高效果最为显著,3×3群桩次之,4×4群桩最小,本文的数值分析结果具有一定的工程应用价值。%The finite element software “plaxis” is adopted to calculate and analyze the establishment of three micro -pile groups with the inclined pile .The analysis showed that the ability of compressive resistance , anti-pulling and lateral bearing capacity has improved a lot than those without inclined pile .After further analysis , the settlement of the inclined pile has the most remarkable effect for 2 ×2 pile groups , the 3 ×3 pile groups second , and the 4 ×4 pile groups is minimum .The result of the numerical calculation analysis has great value in engineering field .

  17. Decision-Making Model of Power Network Planning with Wind Power Integration Considering Environmental Bearing Capacity%计及环境承载力的风电并网规划决策模型

    Institute of Scientific and Technical Information of China (English)

    曾鸣; 向红伟; 陈英杰; 刘晓立; 刘洋; 邹晖

    2013-01-01

    To maintain the reliability of wind power integration, a four-dimensional environment of decision-making of power network planning with wind power integration is proposed. To consider the features of new energy integration, this article focuses especially on the impact of technical environment and ecological environment on power network planning. Based on the theory of environmental bearing capacity, the decision of power network planning with wind power integration considered is studied, which helps to make a comprehensive and accurate decision of power network planning from aspects of technique, ecology, economy and policy.%为维持风电并网的可靠性,以某区域电网为例,提出了风电并网规划决策的四维环境并分别进行了承压度建模,针对新能源接入特性分析了技术环境和生态环境对电网规划的影响,基于环境承载力理论研究了风电接入电网规划决策,从技术、生态、经济及政策等方面准确地作出电网规划的决策.

  18. 基于 GM(1,N)模型的加固木柱承载力预测%Forecast of Strengthened Timber Column’ s Load-bearing Capacity Based on GM(1,N) Model

    Institute of Scientific and Technical Information of China (English)

    谢成新; 黄文金

    2015-01-01

    在7根木柱加固试验数据的基础上,利用GM(1,N)模型建立了加固木柱承载力的预测模型。通过实例分析预测结果表明,该模型预测结果与试验数据吻合较好,由驱动系数得出各影响因素的影响大小和趋势。提出的预测模型可应用于木柱加固工程分析和设计。%Based on the test of seven timber columns, the forecast model of strengthened timber column's load-bearing capacity was presented with GM(1,N) model.It is shown that experiment data and corresponding forecast results are consistent.The influence degree and tendency of various influence factors can be obtained by driving coefficient.So, the proposed model can be applied to the engineering design.

  19. Load-bearing capacity of indirect inlay-retained fixed dental prostheses made of particulate filler composite alone or reinforced with E-glass fibers impregnated with various monomers.

    Science.gov (United States)

    Özcan, Mutlu; Koekoek, Winand; Pekkan, Gurel

    2012-08-01

    The load-bearing capacity and failure types of indirect inlay-retained fixed dental prostheses (FDP), made of particulate filler composite (PFC) (Estenia) alone or reinforced with E-glass fibers impregnated with various monomers were evaluated. Indirect inlay-retained FDPs were made between first premolars and first molars (N=30, 10/per group). The inlay parts of the specimens were silica coated and silanized and the specimens were cemented with dual-polymerized resin cement under ultrasonic vibrations. The experimental groups were as follows: Group 1: FRC1 (BR-100, UTMA) + PFC; Group 2: FRC2 (everStick C&B, Bis-GMA/PMMA) + PFC; Group 3: PFC only. The specimens were kept in distilled water at 37 °C for one month and then subjected to fracture strength test. No significant difference was found between the Group 1 and Group 2 FDPs (1357±301 N and 1213±316 N, respectively) (p>0.05) (ANOVA). Group 3 (856±299 N) showed significantly lower results than those of FRC reinforced groups (pinlay cavities. FDPs made of PFC only showed mainly catastrophic fracture of the pontic. In the FRC reinforced groups, predominantly delamination of the veneering was observed. The use of silica coating and silanization in combination with the dual-polymerized resin cement used; under ultrasonic cementation procedure provided sufficient adhesion to withstand static loading forces at the cementation interface, since the failures were predominantly delamination of the veneering in the FRC reinforced groups.

  20. The calculation method analysis of steel reinforced concrete beam-column joints' shear bearing capacity%谈型钢混凝土梁柱节点抗剪承载能力计算方法

    Institute of Scientific and Technical Information of China (English)

    朱琴美

    2012-01-01

    介绍和分析了当前常用的型钢混凝土梁柱节点构造形式,以及国内关于型钢混凝土梁柱节点的抗剪承载力计算公式和节点受力机理,并对其节点的抗震性能和设计研究中存在的主要问题进行分析,以期为型钢混凝土梁柱节点设计提供指导。%This paper introduces and analyzes the current commonly used steel reinforced concrete beam-column joints structure form and the shear bearing capacity calculation formula and nodes stress mechanism of domestic steel reinforced concrete beam-column joints, it also analyzes its seismic performance and the main problems in design and research, in the purpose of offering useful reference for the steel reinforced concrete beam-column joints design.

  1. The high strain dynamic test method of foundation pile bearing capacity based on genetic algorithm%基于遗传算法的基桩承载力高应变动测法

    Institute of Scientific and Technical Information of China (English)

    闫明

    2014-01-01

    为了准确得到桩基的承载力,在实测曲线拟合方面提出了采取遗传算法来代替传统人工试凑的方法,以通过编程实现自动求解,并结合工程实例试验,将采用遗传算法的拟合结果与静载荷试验结果作了对比,证实了该方法的可行性与可靠性。%In order to get the accurate bearing capacity of pile foundation,this paper used the genetic algorithm to replace the traditional manual test in measured curve fitting method,through the program realization of automatic solution,and combining with practical engineering test,con-trasted the fitting results and static load test results of genetic algorithm,verified the feasibility and reliability of the method.

  2. 水平荷载作用下高承台管桩的荷载传递性状及承载力研究%Load Transfer and Bearing Capacity of High-Cap Pipe Piles under Horizontal Load

    Institute of Scientific and Technical Information of China (English)

    雷华阳; 刘利霞; 霍海峰; 陆培毅; 付瑞清; 付海峰

    2012-01-01

    exposing height is less than 1.7m. ultimate horizontal bearing capacity of high cap pipe piles stays constantly, when the exposing height is more than 1. 7 m, it decreases rapidly. Increasing the soil strength, the modulus and diameter of piles could be favorable to the horizontal bearing capacity, while changing the length has little influence.

  3. Analysis of residual bearing capacity of cracked prestressed concrete continuous box bridges%预应力混凝土箱梁桥开裂后的残余承载力分析

    Institute of Scientific and Technical Information of China (English)

    王凌波; 赵煜

    2015-01-01

    为分析开裂预应力混凝土箱形桥梁结构开裂后的残余承载力,以裂缝统计特征参数为基础,用单元退化方式模拟正裂缝,用裂缝间的单向受压杆模拟裂缝间的承压效应,采用空间梁单元和三维杆单元分别模拟梁和预应力筋,以单元降温的方式模拟预加力的效应,形成空间刚架模型模拟斜裂缝。基于开裂后混凝土及预应力钢筋的基本假定,建立开裂后结构的计算方法。按照相似高度、开裂区域截面折减、折减自重补偿的原则将相似裂缝进行合并处理,得到裂缝区域的阶梯型折减刚度模型,提出承载能力折减系数计算方法以体现开裂后结构刚度的变化。经实桥算例验证,本文方法可正确判断静定及超静定预应力混凝土结构开裂后承载力的变化程度。%Based on the crack statistic characteristic parameters,the unit degradation mode was utilized to simu-late the fracture of prestressed concrete box bridges and analyze its residual bearing capacity.In the meantime, unidirectional compressive rod,space beam element and cooling unit form were adopted to simulate the effects of pressure among cracks,prestressed tendons and the pre -tension effect,in order to form a space rigid frame model.Based on some basic assumptions of cracked concrete and prestressed steel,the calculation method was established after cracking.Merging similar cracks by the principle of similar height,reduction of cracking area and reduction gravity compensation,the ladder -type stiffness degradation model of crack area was then estab-lished and a capacity reduction calculation method was proposed to reflect the change of the crack stiffness.The real bridge example proves that the method can correctly judge the change of bearing capacity for cracked static determinacy and indeterminacy concrete structures.

  4. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  5. Bearing capacity and load transfer mechanism of static drill rooted nodular piles%静钻根植竹节桩承载力及荷载传递机制研究

    Institute of Scientific and Technical Information of China (English)

    周佳锦; 王奎华; 龚晓南; 张日红; 严天龙; 许远荣

    2014-01-01

    The static drill rooted nodular pile is a new type of composite pile foundation which consists of precast nodular pile and the cemented soil along the pile shaft. This kind of composite pile has a good bearing capacity, and the mud pollution will largely be reduced in its construction process. A group of experiments were conducted to provide a comparison between this composite pile and the bored pile. The axial force of the nodular pile was measured by the strain gauges attached on the pile shaft to analyze the distribution of the axial force and the skin friction along the shaft; and then a three-dimensional model was built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail. The results of the field tests and ABAQUS simulation showed that:the bearing capacity of the static drill rooted nodular pile is better than that of the bored pile in soft soil area. The settlement of the composite pile is controlled by the precast pile, and the deformation of the precast pile and the cemented soil can be considered as deformation compatibility. The nodes on the nodular pile play an important role during the load transfer process;and the skin friction of the static drill rooted nodular pile is about 1.05-1.10 times of the skin friction of the bored pile in the same soil layer.%静钻根植竹节桩是由预应力竹节桩和桩周水泥土构成的一种新型组合桩基,该新型桩不仅承载性能较好,而且可以大量减少桩基施工过程中所产生的泥浆污染。通过静钻根植竹节桩和钻孔灌注桩的静荷载对比试验及埋设在竹节桩桩身上的应变计对桩身轴力进行测量,分析了静钻根植竹节桩桩身的轴力分布情况以及侧摩阻力的分布,用有限元软件ABAQUS对静钻根植竹节桩进行三维建模计算,详细地分析这种新型组合桩的荷载传递机制。结合现场试验与模拟计算可以得到:在软土地区,静

  6. Mechanical behavior and bearing capacity calculation of recycled aggregate concrete-filled circular steel tube columns under eccentric loading%钢管再生混凝土偏压柱受力性能及承载力计算

    Institute of Scientific and Technical Information of China (English)

    陈宗平; 李启良; 张向冈; 薛建阳; 陈宝春

    2012-01-01

    To study the mechanical behavior of recycled aggregate concrete-filled circular steel tube(RACFCST) columns under eccentric loading,15 specimens with different replacement ratio of recycled coarse aggregate,slenderness ratio and eccentricity were tested under the monotonic static loading.The failure modes were observed,and then the curve of the entire loading process as well as the strain distribution over the cross section were obtained.The influence of varying parameters on the mechanical behavior of RACFCST columns was analyzed,and then the ultimate bearing capacity was calculated using existing theories.It is shown that about the failure process and failure mode RACFCST columns are similar to the eccentrically loaded concrete-filled circular steel tube columns,in which the circular steel tube fails eventually in the drum-like buckling mode.It is found that RACFCST columns have high bearing capacity and good deformation performance,and the influences of eccentricity and slenderness ratio on the mechanical behavior of RACFCST columns are obvious,while the influence of aggregate replacement ratio is comparatively unobvious.%为了研究钢管再生混凝土偏压柱的受力性能,设计15个试件进行静力单调加载试验,考虑了再生粗骨料取代率、长细比和偏心距3个变化参数。观察试件的破坏形态,获取试件受力的全过程曲线,给出截面应变的分布情况,分析各变化参数对钢管再生混凝土偏压柱受力性能的影响,利用相关理论方法计算钢管再生混凝土偏压柱的极限承载能力。研究结果表明:钢管再生混凝土偏压柱与普通钢管混凝土偏压柱的受力过程及破坏形态相似,钢管最终表现为鼓曲破坏;钢管再生混凝土偏压柱具有较高的承载能力和良好的变形性能;偏心距、长细比对钢管再生混凝土偏压柱的受力性能影响显著,而再生粗骨料取代率对其影响不大。

  7. 环口板加强型T型圆钢管节点承载力的试验研究%EXPERIMENTAL STUDY ON BEARING CAPACITY FOR CIRCULAR TUBULAR T-JOINTS WITH COLLAR PLATE REINFORCEMENT

    Institute of Scientific and Technical Information of China (English)

    蔡艳青; 邵永波; 岳永生

    2011-01-01

    For a circular tube member, its radial stiffness is generally much smaller than its axial stiffness due to its hollow section and thin wall. In a welded tubular joint, the brace is mainly subjected to axial loading, and thus makes the chord be subjected to radial loading. Furthermore, high stress concentration exists at the joint because the curvature is not continuous. Due to the above reasons, the common failure mode for a tubular joint is the local yielding or buckling on the chord surface near the weld toe. To improve the bearing capacity of a tubular joint, a collar plate is welded around the weld toe to increase the radial stiffness of the chord, and thus to increase the static strength of the joint. Through experimental tests on the static bearing capacity of 3 un-reinforced and 3 collar plate reinforced tubular T-joints under axial compression, the reinforcing efficiency is verified. The experimental results show that the failure mode and the failure position are both changed due to the reinforcement of the collar plate, and the collar plate improves the static strength of the T-joints remarkably.%对于圆钢管构件,由于空心薄壁的特点,管件在径向的刚度通常要远远小于其轴向刚度。焊接相贯圆钢管节点中,支管主要承受轴向荷载,从而导致主管要承受径向作用力。此外,节点部位由于曲率不连续而带来很大的应力集中现象。这些原因造成管节点最常见的破坏方式是主管表面靠近焊接部位的局部屈曲或屈服破坏。为了提高管节点的承载能力,通过在主管表面焊接环口板的方式未提高主管在节点部位的径向刚度,进而提高管节点的静力强度。通过对3个T型圆铡管节点试件以及3个采用环口板加固的T型圆钢管节点试件在轴压作用下静力承载力的试验测试,验证了环口板对提高管节点静力强度的效果。试验测试结果表明:由于环口板增加了主管在焊接部

  8. Reliability analysis of foundation bearing capacity based on combined coefficients of variation%基于综合变异系数的地基承载力可靠性分析

    Institute of Scientific and Technical Information of China (English)

    曹宇春; 刘富玲

    2014-01-01

    A simplified reliability and risk analysis method of foundation bearing capacity based on combined coefficients of variation of random variables is proposed using first order second moment technique. The laboratory results and historical published ones of coefficients of variation are taken into consideration as the combined coefficients of variation, which are adopted as the calculated coefficients of variation. The most likely values and their possible ranges of degrees of reliability, probabilities of failure and average expected losses can be obtained using suitable coefficients of variation besides the conventional deterministic analysis. This enables to make optimal design scheme and engineering decision. It has shown that the degrees of reliability of foundation bearing capacity are more sensitive to the internal friction angle compared with the unit weight and the cohesion. The width or area of foundation can be decided upon in terms of the required factor of safety, degree of reliability and probability of failure. Moreover, the combined coefficients of variation of random variables will gradually decrease with the weights increasing of coefficients of variation based on the in-situ investigation results;the corresponding degrees of reliability will increase and the probabilities of failure decrease due to that decrease of combined coefficients of variation.%采用一次二阶矩法,考虑岩土参量变异系数的试验及历史数据,提出了基于综合变异系数的地基承载力简化可靠性与风险分析方法。利用提出的简化可靠性与风险分析方法,可在传统确定性分析的基础上,采用合理的变异系数,分别得到与地基承载力有关的可靠度、破坏概率和平均期望损失的最可能值及其变化范围,为提出优化的地基基础设计方案和工程决策奠定基础;相对于土重度和黏聚力,地基承载力可靠度对于内摩擦角的变化更加敏感;设计时可以

  9. CFRP板加固受弯钢梁的承载力及挠度分析%Bearing Capacity and Deflection Analysis of Bending Steel Beams Strengthened with CFRP Plates

    Institute of Scientific and Technical Information of China (English)

    张鹏; 叶黎明; 邓朗妮; 钟鑫

    2011-01-01

    采用截面等效代换法,对碳纤维板加固受弯钢梁进行了承载力及挠度分析,推导出CFRP板加固受弯钢梁的理论计算公式.为验证公式,进行了5根CFRP板加固钢梁的单调静力试验,并用有限元软件进行模拟分析,将计算结果分别与试验结果和有限元分析结果进行比较后发现:弯矩理论计算值比试验值略小,挠度理论计算值比试验值略大,且都与有限元模拟值相近,说明理论计算安全,计算方法具有良好的适用性.%The method of using one section to exchange another is used to study bearing capacity and deflection analysis of bending steel beams strengthened with carbon fiber-reinforced polymer (CFRP) plates. The theoretical formula of bending steel reinforced beams is worked out. Five reinforced beams are used in the monotonic static experiment for validating the formula. Finite element software is applied to simulate and analyze the strengthened beams. The calculation result is compared with the experiment and finite element simulation results and analyzed. The calculated value is less than experimental value of bending moment while the calculated value is bigger than experimental value of deflection. Both calculated values are approaching to the simulation results. It shows that the calculating is safe and the calculating method has good applicability. The formula can be used as reference in the project of designing steel beams reinforced by CFRP plates.

  10. 闭口截面压型钢板组合楼板纵向剪切粘结承载力研究%Longitudinal shear-bond bearing capacity study of cold-formed steel deck and concrete composite floors

    Institute of Scientific and Technical Information of China (English)

    张欣颖; 史庆轩

    2012-01-01

    This paper refers to the normative test method advanced by American ASCE Standard for the Structural Design of Composite Slabs, to use ranges of thickness and shearspanlength,compare of the failure mode under the continuous loading. It show that the longitudinal shearing have greater control function to the shorter shearspanlength test specimen. According to practical dataes, the shear-bond coefficients m & k whichs are characterized by concrete tension strength f1 and the equation for calculating the longitudinal shear-bond bearing capacity is advanced in regression analysis. Experiment results show that this type of cold-formed steel deck has better cooperative capability with the concrete and displacement ductility. So it can be used in engineering.%参照美国ASCE组合楼板结构设计规范提出的标准试验方法,采用不同厚度和不同剪跨的试件进行连续加载,对比其纵向剪切粘结破坏形态及受力性能,发现纵向剪力对小剪跨组合板的破坏有较大的控制作用.采集试验数据并进行回归分析,得到以混凝土抗拉强度值f1表征的试验板型剪切粘结系数m,k,进而提出相应的组合楼板纵向剪切粘结承载力计算公式,为工程应用提供参考.试验表明此类压型钢板与混凝土协调工作较好,且延性较大,能够在实际工程中投入使用.

  11. THE NUMERICAL ANALYSIS ON BEARING CAPACITY OF CFG PILE COMPOSITE FOUNDATION UNDER BLASTING%爆破地震作用下CFG桩复合地基动力特性的数值分析

    Institute of Scientific and Technical Information of China (English)

    王维玉; 赵拓; 孟艳杰

    2012-01-01

    Through CFG pile composite foundation dynamic test, a test model was built by using finite element analysis software. The analyses were made for the horizontal acceleration, vertical acceleration, horizontal displacement, vertical displacement and stress, which were dynamic response about the same position different depth and the same depth different locations. The analysis results of the dynamic response were in good agreement with the test results. The factors of dynamic response were studied by numerical simulation. Compared with the dynamic response results of natural foundation, we obtained the conclusions in guiding the significance. A basis is supplied for load bearing capacity, deformation and dynamic characteristics of a CFG pile composite foundation.%该文以CFG桩复合地基在爆破地震作用下的现场动力试验为背景,应用有限元软件建立有限元动力分析的数值模拟模型,从水平加速度、竖向加速度、水平位移、竖向位移及应力几个方面对复合地基同一位置不同深度和同一深度不同位置的动力响应进行了分析,其分析结果与试验结果吻合较好.通过数值模拟对动力响应的影响因素进行了比较研究.并与天然地基的动力响应结果进行对比,得出了有指导意义的结论.为今后探讨CFG桩复合地基的承载力、变形和动力特性提供了研究基础.

  12. Fabrication and bending bearing capacity analysis of an integrated manufacturing composite truss%一种复合材料桁架的制备及弯曲承载性能分析

    Institute of Scientific and Technical Information of China (English)

    熊波; 林国昌; 张印桐; 罗锡林; 谭惠丰

    2014-01-01

    An innovative fabrication method of integrated manufacturing composite truss is developed to improve the geometric accuracy and rods connecting efficiency. Unlike previous research, the rods are connected by bonding composite shell, winding fiber tow and wrapping fabric together with the designed rod fixture. Fabrication process demonstrates good operability and stability of truss manufacture and advanced geometry accuracy of fabrication. Three-point bending test on bending bearing capacity of the truss suggests a high specific bending stiffness with rods connection of high efficiency. In addition, consistent results from a finite element simulation based on a simplified model show its potential in high computational efficiency to evaluate the bending stiffness of the truss.%为提高复合材料桁架成型几何精度和杆件连接效率,提出一种一体化成型的复合材料桁架制备方法,同时设计了杆件固定工装,通过胶接薄壳、缠绕纤维束和包裹织物实现杆件连接,制备过程表明该制备方法操作性强、稳定性好,制备桁架几何精度高;通过3点弯曲实验和有限元仿真分析了桁架的弯曲承载性能。结果表明:杆件连接效率高,桁架比弯曲刚度高;基于简化模型的有限元模拟方法计算效率高,结果可靠,可用于桁架弯曲刚度的表征。

  13. The Determination Method of Characteristic Values of Bearing Capacity of Composite Foundation Value Base on a Project Case%基于某工程实例讨论复合地基承载力特征值的确定方法

    Institute of Scientific and Technical Information of China (English)

    刘豪; 朱帅

    2015-01-01

    In this paper ,the small pressure plate substitutes for the big one to test the bearing capacity influenced by single pile ,and the bearing capacity values of composite foundation can be determined by an‐alyzing the tested characteristic values above .%多桩型复合地基承载力检测通常采用大型承压板,本文采用小承压板检测单根桩影响范围内的地基承载力,通过分析试验所得的承载力特征值来确定复合地基承载力的大小。

  14. Tooling Converts Stock Bearings To Custom Bearings

    Science.gov (United States)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  15. 空间扭背索组合梁斜塔斜拉桥极限承载力分析%Analysis about Ultimate Bearing Capacity of Space-Twisting Cable Composite Beam Leaning Tower Cable-Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    任伟; 刘刚; 刘利

    2015-01-01

    为进一步研究新兴空间扭背索组合梁斜塔斜拉桥的力学行为,以某主跨220 m 的空间扭背索组合梁斜塔斜拉桥为研究背景,采用非线性数值分析方法,并通过现场实测值验证数值模型的有效性,讨论了该桥的非线性响应和稳定性,同时用塑性铰法理论对结构极限承载能力进行了计算。研究发现:与常规斜拉桥相比,由于扭背索索长均匀,降低了拉索垂度影响差异;由于扭背索对主塔的水平约束作用较小,主塔较容易出现失稳;由不同工况分析得出,空间扭背索组合梁斜塔斜拉桥的破坏断面位于中塔柱顶部,锚固区下缘。本文研究结论可为类似桥型的进一步研究提供借鉴。%In order to further study the mechanical behavior of emerging bridge type———space‐twisting cable composite beam leaning tower cable‐stayed bridge ,one space‐twisting cable composite beam cable‐stayed bridge with 220 m main span was taken as example ,nonlinear nu‐merical analysis method was adopted ,and the effectiveness of numerical model was proved by field measured values .T he nonlinear response and stability of the bridge w ere discussed ,and the ulti‐mate bearing capacity was calculated by plastic hinge method .Research shows that :compared with conventional cable‐stayed bridge ,because the length of twisted cable is uniform ,the cable sag effect difference is little;because the horizontal restraint of twisted cable to main tower is little , main tower is easy to appear instability ;from the analysis on different working condition ,it is con‐cluded that the damaged section of space‐twisting cable composite beam inclined tower cable‐stayed bridge is located at the top of middle pylon ,the bottom edge of anchorage zone .

