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Northeast Extreme Tee (NEXT) beams have been recently developed for the accelerated bridge construction. The skew effect on live load distribution in a NEXT beam bridge, especially with integral abutments, is not clear and shall be assessed. In this paper, various skew NEXT beam bridges are evaluated through validated finite element (FE) analyses with solid brick elements. Parameters as studied include beam section, span length, and skew angle. Per AASHTO LRFD specifications, one- and two-lane loaded cases are examined to obtain the maximum tensile strains in beam stems under the design live loading (HL-93). Unskewed bridges are used as control specimens to compute skew reduction factors (SRF) for moment from the obtained FE strains. The FE- and LRFD-SRFs for moment are compared in terms of figures, which indicate the LRFD-SRFs have good agreements with the FE-SRFs at large. For the majority of the bridges, LRFD-SFRs govern the FE-SRFs. The research findings from this paper are useful for practicing engineers to safely design a skew NEXT beam bridge with integral abutments.

In order to break through the limitation of the width of river, depth of water, channel and etc., it is an optimal choice to construct a long-span suspension bridge. In a suspension bridge, the main cable is the major bearing member; and the use of super high strength cable wire can lighten the dead weight and obtain an economical design. 1960 Mpa cable wire is adopted by an under-construction suspension bridge, namely Ni-Zhou Channel Bridge, for the first time in China. In this paper, taking the Ni-Zhou Channel Bridge as a case-study, comparative analyses on dynamic characteristic and seismic response of long-span suspension bridge with 1960 Mpa cable wire are performed. Firstly, dynamic calculating model for Ni-Zhou Channel Bridge is built and its dynamic characteristics are studied; then by using response spectrum and time history analysis method, seismic response of Ni-Zhou Channel Bridge is investigated on the basis of design response spectrum and artificial seismic ground motions; finally, the energy dissipation performances of a seismic protection devices (viscous damper) are also discussed. The results show that long-span suspension bridge with 1960 Mpa cable wire has a longer natural vibration period; the use of viscous damper can effectively reduce the peak value of bending moment in stiffening girder. This paper can provide references for the project’s construction.

Primary water stress corrosion cracking (PWSCC) has been observed in CRDM nozzles, BMI nozzles and other penetration nozzles. The industry has used the repair method of replacement of nozzles fabricated of Alloy 690. After the replacement of the nozzle, the structural integrity analysis of new nozzle and welds should be performed to ensure the pressure boundary compliance with the original design requirement. In this paper, the pressurizer top head instrument nozzle of PWR nuclear power plant is evaluated as a typical pressure vessel penetration nozzle. The results showed that the repaired nozzle satisfies the ASME Code design requirement and the crack growth of the postulated flaw in 40 years of the nuclear plant life is acceptable.PWSCC degradation mechanism has been observed in CRDM nozzles, BMI nozzles and other penetration nozzles [1]. In some nuclear power plants built in China earlier, such as DAYABAY nuclear power plant and QINSHAN nuclear power plant, PWSCC degradation mechanism has been found in CRDM nozzle welds which manufactured of Alloy 600 and welded of Alloy 82/182[2]. The repair of the degraded nozzles is the popular choice for the nuclear power plant owners. After the replacement of the nozzle, the structural integrity analysis of new nozzle and welds should be performed to ensure the pressure boundary compliance with the original design requirement. In this paper, the pressurizer top head nozzle of PWR nuclear power plant is evaluated as a typical pressure vessel penetration nozzle. Stress intensities were conservatively determined for pressure and applicable thermal transients and compared to the allowable values of the ASME Code, Section III. Thermal stress of the transients was obtained from 3D finite element model (FEM). Residual stress of J-groove weld was obtained from 2D FEM analysis and used for fracture mechanics analysis. All of the analysis showed that the repaired nozzle satisfies the ASME Code design requirement and the crack growth of the postulated flaw in 40 years of the nuclear plant life is acceptable.