  16. Study on the Bearing Capacity of High Strength Large Size Equal Angles Steels Under Axially Loaded Compression%高强大规格等边角钢轴压承载力研究

    Institute of Scientific and Technical Information of China (English)

    赵楠; 李正良; 刘红军

    2013-01-01

    进行了19个长细比λ=30~90的Q420 L220 mm×20 mm角钢试件的轴压试验研究.结果表明:此类构件在长细比λ>45时,以弯曲失稳破坏为主;长细比λ≤45时,以弯扭失稳为主.研究了现行钢结构规范中防止局部屈曲宽厚比限值公式和计算弯扭失稳的换算长细比取值公式的适用性.采用逆算单元长度法得到了大规格等边角钢的柱子曲线,研究了此类构件与普通规格等边角钢的差异以及肢厚、肢宽和钢材强度等对柱子曲线的影响.提出了高强大规格等边角钢轴压构件的承载力计算方法.并且研究了高强大规格等边角钢两端偏心受压的柱子曲线,给出了长细比修正系数的建议公式.%The axial compression member test was conducted to investigate the stability performance of these members, including nineteen Q420 L220×20 specimens which slenderness ratio(λ) ranged from 30~90. The test results showed that when slendemess is λ > 45, flexural buckling was observed and when slenderness is λ ≤45, local or flexural-torsion or torsion buckling was observed. The applicability of local buckling wide thickness ratio formula and flexural-torsional buckling conversion slenderness ratio formula was researched. By means of inverse calculation segment length method, the column curve of the large size equal angle was got. The comparison with common size angle and parameter analysis was made. Calculation method of bearing capacity of large size equal angle was given. Two ends eccentric compression column curve was also researched, and a suggestion formula of slenderness ratio correction coefficient was given.

  17. Study on the Shear Load-Bearing Capacity of Steel Reinforced Concrete Beams%型钢混凝土梁斜截面抗剪承载力研究

    Institute of Scientific and Technical Information of China (English)

    常春丽

    2014-01-01

    本文介绍了型钢混凝土结构的特性、研究概况和现有两部规程的计算方法。通过采用计算结果与试验结果比较分析的方法,得出按照《型钢混凝土组合结构技术规程》中的计算方法计算的结果更为安全可靠。因此以《型钢混凝土组合结构技术规程》中型钢混凝土非抗震设计时梁斜截面抗剪承载力的计算公式为基础,通过改变混凝土项抗剪承载力作用的分项系数,建立了简化计算公式。通过采用简化计算公式计算的结果与试验结果比较,表明与试验结果吻合良好。%Features and outline of the steel reinforced concrete composite structure are introduced. The calculating methods of the two existing regulation are described. The calculation method according to the“Technical specification for steel reinforced concrete composite structures”is more safely and reliably by comparing the calculation results and the experimental results. In non-seismic design, the simplified formula for calculating the shear strength is established by changing the sub-item coefficient of the concrete shear capacity based on the shear strength formula of the shear load-bearing SRC beams according to“Technical specification for steel reinforced concrete composite structures”. The experimental results are compared with the calculation results of the simplified formula, the results showed that experimental results have a good agreement with calculated results.

  18. Prediction of Vertical Ultimate Bearing Capacity and Dynamic Stability Analysis of Super-Long Pile%超长桩竖向极限承载力预测与动力稳定性分析

    Institute of Scientific and Technical Information of China (English)

    姚文娟; 钟倩倩; 郭志兴; 胡宝琳; 仇元忠

    2011-01-01

    Based on the catastrophe theory, a cusp catastrophe model of super-long pile under vertical sta-tic load was established, and the predictor formula was derived. Based on the above analysis, dynamic load was tested, the double cusps catastrophe model of super-long pile under combined load was proposed and used in the analysis of the dynamic stability. Dynamic analysis showed that; The relationship among the amplitude H, the Frequency q and the nonlinear coefficient a was conformed to the double cusps ca-tastrophe model when combined load was applied on super-long pile; there was a certain relationship a-mong the change value of dynamic loading frequency, the previous deformation value of pile and the non-linear coefficient of systems in the process of destabilization of super-long pile; important influence on the response characteristics of super-long pile was obtained under the different dynamic loading path. Project example results show that: the cusp catastrophe model is applicable in predicting vertical ultimate bearing capacity of super-long pile.%应用突变理论建立了超长桩在竖向静荷载作用下的尖点突变模型,推导得到了超长桩的竖向极限承载力预测公式.在静荷载分析的基础上,引入动荷载,建立了超长桩在动静组合荷载作用下的双尖点突变模型,并对其动力稳定性进行了分析.动力分析表明:动静组合荷载作用下超长桩的振幅H、频率关系q与结构非线性系数a三者之间符合双尖点突变模型;超长桩失稳时动载频率的变化值与桩顶预变形值及系统非线性系数有一定的关系;动载作用“路径”对超长桩的响应特征有很大的影响.工程算例表明:应用尖点突变理论对超长桩的竖向极限承载力进行预测具有较好的适用性.

  19. Capacidade de suporte e compressibilidade de um argissolo, influenciadas pelo tráfego e por plantas de cobertura de inverno Bearing capacity and compressibility of argisol (paleudult as affected by traffic and winter cover crops

    Directory of Open Access Journals (Sweden)

    Henrique Debiasi

    2008-12-01

    Full Text Available Uma das medidas mais efetivas na prevenção da compactação do solo é a aplicação de pressões inferiores à sua capacidade de suporte de carga, estimada pela tensão de pré-consolidação (σp. Visando a quantificar o efeito de plantas de cobertura de inverno e do tráfego de rodados de trator sobre a σp e sobre o índice de compressibilidade (IC, vem sendo realizado, desde 2002, um experimento em Eldorado do Sul (RS, em Argissolo Vermelho distrófico franco-argilo-arenoso. Os tratamentos, sob semeadura direta, abrangem três coberturas de inverno (pousio, aveia preta e aveia preta + ervilhaca, substituída em 2006 por nabo forrageiro e duas condições de tráfego (com ou sem tráfego de rodados de trator. No verão, foram semeados milho e soja, em rotação anual. Amostras de solo indeformadas, visando à determinação de algumas propriedades físicas e da σp e do IC, foram coletadas, em junho e novembro de 2006, nas camadas de 0,03-0,06 e 0,12-0,15 m, e equilibradas a diferentes tensões de água. Independentemente da época de avaliação e do tráfego, o pousio resultou nos maiores valores de σp e menores de IC na camada de 0,03-0,06 m. Com menor teor de água no solo, as diferenças na σp entre o pousio e as plantas de cobertura tenderam a diminuir. A realização de sete tráfegos em cinco anos aumentou a σp apenas na superfície do solo, mas não afetou o IC. O uso de plantas de cobertura de inverno, aliado à ausência de tráfego, ao reduzir a densidade do solo e aumentar a macroporosidade, diminuiu a capacidade de suporte de carga e aumentou a susceptibilidade da superfície do solo à compactação.One of the most effective practices in preventing soil compaction is to apply stresses below the bearing capacity of the soil, often estimated by the pre-compression stress (σp. To evaluate the effects of cover crops and tractor traffic on σp and compression index (CI, a field experiment was initiated in 2002 on sandy clay

  20. Pogo's Bear.

    Science.gov (United States)

    Spacks, Barry

    1980-01-01

    Shows that the task of the poet-teacher is to teach students not only how to write poetry but also how to read and appreciate poetry. Notes that the poetry workshop should stimulate critical capacity and taste by reconnecting study and thought to the personal. (RL)

  1. Research on Bored Bearing Characteristics in Xi’an

    Directory of Open Access Journals (Sweden)

    Zhang Lipeng

    2015-01-01

    Full Text Available To analyze the influence of different soil properties on pile foundation load-bearing characteristics, taking a section of railway in Xi’an and a bridge of Xi’an as test area, and by field static load test to study load transfer characteristics after the test piles under axial pressure, including the distribution of axial force, pile lateral friction, tip resistance traits, ultimate bearing capacity determine, and compare with the theory bearing capacity. Experimental results show that, adjacent soil properties change large, axial force and lateral friction mutation at the junction of corresponding soil layer. Silty clay in different parts is below ground, and its lateral friction plays much difference. Pile lateral friction plays an important role in bearing capacity, but the role of round gravel soil end bearing capacity to pile bearing capacity can’t be ignored. Tests calculate pile bearing capacity significantly larger than standardized formula calculation bearing capacity, which are respectively 55.35% and 119.1%. And give the similar project condition the suggested values of pile bearing capacity and soil friction, to provide reference for similar pile foundation design.

  2. Analysis & Calculation on Axial Compression Allowable Bearing Capacity of Rock-Socketed Pile in Xiamen City%厦门地区嵌岩桩单桩轴向受压容许承载力分析计算*

    Institute of Scientific and Technical Information of China (English)

    马朝旭; 刘世忠; 杨子江

    2013-01-01

    依照厦门市疏港路下穿仙岳路通道工程地质勘测资料,根据公路规范、建筑规范和福建省当地规范对基坑开挖过程中单排围护桩的单桩轴向受压容许承载力进行计算,并对各规范计算值进行分析比较。同时结合大型有限元软件 ANSYS建立桩基础三维弹塑性模型分析桩土共同工作机理,将规范计算值以面荷载的形式在模型中施加于桩顶,对此荷载下的桩体位移和桩底反力进行计算分析,同时对门机轴向荷载作用下的桩顶位移实测值和模型计算值进行对比分析,得出在规范计算值范围内,桩体未发生破坏。结果表明各个规范公式在计算桩基轴向受压容许承载力时对岩土参数取值各异,采用的计算模式存在差异,因此规范计算值差别较大,ANSYS模型数值分析结果与现场实测结果吻合良好,可为该地区桩基础设计提供参考。%According to the channel construction engineering geology survey material of Xianyue Road and Shugang Road in Xiamen,the axial compression allowable bearing capacity of fender pile in the process of excavation is calculated by highway criterion,building code and local regulations in Fujian Province and all standard calculation values are compared.With the large finite element software ANSYS,the pile founda-tion three-dimensional elastic-plastic model is established to analyze the pile and soil common working mechanism.The model uses the standard calculation value as the surface load applied to the pile and gets the displacement of the pile and the reaction at the bottom of pile.The displacement of pile under the axial load of the crane is also measured and analyzed.It is found that the pile foundation is not destroyed in the range of standard calculation values.The results show that all codes adopt different geotechnical parame-ters and the calculation method is different,so the difference of standard calculation values is big

  3. BEARING CAPACITY AND SCREW PLATE TEST FOR EVALUATION OF SURFACE SEDIMENTS IN HUAIBEI PLAIN%淮北平原浅表层沉积土承载力特征及其螺旋板检测评定方法研究

    Institute of Scientific and Technical Information of China (English)

    段海澎; 余飞; 戴张俊; 陈善雄

    2013-01-01

    针对淮北平原地区浅表层沉积土典型地质单元,选取代表性试验区域,开展了螺旋板载荷、平板载荷和静力触探等原位测试,分析了含钙质结核黏土、新近沉积粉土、粉砂3种地基的承载力特性,重点探讨了不同类型土体的螺旋板载荷试验p-s曲线特征、承载力特征值确定方法和值域范围,并与静探和平板载荷试验数据进行对比,分析其相关关系和变化规律.研究结果表明:一般性黏土、粉质黏土和粉土的承载力较低,钙质结核黏性土和粉砂的承载力相对较高,值域范围较宽,密实程度是决定粉土、粉砂承载力大小的主要因素.螺旋板载荷试验能较好的反映多元互层地基土体力学性质的变化特征,采用等应变控制法可达到快速、分层检测的目的,并通过等应力控制法对比试验验证了其可靠性.最后通过与平板载荷试验结果进行线性拟合,给出了螺旋板载荷试验确定淮北平原浅表层地基承载力的经验公式.%This paper is about the typical geological units of surface sediments in Huaibei plain. In situ tests including screw plate tests, plate loading tests and static cone penetration tests are carried out in representative test work sites. Bearing capacity features of the calcareous concretion clay, recently deposited silt and silty sand are analyzed. The p-s curve characteristics of different soils from the screw plate test and determination method and range of bearing capacity are discussed. Their correlation and variation are analyzed compared with the data from static cone penetration tests and plate loading tests. The results show that bearing capacities of the clay, silty clay and silt are lower. The calcareous concretions in clay and silty sand have relatively higher bearing capacity and wide range ' of values. The degree of compaction is the main factor to determine the bearing capacity of silt and silty sand. The modified mechanical property

  4. 渡槽贝雷钢拱架稳定性及承载能力分析%Analysis for Stability and Bearing Capacity of Aqueduct Bailey Steel Arches

    Institute of Scientific and Technical Information of China (English)

    钟伟; 肖阳剑

    2014-01-01

    with some arch aqueduct which arch rings are constructed with suspended Bailey steel arches as background, this paper discloses mechanical behaviors of arches during cast-in-situ of arch rings by analyzing stability and bearing capability of arch structures, and compares changes of stability and bearing capability of arches under different constraints to draw a conclusion that consolidation constraint hinge joint adopts for arches can remarkably improve stability of arches without reduction of bearing capability of arches. This conclusion can provide a reference for design and construction of similar projects in the future.%以悬拼贝雷钢拱架施工拱圈的某拱式渡槽为背景,通过对拱架结构的稳定性及承载能力进行分析,揭示拱圈现浇过程中拱架的力学行为,并对拱架不同约束形式下其稳定性和承载力的变化进行比较,得出拱架采用固结约束较铰接能显著提高拱架稳定性且不降低拱架承载能力的结论,可为以后类似工程设计施工提供参考。

  5. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  6. 基于主成分分析法的福建省资源环境承载力空间差异研究%Study of Spatial Differences of Resource and Environmental Bearing Capacity in Fujian Province Based on Principal Component Analysis

    Institute of Scientific and Technical Information of China (English)

    李庆贺; 伍博炜; 曾月娥; 王佳韡

    2014-01-01

    基于主成分分析法,利用SPSS19.0软件对福建省的资源环境承载力进行了研究分析。结果表明:从总体上看,沿海地区资源环境承载力综合得分大于内陆地区,但沿海地区内部差异较大,其中,厦漳泉地区以及福州地区资源环境承载力明显高于其它地区。为了促进经济社会的可持续发展,必须充分合理地利用资源环境。%Based on principal component analysis , this article analyzes the spatial differences of resource and environmental bearing capacity in Fujian Province by using SPSS19 .0 .The results show that on the whole ,the composite scores of resource and environmental bearing capacity in coastal areas are greater than those in inland areas .But there are obvious differences in coastal areas ,for example ,the areas of Xiamen-Zhangzhou-Quanzhou and Fuzhou get the significantly higher scores than others .Finally ,it points out that the resource and environment must be utilized reasonably and efficiently in order to ensure sustainable socio -economic development .

  7. Maintenance Free Bearings

    OpenAIRE

    S. M. Muzakkir & Harish Hirani

    2015-01-01

    In the present research work the need of a Maintenance Free Bearings (MFB) is established. The paper presents preliminary friction calculations to highlight the ways to achieve maintenance free bearings. The existing technologies of well established maintenance free bearings are described. The hybridization of bearing technologies to achieve low cost maintenance free bearings has been exemplified. Finally a combination of passive magnetic repulsion and hydrodynamics ha...

  8. 钢管陶粒混凝土短柱火灾后承载力及力学性能的试验研究%EXPERIMENTAL STUDY ON BEARING CAPACITY AND MECHANICAL BEHAVIOR OF THE CERAMSITE CONCRETE FILLED STEEL TUBULAR SHORT COLUMNS AFTER FIRE

    Institute of Scientific and Technical Information of China (English)

    周明; 王新堂; 王万祯

    2013-01-01

    The experimental investigation on post-fire mechanical behavior of ten of four sets of unprotected short columns of ceramsite concrete filled steel tubes ( CCFST) was conducted, variation of remaining bearing capacity and failure form of the short columns of CCFST after exposure to fire was discussed for different parameters. Based on the test results, effect of the factors, such as the maximum value of fire temperatures, dimension of cross section of the specimen, slender ratio and concrete mix proportion on the remaining bearing capacities and ductility of CCFST short columns were especially investigated. The results showed that the CCFST short columns after exposure to fire had higher post-fire bearing capacity and better ductility, and there was no descent segment in load-displacement curves of the most of specimens. It was concluded that effect law of the maximum values of response temperature on bearing capacities of CCFST short columns after exposure to fire were related to some key parameters of the specimens, which were mix proportion, slender ratio and dimension of cross section of the specimens. It was shown that the post-fire bearing capacities of the CCFST short columns decreased with increase of water cement ratios of the concrete of the specimens subjected to fire load.%通过对4组10根钢管陶粒混凝土短柱受火后性能的对比试验研究,讨论不同参数的钢管陶粒混凝土短柱受火后的剩余承载力和破坏形态的变化.基于试验结果讨论火灾炉试验保持最高温度、截面尺寸、试件长细比及混凝土配合比等参数对轻骨料钢管混凝土短柱承载力和延性的影响.结果表明,以轻质材料——陶粒为粗骨料制成的钢管混凝土短柱,受火后仍然具有较高的承载力和良好的延性,且火灾后多数试件的荷载-位移曲线并没有出现下降段.最高炉温对钢管陶粒混凝土短柱火灾后承载力的影响程度与试件自身特征参数有关,主要

  9. CFD Investigation of Influences of Reverse Textures on Bearing Surface of a Journal Bearing

    Directory of Open Access Journals (Sweden)

    Santosh Mishra

    2014-01-01

    Full Text Available It has always been the subject of interest and research to find out most efficient method to minimize the frictional loss of any mating surface in any mechanism. But it has been identified that only improvement of lubricating material cannot help much. For this reason research on design modification was started and still going on to optimize the design of mating surfaces so that losses be minimum. In this paper a research has been done on the design of bearing surface of a journal bearing. Journal bearing is a very important part of many machines specially turbines used in Power generation and rolling mills used in steel making sectors. By modifying the design of the bearing surface, load carrying capacity of a journal bearing can be increased and thus its performance can be improved. It is proved by many researches that, by putting cylindrical dimples on bearing surface the performance of a journal bearing can be increased. To measure the performance of a journal bearing three parameters are usually used. Those are, (i Load Carrying Capacity, (ii Frictional resisting force and (iii Ratio of Frictional resistance and Load carrying capacity, which is called Frictional coefficient. In this work a modification has been done on the work of Cupillard. Cupillard considered only the cylindrical dimples for the sake of manufacturing simplicity, but in this work a different configuration of dimple has been considered and its influence on bearing performance has been studied. It is proved by many researches that, by putting cylindrical dimples on bearing surface the performance of a journal bearing can be increased. To measure the performance of a journal bearing three parameters are usually used. Those are, (i Load Carrying Capacity, (ii Frictional resisting force and (iii Ratio of Frictional resistance and Load carrying capacity, which is called Frictional coefficient. In this work a modification has been done on the work of Cupillard at all (reference

  10. Comparison of field and laboratory models of the load bearing capacity in coffee plantations Comparação de modelos de capacidade de suporte de carga do solo de campo e laboratório em plantações de café

    Directory of Open Access Journals (Sweden)

    Piero Iori

    2013-04-01

    Full Text Available Precompression stress is an important property for assessment of tropical soil structure sustainability and is often determined in laboratory tests. The objective of this study was to compare the load bearing capacity models obtained with controlled moisture in laboratory and those obtained with natural field moistures determined a long one year. The evaluation of soil structural sustainability follows four distinct steps: soil sampling in the field, uniaxial compression test of the samples in the laboratory, determination of precompression stress and estimation of the load bearing capacity models. Laboratory estimates of precompression stress were obtained from moisture controlled in laboratory and from natural moisture determined in a field a long one year. In this process, the soil samples were saturated by capillarity with distilled water in laboratory, and after 48 hours, the samples were air dried to obtain the different moisture contents. Then, the precompression stress was determined for this both conditions. To verify if the load bearing capacity models obtained with controlled moisture in laboratory may represent the load bearing models obtained with natural field moisture, these models were compared using the homogeneity test procedure. It was observed that 75% of field models analyzed were similar to the laboratory models. Thus, due to the similarity on the load-bearing capacity models obtained using natural (field or controlled (laboratory moisture contents, the assessment of the soil structure sustainability can be done using both methods.Pressão de pré-consolidação é uma importante propriedade na avaliação da sustentabilidade estrutural do solo e é determinada em testes de laboratório. Neste estudo, objetivou-se comparar modelos de capacidade de suporte de carga obtidos com umidade controlada em laboratório e com umidade natural de campo ao longo de um ano. A avaliação da sustentabilidade estrutural do solo ocorreu em

  11. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    carrying capacity (SCC) and assimilative carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts...... carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts/cities. Four different sectors (water...

  12. 铁路桥梁群钉组合结构极限承载力和静力行为分析%Analysis on the Ultimate Bearing Capacity and the Statical Behavior of the Composite Structures with Grouped Studs in Railway Bridge

    Institute of Scientific and Technical Information of China (English)

    侯文崎; 叶梅新

    2011-01-01

    Aiming at the application of the composite structures in railway bridges, and according to the results of the push-out tests, the load-slip relationship expressions of Φ13 and Φ22 studs in C50 concrete were acquired by nonlinear least-square fit. Through the ultimate bearing capacity experiments of the composite structures with grouped studs, adopting the proposed FEA simulating method, the reduction of the average ultimate bearing capacity and the shear force distribution of the grouped studs were well studied, as well as the relative influencing factors. Research results reveal that the average ultimate bearing capacity of the grouped studs shows quite big reduction compared with a single stud, which is at most 18%. The shear force distribution of the grouped studs presents an evident non-uniformity with a shape of saddle from top to bottom, which is redistributed as the load increasing. When the load is near to the ultimate bearing capacity, the grouped studs tend to bear the even shear force. The stud stiffness and ways of the load transmission are both important influencing factors on the non-uniform shear force distribution of the grouped studs. The bigger the stud stiffness is, the more the average ultimate bearing capacity of grouped studs will be reduced. The ways of load transmission have little influence on the ultimate bearing capacity of the composite structures with the grouped studs, but have important influence on the non-uniform shear force distribution of grouped studs when the load is at a low level, and the influence will be diminished with load increasing. Analytical results of FEA show good agreement with the experimental results, which demonstrates the correctness and the feasibility of the proposed FEA method.%针对我国铁路桥梁中应用钢-混凝土组合结构,根据推出试验结果,采用最小二乘非线性拟合得到C 50混凝土中φ13和φ22栓钉的荷载-滑移关系式.通过群钉组合结构极限承载力试验,

  13. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  14. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...

  15. Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

    Science.gov (United States)

    Walicka, A.; Walicki, E.; Jurczak, P.; Falicki, J.

    2014-11-01

    In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

  16. 基于模糊综合评价对山东省水资源承载力的研究%The study of comprehensive evaluation on Shandong's water resources bearing capacity based on fuzzy comprehensive model

    Institute of Scientific and Technical Information of China (English)

    黄玲; 杨鹏辉

    2016-01-01

    This article is about the evaluation of water resources carrying capacity. From the point of physical scarcity and economic scarcity,we took social,economy,ecology and water composite system into consideration. We es-tablished fuzzy comprehensive evaluation model and grey prediction model,and used MATLAB software to water resources carrying capacity in Shandong Province,and forecast the development trend of water resources carrying capacity in the next fifteen years. The results showed that Shandong province was now in a state of severe water shortage,even worse if not take action Shandong province would step into the stage of excessive water resources shortage.%文章针对水资源承载力的评价,综合社会、经济、生态和水资源的复合系统来构建评价体系,并从物理性和经济性角度分析水资源稀缺状况,建立模糊综合评价模型、灰色预测模型;同时运用Matlab软件求解得出山东省近10年的水资源承载力水平,并预测未来15年水资源承载力的发展趋势,发现山东省现处于重度缺水状态,若不加以治理未来15年将会步入水资源过度短缺阶段。

  17. ANALYSIS OF BEARING CAPACITY OF DOUBLE COLD-FORMED THIN-WALLED C STEEL BACK-TO-BACK COMPOSITE COLUMN WITH PLATE COUPLED%带垫板的双肢背靠背C型钢组合柱承载力分析

    Institute of Scientific and Technical Information of China (English)

    陈明; 芦文文; 刘凯

    2014-01-01

    According to the composite column of double cold-formed thin-walled C steel back to back connected with gusset plate, the test and finite element analysis were carried out to study the stability bearing capacity and failure modes of the specimen under eccentric loading.The elements such as slenderness ratio, gusset plate thickness and gusset plate spacing were discussed , which produced the impacts to composite column ’ s bearing capacity, the relationship between stiffness and axial loading, and the curves of M-φof eccentricity.The results revealed that before the overall instability the local-buckling was occurred, the failure modes were belonging to the in-plane-flexural buckling.The major factors are slenderness ratio, eccentricity and gusset plate spacing which effected the mechanical behavior, while the gusset plate thickness has no obvious impact.In the end, the calculation method of the bearing capacity of the cold-formed thin-walled column was compared with that in“Technical Code of Cold-Formed Thin-Walled Section Steel Structures” ( GB 50018-2002 ) , some suggestions based on the type of composite section column calculation were put forward , and the bearing capacity correction coefficient of the steel composite columns was given .%针对带垫板的双肢背靠背C型钢组合柱,通过试验和有限元模拟分析,研究该类型组合柱在偏心荷载作用下的受力特性,就偏心距、长细比、垫板厚度和间距等参数对组合柱承载力、刚度与轴向荷载的关系和M-φ曲线的影响进行讨论。结果表明:C型钢腹板和受压翼缘在整体失稳之前出现了严重的局部屈曲,组合柱的破坏模式均为弯矩作用平面内的弯曲失稳。长细比、偏心距和垫板间距是影响组合柱受力性能的主要因素,垫板厚度的影响有限。最后与规范GB 50018-2002《冷弯薄壁型钢结构技术规范》规定的柱承载力的计算方法进行对比,对该类组合柱的

  18. Discussion on ground bearing capacity of the sandy pebble in the foundation of tall buildings in Chengdu area%成都地区超高层建筑砂卵石土地基承载力取值探讨

    Institute of Scientific and Technical Information of China (English)

    谭方; 吴帅; 黄宗芳; 陈哲

    2013-01-01

    Taking the actual case of Chengdu Panda City Ⅱ as an example,based on the in-situ plate loading tests and numerical analysis results,the reasonable determination method of ground bearing capability was discussed.The overcharge was improved through increasing the numbers of anti-floating anchor,so revised bearing capacity can meet the design requirement.The deformation modulus from the in-situ plate loading tests was used to calculate the settlement.Modified by the experience in Chengdu area,the calculation results agree well with the measured settlements and the average settlement is small.The successful application of shallow foundation is beneficial to apply to similar projects.%以成都熊猫城二期为例,通过原位平板荷载试验,并结合数值分析结果,探讨了合理确定地基承载力的方法,通过增加抗浮锚杆提高超载,修正后的承载力可满足设计要求.用原位试验的变形模量计算建筑物的沉降量,经成都地区经验修正后,接近实测值且平均沉降量较小.天然基础的成功应用可为类似工程提供参考.

  19. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  20. Novel nano bearings constructed by physical adsorption

    Science.gov (United States)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  1. Mass Loss Rates of Fasting Polar Bears.

    Science.gov (United States)

    Pilfold, Nicholas W; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E; Lunn, Nicholas J; Richardson, Evan

    2016-01-01

    Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive polar bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009-2014. Polar bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult males was identical to that lost by free-ranging individuals, suggesting that terrestrial feeding contributes little to offset mass loss. The inferred metabolic rate was comparable to a basal mammalian rate, suggesting that while on land, polar bears can maintain a depressed metabolic rate to conserve energy. Finally, we estimated time to starvation for subadults and adult males for the on-land period. Results suggest that at 180 d of fasting, 56%-63% of subadults and 18%-24% of adult males in this study would die of starvation. Results corroborate previous assessments on the limits of polar bear capacity to withstand lengthening ice-free seasons and emphasize the greater sensitivity of subadults to changes in sea ice phenology. PMID:27617359

  2. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    Directory of Open Access Journals (Sweden)

    Ruiqing Lang

    2014-01-01

    Full Text Available Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  3. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375

  4. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  5. The shear bear capacity of reactive powder concrete beam with high strength stirrup%配筋活性粉末混凝土梁抗剪承载力

    Institute of Scientific and Technical Information of China (English)

    邓宗才; 周冬至; 程舒锴

    2014-01-01

    为掌握高强箍筋活性粉末混凝土( reactive powder concrete,RPC)梁的抗剪性能,通过6根T形梁的抗剪试验,获得了抗剪承载力试验值,并将试验值与压力场理论值进行了比较,探讨了压力场理论应用于RP C梁抗剪分析和承载力计算存在的问题,充分考虑斜裂缝截面上钢纤维拉拔阻力的抗剪贡献,对该理论进行了改进。并将剪切试验结果与塑性剪切理论、粘结滑移理论和法国规范等进行了比较,分析现有抗剪理论的适用条件、存在的问题,这些对揭示RP C梁抗剪破坏机理、建立承载力计算理论与设计方法有参考价值。%To grasp the shear strength properties of reactive powder concrete ( RPC) beams with high strength stir-rup, through 6 T-shaped beams test, the shear strength test values were obtained.The test values and the theoreti-cal values of the compression field theory were compared and the questions of applying the compression field theory in the analysis and calculation of shear capacity for RPC beams were also discussed.The modified compression field theory was proposed by considering the shear crack resistance improvement from the contribution of the steel fibers at the diagonal crack during pull out.Results of the shear test were also compared with the plastic shear theory, the interfacial bond shear strength theory and French code specifications.An analysis of problems facing the existing theories and their applications was also conducted.The analysis results and comparison conducted on the different shear capacity theories provided a solid base for future researches on the shear failure mechanism and further devel-opment of shear capacity design models for RPC beams.

  6. Actual Analysis of Bearing Capacity of Piles with Super-large Diameter and Deep Penetration Based on Statnamic Method%基于静动法的大直径超长桩承载力实测分析

    Institute of Scientific and Technical Information of China (English)

    王湛; 刘宇峰; 娄学谦; 戴宇文; 桑登峰

    2014-01-01

    Piles with super-large diameters and deep penetration are widely used in ocean and bridge engineering;however,traditional capacity test methods used for such piles have limitations.Focusing on the imperfections of nor-mal static load and Osterberg cell (O-cell)methods,the statnamic testing method is investigated on the basis of the Second Penang Bridge project in Malaysia.The capacities of piles with super-large diameters and deep penetration in sandy strata are studied.Compared with the results of the O-cell method used on the same pile,the applicability of statnamic testing for super-large diameter,deep-penetration piles is analyzed.Results indicate that the equivalent stat-ic capacities resulting from the Unloading Point Method (UPM)and the Segmental Unloading Point Method (SUPM)are 30% larger than the results when using the O-cell method.Because of the influences of dynamic soil re-sistance and pore pressure,the side friction of statnamic testing is also larger than that when using the O-cell meth-od.Therefore,the statnamic method still requires modification.%大直径超长桩在海洋工程和桥梁工程中应用广泛,但目前常用的测试方法均有各自的局限性。针对普通静载费时费力,自平衡测试方法研究不够完善等不足,基于马来西亚槟城二桥工程,采用现场实测方法对砂土地层中大直径超长嵌岩桩的静动法测试进行研究。通过对同一根桩上的自平衡法测试结果进行对比,分析静动法测试大直径超长桩承载力的适用性。通过对比发现,静动法测试结果用传统卸荷点法和分段卸荷点法处理得到的等效静承载力比自平衡法大30%左右;且由于土动摩阻和孔隙水压力影响,静动法测得的桩身摩阻力也大于自平衡测试结果,需要进行修正。

  7. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    Science.gov (United States)

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  8. On the computation of electrical resistance of hydrodynamic journal bearing

    Directory of Open Access Journals (Sweden)

    Eleonora Pop

    2014-12-01

    Full Text Available The paper approaches the mathematical model of electrical resistance of hydrodynamic journal bearing under different parameters of operation so as to predict bearing performance and safe load carrying capacity. The currents circulating in the journal bearing of electrical machine causes reducing of lifespan by appearance of pitting on their surface and the degradation of the lubricant. In a hydrodynamic journal bearing, the zone of minimum film thickness, load-carrying oil film varies along the circumference of a bearing through its length. This has been found to form a capacitor of varying capacitance between the journal and the bearings dependent on permittivity of the lubricant used, the bearing length, the eccentricity ratio and the clearance ratio. Besides this, load-carrying on oil film offers resistance that depends on operating parameters and resistivity of the lubricant.

  9. The Giant Magellan telescope (GMT): Gregorian instrument rotator bearing

    Science.gov (United States)

    Gunnels, Steve

    2014-07-01

    The Giant Magellan Telescope (GMT) is an optical-infrared 25 Meter ELT to be located in Chile. It is being designed and constructed by a group of U.S. and international universities and research institutions. The Gregorian Instrument Rotator (GIR) for GMT will be a structural-mechanical assembly 9.4 meters in diameter and 6.9 meters long. The complete assembly including structure, instruments and mechanisms has a rotating mass of 117,000 kg. It will be supported by a unique bearing system using high-capacity precision industrial rollers. The rollers will support the GIR via two large hardened and ground runner bearings integral with the structure. The bearing system includes an upper axial bearing with (8) rollers and an upper and lower radial bearing, each using (10) identical rollers. The bearing system will have the advantages of adjustability, low friction, low noise (jitter), and low cost. The rollers have a manufacturer-rated capacity 4 times greater than their maximum working load in GMT. It is important that the hardened runner bearings have a life in this application comfortably greater than the life of the GIR in the telescope. A test was devised and executed to confirm the life of the runner bearing surface (track) and to characterize the bearing friction. The bearing system design and test details and results are described.

  10. 天津厚地层超长钻孔灌注桩单桩承载特性研究%Research on vertical bearing capacity of single super-long bored pile in thick stratum of Tianjin

    Institute of Scientific and Technical Information of China (English)

    柯洪; 吴翔; 王继华; 曾云川; 赵春宏; 冯庆高

    2011-01-01

    The layers of a main tower construction site in Tianjin are mainly clay, silt and silt sand. Two groups of the super-long bored test piles with post pressure-grouting (a total of eight piles) are designed to take bearing behavior test using single pile vertical static load test of compression to master the engineering properties in the main tower construction site. Vibrating wire reinforcement meter and stratified settlement tube are installed to find out the pile side friction and the pile body layered settlement state. After the test, the results of the data analysis show that the pile side grouting can significantly improve the long pile side skin friction; pre-load pressure can enhance the flexibility of the super-long pile and reduce the settlement of the top of the pile in some degree. After unloaded stability, the test pile also has side resistance; the resistance of the upper segment is negative skin friction; and the lower segment is positive skin friction; and the pile body axial force causes the test pile to have some compression volume; that is an important part of the residual deformation.%天津市某主塔楼桩基选用后压浆超长钻孔灌注桩,为了掌握超长后压浆钻孔灌注桩在该地层的工程特性,共设计了2组(共8根)试桩进行单桩竖向抗压静载试验.试桩中安装了振弦式钢筋计和分层沉降管以反映桩侧摩阻力和桩身分层沉降状态.对试验数据进行对比分析和计算结果表明,桩侧注浆可以明显提高超长桩的侧摩阻力;采用预压加载可以增强超长桩的弹性,减少桩项的沉降;卸荷稳定后试桩具有桩侧阻力,桩身上段所受阻力为负摩阻力,下段为正摩阻力,同时具有的桩身轴力使试桩产生一定的压缩,其压缩量为残余变形量的重要组成部分.

  11. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  12. Optimal Synchronizability of Bearings

    OpenAIRE

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S.

    2013-01-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)]. We show that, in analogy...

  13. Bear Spray Safety Program

    Science.gov (United States)

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  14. Bearing restoration by grinding

    Science.gov (United States)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  15. 砂土中吸力式沉箱基础的最大承载力计算方法%Calculation method for maximum bearing capacity of suction caisson foundation in sand

    Institute of Scientific and Technical Information of China (English)

    黎冰; 高玉峰; 沙成明; 童小东

    2012-01-01

    To accurately determine the maximum pull-out loading capacity of suction caisson foundation in sand, the limit equilibrium method is applied. Based on the mechanical characteristics of suction caisson foundation with horizontal translation, a method for three-dimensional limit equilibrium analysis of maximum pull-out loading capacity of suction caisson foundation in sand is proposed. In the proposed method, the development process of earth pressure and shear resistance with displacement, and the characteristics of different earth pressure and side shear resistance over the caisson cross-section are considered. The earth pressure acting on the caisson is assumed to obey the Winkler model and is not in excess of the limiting earth pressure. The shear resistance between caisson and soil is assumed to be linearly proportional to the relative displacement between them before reaching its ultimate value. Fifteen model tests of suction caisson foundation under horizontal loading in sand are conducted to investigate its pull-out behaviors, and the load-displacement curves are obtained. The calculation results by the proposed method agree well with the experimental results, indicating that the proposed method is accurate and effective. Key w%为了准确确定砂土中吸力式沉箱基础的最大承载力,应用极限平衡法对其进行分析.基于吸力式沉箱基础平动时的受力特点,充分考虑土压力和摩擦力的发挥过程以及沉箱横截面上各点土压力大小的不同,提出了一种计算砂土中吸力式沉箱基础最大承载力的三维极限平衡方法.方法中假定沉箱侧壁土压力满足Winkler模型,但其值不超过水平极限土压力值;假定沉箱侧壁与地基土之间的摩擦力在达到最大值之前与两者之间的相对位移成线性正比关系.开展了15组水平荷载作用下吸力式沉箱基础的模型试验,得到了吸力式沉箱基础的荷载-位移曲线.利用所提方法得到的计

  16. An Experimental Test Method of Determining the Foundation Bearing Capacity of Existing Buildings through Allowable Subsoil Deformation%按地基允许变形确定既有建筑地基承载力的试验方法

    Institute of Scientific and Technical Information of China (English)

    李平

    2013-01-01

    The foundation bearing capacity of existing buildings should be determined through load test,the allowable subsoil deformation is the control standard.The settlement of load test is different from that of practical foundation because of size effect and space effect of loading plate.The proportional relation between load test settlement and practical foundation settlement combined with instance is analyzed through large scale indoor model test.The seven days sustained load test is done on the soil of same nature near the buildings when determining the foundation soil bearing capacity of existing buildings in practical engineering,the settlement of seven days sustained load test and the settlement of instance analysis are compared and analyzed.The practical foundation settlement can be changed into load test settlement through certain proportion relationship combined with evaluation of buildings' allowable deformation before story-adding reconstruction on the existing buildings and allowable subsoil deformation ruled by the code,then the appropriate allow deformation index can be chosen to determine the foundation soil bearing capacity of existing buildings through the range of load test allowable deformation.%通过持载的荷载试验确定既有建筑的地基承载力,地基允许变形是其控制标准.实际工程中通过荷载试验确定的地基承载力特征值所对应的沉降值与实际基础沉降值会因荷载板尺寸效应和空间效应出现差异.本文通过大比尺室内模型试验,结合实例分析荷载试验沉降值与实际基础沉降值之间的比例关系.在实际工程确定既有建筑地基承载力时,是在建筑物旁相同性质的土体上做持载7d的荷载试验,将持载7d的试验沉降值与实例计算的基础最终沉降值对比分析,结合既有建筑增层改造前对建筑物允许变形的鉴定评价以及规范规定的地基允许变形值,通过一定的比例关系将实际基础沉降允许值转

  17. Bearing fatigue investigation 3

    Science.gov (United States)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  18. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager;

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setti...

  19. Large deflection analysis of a tension-foil bearing

    Science.gov (United States)

    Elrod, David A.

    1996-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are as follows: rolling or sliding contact within the bearing has life-limiting consequences; and REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's. CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contacts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exist for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. Recently, a new tension-foil bearing configuration has been proposed for turbomachinery applications.

  20. Arcturus and the Bears

    Science.gov (United States)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  1. 纤维编织网增强细粒混凝土加固RC受弯构件的正截面承载性能研究%Investigation on the bearing capacity of the normal section of RC flexural component strengthened with textile-reinforced concrete

    Institute of Scientific and Technical Information of China (English)

    徐世烺; 尹世平

    2012-01-01

    The structural performance can be enhanced without increasing the section size of the component when the new composite of textile reinforced concrete (TRC) is applied to strengthen and retrofit existing structures. However, due to the brittle feature of fiber materials, tensile failure would occur if the ultimate tensile strength of textile is reached, which is unsafe for structures. Therefore, for a single rectangular beam, two types of limit failure states of beams strengthened with TRC are presented for different amounts of textile, and for each state, the relationship between the textile ratio and the steel reinforcement ratio is derived. Based on the plane section assumption, calculation methods for the ultimate bearing capacity of the normal section of the component strengthened with TRC in three types of failure mode are also presented, including first load and secondary load. The experimental results show that the first failure mode is unfavorable to the component and the calculated values of ultimate bearing capacity agree well with the experimental values.%采用纤维编织网增强混凝土(TRC)这种新型材料对结构进行修补加固不仅可以改善结构的性能,而且可以几乎不增加结构的截面尺寸。但由于纤维材料的脆性特征,在达到其极限抗拉强度时会发生拉断破坏,这对于结构来说是不安全的。为此,取单筋矩形梁研究,针对不同的纤维编织网的用量给出增强梁的两种界限破坏状态。并给出这两种状态分别对应的配网率与钢筋配筋率之间的关系。然后,基于平截面假定,给出TRC增强受弯构件在三种破坏形态下正截面极限承载能力的计算方法,包括一次受力和二次受力的情况。最后,结合试验数据说明第一种破坏模式的不利性,且采用该方法得到的承载力计算值与试验结果吻合得较好。

  2. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  3. Probing Capacity

    CERN Document Server

    Asnani, Himanshu; Weissman, Tsachy

    2010-01-01

    We consider the problem of optimal probing of states of a channel by transmitter and receiver for maximizing rate of reliable communication. The channel is discrete memoryless (DMC) with i.i.d. states. The encoder takes probing actions dependent on the message. It then uses the state information obtained from probing causally or non-causally to generate channel input symbols. The decoder may also take channel probing actions as a function of the observed channel output and use the channel state information thus acquired, along with the channel output, to estimate the message. We refer to the maximum achievable rate for reliable communication for such systems as the 'Probing Capacity'. We characterize this capacity when the encoder and decoder actions are cost constrained. To motivate the problem, we begin by characterizing the trade-off between the capacity and fraction of channel states the encoder is allowed to observe, while the decoder is aware of channel states. In this setting of 'to observe or not to o...

  4. Compliant Foil Journal Bearing Performance at Alternate Pressures and Temperatures

    Science.gov (United States)

    Bruckner, Robert J.; Puleo, Bernadette J.