Creep crack within weldments are very common in engineering practices, and the cracking location in these welding structures always appears at the HAZ location. The mismatch effect on the mixed mode creep crack is still not clear in these available literatures. The aim of this paper is to investigate the mismatch influence on the creep crack of mixed mode thoroughly. A mixed mode creep crack within HAZ is established in this paper. The leading factor that dominates the creep crack tip field under mixed loading mode is studied. The influences of mismatch effect on mode mixity, stress distribution and stress triaxiality are proposed. The difference of mixed mode creep crack and normal mode I or mode II creep crack are compared. The influence of mixity factor on the transient and steady state creep of crack tip are also analyzed.

Published paper on modelling of propeller turbine blade and runner is not commonly found, especially those using Autodesk Inventor. One of them is titled CAD Modelling of Axial Turbine Blade using Autodesk Inventor. However, the road taken is quite complicated and should be repeated from the beginning whenever new geometrical characteristics of a new axial propeller turbine will be modelled. Currently, Autodesk Inventor has introduced the new tool that help sketching the spline lines either in 2D plane or 3D space simplifying the task of 3D modelling of propeller turbine blade, called Equation Curve. The Equation Curve tool requires the codes for creating the spline lines. To create the codes, two sources have been used: NACA report no. 460 and modelling methodology proposed by Milos in his paper. In NACA report no. 460, it is explained that NACA 4 Digit Series is created by combining mean line with the thickness variation curve of Gottingen 398 and Clark Y. This airfoil has 4 different lines with their own equation. The equations can be used for sketching in 2D plane. However, the solid model of the runner blade is formed from the airfoils in cylindrical surface. Then, as explained by Milos in his paper, the procedure is as follows: sketch the airfoil in 2D plane that is the tangent of cylindrical surface, move the airfoil to its center, rotate to its stagger angle, and project it to cylindrical surface. The result of this process will be the equations of lines in 3D space. Transform them to the Inventor codes. Input these codes to 3D Equation Curve tool to create the 4 lines for each cylindrical surface section of blade. Making the solid model of runner the following step is required: use loft command to create blade surfaces, use the stitch command to solidify, use the pattern command to create other blades, create hub, and lastly combine blades and hub. The solid model of the runner then is tested by simulating it using ANSYS Fluent. The hydraulic efficiency of the model is 85%.

The present paper proves the feasibility of a semi-automatic control system of high frequency ultrasound for welded plastic pipes, by ultrasonic methods. The paper presents the main existing types of plastic materials, the technological joining possibilities, the problems that may occur in welding and control and the reasoning of the chosen examination method. The theoretical size of the reference ultrasonic parameters for the propagation of ultrasounds through the flawless juncture. The samples were welded using electro fusion (EF) under different working conditions. The samples were assessed circumferentially, every 10 degrees, on different working frequencies. A semi-automatic control system was designed and developed. For the optimal working frequency, a set of 10 measurements was done, in similar working conditions, on the automatic control stand, in order to test the systems’ capability and the results’ repeatability. The measured values were compared with the limits considered to be admissible using Shewhart statistic control charts.

This paper deals with an experimental analysis of hard rubber dynamic tests under finite torsion deformations. The experimental test rig was designed and composed for torsion loading of rubber under defined amplitudes, frequencies and temperatures. The present paper brings an amplitude-temperature analysis of isoprene-butadiene rubber ascertained by the use of the test rig. The mathematical rheological model of rubber was designed for phenomenological description and parametric identification of rubber.

An experimental investigation was presented in this paper on reinforced concrete box beams subjected to shear, torsion, and bending moment strengthened by carbon fiber reinforced polymer (CFRP). Eight box beams were cast and separated into two groups according to two different torque-to-shear and torque-to-bending moment ratios. Three box beams from each group strengthened by CFRP in different configurations and one control box beam were tested. The main parameters of this experiment were the different ratios and configurations, including U-jacket layers and U-jacket strips with or without longitudinal strips. The cracking and failure mode, effect of wrapping configuration, torsional capacity, and behavior of the different torque-to-shear and torque-to-bending moment ratios were studied in the paper.