    2008-01-01

    An experimental test program has been conducted to determine the highly loaded performance of current generation gas foil bearings at alternate pressures and temperatures. Typically foil bearing performance has been reported at temperatures relevant to turbomachinery applications but only at an ambient pressure of one atmosphere. This dearth of data at alternate pressures has motivated the current test program. Two facilities were used in the test program, the ambient pressure rig and the high pressure rig. The test program utilized a 35 mm diameter by 27 mm long foil journal bearing having an uncoated Inconel X-750 top foil running against a shaft with a PS304 coated journal. Load capacity tests were conducted at 3, 6, 9, 12, 15, 18, and 21 krpm at temperatures from 25 to 500 C and at pressures from 0.1 to 2.5 atmospheres. Results show an increase in load capacity with increased ambient pressure and a reduction in load capacity with increased ambient temperature. Below one-half atmosphere of ambient pressure a dramatic loss of load capacity is experienced. Additional lightly loaded foil bearing performance in nitrogen at 25 C and up to 48 atmospheres of ambient pressure has also been reported. In the lightly loaded region of operation the power loss increases for increasing pressure at a fixed load. Knowledge of foil bearing performance at operating conditions found within potential machine applications will reduce program development risk of future foil bearing supported turbomachines.

  5. Management recommendations: Bear River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Bear River Migratory Bird Refuge, by a land use specialist. Recommendations, time frame and additional...

  6. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  7. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  8. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  9. Estimation of optimum operating point for thrust magnetic bearing with solid magnet

    Institute of Scientific and Technical Information of China (English)

    孙首群; 田育民

    2003-01-01

    A carrying capacity-temperature rise analysis model has been established for analysis of the carrying capacity, temperature rise and carrying capacity-temperature rise characteristic of a thrust magnetic bearing with solid magnet. The results indicate that there must be an optimal operating point for the thrust magnetic beating with solid magnet. The main factors having effect on carrying capacity-temperature rise include static gap and/or ampere-turns. With proper static gap chosen, the bearing can be run near the optimal operating point by adjhusting ampere-turns, thereby optimizing the bearing properties.

  10. Effect of Bearing Compliance on Thermo-hydrodynamic Lubrication of High Speed Misaligned Journal Bearing Lubricated with Bubbly Oil

    Directory of Open Access Journals (Sweden)

    Basim Ajeel Abass

    2015-03-01

    Full Text Available In the present work the effect of bearing compliance on the performance of high speed misaligned journal bearing lined with a compliant PTFE liner lubricated with bubbly oil at high speeds has been studied. The effect of induced oil film temperature due to shearing effect has been implemented. Hydrodynamic effect of the complaint bearing and the influence of aerated oil have been examined by the classical thermohydrodynamic lubrication theory modified to include the effect of oil film turbulence and oil film temperature with suitable models for bubbly oil viscosity and density. The effect of liner elastic deformation has been implemented by using Winkler model. The effects of variable density and specific heat on the most importantbearing parameters such as maximum pressure, maximum temperature, bearing load carrying capacity and power losses have been investigated.The results obtained show that the oil film pressure and load carrying capacity increased for the bearing lubricated with bubbly oil of higher aeration level and smaller size of air bubbles. Including the effect of elastic deformation of the bearing liner reduces the oil film pressure, load carrying capacity and frictional power loss for the misaligned bearing working at the same circumstances

  11. 液压高频振动沉桩的饱和土超静孔压及单桩静载特性试验研究%Experimental studies on pore pressure of saturated soils and bearing capacity of piles driven by high-frequency hydraulic vibrator

    Institute of Scientific and Technical Information of China (English)

    邓俊杰; 陈龙珠; 邢爱国; 宋春雨

    2011-01-01

    为解决常规锤击、电动中低频振动法进行桩基施工时引起较为严重的噪声、振动和增大电网负荷等问题,发达国家已在应用液压高频振动施工技术,但沉桩的土动力学机理以及单桩静力荷载-沉降特性等尚缺乏深入的室内外试验研究.利用大吨位液压高频振动锤,在某深厚饱和软土场地对直径500 mm、长度26~29 m的预应力管桩进行了沉桩施工试验,观测了邻近地基土超静孔压随沉桩深度而上升及其后续消散的过程;在休止期满后进行了单桩怪向静载荷试验,并将实测极限承载力与其它常规施工方法的进行了比较分析.试验结果对推广应用液压高频振动沉桩新技术,具有重要的学术和应用参考价值.%To solve the serious noise and vibration problems as well as the high pressure on the capacity of city power supply caused by the existing piling methods with falling hammers and low-frequency electric vibrators, a new piling technique using high-frequency hydraulic vibrators has been used in some developed european countries and the USA.The piling mechanism related to soil dynamics at high frequency and the bearing capacity of piles after installation with the hydraulic vibrators should be investigated in laboratory and construction sites.Using a high-frequency hydraulic vibrator manufactured by a Shanghai machinery company, pre-casted/pre-stressed concrete pipe piles with diameter of 500 mm and length of 26-29 m are driven into the saturated soft ground in the Minhang campus of Shanghai Jiaotong University in China, and the induced excess pore water pressures of adjacent soil at different depths are investigated for about one month.After the specified interruption period of 28 days after piling, the ultimate bearing capacity of each pile is studied by means of the conventional static loading tests and compared with that of piles installed with falling hammers and statically jetting.The experimental

  12. Capacity Building

    International Nuclear Information System (INIS)

    Outcomes & Recommendations: • Significant increase needed in the nuclear workforce both to replace soon-to-retire current generation and to staff large numbers of new units planned • Key message, was the importance of an integrated approach to workforce development. • IAEA and other International Organisations were asked to continue to work on Knowledge Management, Networks and E&T activities • IAEA requested to conduct Global Survey of HR needs – survey initiated but only 50% of operating countries (30% of capacity) took part, so results inconclusive

  13. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  14. Numerical investigation of cavitation flow in journal bearing geometry

    Science.gov (United States)

    Riedel, M.; Schmidt, M.; Stücke, P.

    2013-04-01

    The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  15. Numerical investigation of cavitation flow in journal bearing geometry

    Directory of Open Access Journals (Sweden)

    Stücke P.

    2013-04-01

    Full Text Available The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  16. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  17. On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2010-01-01

    Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... of a compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping...... conventional oil bearings, carrying capacity and dynamic characteristics of passive systems are generally poorer. In order to enhance these characteristics, one solution is to employ active control strategies. The present contribution presents a detailed mathematical modeling for active lubrication...

  18. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  19. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  20. Numerical simulation and experimental research on passive hydrodynamic bearing in a blood pump

    Science.gov (United States)

    Han, Qing; Ruan, Xiaodong; Chen, Wenyu; Fu, Xin

    2013-09-01

    The current research of hydrodynamic bearing in blood pump mainly focuses on the bearing structure design. Compared with the typical plane slider bearing and Rayleigh step bearing, spiral groove bearing has excellent performance in load-carrying capacity. However, the load-carrying capacity would decrease significantly with increasing flow rate in conventional designs. In this paper, the special treatment is made to the upper spiral groove bearing to make sure that both the circulatory flowing and load-carrying capacity are high. Three-dimensional computational fluid dynamics(CFD) models in the space between rotor and shaft are developed by using FLUENT software. Effects of groove number, film height and groove depth on load-carrying capacity of the spiral groove bearings are investigated by orthogonal experiment design. The experimental results show that film height is the most remarkable factor to the load-carrying capacity. The variation tendency of load-carrying capacity reveals that the best combination of geometry is the one with groove number of 8, film height 0.03 mm and groove depth 0.08 mm. The velocity and pressure distributions in spiral groove bearings are also analyzed, and the analysis result shows that the distributions are in conformity with the design of the blood pump based on the principle of hydrodynamic bearing. The displacement of the rotor with the best combination parameters is tested by using laser displacement sensors, the testing result shows that the suspending performance is satisfactory both in axial and radial directions. This research proposes a bearing design method which has sufficient load-carrying capacity to support rotor as an effective passive hydrodynamic bearing.

  1. 岛状多年冻土地区桥梁桩基回冻后承载力的静载与动测对比试验研究%STATIC AND DYNAMIC CONTRAST TEST FOR BEARING CAPACITY OF REFROZEN BRIDGE PILE FOUNDATION IN PATCHY PERMAFROST REGIONS

    Institute of Scientific and Technical Information of China (English)

    宇德忠; 程培峰; 季成; 崔志刚

    2015-01-01

    为了准确掌握岛状多年冻土地区桥梁钻孔灌注桩的回冻时间及桩基回冻后的承载力,在岛状多年冻土地区选择2个试验地点,每个试验地点浇筑了2根15 m长的试验桩,并在其中一根试验桩处布设温度监测系统,采集桩基回冻过程中的温度数据,根据温度监测结果判断桩基回冻状态,在桩基完成回冻后进行静载与动测试验,测出桩基极限承载力。监测及试验结果表明:试验桩所在区域岛状多年冻土地温约为-1.9℃,桩基完成回冻后桩身内部温度与桩侧1 m处的土体温度变化趋势相同,相同深度处的温差小于0.1℃;用静载法实测出的各土层回冻后的桩侧摩阻力值修正高应变动测法桩–土力学模型中的土层参数,计算曲线与实测曲线拟合较好;动测与静载试验所得到的桩基极限承载力误差为3.91%,试验结果相符合。研究成果可为类似冻土条件下的桩基设计及承载力检测提供理论依据。%To accurately know the refreezing time and capacity of the bridge bored pile constructed in polygonal permafrost regions,two test sites were chosen. Within each site,two 15 m test piles were built. The temperature monitoring system was established in one of the two sites to record and monitor the pile refreezing process. Based on the refreezing condition,static load and dynamic load tests were performed to determine the bearing capacity of the pile. Test results indicate that the mean permafrost temperature is-1.9℃. The trend of temperature change within the pile in refreezing process is similar to that of the permafrost temperature change 1 m beside the pile, which indicates that the difference of temperature change is smaller than 0.1℃. The calculated pile capacity fits well with the testing data by introducing the refreezing pile lateral frictional parameter to modify the soil mechanical model. The capacity error obtains from static load test

  2. Blood Pump Bearing System

    Science.gov (United States)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  3. WORK PRINCIPLE AND CHARACTERISTIC ANALYSES OF HYDROSTATIC BEARING

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aiming at the new characteristic of water hydraulic system, a kind of hydrostatic bearing with a concentric gap damper is introduced. The lubricative film thickness of the hydrostatic bearing possesses inflexibility and the loading capacity is just determined by the geometrical dimension of the piston-slipper subassembly and has no relation with system pressure, viscosity and temperature of water and speed of rotor. Theoretical analyses and the verification of scheme done at the test rig show that the hydrostatic bearing with a concentric gap damper is especially fit for water hydraulic components.

  4. The Little Bear

    Institute of Scientific and Technical Information of China (English)

    林战峰; 乐伟国

    2007-01-01

    @@ 一、故事内容 A little bear has a magic stick.It can make his wishes come true. One day,the little bear is walking in the forest.He sees a bird.It is flying in the sky.It has two beautiful wings."I want two beautiful wings.I wish I can fly like a bird,"he says to the magic stick.Two beautiful wings come out from his back and he can fly like a bird now.He is very happy.

  5. Force and stiffness characteristics of superconducting bearing prototype

    International Nuclear Information System (INIS)

    The radial-axial superconducting bearing prototype was designed, fabricated and tested. The YBaCuO high-temperature superconducting (HTS) monodomain disks diameter 28 mm and thickness of h = 4; 6; 8; 10 mm, capable to trap magnetic field 1 T, were fabricated to be employed in bearing prototype. Force interaction of single field cooled HTS disks with NdFeB magnets depending on disk thickness under 1 mm magnet air gap was studied. It was found that the increase in disk thickness results in reducing radial stiffness and in growing axial one. The results obtained were used for optimization of HTS-PM arrangement, and for developing the bearing design. The designed bearing incorporates a rotor with 7 HTS disks of 4 mm thickness, total mass 90 g, and stator with two pairs of permanent annular magnets of NdFeB. It is established that the force-displacement dependencies of the bearing have three zones: non-hysteresis (elastic) zone with high stiffness up to 560 N/mm; zone of elastic interaction with stiffness 190 N/mm; hysteretic zone with stiffness 150 N/mm in which a rotor residual displacement being observed after unloading. The outer bearing diameter is 130 mm, thickness 30 mm, and mass 1.8 kg. The maximal radial load capacity of the bearing is 190 N at the rotor displacement of 1.3 mm, and the maximal axial load capacity is 85 N at the displacement of 1 mm

  6. Method to Increase Performance of Foil Bearings Through Passive Thermal Management

    Science.gov (United States)

    Bruckner, Robert

    2013-01-01

    This invention is a new approach to designing foil bearings to increase their load capacity and improve their reliability through passive thermal management. In the present case, the bearing is designed in such a way as to prevent the carryover of lubricant from the exit of one sector to the inlet of the ensuing sector of the foil bearing. When such passive thermal management techniques are used, bearing load capacity is improved by multiples, and reliability is enhanced when compared to current foil bearings. This concept has recently been tested and validated, and shows that load capacity performance of foil bearings can be improved by a factor of two at relatively low speeds with potentially greater relative improvements at higher speeds. Such improvements in performance with respect to speed are typical of foil bearings. Additionally, operation of these newly conceived bearings shows much more reliability and repeatable performance. This trait can be exploited in machine design to enhance safety, reliability, and overall performance. Finally, lower frictional torque has been demonstrated when operating at lower (non-load capacity) loads, thus providing another improvement above the current state of the art. The objective of the invention is to incorporate features into a foil bearing that both enhance passive thermal management and temperature control, while at the same time improve the hydrodynamic (load capacity) performance of the foil bearing. Foil bearings are unique antifriction devices that can utilize the working fluid of a machine as a lubricant (typically air for turbines and motors, liquids for pumps), and as a coolant to remove excess energy due to frictional heating. The current state of the art of foil bearings utilizes forced cooling of the bearing and shaft, which represents poor efficiency and poor reliability. This invention embodies features that utilize the bearing geometry in such a manner as to both support load and provide an inherent and

  7. Silver Bear for Screenplay

    Institute of Scientific and Technical Information of China (English)

    LIU YUNYUN

    2010-01-01

    @@ Chinese director Wang Quan'an won the Silver Bear Prize at the 60th Berlin International Film Festival that lasted during February 11 to 21 tor the best screenplay for his movie Apart Together.The film also opened the festival.

  8. Hybrid superconductor magnet bearings

    Science.gov (United States)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  9. Influence of load capacity on hydrostatic journal support deformation in finite element calculation

    Institute of Scientific and Technical Information of China (English)

    邵俊鹏; 张艳芹; 李永海; 于晓东; 姜辉

    2008-01-01

    Based on the application of the four-oil-pad radial hydrostatic bearing in heavy equipments, the deformation of the four-oil-pad radial hydrostatic bearing was calculated by using the finite element method. The formula of film stiffness, film thickness and carrying capacity were established; the influence of the main parameters, such as load, load area and deformation on the supportability was analyzed; and the capacity of the two kinds of bearings was compared. The result shows that the carrying capacity of typeⅠ is prior to that of type Ⅱ . Calculations provide a theoretical basis for the bearing choosing and structure designing in the actual project.

  10. 冷弯薄壁型钢自攻螺钉连接抗剪性能试验研究%Experimental investigation on shear-bearing capacity for self-drilling screw connections of cold-formed thin-walled steel

    Institute of Scientific and Technical Information of China (English)

    卢林枫; 张亚平; 方文琦; 杨东华

    2013-01-01

    介绍单颗自攻螺钉连接件和多颗自攻螺钉连接件的试件制作、加载装置及它们抗剪承载力的试验全过程.根据试验过程和破坏现象,总结不同试件的荷载-变形曲线、抗剪承载力试验值及破坏模式.依据各国规范及相关文献,结合试验数据,验证中国规范GB 50018-2002及美国AISI规范对于计算单颗螺钉抗剪承载力的可行性及可靠性.通过探讨不同母材厚度、不同螺钉数目、不同螺钉排列方式及不同螺钉间距对自攻螺钉连接抗剪承载力的影响,总结得到自攻螺钉连接抗剪试验破坏的几个阶段、主要破坏模式和影响因素:(1)螺钉数目及间距是影响自攻螺钉连接抗剪性能的最主要因素;(2)螺钉排列方式对连接的抗剪性能影响较小;(3)在某些破坏模式下,母材厚度也是影响连接件抗剪性能的主要因素之一.通过对试验数据统计分析,发现自攻螺钉群的抗剪承载力具有“群体折减效应”,并给出能反映“群体折减效应”的螺钉群效率系数的分布范围,发现螺钉间距及数目也是影响效率系数的主要因素.%The production of specimens,loading equipment and the whole test process of both single and multiple self-drilling screw connections were introduced.According to the test and failure phenomenon,the load-deformation curves,shear-carrying capacity and failure modes were testified.The feasibility and reliability of the calculating methods in GB 50018-2002 and AISI were verified by the experiment data.Through considering the influence of different base materials,screws numbers,arrangements and screw spacing,the loading stages,main failure mode and influencing factors of the test are concluded:(1) Screw numbers and spacing are the main factors to the bearing capacity of self-drilling screws connections; (2) The screw arrangements have little effect on the shearing behavior of connections;(3) In certain situations,the thickness of base

  11. Performance of Simple Gas Foil Thrust Bearings in Air

    Science.gov (United States)

    Bruckner, Robert J.

    2012-01-01

    Foil bearings are self-acting hydrodynamics devices used to support high speed rotating machinery. The advantages that they offer to process fluid lubricated machines include: high rotational speed capability, no auxiliary lubrication system, non-contacting high speed operation, and improved damping as compared to rigid hydrodynamic bearings. NASA has had a sporadic research program in this technology for almost 6 decades. Advances in the technology and understanding of foil journal bearings have enabled several new commercial products in recent years. These products include oil-free turbochargers for both heavy trucks and automobiles, high speed electric motors, microturbines for distributed power generation, and turbojet engines. However, the foil thrust bearing has not received a complimentary level of research and therefore has become the weak link of oil-free turbomachinery. In an effort to both provide machine designers with basic performance parameters and to elucidate the underlying physics of foil thrust bearings, NASA Glenn Research Center has completed an effort to experimentally measure the performance of simple gas foil thrust bearing in air. The database includes simple bump foil supported thrust bearings with full geometry and manufacturing techniques available to the user. Test conditions consist of air at ambient pressure and temperatures up to 500 C and rotational speeds to 55,000 rpm. A complete set of axial load, frictional torque, and rotational speed is presented for two different compliant sub-structures and inter-pad gaps. Data obtained from commercially available foil thrust bearings both with and without active cooling is presented for comparison. A significant observation made possible by this data set is the speed-load capacity characteristic of foil thrust bearings. Whereas for the foil journal bearing the load capacity increases linearly with rotational speed, the foil thrust bearing operates in the hydrodynamic high speed limit. In

  12. Magnetic bearings grow more attractive

    Science.gov (United States)

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  13. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  14. Passive magnetic bearing system

    Science.gov (United States)

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  15. Centrifugally decoupling touchdown bearings

    Science.gov (United States)

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  16. Magnetic bearing and motor

    Science.gov (United States)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  17. Rotating plug bearing and seal

    International Nuclear Information System (INIS)

    Disclosed is a bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing. 19 claims, 3 figures

  18. Rotating plug bearing and seal

    Science.gov (United States)

    Wade, Elman E.

    1977-01-01

    A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

  19. Static characteristic analysis on a hydrodynamic bearing of a hydraulic suspended micropump

    International Nuclear Information System (INIS)

    A hydraulic suspended micropump was designed based on the conception of double suction impeller. To study the running performance of the micropump, three dimensional simulation of the static characteristic of the hydrodynamic bearing at rated condition was performed. Parameters such as the eccentricity and rotational speed, having effect on the bearing capacity, were analyzed. Results show that the eccentricity and rotational speed have a certain effect on the bearing capacity. The region of the maximum static pressure and the positive pressure changes as the eccentricity increases. The bearing capacity improves as the rotational speed increases. All the results can provide a academic basis for the improvement and application of a hydrodynamic bearing of a micropump

  20. Magnetic translator bearings

    Science.gov (United States)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  1. Ontario Hydro`s Sir Adam Beck Pump Generating Station : thrust bearing and runner servomotor rehabilitation

    Energy Technology Data Exchange (ETDEWEB)

    Barbour, J.; Garro, A. [Ontario Hydro, Toronto, ON (Canada)

    1998-12-01

    A study was conducted to examine the reasons for the recurring failure of generator thrust bearings at Ontario Hydro`s Sir Adam Beck Pump Generating Station (Niagara Falls) comprised of six 25 MW Deriaz turbines. The possible causes for the thrust bearing failures were listed and commented upon. The suspected causes include: (1) marginal bearing capacity, (2) shoes not flat, (3) sub standard oil, (4) dirt in bearing, (5) bearing cooling problems. To solve the problem, extra precaution was taken in the assembly of the bearing parts and extra capacity was added to the oil lift system. Following implementation of these measures, the unit has been operating smoothly for 3 years. 3 tabs., 4 figs.

  2. Study on the seismic performance of a double spherical seismic isolation bearing

    Institute of Scientific and Technical Information of China (English)

    Peng Tianbo; Li Jianzhong; Xu Yan; Fan Lichu

    2008-01-01

    In this paper,the configuration and working mechanism of the recently developed double spherical seismic isolation (DSSI) bearing are introduced in detail.Then,vertical displacement of the DSSI bearing due to sliding on a spherical surface is analyzed.The results from seismic performance testing of the bearing are given,and a numerical analysis of a four span continuous girder bridge is performed.The numerical analysis compares the influence of three different bearing arrangement schemes on the structural seismic response,and the results show that the DSSI bearing is effective in increasing the vertical load bearing capacity,reducing the vertical displacement,and controlling the energy dissipation capacity within a certain range.

  3. Bearing Behaviors of Stiffened Deep Cement Mixed Pile

    Institute of Scientific and Technical Information of China (English)

    WU Mai; ZHAO Xin

    2006-01-01

    A series of investigations were conducted to study the bearing capacity and load transfer mechanism of stiffened deep cement mixed (SDCM) pile.Laboratory tests including six specimens were conducted to investigate the frictional resistance between the concrete core and the cementsoil.Two model piles and twenty-four full-scale piles were tested to examine the bearing behavior of single pile.Laboratory and model tests results indicate that the cohesive strength is large enough to ensure the interaction between core pile and the outer cement-soil.The full-scale test results show that the SDCM piles exhibit similar bearing behavior to bored and cast-in-place concrete piles.In general, with the rational composite structure the SDCM piles can transmit the applied load effectively, and due to the addition of the stiffer core, the SDCM piles possess high bearing capacity.Based on the findings of these experimental investigations and theoretical analysis, a practical design method is developed to predict the vertical bearing capacity of SDCM pile.

  4. Optimization of conical hydrostatic bearing for minimum friction.

    Science.gov (United States)

    Nypan, L. J.; Hamrock, B. J.; Scibbe, H. W.; Anderson, W. J.