This is Part-1 of the two-part paper in considering the effect of cambered airfoil blades on self-starting of vertical axis wind turbine. Part 1 reports the numerical studies on self-starting of vertical axis wind turbine with comparative studies involving NACA 0012 and cambered airfoil NACA 4415. Part 2 of the paper deals with numerical studies of NACA 0018 and cambered air foil NACA 63415. Darrieus type VAWT is attracting many researchers attention for its inherent advantages and its diversified applications. However, a disadvantage is when the rotor is stationary, no net rotational forces arises, even at high-wind speed. The principal advantage of the vertical axis format is their ability to accept wind from any direction without yawing mechanism. However, self-starting capability is the major drawbacks. Moreover, literatures based on computational analysis involving the cambered airfoil are few only. The objective of this present study is to select the suitable airfoil blades on self-starting of VAWT at low-Reynolds number. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. The commercial CFD code, ANSYS CFX 13.0© was used for the present studies. Initially, the flow over NACA 0012 was simulated and analyzed for different angles of attacks and similarly carried out for NACA 4415. The contours of static pressure distribution and velocity as well as the force and torque were obtained. Even though the lift force for cambered airfoil NACA 4415 is higher, based on the torque values of the above blade profiles, asymmetrical airfoil NACA 0012 is found to be appropriate for self-starring of VAWT.

The function of the fan is to reduce heat in the radiator where hot cooling liquid is circulated. The radiator fan blades are made up of various materials nowadays and the legacy material used is steel. This paper presents the static analysis of the radiator fan and at the outcome we analyze the failure of the entire blade taking into design consideration. The analysis of the radiator fan is executed to different types of materials to check and evaluate the material and process conditions which withstand the dynamic and structural loads. In the paper design of the blade is done through reverse engineering. The static analysis is done using ANSYS where the 3D solid model of the radiator fan is considered for structural analysis. The various loads and properties and applied through the entire length of the radiator fan. The analysis leads us to proposal of suitable material to withstand all the loads. The Fiber Reinforced Plastic (FRP) material is tested and considered.

For an arch rib of concrete filled steel tube (CFST) erected by cable-stayed cantilever method, the construction control becomes increasingly difficult along with the erection of rib segments, owing to more system transformation, and higher degrees of static indeterminacy. First, for the problems usually occurred in the process of ribs erection, this paper presented a line-shape control principle that is “erecting higher, remaining stationary”. Secondly, based on analysis of the merits and demerits of common methods for cable forces calculation, and according to the principle of “remaining stationary”, a new calculation method for cable forces was proposed. At last, based on an X-style CFST railway arch bridge with a span of 360m, this paper compared the cable forces calculated by the new method with the actual tensioned forces, analyzed the variation of segments displacement in the process of erection, and discussed the influence of prearranged height on weld width. The control principle and the calculation method for cable forces presented in this paper have been proved effective, by the line-shape data measured after the closure of arch ribs, which may provide valuable reference for the construction control of similar CFST arch bridges.

Fiber reinforced concrete is composite material containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. This paper deals with a comparison of both models made of reinforced concrete and fiber reinforced concrete as well as their optimization. The problem was modeled in ANSYS program. Some results of optimal design are presented at the end of this paper.

Various studies on the quality characteristics of products manufactured in different industrial conditions have been accomplished. The quality characteristics of welded metallic structures depend of the material and geometrical characteristics of the components, welded gap, welding speed, scheme and time of components fixing, etc. The paper presents main elements of an industrial research on the dimensional characteristics of a certain welded metallic structure. The research method used in this paper is the systematic analyse in industrial conditions, including welding robotised cell and 3D advanced measurement system.

High-strength steel is often used in the design and manufacture of the pressure vessel and the failure accident often happens in the weld area after used. CF62 is chosen in this paper which is the large-scale sphere steel for manufacture and the equal-loading butt joint of whose three different sizes are designed. The weld simulations of the equal-loading joints are made by 3D FEM, then the residual stress distributions and the influence of the thickness are analyzed in this paper. The results show that the equal-loading butt joint's weld toe is without stress concentration and the equal-loading butt joint can reduce the residual stress during the welding process. The thinner equal-loading butt joint has the lower residual stress. The joint designed by the equivalent Von Mises calculation has the lower stress than the one designed by the maximum stress calculation as well and the same as the weld toe's stress concentration. But the half reinforcement width of the maximum stress calculation butt joint is smaller than that of the equivalent Von Mises joint and whose welding electrode is economical, so the maximum stress equal-loading joint fits the engineering practical more.