    1971-01-01

    Equations for the flow rate, load capacity, and friction torque for a conical hydrostatic bearing were developed. These equations were solved by a digital computer program to determine bearing configurations for minimum friction torque. Design curves are presented that show optimal bearing dimensions for minimum friction torque as a function of dimensionless flow rate for a range of dimensionless load capacity. Results are shown for both laminar and turbulent flow conditions. The results indicate that hydrostatic pocket friction is a significant portion of the total friction torque. However, the bearing dimensions for a minimum friction design are affected very little by inclusion of pocket friction in the analysis. For laminar flow the values of the outer-land radius ratio X3 and outer bearing radius ratio X4 did not change significantly with increasing friction factor. For turbulent flow, the outer bearing radius ratio X4 did not change with increasing friction factor; therefore the value determined for X4 in the laminar flow case is valid for all turbulent flows.

  5. Adaptação de métodos semi-empíricos para estimar capacidade de carga de estacas de pequeno diâmetro no solo de Londrina, Estado do Paraná = Adaptation of the semi-empiric methods to calculate small diameter piles bearing capacity in the soil of Londrina City, Paraná State

    Directory of Open Access Journals (Sweden)

    Miriam Gonçalves Miguel

    2005-07-01

    Full Text Available A cidade de Londrina, Estado do Paraná, possui um perfil geotécnicoconstituído de uma camada superficial de solo argilo-siltoso, poroso, laterítico e muitas vezes colapsível, que se estende até a profundidade máxima de 12 metros. As estacas utilizadas em obras de pequeno a médio porte se encontram totalmente embutidas nesta camada, sofrendo a influência de seu comportamento laterítico e colapsível. Os métodos clássicos brasileiros de estimativa de capacidade de carga de estacas tornam-se conservadores, frente aos resultados reais, quando aplicados em solos lateríticos e, contra a segurança, quando aplicados em solos colapsíveis, isto é, na condição crítica ao colapso. Este trabalho avalia os coeficientes de ajuste das resistências de ponta e ao atrito lateral para esses métodos, no caso de estacas apiloadas, sendo estes coeficientes obtidos pela retro-análise de resultados de provas de carga estática à compressão, realizadas no Campo Experimental de Engenharia Geotécnica da Universidade Estadual de Londrina.The city of Londrina, Paraná, has a typical geotechnical profile defined by a superficial layer of porous silty clay with maximum depth of about 12 meters, that shows lateritic characteristics, andmany times, collapsibility. Casts in place piles are often used for small buildings in the region and are fully embedded in this soil layer. Therefore, this type of foundation is subjected to the lateritic and occasionally collapsible influence of soil. Brazilian pile bearing capacity methods may yield conservative results when applied to tropical soils, as far as the lateritic origin in concerned. On the other hand, it can be unsafe if collapsibility prevails. This paper evaluates coefficients to adjust both point and lateral resistance of cast in place small diameter piles in the situation described. The work was carried out at the Londrina State University Geotechnical Experimental Site, and back analysis from static

  6. Design charts for arbitrarily pivoted, liquid-lubricated flat-sector-pad thrust bearing

    Science.gov (United States)

    Etsion, I.

    1977-01-01

    A flat, sector-shaped geometry for a liquid-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. Results are presented in design charts that enable a direct approach to the design of point- and line-pivoted, tilting pad bearings. A comparison is made with the Mitchell bearing approximation and it is found that this approximation always overestimates load capacity.

  7. Bear Creek Project. Final environmental statement

    International Nuclear Information System (INIS)

    The Bear Creek Project consists of certain mining and milling operations involving uranium ore deposits located in Converse County, Wyoming. Mining of uranium from nine known ore bodies will take place over a period of ten years (estimated); a mill with a nominal capacity of 1000 tons per day of ore will be constructed and operated as long as ore is available. The waste material (tailings) from the mill, also produced at a rate of about 1000 tons per day, will be stored onsite in an impoundment. Environmental impacts and adverse effects are summarized

  8. Numerical analysis of bump foil bearings without nominal radial clearance

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-sheng; XU Huai-jin; ZHANG Guang-hui

    2008-01-01

    Bump foil bearings without nominal radial clearance were analyzed. An air film thickness model and a bearing theoretical analytical model were developed accounting for air compressibility and foil deformation. To analyze hydrodynamic characteristics of bump foil beatings with different operating eccentricities, the air film thickness equation and Reynolds equation were coupled through pressure and solved by Newton-Raphson Method(NRM) and Finite Difference Method (FDM). The characteristics of an bump foil bearing model were dis-cussed including load carrying capacity, film thickness and pressure distributions. The results of simulation show that bump foil beating without nominal radial clearance can provide better stability and greater load capaci-ty. This numerical analytical method also reveals a good convergence in numerical calculation.

  9. Damping Bearings In High-Speed Turbomachines

    Science.gov (United States)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  10. Effect of Bearing Cleaning on Long Term Bearing Life

    Science.gov (United States)

    Jett, Tim; Thom, R. L.

    1999-01-01

    For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

  11. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

  12. Simulation of the fluid structure interaction for an aerostatic bearing and a flexible substrate

    NARCIS (Netherlands)

    Olieslagers, R.; Wild, M. de; Melick, S. van; Knaapen, R.

    2014-01-01

    The fluid structure interaction for an aerostatic bearing and a substrate is solved numerically by a semi-analytical model, programmed in the software package MATLAB. This semi-analytical model uses a fluidic network of resistances and capacities to solve the pressure field in the bearing channel. T

  13. Lubrication characteristics of a textured porous sliding bearing

    Directory of Open Access Journals (Sweden)

    Sooyoung Lee

    2015-03-01

    Full Text Available This study investigates the lubrication characteristics of a textured bearing sliding on a porous layer. To properly implement the porous layer effect in the bearing, the Brinkman-extended-Darcy model is employed, which results in a modified Reynolds equation. This equation is then evaluated to examine the effects of the porous layer’s material and geometric properties on the lubrication characteristics through the use of (semi-analytic and numerical approaches. The cavitation effect is reflected in the numerical treatment of the model equation, and an adaptive finite difference scheme is employed to efficiently model the bearing system with finite dimples that may be far smaller than the overall bearing dimensions. Along with the variation trends of the bearing performance with respect to the material and geometric properties of the porous layer, the pattern effects of textured surfaces on the bearing performance indices (load capacity and equivalent friction coefficient are also thoroughly investigated. Here, the pattern comprised a set of regularly spaced identical dimples either in semi-spherical or semi-ellipsoidal shape, and the effects of size and orientation of the dimples are comprehensively explored to separately identify their influence on the bearing performance indices.

  14. Ultimate Flexural Capacity of Unbounded Prestressed Concrete Pier

    OpenAIRE

    Wang Hui-li; Zhang Lin; Qin Si-Feng

    2014-01-01

    Based on the plastic-hinge method, the influence of different factors on the ultimate flexural capacity is analyzed, including relationship between the ultimate bearing capacity and prestressing tendon area, the regular reinforcement area, the strength of concrete and other influence factors. The results show that, the increase in the area of regular reinforcement and the strength of concrete can enhance the ultimate flexural capacity. Moreover, the ultimate bending moment increases first and...

  15. The Effect of Additives on The Performance of HydrostaticThrust Bearings

    OpenAIRE

    Muhammed Abdul Sattar; Albert E. Yousif

    2008-01-01

    The paper is concerned with, the behavior of the hydrostatic thrust bearings lubricated with liquid-solid lubricants using Einstein viscosity formula, and taking into account the centrifugal force resulting from high speed. Also studied is the effect of the bearing dimensions on the pressure, flow rate, load capacity, shear stress, power consumption and stiffness. The theoretical results show an increase in load capacity by (8.3%) in the presence of solid graphite particles with concentration...

  16. Bearings only naval tracking

    Energy Technology Data Exchange (ETDEWEB)

    Barth, M.J.

    1984-11-01

    Two commonly used Extended Kalman Filter tracking algorithms utilize the Relative Cartesian and Modified Polar coordinate systems. This report compares the two algorithms by exercising a destroyer-Submarine (DD/SS) computer simulation. A simple engagement geometry is employed which encompasses the major DD/SS options available. Error statistics are developed by Monte Carlo methods. Results are presented which show that the circular error depends upon the diagonal values of the error covariance matrix. The results also support (but do not establish) that the optimum DD manuevuer is that which minimizes the range while maximizing the bearing rate. 4 refs., 5 figs., 4 tabs.

  17. Nanoprecipitation in bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, A.T.W. [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2011-11-15

    {theta}-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The {theta}-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

  18. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  19. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  20. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  1. Dynamic Analysis of Engine Bearings

    Directory of Open Access Journals (Sweden)

    H. Hirani

    1999-01-01

    Full Text Available This paper presents a simple methodology to evaluate the stiffness and damping coefficients of an engine bearing over a load cycle. A rapid technique is used to determine the shaft ‘limit cycle’ under engine dynamic loads. The proposed theoretical model is based on short and long bearing approximations. The results obtained by present approximation are compared with those obtained by numerical method. The influence of thermal effects on the stiffness and damping coefficients is predicted by using a simplified thermal analysis. In order to illustrate the application of the proposed scheme, one engine main bearing and a connecting rod bearing are analysed.

  2. Fish of Bear Lake, Utah

    OpenAIRE

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    There are 13 species of fish found in the waters of Bear Lake. Of those 13, 4 are endemic (found only in Bear Lake). The 4 endemics species are Bonneville cisco, Bonneville whitefish, Bear Lake whitefish, and Bear Lake sculpin. Five of the remaining 9 fish species are native to the region, and 4 are exotic introductions. These native fishes are the Bonneville cutthroat trout, Utah sucker, redside shiner, speckled dace and Utah chub. The exotic fishes are lake trout, common carp, yellow p...

  3. 四肢缀条轴压钢管混凝土格构柱承载能力分段合成法%Piecewise synthesis method of bearing capacity on axial compressed four-tube concrete-filled steel tubular laced column

    Institute of Scientific and Technical Information of China (English)

    周旺保; 蒋丽忠

    2011-01-01

    Based on the equilibrium condition of several sections, the stress-strain relationship of the concrete-filled steel tube under the effect of confinement and the influence of the initial bending and shear, the equilibrium equation of the section was established. At the same time, the numerical method for calculating the elastic-plastic ultimate loads of the concrete-filled tubular laced columns was presented by adopting the Taylor's series as the piecewise interpolation function and the corresponding computer program was compiled. Some axial compressed four-tube concrete-filled steel tubular taced columns were computed using the numerical method and the program, and the results were compared with the calculation results of some existing codes. The calculation formula of slender ratio reduced coefficient was proposed combining numerical calculation results and the slender ratio reduced coefficient model. The calculation results were compared with the numerical calculation results and the test results. The results show that this method is suitable for the elastoplasticity ultimate bearing capacity calculation of the long and short axial compressed columns. The code computational methods are conservative, the computational errors are great, and the computed results in this article agree well with the test results. The rationality of slender ratio reduced coefficient calculation formula has been attested.%采用泰勒级数作为分段插值函数,在考虑多个截面的平衡条件和紧箍效应钢管混凝土应力-应变关系、剪切变形及初弯曲影响的基础上,建立杆件截面的平衡方程,提出四肢缀条轴压钢管混凝士格构柱弹塑性极限承载力数值方法,并编制相应的计算程序.利用提出的计算方法和编制的程序对国内已有轴压四肢钢管混凝土格构柱试件进行计算,并与现有一些规程进行比较.同时,结合数值计算结果及长细比折减系数计算模型,提出长细比折减系数计

  4. Study on Bearing Capacity of Circular Tubular T-Joints with Collar-Plate Reinforcement Loaded by In-Plane Bending Load%平面内弯矩作用下环口板加强T型圆钢管节点的承载力分析

    Institute of Scientific and Technical Information of China (English)

    陈德胜; 杨冬平; 蔡艳青; 龙凤乐; 牛更奇; 邵永波

    2014-01-01

    环口板加固管节点是一种比较新颖的加固方法,施工方便快捷而且加固效果显著。运用有限元方法对平面内弯矩作用下的环口板加固 T 型圆钢管节点的极限承载力进行了研究。对环口板加固 T 型圆钢管节点的面内弯曲承载力进行了参数分析,参数包括支管直径与主管直径比β,主管直径与2倍主管壁厚的比γ,环口板厚度与主管管壁厚之比τc 和环口板长度与支管直径之比 lc/d1等计算。结果表明,采用适当尺寸的环口板加固后的 T 型管节点的承载力相对于未加固 T 型管节点的承载力得到显著提高。改变环口板的厚度相对于改变环口板的长度对静力强度的提高更有效。最后,在参数分析的基础上提出了环口板加强型 T 型圆钢管节点在平面内弯矩作用下的承载力计算公式。%Collar plate reinforcement is a new method for reinforcing tubular joints, and it is of fast fabrication and effective. Finite element method is used to investigate the static strength of collar plate reinforced circular hollow section (CHS) T-joints subjected to in-plane bending load. A study is conducted to analyze the effect of geometrical parameters, i.e. brace-to-chord diameter ratio β, collar-plate to chord wall thickness ratio τc, and collar-plate length to brace diameter ratio lc/d1, on the static strength of tubular T-joints. It is found that significant strength enhancement can be achieved for a collar plate reinforced tubular joint through suitable size design comparing with the un-reinforced one. Compared to the length of the collar plate, the thicknesses of the collar plate is more effective for improving the static strength of the T-joints. Finally, a parametric equation for predicting the load bearing capacity of circular tubular T-joints with collar plate reinforcement subjected to in-plane bending load is presented.

  5. Stiffness and Damping Coefficient Estimation of Compliant Surface Gas Bearings for Oil-Free Turbomachinery

    Science.gov (United States)

    Della-Corte, Christopher

    2012-01-01

    Foil gas bearings are a key technology in many commercial and emerging oilfree turbomachinery systems. These bearings are nonlinear and have been difficult to analytically model in terms of performance characteristics such as load capacity, power loss, stiffness, and damping. Previous investigations led to an empirically derived method to estimate load capacity. This method has been a valuable tool in system development. The current work extends this tool concept to include rules for stiffness and damping coefficient estimation. It is expected that these rules will further accelerate the development and deployment of advanced oil-free machines operating on foil gas bearings.

  6. Modeling and Development of RMD Configuration Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    K.P. Lijesh

    2015-06-01

    Full Text Available The low load carrying capacity of Passive Magnetic Bearings (PMBs has restricted their use in many industrial applications. The Rotation Magnetized Direction (RMD configuration has emerged as a strong and viable method that is able to substantially enhance the load carrying capacity of passive magnetic bearings. It consists of both radially and axially polarized passive magnets. But the physical realization of a radially polarized magnet is difficult to achieve. In the present work, a RMD structure consisting of aluminum ring and cubical shaped magnets is proposed by developing the radially polarized magnets required for RMD structure. A theoretical model is derived by simulating the cuboid magnets in form of sector magnets by developing equivalent surface area. An experimental setup was designed and developed to conduct experimental verification. The theoretical model is validated by conducting experiments on RMD configuration magnetic bearing and axially magnetized full ring bearing. The comparison of the load carrying capacity by different configuration is performed and results are presented.

  7. Autosizing Control Panel for Needle Bearing

    OpenAIRE

    Prof.A.R.Wadhekar,; Ms Jyoti R. Rajput

    2016-01-01

    A needle roller bearing is a bearing which uses small cylindrical rollers. Bearings are used to reduce friction of any rotating surface. Needle bearings have a large surface in contact with the bearing outer surfaces as compared to ball bearings. There is less added clearance(Diameter of the shaft and the diameter of the bearing are different) so they are much compact. The structure consists of a needle cage which contains the needle rollersthemselves and an outer race (The housin...

  8. Superconducting bearings for flywheel applications

    OpenAIRE

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings in flywheels.

  9. High-Performance Ball Bearing

    Science.gov (United States)

    Bursey, Roger W., Jr.; Haluck, David A.; Olinger, John B.; Owen, Samuel S.; Poole, William E.

    1995-01-01

    High-performance bearing features strong, lightweight, self-lubricating cage with self-lubricating liners in ball apertures. Designed to operate at high speed (tens of thousands of revolutions per minute) in cryogenic environment like liquid-oxygen or liquid-hydrogen turbopump. Includes inner race, outer race, and cage keeping bearing balls equally spaced.

  10. What about the Javan Bear?

    NARCIS (Netherlands)

    Jentink, F.A.

    1898-01-01

    The other day I read in a dutch popular periodical a paper dealing with the different species of Bears and their geographical distribution. To my great surprise the Malayan Bear was mentioned from Java: the locality Java being quite new to me I wrote to the author of that paper and asked him some in

  11. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  12. An Assessment of Gas Foil Bearing Scalability and the Potential Benefits to Civilian Turbofan Engines

    Science.gov (United States)

    Bruckner, Robert J.

    2010-01-01

    Over the past several years the term oil-free turbomachinery has been used to describe a rotor support system for high speed turbomachinery that does not require oil for lubrication, damping, or cooling. The foundation technology for oil-free turbomachinery is the compliant foil bearing. This technology can replace the conventional rolling element bearings found in current engines. Two major benefits are realized with this technology. The primary benefit is the elimination of the oil lubrication system, accessory gearbox, tower shaft, and one turbine frame. These components account for 8 to 13 percent of the turbofan engine weight. The second benefit that compliant foil bearings offer to turbofan engines is the capability to operate at higher rotational speeds and shaft diameters. While traditional rolling element bearings have diminished life, reliability, and load capacity with increasing speeds, the foil bearing has a load capacity proportional to speed. The traditional applications for foil bearings have been in small, lightweight machines. However, recent advancements in the design and manufacturing of foil bearings have increased their potential size. An analysis, grounded in experimentally proven operation, is performed to assess the scalability of the modern foil bearing. This analysis was coupled to the requirements of civilian turbofan engines. The application of the foil bearing to larger, high bypass ratio engines nominally at the 120 kN (approx.25000 lb) thrust class has been examined. The application of this advanced technology to this system was found to reduce mission fuel burn by 3.05 percent.

  13. Geophagy by yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  14. Symmetric, coherent, Choquet capacities

    OpenAIRE

    Kadane, Joseph B.; Wasserman, Larry

    1996-01-01

    Choquet capacities are a generalization of probability measures that arise in robustness, decision theory and game theory. Many capacities that arise in robustness are symmetric or can be transformed into symmetric capacities. We characterize the extreme points of the set of upper distribution functions corresponding to coherent, symmetric Choquet capacities on [0, 1]. We also show that the set of 2-alternating capacities is a simplex and we give a Choquet representation of this set.

  15. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

    OpenAIRE

    Cahill, J.; Stirling, I.; Kistler, L.; Salamzade, R.; Ersmark, E.; Fulton, T.; Stiller, M.; Green, R.; Shapiro, B.

    2015-01-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear...

  16. Body and diet composition of sympatric black and grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Fortin, Jennifer K.; Teisberg, Justin E.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2013-01-01

    The Greater Yellowstone Ecosystem (GYE) has experienced changes in the distribution and availability of grizzly bear (Ursus arctos) food resources in recent decades. The decline of ungulates, fish, and whitebark pine seeds (Pinus albicaulis) has prompted questions regarding their ability to adapt. We examined body composition and diet of grizzly bears using bioelectrical impedance and stable isotopes to determine if 1) we can detect a change in diet quality associated with the decline in either ungulates or whitebark pine, and 2) the combined decline in ungulates, fish, and pine seeds resulted in a change in grizzly bear carrying capacity in the GYE. We contrasted body fat and mass in grizzly bears with a potential competitor, the American black bear (Ursus americanus), to address these questions. Grizzly bears assimilated more meat into their diet and were in better body condition than black bears throughout the study period, indicating the decline in ungulate resources did not affect grizzly bears more than black bears. We also found no difference in autumn fat levels in grizzly bears in years of good or poor pine seed production, and stable isotope analyses revealed this was primarily a function of switching to meat resources during poor seed-producing years. This dietary plasticity was consistent over the course of our study. We did not detect an overall downward trend in either body mass or the fraction of meat assimilated into the diet by grizzly bears over the past decade, but we did detect a downward trend in percent body fat in adult female grizzly bears after 2006. Whether this decline is an artifact of small sample size or due to the population reaching the ecological carrying capacity of the Yellowstone ecosystem warrants further investigation.

  17. Development of bearings and a damper based on magnetically controllable fluids

    Science.gov (United States)

    Guldbakke, J. M.; Hesselbach, J.

    2006-09-01

    This paper presents two different kinds of magnetically controllable fluid bearings and a new magnetorheological fluid damper based upon open porous metallic foams. For the bearings, it will distinguish between a magnetohydrostatic bearing and a hydrostatic bearing with a magnetically controllable fluid. The magnetohydrostatic bearings get their load bearing capacity from the magnetohydrostatic pressure that is generated by the gradient of the magnetic field along a fluid surface. With such magnetohydrostatic bearings a specific load up to 1.6 N cm2 can be reached. To support heavier loads hydrostatic bearings with magnetically controllable fluids can be used. This bearing concept makes it possible to achieve a constant bearing gap even if the load of the bearing changes. For this purpose the fluids are used as a hydraulic medium. Due to the magnetically controlled rheological behaviour of the fluid the bearing gap remains constant. The great advantage of this closed loop system compared to that of common hydrostatic bearings using valves is the quicker response to payload changes. The reason for that is that the active element (i.e. the fluid) acts directly inside the bearing gap and not outside like in the case of valves. The foam damper developed uses the fluid to produce controllable damping forces. The open porous foam is directly placed in the active volume of the damper. By moving the foam piston the magnetically controllable fluid is pressed through the pores. The flow in the pores can be controlled by changing the fluid viscosity by applying a magnetic field. With this damper structure it is possible to reach higher damping forces whilst featuring a small design space.