This paper reports on an experimental study on the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double skin cantilever beams (referred to as DSTBs) that were tested under reversed cyclic loading. The beams were manufactured using a high-strength concrete (HSC) mix and they were 150 mm in diameter and 1.2 m in length. The main parameters of the experimental study included the size of the inner steel tube and the use of mechanical connectors in the form of steel rings welded on the inner steel tube. Test results indicate that DSTBs are capable of developing a highly ductile behavior under reversed cyclic lateral displacement excursions. It is found that the addition of mechanical connectors on the steel tube has no significant influence on the lateral displacement capacity of the test specimens, but they can eliminate the slippage between the concrete and inner steel tube. Examination of the test results has led to a number of significant conclusions on the influence of the beam parameters on the performance of DSTBs, which are discussed in the paper.

The topic of this paper is the short review of current state-of-the-art in the field of material models of concrete and its utilization for numerical analysis of concrete and prestressed concrete structures. The problem of compiling constitutive relations for numerical simulation of concrete structures is not yet closed. It is caused by different behavior of concrete in tension and compression. Due to formation and development of cracks it is necessary to describe material model of concrete in tension as precisely as possible. The paper aims to create a brief historical overview in this field and then aims to create a short summary of current approaches that were published in conference contributions and in journals during recent years.

Aiming at problems of lack of theoretical research and existing resources, etc., in equipment’s combat resilience design for the chinese military, a new kind of equipment’s combat resilience design theory-TRIZ contradiction maters are used to describe the technical conflict in practical problem, the conflict resolving matrix is used to analysis problem, and the principle to solve the contradiction is given at last. This theory is strongly to solve the contradiction problem. For these reasons, the equipment’s combat resilience design process is proposed in this paper, and then taking the battlefield maintenance of radar phased array antenna as an example, this paper analyses the improvement design method to introduce the design of phased array antenna by using the TRIZ conflict matrix. The results show that, TRIZ conflict matrix can effectively guide the equipment’s combat resilience design, and can indicate the direction for the equipment’s combat resilience design to improve design efficiency.

Pipe fracture and compensator tear may happen when directly buried pipes with large diameter, high temperature and pressure adopt preheated installation. Combined with engineering, this paper analyzes theoretically the fracture accident on DN1200 return water pipe during the period of cold operation and analyzes various factors which cause the pipeline fracture, when adopt open ditch electric preheating. By the numerical simulation, the size of influence factors on fracture was obtained, and the conclusion that the tensile stress is greater than the compressive stress was also obtained, where the preheating temperature was defined by means of “intercycle temperature”. It is worth nothing, the buried pipeline will emerge vertical bending under the main impact of soil and transportation loads. The vertical bending is related to pipe base, and the value of curving stress will be very big if the pipe base is mishandled. The coupling effect of curving stress and the temperature tensile stress can lead the pipeline to fracture, such as the disposable compensator place, the pipeline welding place, corners, the pipe wall flaw place and so on. This paper proposed the effective preventive measure which may reduce the occurrence probability of pipeline fracture during temperature drop process.

According to the structural characteristic of LNG cryogenic storage tank concrete prestressed wall and heat transfer theory, the paper obtain the calculation formula of the temperature field distribution, emphasis studying the heat flux distribution along the radial and axial and node temperature distribution of the section nodes for a 160,000 m3 capacity LNG cryogenic tank by ABAQUS. The paper also establish a set of method which is suitable for the temperature field analysis, proof the feasibility of finite element analysis technique in the analysis of the LNG cryogenic storage tank, and have a certain reference for the prestressed concrete walls and insulation layer design of the large LNG storage tank.

This paper present a procedure to detect wear or corrosion in structural elements based on frequency changes. Several methods to damage assessment are known, but these are mainly addressed to open cracks without considering the loss of mass. Since the mass decrease is a phenomenon associated with numerous corrosion mechanisms, the idea of this paper was to establish the influence of mass changes upon the natural frequencies of beam and to use it as a baseline in damage detection methods. Consequently, the research was conducted in two steps; first we analyzed the beam dynamics for a segment with reduced volumetric mass density but maintaining the global beam rigidity, succeeding to find the correlation between the frequency changes in the transversal vibration modes and mass loss in form of a mathematical relation. Afterwards, this relation was incorporated in the relation who predicts the frequency decreases due to stiffness diminish, in order to fit it for wear and corrosion assessment. The method’s robustness and reliability was proved by FEM simulations as well as by experiments.