  18. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  19. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  20. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  1. 模拟失重对大鼠承重骨骨髓基质细胞数量及体外成骨能力的影响%Effects of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats

    Institute of Scientific and Technical Information of China (English)

    付崇建; 郁冰冰; 杨连甲; 曹新生; 张立藩

    2007-01-01

    of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats so as to reveal the mechanism of bone loss.DESIGN : Randomized pairing and controlled study.SETTING: College of Aerospace Medicine and Department of Pathology of Stomatology College, the Fourth Military Medical University of Chinese PLA.MATERIALS: A total of 20 adult healthy male SD rats were selected in this study. At the beginning of experiment, rats based on their body mass were randomly divided into control group and suspension group with 10 in each group. Alkaline phosphatase kit was provided by Beijing Zhongsheng Bioengineering High-technological Company.METHODS: The experiment was carried out in the Department of Pathology, Collage of Stomatology, the Fourth Military Medical University of Chinese PLA from November 1999 to July 2000. Rats were randomly divided into tail suspension group and control group with 10 in each group. Rats in the tail suspension group were given tail suspension for 28 days. Their heads maintained 30° low position, and their hindlimbs freely suspended and were not given weight loading. While, rats in the control group were fed normally. At the end of experiment, bone marrow stromal cells were obtained from femur for primary and transferring cultures.MAIN OUTCOME MEASURES: Cell counting and methylthianolyldiphenyl-tetrazolium bromide (MTT) assay were used to draw growth curve of cells in primary and transferring cultures and to measure activity of alkaline phosphatase and forming quantity of mineralized nodules in vitro.RESULTS : ① Activity of alkaline phosphatase: Activity of alkaline phosphatase of cells in the primary and transferring cultures in the suspension group was lower than that in the control group, and there was significant difference between them (P<0.05). ② Forming quantity of mineralized nodules: Forming quantity of mineralized nodules in the suspension group was less than that in the control group

  2. Active Displacement Control of Active Magnetic Bearing System

    Directory of Open Access Journals (Sweden)

    Kertész Milan

    2014-12-01

    Full Text Available The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES. The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL. APDL is used to create the loops of transient simulations where boundary conditions (BC are updated based upon a “gap sensor” which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  3. Mixed-mu superconducting bearings

    Science.gov (United States)

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  4. A Passive Magnetic Bearing Flywheel

    Science.gov (United States)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  5. Bear study, Karluk Lake, 1956

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Based on observations, 117 bears were estimated to live in the Karluk Lake area. The estimate was lower than estimates from 1952, and 1954-1955. Annual loss to...

  6. Myrmecophagy by Yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.

    2001-01-01

    I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging 8 mm long) nested in logs over small ants (6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4a??5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

  7. Total iron binding capacity

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003489.htm Total iron binding capacity To use the sharing features on this page, please enable JavaScript. Total iron binding capacity (TIBC) is a blood test to ...

  8. Discontinuous symplectic capacities

    NARCIS (Netherlands)

    Zehmisch, K.; Ziltener, F.J.

    2014-01-01

    We show that the spherical capacity is discontinuous on a smooth family of ellipsoidal shells. Moreover, we prove that the shell capacity is discontinuous on a family of open sets with smooth connected boundaries.

  9. Non-fuel bearing hardware melting technology

    International Nuclear Information System (INIS)

    Battelle has developed a portable hardware melter concept that would allow spent fuel rod consolidation operations at commercial nuclear power plants to provide significantly more storage space for other spent fuel assemblies in existing pool racks at lower cost. Using low pressure compaction, the non-fuel bearing hardware (NFBH) left over from the removal of spent fuel rods from the stainless steel end fittings and the Zircaloy guide tubes and grid spacers still occupies 1/3 to 2/5 of the volume of the consolidated fuel rod assemblies. Melting the non-fuel bearing hardware reduces its volume by a factor 4 from that achievable with low-pressure compaction. This paper describes: (1) the configuration and design features of Battelle's hardware melter system that permit its portability, (2) the system's throughput capacity, (3) the bases for capital and operating estimates, and (4) the status of NFBH melter demonstration to reduce technical risks for implementation of the concept. Since all NFBH handling and processing operations would be conducted at the reactor site, costs for shipping radioactive hardware to and from a stationary processing facility for volume reduction are avoided. Initial licensing, testing, and installation in the field would follow the successful pattern achieved with rod consolidation technology

  10. Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis (Chip) E., III

    2014-01-01

    Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings.

  11. Failure analysis of superconducting bearings

    International Nuclear Information System (INIS)

    The dynamics of superconductor bearings in a cryogenic failure scenario have been analyzed. As the superconductor warms up, the rotor goes through multiple resonance frequencies, begins to slow down and finally touches down when the superconductor goes through its transition temperature. The bearing can be modelled as a system of springs with axial, radial and cross stiffness. These springs go through various resonant modes as the temperature of the superconductor begins to rise. We have presented possible explanations for such behaviour

  12. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  13. CDMA systems capacity engineering

    CERN Document Server

    Kim, Kiseon

    2004-01-01

    This new hands-on resource tackles capacity planning and engineering issues that are crucial to optimizing wireless communication systems performance. Going beyond the system physical level and investigating CDMA system capacity at the service level, this volume is the single-source for engineering and analyzing systems capacity and resources.

  14. Application of computational fluid dynamics on cavitation in journal bearings

    Directory of Open Access Journals (Sweden)

    Riedel Marco

    2014-03-01

    Full Text Available Journal bearings are applied in internal combustion engines due to their favourable wearing quality and operating characteristics. Under certain operating conditions damage of the journal bearing can occur caused by cavitation. The cavitation reduces the load capacity and leads to material erosion. Experimental investigations of cavitating flows in dimension of real journal bearing are difficult to realize or almost impossible caused by the small gap and transient flow conditions. Therefore numerical simulation is a very helpful engineering tool to research the cavitation behaviour. The CFD-Code OpenFOAM is used to analyse the flow field inside the bearing. The numerical cavitation model based on a bubble dynamic approach and requires necessary initial parameter for the calculation, such as nuclei bubble diameter, the number of nuclei and two empirical constants. The first part of this paper shows the influence of these parameters on the solution. For the adjustment of the parameters an experiment of Jakobsson et.al. [1] was used to validate the numerical flow model. The parameters have been varied according to the method Design of Experiments (DoE. With a defined model equation the parameters determined, to identify the parameter for CFD-calculations in comparison to the experimental values. The second part of the paper presents investigations on different geometrical changes in the bearing geometry. The effect of these geometrical changes on cavitation was compared with experimental results from Wollfarth [2] and Garner et.al. [3].

  15. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Science.gov (United States)

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  16. Capacity Statement for Railways

    DEFF Research Database (Denmark)

    Landex, Alex

    2007-01-01

    The subject “Railway capacity” is a combination of the capacity consumption and how the capacity is utilized. The capacity utilization of railways can be divided into 4 core elements: The number of trains; the average speed; the heterogeneity of the operation; and the stability. This article...... describes how the capacity consumption for railways can be worked out and analytical measurements of how the capacity is utilized. Furthermore, the article describes how it is possible to state and visualize railway capacity. Having unused railway capacity is not always equal to be able to operate more...... trains. This is due to network effects in the railway system and due to the fact that more trains results in lower punctuality....

  17. Numerical Investigation of the Undrained Compression and Pull-Out Capacity of Suction Foundations in Clay

    Directory of Open Access Journals (Sweden)

    Du Jiaqing

    2015-09-01

    Full Text Available This paper presents the results of three-dimensional finite difference analysis of suction foundations in uniform and non-uniform clays under undrained conditions. The Tresca criterion was used to simulate the stress-strain response. The bearing capacity of the foundations was investigated, with the degree of nonhomogeneity (kD/sum of soil varying from 0 to 5, and the embedment depth being up to four times the foundation diameter. The end bearing capacity factor in compression and the reverse bearing capacity factor in tension were both calculated and were compared with each other under different foundation displacements. Numerical results showed that the ultimate bearing capacity factor can have the same value in cases of both compression and tension. The recommended ultimate bearing capacity factor is determined on the basis of the embedment ratio and displacement magnitude, and the displacement is not more than 30% of the foundation diameter. Finally, two equations are proposed to evaluate both the bearing capacity factor and the effective depth factor.

  18. Steady State Performance Characteristics of a Single Pad Externally Adjustable Fluid Film Bearing

    Science.gov (United States)

    Shenoy, Satish B.; Pai, Raghuvir

    The steady state performance characteristics of centrally loaded 60 degree single pad externally adjustable partial arc bearing is studied theoretically. Principal feature of the bearing is the facility to control its radial clearance and circumferential film thickness gradient, during operation. The bearing has aspect ratios of 1.0, 0.5 and 0.25 and operates over a wide range of eccentricity ratios and adjustments. Steady state performance characteristics of the bearing are presented in terms of attitude angle, load carrying capacity, oil flow and friction variable. The steady state form of Reynolds equation in two dimensions is solved numerically using the finite difference method. The effect of tilt and the radial adjustments on the steady state performance characteristics are presented in the form of plots. A comparative study predicts that negative radial and negative tilt adjustment results in better load carrying capacity with reduced oil flow and friction.

  19. Lubrication performances of short journal bearings operating with non-Newtonian ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jaw-Ren [Taoyuan Innovation Inst. of Tech., Jhongli, TW (China). Dept. of Mechanical Engineering; Li, Po-Jui [National Taipei Univ. of Technology, Taipei, TW (China). Dept. of Inst. of Mechatronic Engineering; Hung, Tzu-Chen [National Taipei Univ. of Technology, Taipei, TW (China). Dept. of Mechanical Engineering

    2013-03-15

    The lubrication performances of short journal bearings operating with non-Newtonian ferrofluids have been investigated in the present study. Based upon the ferrofluid model of Shliomis and the micro-continuum theory of Stokes, a two-dimensional modified Reynolds equation is derived by taking into account the effects of rotation of ferromagnetic particles and the effects of non-Newtonian properties. As an application, the short-bearing approximation is illustrated. Comparing with the conventional non-ferrofluid case, the short journal bearings with ferrofluids in the presence of magnetic fields result in a higher load capacity. Comparing with the Newtonian ferrofluid case, the non-Newtonian effects of couple stresses provide an enhancement in the load capacity, as well as a reduction in the friction parameter. The inclusion of non-Newtonian couple stresses signifies an improvement in performance characteristics of ferrofluid journal bearings. (orig.)

  20. 49 CFR 229.69 - Side bearings.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  1. 36 CFR 13.1236 - Bear orientation.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  2. The Effect of Computerized Testing on Sun Bear Behavior and Enrichment Preferences

    Directory of Open Access Journals (Sweden)

    Bonnie M. Perdue

    2016-09-01

    Full Text Available The field of comparative cognition investigates species’ differences and similarities in cognitive abilities, and sheds light on the evolutionary origins of such capacities. Cognitive testing has been carried out in a variety of species; however, there are some taxa that are underrepresented in this field. The current work follows on a recent increase in cognitive research in the order Carnivora with a specific focus on sun bears. Sun bears are the smallest existing bear species and live in tropical regions of Southeast Asia. They have an omnivorous diet and use their tongues to forage for insects and sap. Little is known about sun bear cognition, although much like other bear species, anecdotes suggest a high level of intelligence. The current work explored training sun bears to use a touchscreen computer. This effort allows for insight into cognitive abilities as well as providing a complex source of enrichment for the bears. The bears use their tongues to respond to a touchscreen computer, and the effects on stereotypic behaviors on exhibit and preference for this over other forms of enrichment were examined. Overall, bears performed well on the task and showed a preference for the computer.

  3. Superconductor bearings, flywheels and transportation

    Science.gov (United States)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  4. Superconductor bearings, flywheels and transportation

    International Nuclear Information System (INIS)

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS–FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  5. Future Bearing Surfaces in Total Hip Arthroplasty

    OpenAIRE

    Chang, Jun-Dong

    2014-01-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom...

  6. The Effect of Additives on The Performance of HydrostaticThrust Bearings

    Directory of Open Access Journals (Sweden)

    Muhammed Abdul Sattar

    2008-01-01

    Full Text Available The paper is concerned with, the behavior of the hydrostatic thrust bearings lubricated with liquid-solid lubricants using Einstein viscosity formula, and taking into account the centrifugal force resulting from high speed. Also studied is the effect of the bearing dimensions on the pressure, flow rate, load capacity, shear stress, power consumption and stiffness. The theoretical results show an increase in load capacity by (8.3% in the presence of solid graphite particles with concentration of (16% by weight as compared with pure oil, with increasing shear stress. . In general the performance of hydrostatic thrust bearings improve for load carrying capacity, volume flow rate, pumping power subjected to centrifugal parameter (S, recess position (r1, film thickness ratio (, particle concentration (.

  7. Development and characterization of magnetic HTS bearings for a 400 kW synchronous HTS motor

    International Nuclear Information System (INIS)

    Promising results of static and dynamic investigations on various journal type test bearings encouraged us to develop a scaled-up HTS bearing, able to carry the HTS rotor of a 400 kW superconducting motor. The stator, a YBCO hollow cylinder of 203 mm inner diameter and 250 mm length, is cooled by liquid nitrogen. Permanent magnet rings with a diameter of 200 mm were mounted on a shaft with alternating polarity. Characterization of the bearing capacity was performed with three different YBCO stators at temperatures between 66 and 86 K in a test set-up. A significant influence of the temperature was found. At a stator temperature of 72 K and a rotation frequency of 25 Hz (corresponding to nominal motor speed) a radial bearing force of 2700 N was measured for the shaft at centre position. Under rotation of the shaft the bearing capacity is reduced. At present our results range within the highest radial bearing capacities reported world-wide

  8. Evaluation of railway capacity

    DEFF Research Database (Denmark)

    Landex, Alex; Kaas, Anders H.; Schittenhelm, Bernd;

    2006-01-01

    This paper describes the relatively new UIC 406 method for calculating capacity consumption on railway lines. The UIC 406 method is an easy and effective way of calculating the capacity consumption, but it is possible to expound the UIC 406 method in different ways which can lead to different...... of a railway network. Some of the aspects which have to be paid attention to making annual capacity statements are presented too....

  9. Nuclear Capacity Auctions

    OpenAIRE

    Fridolfsson, Sven-Olof; Tangerås, Thomas

    2011-01-01

    We propose nuclear capacity auctions as a means to improve the incentives for investing in nuclear power. A properly designed auction would (i) allocate the license to the most efficient bidder; (ii) sell the license if and only if new nuclear power was socially optimal. In particular, capacity auctions open the market for large-scale entry by outside firms. Requiring licensees to sell a share of capacity as virtual power plant contracts increases auction efficiency by softening incumbent pro...

  10. Capacity Building in Vietnam

    OpenAIRE

    Adam McCarty

    2001-01-01

    This report is the outcome of a study commissioned to examine the capacity building needs in Vietnam, and is a supplementary document to the Asian Development Bank's Country Operational Strategy for Vietnam. Vietnam's needs in terms of capacity building are particularly important given that is it a transitional economy and also one with little institutional experience in dealing with the international donor community. This paper examines the international awareness of capacity building and ca...

  11. Dynamic characteristics of lead rubber bearings with dynamic two-dimensional test equipment

    International Nuclear Information System (INIS)

    Although studies have previously been done on the static mechanical properties of lead rubber bearings, this study aims to grasp the dynamic characteristics of lead rubber bearings from experimental results, using two-dimensional dynamic test equipment which is designed to grasp in detail such dynamic characteristics as deformation capacity and proof stress. This paper describes the results from three types of tests: (1) dynamic mechanical properties tests, (2) cyclic loading tests, and (3) dynamic ultimate tests. Through these tests, it was confirmed that the dynamic characteristics of lead rubber bearings are independent of strain rate

  12. Dynamic Performance Characteristics of a Curved Slider Bearing Operating with Ferrofluids

    Directory of Open Access Journals (Sweden)

    Udaya P. Singh

    2012-01-01

    Full Text Available In the present theoretical investigation, the effect of ferrofluid on the dynamic characteristics of curved slider bearings is presented using Shliomis model which accounts for the rotation of magnetic particles, their magnetic moments, and the volume concentration in the fluid. The modified Reynolds equation for the dynamic state of the bearing is obtained. The results of dynamic stiffness and damping characteristics are presented. It is observed that the effect of rotation of magnetic particles improves the stiffness and damping capacities of the bearings.

  13. The French capacity mechanism

    International Nuclear Information System (INIS)

    The French capacity mechanism has been design to ensure security of supply in the context of the energy transition. This energy transition challenges the electricity market design with several features: peak load growth, the development of renewables, demand response,... To ensure security of supply in this context, a capacity mechanism is being implemented in France. It is a market wide capacity obligation on electricity suppliers, based on market principles. Suppliers are responsible for forecasting their obligation, which corresponds to their contribution to winter peak load, and must procure enough capacity certificates to meet their obligations. Capacity certificates are granted to capacities through a certification process, which assesses their contribution to security of supply on the basis of availability commitments. This certification process is technology neutral and performance based, associated with controls and penalties in case of non compliance. Demand Side is fully integrated in the market, either through the reduction of suppliers' capacity obligation or direct participation after certification. In addition to the expected benefits in terms of security of supply, the French capacity market will foster the development of demand response. The participation of foreign capacities will require adaptations which are scheduled in a road-map, and could pave the way for further European integration of energy policies. (authors)

  14. The Bear That Isn't a Bear

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Koalas aren't bears.They belong to the same family as kangaroos.Animals of this family are called pouch animals.That's because the mother carries her baby around in a pouch in the front of her stomach.lt's like a built-in papoose basket, only it's in the front instead of the back.

  15. Theoretical Analysis and Optimum Design of High Speed Air Film Thrust Bearings

    Science.gov (United States)

    Hashimoto, Hiromu; Ochiai, Masayuki; Nanba, Tadashi

    Hydrodynamic air film thrust bearings are widely used for very high speed, lightly loaded rotating machinery such as gas expander, compressor, gyroscope and business machines, etc. In the design of hydrodynamic air film thrust bearings, it is of cardinal importance to enhance the friction and stability capacities of air films for keeping the minimum friction loss within a particular level and for minimizing the vibration due to external excitations. Among various types of hydrodynamic air film thrust bearings, spiral and herring bone types of grooved bearings have an advantage of high stability and load carrying capacity, but the characteristics of the bearings depend on many design parameters. Therefore, when these parameters are designed suitably, it is expected to improve considerably the friction and stability characteristics of the bearings. In this paper, the optimum design methodology is presented to minimize the friction torque and also to maximize the stiffness of air film for spiral and herring bone types of grooved air film thrust bearings, and the applicability of the methodology is verified experimentally.

  16. The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

    Science.gov (United States)

    Bruckner, Robert

    2013-01-01

    An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

  17. Heat Capacity Analysis Report

    International Nuclear Information System (INIS)

    The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore

  18. Analysis of the gas-lubricated flat-sector-pad thrust bearing

    Science.gov (United States)

    Etsion, I.

    1976-01-01

    A flat sector-shaped pad geometry for a gas-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. It is shown that maximum load capacity is achieved when the pad is tilted so as to create uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves, and a comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

  19. Liquid heat capacity lasers

    Science.gov (United States)

    Comaskey, Brian J.; Scheibner, Karl F.; Ault, Earl R.

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  20. The correct "ball bearings" data.

    Science.gov (United States)

    Caroni, C

    2002-12-01

    The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

  1. Designing functionally graded materials with superior load-bearing properties.

    Science.gov (United States)

    Zhang, Yu; Sun, Ming-Jie; Zhang, Denzil

    2012-03-01

    Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidelines for designing FGMs with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (E(b)/E(s)) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15materials with various n values and E(b)/E(s) ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20-50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications.

  2. Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model

    International Nuclear Information System (INIS)

    In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS

  3. EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

    Directory of Open Access Journals (Sweden)

    Jarosław KACZOR

    2014-06-01

    Full Text Available Durability deep groove ball bearings depends on factors (called attributes design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bearings to work three-bearing shafts, including elasticity and resilience three-bearing shafts.

  4. Novel Super-Elastic Materials for Advanced Bearing Applications

    Science.gov (United States)

    Dellacorte, Christopher

    2014-01-01

    Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Ni-Ti alloys are an emerging solution. Ni-Ti alloys are intermetallic materials that possess characteristics of both metals and ceramics. Ni-Ti alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. Ni-Ti alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of hard, resilient Ni-Ti alloys for corrosion-proof, shockproof bearing and gear applications are presented. Through a series of bearing and gear development projects, it is demonstrated that Ni-Tis unique blend of materials properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. Ni-Ti thus represents a new materials solution to demanding tribological applications.

  5. Active control of multi-input hydraulic journal bearing system

    Science.gov (United States)

    Chuang, Jen-Chen; Chen, Chi-Yin; Tu, Jia-Ying

    2016-09-01

    Because of the advantages of high accuracy, high capacity, and low friction, the development of hydrostatic bearing for machine tool receives significant attention in the last decades. The mechanics and mechanical design of hydrostatic journal bearing with capillary restrictors has been discussed in literature. However, pragmatically, the undesired loading effects of cutting force tend to result in resonance and instability of the rotor and damage the shaft during operation. Therefore, multi-input, active flow control using state feedback design is proposed in this paper. To this purpose, the proportional pressure valves are added to the hydraulic system as active control devices, and the linearised models of the bearing and valve are discussed and identified. Simulation and experimental work is conducted to verify the proposed active control and parameter identification techniques. The results show that the unbalance responses of the rotor are reduced by the proposed state feedback controller, which is able to regulate the flow pressure effectively, thus enhancing the stability and accuracy of the hydraulic journal bearing.

  6. Fatigue Damage Mechanism of Oil Film Bearing Sleeve

    Institute of Scientific and Technical Information of China (English)

    HUANG Qing-xue; WANG Jian-mei; MA Li-feng; ZHAO Chun-jiang

    2007-01-01

    With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.

  7. Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies

    DEFF Research Database (Denmark)

    Christiansen, Christian Kim; Klit, Peder; Walther, Jens Honore;

    2015-01-01

    The paper presents a two-sided approach to establish understanding of the cavitation phenomenon in dynamically loaded journal bearings, more specifically the engine bearings of large two-stroke marine diesel engines. One disadvantage of the journal bearing is the converging-diverging geometry...... making it prone to cavitation which again affects the load carrying capacity of the bearing. In combustion engines the journal bearing plays a vital role especiallyas main and crosshead bearings transmitting the combustion forces. Those forces vary highly during one combustion cycle which is further....... Validation of the results is done against the Ruston and Hornsby 6VEB-X Mk III engine. Besides the numerical investigations a cavitation test rig has been developed. With this rig it is possible to generate cavitation under controlled conditions in terms ofload/eccentricity and rotational speed...

  8. Simulation of Plain Bearings in Turbo-Generators Using the Stand ISO7902

    Directory of Open Access Journals (Sweden)

    Alejandra Elena García Toll

    2011-02-01

    Full Text Available The study of plain bearings is fundamental in guaranteeing the full running and maintenance of machines. Due to the fluctuations in working conditions, the simulation of plain bearing in turbines and generators has become increasingly necessary. The procedure used to obtain data is based on ISO Standards 7902:1998 which involves the calculation of the load capacity of plain bearings under hydrodynamic lubricant conditions. This method can be used to determine if the plain bearing under load and working conditions will be able to form and maintain a film of lubricant which is important to separate completely the shaft and bearing sliding surfaces in order to prevent friction between these two. Also, with this method it is possible to determine the ideal working conditions and limiting factors in the functioning of plain bearing. Some of these factors are: relative bearing clearance, shaft velocity, lubricant viscosity, diameter and width of bearing, average peak-to-valley height of sliding surfaces and nominal radial. Additionally, a calculation sample is presented

  9. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  10. Mobile bearing and fixed bearing total knee arthroplasty

    Science.gov (United States)

    Dolfin, Marco; Saccia, Francesco

    2016-01-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  11. Mobile bearing and fixed bearing total knee arthroplasty.

    Science.gov (United States)

    Capella, Marcello; Dolfin, Marco; Saccia, Francesco

    2016-04-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  12. Effects of bearing deadbands on bearing loads and rotor stability

    Science.gov (United States)

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  13. Live-trapping and handling brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper reports techniques developed to live trap and handle brown bears on the Kodiak National Wildlife Refuge. The brown bears (Ursus middendorffi) on the...

  14. Goose Eggs Could Save Polar Bears

    Institute of Scientific and Technical Information of China (English)

    孙淑敏

    2009-01-01

    Polar bears could avoid extinction despitemany starving to death in coming years, ac-cording to scientists and other observers whohave discovered that some of the bears havefound a new food source--goose and duckeggs.

  15. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  16. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... the years. In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work...

  17. Brown bear telemetry and trapping: Special report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brown bear studies were continued during the 1967 field season with emphasis on development of techniques for instrumenting bears with radio transmitters and...

  18. Hybrid Superconducting Magnetic Bearing (HSMB) for high load devices

    Science.gov (United States)

    McMichael, C. K.; Ma, K. B.; Lamb, M. A.; Lin, M. W.; Chow, L.; Meng, R. L.; Hor, P. H.; Chu, W. K.

    1992-05-01

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  19. Hybrid Superconducting Magnetic Bearing (HSMB) for high-load devices

    International Nuclear Information System (INIS)

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  20. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Science.gov (United States)

    Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  1. Oil film pressure in hydrodynamic journal bearings

    OpenAIRE

    Valkonen, Antti

    2009-01-01

    Hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in various machines. Therefore, knowing the true operating conditions of hydrodynamic journal bearings is essential to machine design. Oil film pressure is one of the key operating parameters describing the operating conditions in hydrodynamic journal bearings. Measuring the oil film pressure in bearings has been a demanding task and theref...

  2. Technology development for indigenous water lubricated bearings

    International Nuclear Information System (INIS)

    Water Lubricated Bearings (WLB) are used in various mechanisms of fuel handling systems of PHWRs and AHWR. Availability and random failures of these bearings was a major factor in refuelling operations. Indigenous development of these bearings was taken up and 7 types of antifriction bearings in various sizes (totaling 37 variants) for PHWR, AHWR and Dhruva applications were successfully developed. This paper deals with various aspects of WLB development. (author)

  3. Visual attention capacity

    DEFF Research Database (Denmark)

    Habekost, Thomas; Starrfelt, Randi

    2009-01-01

    Psychophysical studies have identified two distinct limitations of visual attention capacity: processing speed and apprehension span. Using a simple test, these cognitive factors can be analyzed by Bundesen's Theory of Visual Attention (TVA). The method has strong specificity and sensitivity...

  4. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  5. CO diffusion capacity

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, U.

    1979-01-01

    We measured in 287 persons the pulmonary CO diffusion capacity with the steady-state and the single breath methods, applying apnoeic periods of 4 and 10 seconds duration. The aspects methodical significance, polyclinical applicability and pathognostic relevance with respect to other approved pulmonary functional tests are discussed. Differing pulmonary diffusion capacity values found in normal persons or in patients suffering from silicosis, pulmonary fibrosis, Boeck's disease or rheumatoid arthritis, were investigated and critically evaluated.

  6. Capacities in function theory

    OpenAIRE

    O'Farrell, Anthony G.

    1991-01-01

    Ever since the famous thesis of Frostman, capacities have been important in many areas of function theory. In this talk I shall be concerned only with one–variable function theory on arbitrary open subsets of the complex plane, C. It is important to stress that the open sets need not be connected. I will discuss the use of analytic capacities in connection with problems of removable singularities, holomorphic approximation, and boundary smoothness. A brief reference to the applications ...

  7. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  8. 49 CFR 229.64 - Plain bearings.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  9. Passive Thermal Management of Foil Bearings

    Science.gov (United States)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  10. 14 CFR 27.623 - Bearing factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  11. 14 CFR 23.623 - Bearing factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  12. 14 CFR 25.623 - Bearing factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  13. 14 CFR 29.623 - Bearing factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  14. Cool Polar Bears: Dabbing on the Texture

    Science.gov (United States)

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  15. Fractal analysis of polar bear hairs

    Directory of Open Access Journals (Sweden)

    Wang Qing-Li

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus are of superior properties such as the excellent thermal protection. Why do polar bears can resist such cold environment? The paper concludes that its fractal porosity plays an important role, and its fractal dimensions are very close to the golden mean, 1.618, revealing the possible optimal structure of polar bear hair.

  16. Elid superfinishing of spherical bearings

    OpenAIRE

    Raffles, Mark H.

    2007-01-01

    Driven by a requirement to extend the lifespan of self-aligning lined spherical bearings, this research investigates the use of Elid (electrolytic in-process dressing) as a method of improving ball surface finish. Elid is a continuous and self-regulating electrochemical dressing process that modifies the surface of a grinding, lapping, or superfinishing wheel. It provides improved grit protrusion, impedes wheel loading / glazing and promotes effective cutting. The characteri...

  17. Risk-bearing and Entrepreneurship

    OpenAIRE

    Newman, Andrew

    2007-01-01

    In the 'Knightian' theory of entrepreneurship, entrepreneurs provide insurance to workers by paying fixed wages and bear all the risk of production. This paper endogenizes entrepreneurial risk by allowing for optimal insurance contracts as well as the occupational self-selection. Moral hazard prevents full insurance; increases in an agent’s wealth then entail increases in risk borne. Thus, even under decreasing risk aversion, there are robust instances in which workers are wealthier than entr...

  18. Microstructural degradation of bearing steels

    OpenAIRE

    Solano Alvarez, Wilberth

    2015-01-01

    The aim of the work presented in this thesis is to clarify one of the most fundamental aspects of fatigue damage in bearings steels through critical experiments, in particular whether damage in the form of cracks precedes hard ?white-etching matter" formation, which is carbon supersaturated nanoscaled ferrite. Heat treatments have been designed to create four different crack types and distributions: scarce martensite plate cracks, fine grain boundary cracks, abundant martensite plate cracks, ...

  19. Analysis of the Journal Bearing Performance of a Reciprocating Compressor Using Methane

    Directory of Open Access Journals (Sweden)

    Oghenevwaire, Ogheneovo Emmanuel

    2014-04-01

    Full Text Available The performance of the journal bearing of a reciprocating compressor is crutial in industrial applications utilizing reciprocating compressors systems. This study analyzes a system utilizing EXXCOLUB SLG 190 as lubricant and methane, as the compressed gas. Numerical method, specifically the finite element method, is utilized in this study. Reynolds equation is analyzed using the half sommerfield boundary condition. The analysis encompasses a study of the effect of viscosity thinning with solubility of the methane at various operating pressures on the pressure profile and the load capacity of the bearing. The effect of vibration on the performance of the journal bearing is also analyzed by considering the effect of vertical flow. It was observed that the maximum pressure reduced by 50% as well as the load capacity of the journal bearing, when the operating pressure was increased from 0 to 5000 psi (3.447×107 N/m2. The pressure profile flattens out as the operating pressure increases. Increase in vibration (vertical flow effect results in the reduction of load capacity of the journal bearing.

  20. Effect of semi-circular wavy liner on performance of journal bearing

    Science.gov (United States)

    Sheriff, Jamaluddin Md.; Osman, Kahar; Asral

    2012-06-01

    The amount of lubricant present in a bearing can affect its performance. This study compares the load carrying capacity of wavy and smooth surfaces liner bearing so that the potential advantages of the former could be identified. Both types of bearing used palm oil as lubricant and computational analysis was developed to predict the numerical data for full film lubrication condition. The bearing model was 60 mm in diameter and its ratio of length to diameter was 0.5 with clearance and amplitude of 250μm and 200μm respectively. All cases studied included temperature effect under steady flow conditions with speed between 200 and 5000 rpm. The results show, for low eccentricity ratio, semi circular wavy liner bearings were able to produce higher load carrying capacity. The results also show that the overall temperature drop for wavy liner surfaces was higher for all test conditions. The shaft speeds, however, have no direct effect on the magnitude of the load carrying capacity.

  1. Study on water lubricated bearings of high speed pump based on numerical simulation

    Science.gov (United States)

    Bai, Y. X.; Kong, F. Y.; Sun, J. R.; Yuan, X.

    2016-05-01

    A method is presented for calculating and analyzing the performance of water lubricated bearing of high speed pump under different structure. In present work, six kinds of bearings in different radial clearance(C), which are 0.02, 0.04, 0.06, 0.08, 0.10and0.12 respectively, under the same minimum water film thickness, have been designed. The models are built by CREO and numerical simulated by ansys. The main content of the present work is to analyze the relationship between the pressure and the load carrying capacity with different radial clearance(C) by ansys workbench based on Fluid-Solid coupling through ansys workbench.The stress deformations of bearings are also acquired through thermal-structure coupling. From the comparing result among the numerical analysis under the six different model of water lubricated bearing, the relationship between radial clearance(C) and load carrying capacity, as well as the deformation of bearing under different radial clearance(C), are obtained. Further, results indicates that, a proper selection of radial clearance(C) is essential to enhance the bearing performance.

  2. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    OpenAIRE

    Andrzej RACZYŃSKI; Jarosław KACZOR

    2014-01-01

    Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  3. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    Directory of Open Access Journals (Sweden)

    Andrzej RACZYŃSKI

    2014-06-01

    Full Text Available Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  4. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    Science.gov (United States)

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  5. Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder

    2012-01-01

    A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model, it is shown that the proposed flexure journal bearing has vastly increased the hydrodynamic performance compared to the stiff...... bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas...... the liner has practically no influence on the flexure journal bearing's performance....

  6. Valve assembly having remotely replaceable bearings

    Science.gov (United States)

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  7. Heuristic explanation of journal bearing instability

    Science.gov (United States)

    Crandall, S. H.

    1982-01-01

    A fluid-filled journal bearing is viewed as a powerful pump circulating fluid around the annular space between the journal and the bearing. A small whirling motion of the journal generates a wave of thickness variation progressing around the channel. The hypothesis that the fluid flow drives the whirl whenever the mean of the pumped fluid velocity is greater than the peripheral speed of the thickness variation wave is discussed and compared with other simple explanations of journal bearing instability. It is shown that for non-cavitation long bearings the hypothesis predicts instability onset correctly for unloaded bearings but gradually overpredicts the onset speed as the load is increased.

  8. Ball Bearing Analysis with the ORBIS Tool

    Science.gov (United States)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  9. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    OpenAIRE

    Yu Lie; R.B. Bhat

    1995-01-01

    The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distri...

  10. Method Cement Post-grouting to Increase the Load Capacity for Bored Pile

    Directory of Open Access Journals (Sweden)

    Van Loc Nguyen

    2013-05-01

    Full Text Available Drilled shafts foundations are used as an indispensable solution for long span bridges in Vietnam. In order to increase the bearing capacity, aside from the increasing of the pile length and diameter, an interested way now is treatment of pile bases after concrete placement. This study is aimed at investigating the defect at the bottom of the bored pile from the sonic test. The injection of hight pressure of cement grout to the shaft and tip of the defected bored pile was conducted to increase the bearing capacity of pile. The bearing capacity of defected bored pile is calculated by the TCXD-205:1998 an finite element mothod. After post-grouting technique done, the soil investigation tests have been carried out to define the properties of treated soils. The analytic mothod, finite element method an load test also have been applied to determine the bearing capacity of treated bored pile. The results show that the post-grouting to the shaft and tip of pile can increase two times of bearing capacity of defected bored pile and about 20% compared to the normal bored pile.

  11. A prototype construction of bearing heater system

    International Nuclear Information System (INIS)

    A bearing heater system has been successfully constructed using transformer-like method of 1000 VA power, 220 V primary voltage, and 50 Hz electrical frequency. The bearing heater consists of primary coil 230 turns, U type and bar-type iron core with 36 cm2, 9 cm2 ,and 3 cm2 cross-section, and electrical isolation. The bearing heater is used to enlarge the diameter of the bearing so that it can be easily fixed on an electric motor shaft during replacement because the heating is conducted by treated the bearing as a secondary coil of a transformer. This bearing heater can be used for bearing with 3 and 6 cm of inner diameter and 12 cm of maximum outside diameter. (author)

  12. Pratt and Whitney cryogenic turbopump bearing experience

    Science.gov (United States)

    Poole, W. E.; Bursey, R. W., Jr.

    1988-01-01

    Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

  13. Wave Journal Bearings Under Dynamic Loads

    Science.gov (United States)

    Hendricks, Robert C.; Dimofte, Florin

    2002-01-01

    The dynamic behavior of the wave journal bearing was determined by running a three-wave bearing with an eccentrically mounted shaft. A transient analysis was developed and used to predict numerical data for the experimental cases. The three-wave journal bearing ran stably under dynamic loads with orbits well inside the bearing clearance. The orbits were almost circular and nearly free of the influence of, but dynamically dependent on, bearing wave shape. Experimental observations for both the absolute bearing-housing-center orbits and the relative bearing-housing-center-to-shaft-center orbits agreed well with the predictions. Moreover, the subsynchronous whirl motion generated by the fluid film was found experimentally and predicted theoretically for certain speeds.

  14. Simulation on Mechanical Behaviors of Oil-film Bearing Sleeve by Elastic Interference Fit

    Institute of Scientific and Technical Information of China (English)

    HUANG Qingxue; WANG Jianmei; ZHAO Chunjiang; MA Lifeng

    2006-01-01

    Oil film bearing, which works on thin film between sleeve and bush, is widely used in steel industry due to the characteristics of high efficiency and low noise, etc. The backup roll of 1 580PC hot strip mill invested by some steel corporation has been equipped with such bearing. During the process of setup&disassembly and usage period, the sleeve has been dramatically damaged, which results in production accidents and decreases its service life, thus heavily influencing steel production. Aimed at such puzzles, under specific loadcase, mechanical properties of bearing sleeve, as well as estimation of contact status and adhesive force of sleeve by interference fit, are quantitatively simulated by finite element method, which establishes an mechanical foundation for improving the load capacity of bearing and decreasing its wear and adhesion damages. Finally, some measures and conclusions are drawn.

  15. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears.

    Science.gov (United States)

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-03-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862

  16. Development and Evaluation of Titanium Spacesuit Bearings

    Science.gov (United States)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Raymond, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z-series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z-series space suit architecture allows us to reduce mass by an estimated 23 lbs per suit system compared to the previously used stainless steel bearing race designs, without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race- 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility (WSTF) that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approx. 3 years), design parameters for maximum contact stress need to be identified. To identify these design parameters, bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination and design around a cycle life requirement for an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an

  17. Dual capacity reciprocating compressor

    Science.gov (United States)

    Wolfe, Robert W.

    1984-01-01

    A multi-cylinder compressor 10 particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor 16 rotation is provided with an eccentric cam 38 on a crank pin 34 under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180.degree. apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons 24 whose connecting rods 30 ride on a crank pin 36 without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation.

  18. Geothermal Plant Capacity Factors

    Energy Technology Data Exchange (ETDEWEB)

    Greg Mines; Jay Nathwani; Christopher Richard; Hillary Hanson; Rachel Wood

    2015-01-01

    The capacity factors recently provided by the Energy Information Administration (EIA) indicated this plant performance metric had declined for geothermal power plants since 2008. Though capacity factor is a term commonly used by geothermal stakeholders to express the ability of a plant to produce power, it is a term frequently misunderstood and in some instances incorrectly used. In this paper we discuss how this capacity factor is defined and utilized by the EIA, including discussion on the information that the EIA requests from operations in their 923 and 860 forms that are submitted both monthly and annually by geothermal operators. A discussion is also provided regarding the entities utilizing the information in the EIA reports, and how those entities can misinterpret the data being supplied by the operators. The intent of the paper is to inform the facility operators as the importance of the accuracy of the data that they provide, and the implications of not providing the correct information.

  19. Hydrostatic bearings for a turbine fluid flow metering device

    Science.gov (United States)

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  20. Conditioning of alpha bearing wastes

    International Nuclear Information System (INIS)

    Alpha bearing wastes are generated during the reprocessing of spent fuel, mixed oxide fuel fabrication, decommissioning and other activities. The safe and effective management of these wastes is of particular importance owing to the radiotoxicity and long lived characteristics of certain transuranic (TRU) elements. The management of alpha bearing wastes involves a number of stages which include collection, characterization, segregation, treatment, conditioning, transport, storage and disposal. This report describes the currently available matrices and technologies for the conditioning of alpha wastes and relates them to their compatibility with the other stages of the waste management process. The selection of a specific immobilization process is dependent on the waste treatment state and the subsequent handling, transport, storage and disposal requirements. The overall objectives of immobilization are similar for all waste producers and processors, which are to produce: (a) Waste forms with sufficient mechanical, physical and chemical stability to satisfy all stages of handling, transport and storage (referred to as the short term requirements), and (b) Waste forms which will satisfy disposal requirements and inhibit the release of radionuclides to the biosphere (referred to as the long term requirements). Cement and bitumen processes have already been successfully applied to alpha waste conditioning on the industrial scale in many of the IAEA Member States. Cement systems based on BFS and pozzolanic cements have emerged as the principal encapsulation matrices for the full range of alpha bearing wastes. Alternative technologies, such as polymers and ceramics, are being developed for specific waste streams but are unlikely to meet widespread application owing to cost and process complexity. The merits of alpha waste conditioning are improved performance in transport, storage and disposal combined with enhanced public perception of waste management operations. These

  1. Synthesis and characterization of porous microspheres bearing pyrrolidone units

    International Nuclear Information System (INIS)

    Porous microspheres of glycydyl methacrylate (GMA) cross-linked with trimethylolpropane trimethacrylate (TRIM) were prepared with toluene as porogen by suspension-emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly whereas the parameters of porous structure (specific surface area and total pore volume) decreases. In order to obtain adsorbents bearing functional groups the porous methacrylate network was modified by subsequent reaction with pyrrolidone. The materials were studied using elemental analysis, infrared spectroscopy, atomic force microscopy (AFM), attenuated total reflection (ATR) spectroscopy, Raman spectroscopy, thermal gravimetry. Additionally, polymers sorption capacity towards Cu(II) was investigated. - Highlights: • Porous microspheres with reactive epoxy group were synthesized. • Highly developed porous structure was created. • Pyrrolidone units were incorporated during ring–opening reaction. • Polymers sorption capacity towards Cu (II) was investigated

  2. Ultimate Flexural Capacity of Unbounded Prestressed Concrete Pier

    Directory of Open Access Journals (Sweden)

    Wang Hui-li

    2014-01-01

    Full Text Available Based on the plastic-hinge method, the influence of different factors on the ultimate flexural capacity is analyzed, including relationship between the ultimate bearing capacity and prestressing tendon area, the regular reinforcement area, the strength of concrete and other influence factors. The results show that, the increase in the area of regular reinforcement and the strength of concrete can enhance the ultimate flexural capacity. Moreover, the ultimate bending moment increases first and then decreases, with the increasing of the prestressing tendon. Thus, the most effective method to increase the ultimate flexural capacity of prestressed concrete bridge pier is to increase regular reinforcement ratio, and to control the number of prestressing tendon simultaneously.

  3. Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

    Science.gov (United States)

    Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

    2016-01-01

    Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. PMID:26264178

  4. Performance of dynamically loaded journal bearings lubricated with couple stress fluids considering the elasticity of the liner

    Institute of Scientific and Technical Information of China (English)

    Yan-yan MA

    2008-01-01

    To take into account the couple stress effects, a modified Reynolds equation is derived for dynamically loaded journal bearings with the consideration of the elasticity of the liner. The numerical results show that the influence of couple stresses on the bearing characteristics is significant. Compared with Newtonian lubricants, lubricants with couple stresses increase the fluid film pressure, as a result enhance the load-carrying capacity and reduce the friction coefficient. However, since the elasticity of the liner weakens the couple stress effect, elastic liners yield a reduction in the load-carrying capacity and an increase in the friction coefficient. The elastic deformation of the bearing liner should be considered in an accurate performance evaluation of the journal bearing.

  5. Markets and Institutional Capacity

    DEFF Research Database (Denmark)

    Ingemann, Jan Holm

    2010-01-01

    Adequate explanations concerning the introduction of production and consumption of organic food in Denmark imply the necessity to engage a certain understanding of markets. Markets should subsequently not be seen as entities nor places but as complex relations between human actors. Further......, the establishment, maintenance and development of markets are depending on the capacity of the actors to enter into continuous and enhancing interplay....

  6. Flood Bypass Capacity Optimization

    Science.gov (United States)

    Siclari, A.; Hui, R.; Lund, J. R.

    2015-12-01

    Large river flows can damage adjacent flood-prone areas, by exceeding river channel and levee capacities. Particularly large floods are difficult to contain in leveed river banks alone. Flood bypasses often can efficiently reduce flood risks, where excess river flow is diverted over a weir to bypasses, that incur much less damage and cost. Additional benefits of bypasses include ecosystem protection, agriculture, groundwater recharge and recreation. Constructing or expanding an existing bypass costs in land purchase easements, and levee setbacks. Accounting for such benefits and costs, this study develops a simple mathematical model for optimizing flood bypass capacity using benefit-cost and risk analysis. Application to the Yolo Bypass, an existing bypass along the Sacramento River in California, estimates optimal capacity that economically reduces flood damage and increases various benefits, especially for agriculture. Land availability is likely to limit bypass expansion. Compensation for landowners could relax such limitations. Other economic values could affect the optimal results, which are shown by sensitivity analysis on major parameters. By including land geography into the model, location of promising capacity expansions can be identified.

  7. Discontinuous symplectic capacities

    OpenAIRE

    Zehmisch, Kai; Ziltener, Fabian

    2012-01-01

    Comment: We include generalizations to higher dimensions due to the unknown referee and Janko Latschev. We add examples of open sets with connected boundary on which the shell capacity is not continuous. 3rd and 4th version: minor changes, to appear in J. Fixed Point Theory Appl

  8. Vedr.: Military capacity building

    DEFF Research Database (Denmark)

    Larsen, Josefine Kühnel; Struwe, Lars Bangert

    2013-01-01

    Kühnel Larsen and researcher Lars Bangert Struwe of CMS had organized a seminar in collaboration with Royal Danish Defense Colleg and the East African Security Governance Network. The seminar focused on some of the risks involved in Military capacity building and how these risks are dealt with from...