The formability of tailor welded blanks is significantly reduced compared with the homogeneous blanks. This phenomenon is caused by the fact that there is a severe change in the material property sideways the welding line. Within 2-3 mm, in case of laser welding maybe less, there is a gradient of mechanical characteristics of materials. The research work presented in this paper deals with numerical simulation regarding forming of a cylindrical shaped part made from tailored blanks (TWBs), having the welding line situated symmetrical with respect to the part geometry. Due to dissimilar parent materials of the TWBs, it is difficult to anticipate the maximal depth of the formed part. The presented research is trying to determine the maximal depth of the TWBs part based on the maximal depth of the parts obtained from each parent material partly. To simulate the forming process of the cylindrical part the academically version of the Dynaform 5.8.1 software have been used. The obtained results are presented in the final part of this paper work.

The paper describes the crack initiation in the layers which were applied by laser surface cladding. The paper investigates the influence of the chemical composition of layer materials and welding technology on the tendency of the crack formation. Proposed method can dramatically reduce the formation of surface cracks in the applied layers.

In order to optimized the power cable layout design in tunnel, and improved the operation ability of the cable line, this paper analyzed the cable rating and the short-circuit force under different arrangements. 220kV cable circuit was simulated in the tunnel with conditions of the flat and the trefoil arrangements. The temperature and the rating of the 220kV cable under the condition of the two arrangements were calculated in this paper. The short circuit force peak value and its direction of the cable line under short circuit current of 50kA under the condition of the two arrangements were simulated in this paper. The results show that, the cable rating in flat arrangement is better than in trefoil formation. The value and the direction of the short circuit force in tunnel are better in flat arrangement than in trefoil formation. So it is suggested that the flat arrangement is preferred when conditions permit.

This paper investigates the dynamic characteristics of 600MW turbo-generator stator core, including the bending modes, the torsional modes, the elliptical modes, the axial modes and the triangular modes. The magnetic pull formula under the steady-state condition is firstly deduced, based on which the pulsating characters and the core deformation due to the pull excitation are analyzed. Then, the finite element (FE) model of the stator core is set up and imported into ANSYS Workbench to calculate the natural frequencies and the vibration modes. Finally, the calculation is verified via comparing with the experimental data in the published papers. It is shown that the first natural frequency is much larger than the excited working frequency, which means the stator core is in a safe operation condition. The calculation proposed in this paper accords well with the experimental data obtained by other researchers.

In the paper a lift calculation of a two-dimensional airfoil with a plain flap and Krueger flap is investigated. Numerical-analytical method (NAM) is used to predict the flow field around this combination. In order to calculate the complex velocity in the flow field, the complex variable function theory is employed. NAM based on the joint application of conformal mapping and the discrete vortex method (DVM). The paper presents a brief description of the NAM and some results of the lift calculations of the airfoil with the plain flap and Kruger flap. Comparison of the calculation results with the theoretical data of other authors showed a good agreement.

This paper studies the attack method in the condition of the torpedo noise covering the target noise with the help of calculation azimuth guidance. To verify the effectiveness of the scheme, the paper does simulation calculation. The simulation results demonstrated that the effect is good and the scheme haves usage value.

In this paper the influence of cross-coupling effects on the rubbing-related dynamics of rotor/stator systems is investigated. The model considered in this paper is a 4-dof rotor/stator system which takes into account the dynamics of the stator and the deformation on the contact surface as well as the cross-coupling effects. The stability of the synchronous full annular rub solution of the model is first analyzed. Then, the cross-coupling effects on the stability of the system at different system parameters are studied. It is found that the cross-coupling effects of the rotor stiffness as well as those of the stator damping and stiffness will benefit the synchronous full annular rubs while the cross-coupling damping of the rotor will reduced the stability domain of the response and lead the system to a response with a heavier rubbing

Ionic Polymer Composite Material (IPMC) is a flexible material and has concealed many benefits to inspire the scientists and researchers to explore its physiognomies for real-world applications in various fields. Currently, the research area of IPMC can be alienated into two branches. One deals with the upgrading of the material properties to make it further advantageous and dependable while the other encompasses the consideration of new application capacities. In this paper, a new application of IPMC is recommended to stimulate a rigid link that can imitate a bionic knee joint for a grass hopper. Secondly, force-deflection mathematical model has been developed for the proposed design to investigate the amount of deflection that can be achieved by a certain force provided by the IPMC material strips. In this paper, the model is derived for the upward movement of the link; however the same model can be applied to the reverse direction because of the unanimity of the material properties and specifications.

This paper contains a comparative study on the embedded energy in the simple masonry and welded bars reinforced masonry. The calculation starts from a unique study for Romania achieved in the conditions of centralized economy and highlights the amount of energy incorporated in building materials, expressed in J. It is also realized a calculation for the mechanical work, which is an exchange of energy between the system and the environment.

Based on the theories of rotor dynamics, a dynamic model of rotating blade was built. Taking account of the effect of spin softening, the research on vibration characteristics of high-speed rotating blades was carried out under different speeds. The results had shown that frequency of blade vibration increased with rising rotating velocity, whilst the frequency of all orders declined with the influence of spin softening. Meanwhile, the change of each mode shape of blade was not very large at different speed. The conclusion derived from this paper had both theoretical and empirical value on retrofitting, optimal-designing, as well as engineering application for high-speed rotating blades.

The paper presents experimental investigations on cold-formed steel (CFS) wall plate system. The behavior and the modes of failure of the system under uplift were studied. The parameters tested were the presence of gaps and the thickness of connecting plates. Results showed that samples with and without gaps at the supports experienced the same failure mode. Failure began with the yielding of connecting plates followed by the buckling of C-channel. Similar ultimate capacity was also obtained for samples with and without gaps. When connecting plates of different thicknesses were used to connect the wall-plate, different modes of failure were observed. Instead of yielding in the connecting plates, screw pull-out was observed in the connection before the C-channel buckled. Besides, it was observed that the ultimate capacity of the system was reduced when thicker connecting plates were used. It is not conservative to estimate the capacity of screwed connection according to the design standard and it is proposed that the capacity of the wall plate system is taken as the yield capacity of the connecting plates of the same material properties.

The columns are one of the main load bearing elements that are subjected to impact loads, mainly in the form of projectile impact, vehicle impact, etc. The resulting severe damage to column may leads to failures of the supporting structure that are dangerous in nature. However, the columns in existing buildings are seldom designed for impact due to inadequacies of design guidelines. The knowledge about the behavior of dynamic impact loading on the cold formed steel columns is limited. The simulation of transverse impact loading was done using finite element (FE) method. The parameter considered in the finite element study consists, axial compression and its eccentricity under transverse impact. Results showed that axial load carrying capacity decrease with increase in eccentricity of loading. In this paper, cold formed stiffened steel tube considered for the lateral impact assessment.

Stainless steel is now widely used in construction as structural members in recognition to its unique beneficial properties such as corrosion resistance, higher strength and ductility, andnegligible maintenance cost. Recent research on stainless steel has seen development of rational design rules to predict cross-sectional resistances but still lacks in appropriate knowledge at the member level. The current paper investigates the lateral-torsional buckling (LTB) behaviour of welded stainless steel I sections. Available test results were used to develop and validate nonlinear finite element (FE) models. Limited experimental evidences were supplemented by a large number of reliable numerical results covering wider range of member slenderness ratio. All test and numerical results were used to investigate the performance of Eurocode EN-1993-1-4 and Australian code AS/NZS 4673 in predicting member resistances against lateral-torsional buckling.

Everything that happens in the world is an expression of energy in one of its forms. “Energy can neither be created nor be destroyed. It can only be converted from one form into another”. So wind energy is converted from one form to another. Wind energy is readily converted into mechanical energy through the turbine blades. This mechanical energy can be used for saw milling applications. In this paper we concentrate on Design of Shaft, Bevel gear and Torque Transmission system.