  9. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Directory of Open Access Journals (Sweden)

    Yu Lie

    1995-01-01

    Full Text Available The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distribution of journal bearings and the static deflection of the rotor and delays the instability of the system considerably in lateral shaft vibration.

  10. Bearing Health Assessment Based on Chaotic Characteristics

    Directory of Open Access Journals (Sweden)

    Chen Lu

    2013-01-01

    Full Text Available Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM. Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.

  11. Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems

    Directory of Open Access Journals (Sweden)

    Jieyu Chen

    2007-08-01

    Full Text Available Incorporating the velocity slip effect of the gas flow at the solid boundary, theperformance and dynamic response of a micro gas-bearing-rotor system are investigated inthis paper. For the characteristic length scale of the micro gas bearing, the gas flow in thebearing resides in the slip regime rather than in the continuum regime. The modifiedReynolds equations of different slip models are presented. Gas pressure distribution and loadcarrying capacity are obtained by solving the Reynolds equations with finite differentmethod (FDM. Comparing results from different models, it is found that the second orderslip model agrees reasonably well with the benchmarked solutions obtained from thelinearized Boltzmann equation. Therefore, dynamic coefficients derived from the secondorder slip model are employed to evaluate the linear dynamic stability and vibrationcharacteristics of the system. Compared with the continuum flow model, the slip effectreduces dynamic coefficients of the micro gas bearing, and the threshold speed for stableoperation is consequently raised. Also, dynamic analysis shows that the system responseschange with variation of the operating parameters including the eccentricity ratio, therotational speed, and the unbalance ratio.

  12. Cantilever mounted resilient pad gas bearing

    Science.gov (United States)

    Etsion, I. (Inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  13. Probabilistic Aspect of Rolling Bearings Durability

    OpenAIRE

    Styp-Rekowski, Michał

    2007-01-01

    Many factors generate situations that real dimensions of each machine elements are different from nominal ones. In the case of rolling bearings elements mentioned disagreements are small - their values are rank of micrometers. However, such small differences can generate significant changes of operational features of bearings. The analysis of influence of ball dimensional deviation on load distribution in ball bearings is presented in this paper. The probability of occurrence of ball diameter...

  14. A miniature tilting pad gas lubricated bearing

    Science.gov (United States)

    Sixsmith, H.; Swift, W. L.

    1983-12-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  15. Stability and Load Bearing Capacity of a Bars with Built up Cross Section and Elastic Supports / Badania Stateczności I Nosności Prętów Złożonych Z Podporami Sprężystymi

    Science.gov (United States)

    Krajewski, Marcin

    2015-03-01

    The present paper is devoted to the numerical analysis and experimental tests of compressed bars with built-up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static analysis results, with material and geometrical nonlinearity, are presented for the bar with built-up cross section which was used as the top chord of the truss made in reality. Diagonals and verticals which are supports for the top chord between marginal joints were replaced by the elastic supports. The threshold stiffness (minimum stiffness) for the intermediate elastic supports which ensures maximum buckling load was appointed for the beam and shell model of the structure. The magnitude of limit load depended on length of the battens was calculated for models with initial geometric imperfections. The experimental tests results for the axially compressed bars with builtup cross section and elastic support are presented. Niniejsza praca poświecona jest analizom numerycznym i badaniom doświadczalnym ściskanych prętów złożonych, które są często stosowane, jako pasy górne kratownic dachowych. Istotny wpływ na nośność tego typu elementów, przy założeniu wyboczenia z płaszczyzny układu, ma odpowiedni dobór przewiązek zapewniający współpracę poszczególnych gałęzi. W pracy przedstawiono rezultaty liniowych analiz stateczności oraz fizycznie i geometrycznie nieliniowych analiz statycznych dla pręta złożonego, z którego zbudowany jest pas górny kratownicy wykonanej w rzeczywistości. Słupki i krzyżulce podpierające pas między węzłami skrajnymi zastąpiono podporami sprężystymi. Wyznaczono graniczną (minimalna) sztywność sprężystych podpór pośrednich zapewniającą maksymalną wartość obci

  16. Characterization of methacrylate chromatographic monoliths bearing affinity ligands.

    Science.gov (United States)

    Černigoj, Urh; Vidic, Urška; Nemec, Blaž; Gašperšič, Jernej; Vidič, Jana; Lendero Krajnc, Nika; Štrancar, Aleš; Podgornik, Aleš

    2016-09-16

    We investigated effect of immobilization procedure and monolith structure on chromatographic performance of methacrylate monoliths bearing affinity ligands. Monoliths of different pore size and various affinity ligands were prepared and characterized using physical and chromatographic methods. When testing protein A monoliths with different protein A ligand densities, a significant nonlinear effect of ligand density on dynamic binding capacity (DBC) for IgG was obtained and accurately described by Langmuir isotherm curve enabling estimation of protein A utilization as a function of ligand density. Maximal IgG binding capacity was found to be at least 12mg/mL exceeding theoretical monolayer adsorption value of 7.8mg/mL assuming hexagonal packing and IgG hydrodynamic diameter of 11nm. Observed discrepancy was explained by shrinkage of IgG during adsorption on protein A experimentally determined through calculated adsorbed IgG layer thickness of 5.4nm from pressure drop data. For monoliths with different pore size maximal immobilized densities of protein A as well as IgG dynamic capacity linearly correlates with monolith surface area indicating constant ligand utilization. Finally, IgGs toward different plasma proteins were immobilized via the hydrazide coupling chemistry to provide oriented immobilization. DBC was found to be flow independent and was increasing with the size of bound protein. Despite DBC was lower than IgG capacity to immobilized protein A, ligand utilization was higher. PMID:27554023

  17. Absorptive Capacity and Diversity

    DEFF Research Database (Denmark)

    Kristinsson, Kári

    that contribute to the neo-Schumpeterian economics literature and hopefully inspires further research into this area. The main findings of the dissertation can be divided into four distinct parts. First, diversity of individuals within firms is associated with firm innovative performance. This is in line......One of the most influential contributions to neo-Schumpeterian economics is Cohen and Levinthal‘s papers on absorptive capacity. Since their publication in the late 1980s and early 1990s the concept absorptive capacity has had substantial impact on research in economics and management, including...... international business, organizational economics, strategic management, technology management and last but not least neo-Schumpeterian economics. The goal of this dissertation is to examine what many consider as neglected arguments from the work by Cohen and Levinthal and thereby illuminate an otherwise...

  18. Value for railway capacity

    DEFF Research Database (Denmark)

    Sameni, Melody Khadem; Preston, John M.

    2012-01-01

    Growth in rail traffic has not been matched by increases in railway infrastructure. Given this capacity challenge and the current restrictions on public spending, the allocation and the utilization of existing railway capacity are more important than ever. Great Britain has had the greatest growth...... DEA work on the economic efficiency of railways by considering a new combination of input-output that also incorporates quality of service. The constant and variable returns to scale models are applied to the case study of franchised passenger operators in Great Britain. The follow-up Tobit regression...... model shows positive correlation between serving London and the efficiency scores. There is negative correlation between offering regional services (average length of journeys less than 40 mi) and the efficiency scores. The overall study and the results can provide helpful insights for railway...

  19. Deficiency of employability capacity

    OpenAIRE

    Pelse I.; Vilka L.

    2012-01-01

    Young unemployed people have comprised one of the significantly largest groups of the unemployed people in Latvia in recent years. One of the reasons why young people have difficulty integrating into the labour market is the “expectation gap” that exists in the relations between employers and the new generation of workers. Employers focus on capacity-building for employability such individual factors as strength, patience, self-discipline, self-reliance, self-motivation, etc., which having a ...

  20. Heat Capacity Mapping Mission

    Science.gov (United States)

    Nilsson, C. S.; Andrews, J. C.; Scully-Power, P.; Ball, S.; Speechley, G.; Latham, A. R. (Principal Investigator)

    1980-01-01

    The Tasman Front was delineated by airborne expendable bathythermograph survey; and an Heat Capacity Mapping Mission (HCMM) IR image on the same day shows the same principal features as determined from ground-truth. It is clear that digital enhancement of HCMM images is necessary to map ocean surface temperatures and when done, the Tasman Front and other oceanographic features can be mapped by this method, even through considerable scattered cloud cover.

  1. Functional Capacity Evaluation & Disability

    OpenAIRE

    Chen, Joseph J.

    2007-01-01

    Function, Impairment, and Disability are words in which many physicians have little interest. Most physicians are trained to deal with structure and physiology and not function and disability. The purpose of this article is to address some of the common questions that many physicians have with the use of functional capacity evaluation and disability and also to provide a unifying model that can explain the medical and societal variables in predicting disability. We will first define the funct...

  2. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers

    International Nuclear Information System (INIS)

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL)

  3. Bear Capture. Research, and Request for Consideraton of Releases of Bears at Dahomey NWR in 1996

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A series of memos and correspondences concerning the capture of a bear in Cleveland, MS and release on Dahomey NWR along with graduate research on bears from...

  4. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  5. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  6. Capacity Utilization and Market Power

    OpenAIRE

    Fagnart, J.F.; Licandro, O.; Sneessens, Henri

    1997-01-01

    In a monopolistic competition framework, we propose a dynamic model in which capacity underutilization is a macroeconomic equilibrium feature relying on a diversity of microeconomic situations. Capacity underutilization follows from microeconomic uncertainty at the time firms must decide on their productive capacity. We settle a relationship between capacity utilization and markups via the effect of capacity utilization rate changes on firms' market power. We show that such a relationship inf...

  7. Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

    International Nuclear Information System (INIS)

    The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements’ repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings

  8. Sunflower: a potential fructan-bearing crop?

    Science.gov (United States)

    Martínez-Noël, Giselle M A; Dosio, Guillermo A A; Puebla, Andrea F; Insani, Ester M; Tognetti, Jorge A

    2015-01-01

    Grain filling in sunflower (Helianthus annuus L.) mainly depends on actual photosynthesis, being the contribution of stored reserves in stems (sucrose, hexoses, and starch) rather low. Drought periods during grain filling often reduce yield. Increasing the capacity of stem to store reserves could help to increase grain filling and yield stability in dry years. Fructans improve water uptake in soils at low water potential, and allow the storage of large amount of assimilates per unit tissue volume that can be readily remobilized to grains. Sunflower is a close relative to Jerusalem artichoke (H. tuberosus L.), which accumulates large amounts of fructan (inulin) in tubers and true stems. The reason why sunflower does not accumulate fructans is obscure. Through a bioinformatics analysis of a sunflower transcriptome database, we found sequences that are homologous to dicotyledon and monocotyledon fructan synthesis genes. A HPLC analysis of stem sugar composition revealed the presence of low amounts of 1-kestose, while a drastic enhancement of endogenous sucrose levels by capitulum removal did not promote 1-kestose accumulation. This suggests that the regulation of fructan synthesis in this species may differ from the currently best known model, mainly derived from research on Poaceae, where sucrose acts as both a signaling molecule and substrate, in the induction of fructan synthesis. Thus, sunflower might potentially constitute a fructan-bearing species, which could result in an improvement of its performance as a grain crop. However, a large effort is needed to elucidate how this up to now unsuspected potential could be effectively expressed. PMID:26528295

  9. Kyoto discord: who bears the cost?

    International Nuclear Information System (INIS)

    Since 1990, Canada's greenhouse gas emissions are up 20 per cent, meaning that Canada must reduce its emissions by 30 per cent between 2005 and 2010 to meet its commitment under the Kyoto Protocol. Ottawa has indicated that no one sector of the economy should bear the burden of this adjustment. The energy production sector accounts for almost 40 per cent of all greenhouse gas emissions. Our per capita emissions have risen 50 per cent faster than emissions in the United States. The authors compared our situation to that of Europe, where only a 5 per cent reduction is required, which can be explained by high taxes on energy users, and the closure of obsolete East German capacity which led to reductions of 100 million tonne in carbon dioxide emissions. Transportation is the second largest generator of greenhouse gas emissions with approximately 16 per cent. A quick overview of the energy sector was provided, touching on topics such as electric power generation, including coal-fired electrical production, and tar sands with its increasing importance to Canada's economy. Ottawa has released a plan in October 2002, where it indicates that industrial emitters will be required to cut 80 million tonnes through investments in more efficient technology. Tighter vehicle fuel and home insulation standards would account for 35 to 40 million tonnes of reduction, and 40 million tonnes would come from agriculture and forest management. It means there is a 60 million shortfall, and the tar sands industry will more than likely have to adjust, raising investor uncertainty over further development in that area. Climate change is unlikely to be modified by meeting the objectives of the Kyoto Protocol. The authors questioned whether the government shouldn't instead devote its resources to addressing the actual impact of climate change. 9 figs

  10. Competence building capacity shortage

    International Nuclear Information System (INIS)

    The objective of the project 'Competence Building Capacity Shortage' has been 'to increase knowledge about central approaches aimed at solving the peaking capacity problem in restructured power systems'. With respect to reserve markets, a model was developed in the project to analyze the relations between reserve requirements and prices in the spot and reserve markets respectively. A mathematical model was also developed and implemented, which also includes the balance market, and has a good ability to predict the relations between these markets under various assumptions. With some further development, this model can be used fore realistic analyses of these markets in a Nordic context. It was also concluded that certain system requirements with respect to frequency and time deviation can be relaxed without adverse effects. However, the requirements to system bias, Frequency Activated Operating Reserves and Frequency Activated Contingency Reserves cannot be relaxed, the latter because they must cover the dimensioning fault in the system. On the other hand, Fast Contingency Reserves can be reduced by removing requirements to national balances. Costs can furthermore be reduced by increasingly adapting a Nordic as opposed to national approach. A model for stepwise power flow was developed in the project, which is especially useful to analyze slow power system dynamics. This is relevant when analysing the effects of reserve requirements. A model for the analysis of the capacity balance in Norway and Sweden was also developed. This model is useful for looking at the future balance under various assumptions regarding e.g. weather conditions, demand growth and the development of the generation system. With respect to the present situation, if there is some price flexibility on the demand side and system operators are able to use reserves from the demand side, the probability for load shedding during the peak load hour is close to zero under the weather conditions after

  11. Competence building capacity shortage

    Energy Technology Data Exchange (ETDEWEB)

    Doorman, Gerard; Wangensteen, Ivar; Bakken, Bjoern

    2005-02-01

    The objective of the project 'Competence Building Capacity Shortage' has been 'to increase knowledge about central approaches aimed at solving the peaking capacity problem in restructured power systems'. With respect to reserve markets, a model was developed in the project to analyze the relations between reserve requirements and prices in the spot and reserve markets respectively. A mathematical model was also developed and implemented, which also includes the balance market, and has a good ability to predict the relations between these markets under various assumptions. With some further development, this model can be used fore realistic analyses of these markets in a Nordic context. It was also concluded that certain system requirements with respect to frequency and time deviation can be relaxed without adverse effects. However, the requirements to system bias, Frequency Activated Operating Reserves and Frequency Activated Contingency Reserves cannot be relaxed, the latter because they must cover the dimensioning fault in the system. On the other hand, Fast Contingency Reserves can be reduced by removing requirements to national balances. Costs can furthermore be reduced by increasingly adapting a Nordic as opposed to national approach. A model for stepwise power flow was developed in the project, which is especially useful to analyze slow power system dynamics. This is relevant when analysing the effects of reserve requirements. A model for the analysis of the capacity balance in Norway and Sweden was also developed. This model is useful for looking at the future balance under various assumptions regarding e.g. weather conditions, demand growth and the development of the generation system. With respect to the present situation, if there is some price flexibility on the demand side and system operators are able to use reserves from the demand side, the probability for load shedding during the peak load hour is close to zero under the weather

  12. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    Science.gov (United States)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  13. Journal bearing performance and metrology issues

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2009-01-01

    Full Text Available Purpose: In this paper, a radial clearance of a journal bearings and the metrology of the radial clearance measurement is described.Design/methodology/approach: In this experimental study out-of-roundness and radial clearance of journal bearings were measured with high precision and the impact of their metrology was examined on the specific oil film thickness of the bearing. Some metrological issues were emerged and these should be taken into account when bearings are designed.Findings: An investigation showed that the radial clearance measurements can vary from one measuring device to another and the specified clearance may not necessarily meet the design criteria of specific oil film thickness. The study indicates that the radial clearance measurement can differ from one measuring device to another depending upon the precision that can be achieved by the device. The radius of the bearing or the shaft also varies along the circumference, mainly due to out-of-roundness. The out-of-roundness contributes to the error in radial clearance measurement and hence similar to the cut off length specified with the surface roughness, the out-of-roundness needs to be specified with the radial clearance.Practical implications: The radial clearance of a journal bearing is a key design parameter and bearing performance mainly depends upon this parameter. In this paper was showed that the metrology of the radial clearance measurement plays a significant role and not only that the bearing manufacturer or the user of the bearing is aware of this fact but the bearing designer must also take this fact into account while designing bearingsOriginality/value: This paper showed that The radial clearance is a sensitive micro-geometry parameter and hence metrology plays a vital role in making decisions

  14. The stiffness change and the increase in the ultimate capacity for a stiff pile resulting from a cyclic loading

    DEFF Research Database (Denmark)

    Lada, Aleksandra; Ibsen, Lars Bo; Nicolai, Giulio

    In the paper the experimental results of small-scale tests on a stiff monopile are presented to outline the change in stiffness during the cyclic loading and the change in the ultimate pile capacity. The results confirm the increase of stiffness and the increase in bearing capacity resulting from...

  15. Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

    Science.gov (United States)

    Halminen, Oskari; Kärkkäinen, Antti; Sopanen, Jussi; Mikkola, Aki

    2015-01-01

    Active magnetic bearings (AMB) offer considerable benefits compared to regular mechanical bearings. On the other hand, they require backup bearings to avoid damage resulting from a failure in the component itself, or in the power or control system. During a rotor-bearing contact event - when the magnetic field has disappeared and the rotor drops on the backup bearings - the structure of the backup bearings has an impact on the dynamic actions of the rotor. In this paper, the dynamics of an active magnetic bearing-supported rotor during contact with backup bearings is studied with a simulation model. Modeling of the backup bearings is done using a comprehensive cageless ball bearing model. The elasticity of the rotor is described using the finite element method (FEM) and the degrees of freedom (DOF) of the system are reduced using component mode synthesis. Verification of the misaligned cageless backup bearings model is done by comparing the simulation results against the measurement results. The verified model with misaligned cageless backup bearings is found to correspond to the features of a real system.

  16. Phylogeography of mitochondrial DNA variation in brown bears and polar bears

    Science.gov (United States)

    Shields, Gerald F.; Adams, Deborah; Garner, Gerald; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

    2000-01-01

    We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

  17. ANALYSIS ON MOTION STABILITY OF A HIGH-SPEED ROTOR-BEARING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Zhang Junhong; Sun Shaojun

    2005-01-01

    A non-linear dynamic model of one type of high-speed rotor system with gas supporting system is set up. The laws between the capacity force and the parameters of bearing, the static equilibrium position and rotating speed are studied on the basis of above model. Then, the failure rotating speed is given in the working state, and the relation between the minimum failure rotating speed and clearance of bearing is also studied. At last, the stability and failure condition are discussed in different working conditions.

  18. Practice and design of the self-purification system for heavy metals-bearing contaminants

    Institute of Scientific and Technical Information of China (English)

    Qian Guangren

    2008-01-01

    Many minerals in nature have self-purification capacity to hold and stabilize deleterious contaminants into their lattice structures,which can be used for treatment of heavy metals-bearing contaminants.Hydrotalcite Layer Double Hy-droxide(LDH),tobermorite Calcium Silicate Hydrate(CSH)and apatite are ubiquitous minerals in nature,having higher geochemical stability and potential for binding and stabilizing heavy metals.Based on the elucidation of crystal structure property and self-purification principles of the three minerals above,this article discussed how to design the self-purification system of heavy metal-bearing contaminants.

  19. Hydrodynamic and hydrostatic modelling of hydraulic journal bearings considering small displacement condition

    Science.gov (United States)

    Chen, Chi-Yin; Chuang, Jen-Chen; Tu, Jia-Ying

    2016-09-01

    This paper proposes modified coefficients for the dynamic model of hydraulic journal bearing system that integrates the hydrodynamic and hydrostatic properties. In recent years, design of hydraulic bearing for machine tool attracts worldwide attention, because hydraulic bearings are able to provide higher capacity and accuracy with lower friction, compared to conventional bearing systems. In order to achieve active control of the flow pressure and enhance the operation accuracy, the dynamic model of hydraulic bearings need to be developed. Modified coefficients of hydrostatic stiffness, hydrodynamic stiffness, and squeeze damping of the dynamic model are presented in this work, which are derived referring to small displacement analysis from literature. The proposed modified coefficients and model, which consider the pressure variations, relevant geometry size, and fluid properties of the journal bearings, are able to characterise the hydrodynamic and hydrostatic properties with better precision, thus offering the following pragmatic contribution: (1) on-line prediction of the eccentricity and the position of the shaft in the face of external force that results in vibration; (2) development of active control system to regulate the supply flow pressure and to minimize the eccentricity of the shaft. Theoretical derivation and simulation results with different vibration cases are discussed to verify the proposed techniques.

  20. Detection and Quantization of Bearing Fault in Direct Drive Wind Turbine via Comparative Analysis

    Directory of Open Access Journals (Sweden)

    Wei Teng

    2016-01-01

    Full Text Available Bearing fault is usually buried by intensive noise because of the low speed and heavy load in direct drive wind turbine (DDWT. Furthermore, varying wind speed and alternating loads make it difficult to quantize bearing fault feature that indicates the degree of deterioration. This paper presents the application of multiscale enveloping spectrogram (MuSEnS and cepstrum to detect and quantize bearing fault in DDWT. MuSEnS can manifest fault modulation information adaptively based on the capacity of complex wavelet transform, which enables the weak bearing fault in DDWT to be detected. Cepstrum can calculate the average interval of periodic components in frequency domain and is suitable for quantizing bearing fault feature under varying operation conditions due to the logarithm weight on the power spectrum. Through comparing a faulty DDWT with a normal one, the bearing fault feature is evidenced and the quantization index is calculated, which show a good application prospect for condition monitoring and fault diagnosis in real DDWT.