The strain characteristics in the outer surface of the pipe and the stress intensity factor in crack front with internal longitudinal-cracks were analyzed by the finite element method. According to the results of analysis, the outer surface strain variation to crack size was got and the relationship of stress intensity factor and crack size was known. Based on resistance strain gauges and fiber optic sensing technology, pressure pipe crack extension monitoring device was designed and the outer surface circumferential strain were tested .The results of finite element analysis and experiment are in good agreement. The outer surface strain variation in this paper can be used to analyze the situation of internal longitudinal-cracks extension.That relationship of stress intensity factor and crack size has an important reference to the safety assessment of pipe with internal longitudinal-crack.

The girth weld defect is one of the most common types of defects on oil and gas pipelines, which can have a strong impact on the operation safety. Several girth weld failure accidents have occurred on PetroChina’s pipelines in recent years. In this paper, PetroChina’s current work on inspection and fitness for purpose assessment of girth weld defects is summarized. The in-line inspection has been proved to be the best practice for oil and gas pipeline defect inspection, but there are still some technical issues such as defect characterization and parameter selection. Fitness for purpose assessment methods for girth weld defects include strength assessment method based on plastic collapse, FAD method based on both plastic collapse and fracture, simplified factor method and numerical analysis method based on finite element. It is critical to identify the actual type of defects detected in in-line inspection to select an appropriate assessment method. The identification of various loads and the selection of appropriate material parameters are also important issues in assessment procedure. The key techniques to be developed include defect characterization, load identification, assessment of defects on high grade steel pipes, reliability-based assessment, etc.

Currently the fatigue testing of bevel gears are being done by using non rotating type of fixtures that applies fatigue load on a single tooth, which does not resemble the actual loading condition in an automotive differential gear box. This paper discusses the experimental setup with the noise and vibration analysis approach to determine the signature of failures of spiral bevel gears. The proposed experimental setup seems promising for further research and development in the fatigue testing of spiral bevel gears. The Crown pinion and wheel assembly is used for the testing. The pinion is connected to the electric 3 phase AC motor of 75HP with a suitable coupling and the crown wheel is mounted on the half axle shaft, which in turn is connected to an electric dynamometer. The speed/torque of electric motor and the load applied by the dynamometer can be varied. The acoustic sensor is mounted near the differential gear box and the accelerometers are mounted on the Pinion bearing, Crown wheel bearing and the half axle bearing. A four channel data acquisition system is used to log data in time domain (raw data) by three accelerometers and an acoustic sensor. The variations of sound pressure(dB) v/s time, sound Pressure(FFT-(RMS)) amplitude v/s Frequency, Acceleration v/s Time, Octave analysis i.e., Band power v/s Frequency, Noise spectrum Power v/s Frequency, Histogram, Power density v/s Time can be obtained. These data are then used to plot vibration and SPP levels in frequency domain to develop the noise and vibration signature of that crown pinion for given cycles of operation. The tests on Bevel pinion and gear set were performed in the BEC, Bagalkot NVH lab facility. The gear set run successfully at double the rated torque for 30 million pinion cycles. And the signature of pinion failure was obtained. The results demonstrated the suitability of using the given bevel crown pinion and gears set for specified speed, high load application in differential gear box of an automobile.

In this paper, the author uses ANSYS, the software of finite element analysis, to establish the finite element model, the hot spot stress value of different connection structures of steel tube-welded hollow sphere under uniaxial elongation has been analyzed, the theoretical stress concentration factor of this joint has been obtained. Through the static test on the four typical test-piece, 26 steel tube-welded hollow spherical nodes in total, the actually measured stress concentration factor of the joints has been obtained. The theoretical analysis basically coincides with the law of stress concentration factor obtained from the test results.

In scores of experiments indicates that the super-retarding mortar, keeping plasticity long-term, can make cement setting and hardening at a slower speed through chemical additive. Based on large numbers of orthogonal tests and theoretical analyses, the super-retarding mortar which satisfies the demands of actual engineering was developed successfully in present paper. And it is consist of cement, sand, water and composite retarder blended in an appropriate rate. From 0°C to 40°C, setting time can be adjusted from 1 day to 22 days in the light of to the engineering requirements, and after condensation, it begins to harden gradually and ends with the compression strengthen over 30MPa. Experiments were employed to test the influences of accession amounts of composite retarder dosage on setting time and compression strengthen of super-retarding mortar. Besides, the retarding mechanism was studied, and the super-retarding mortar was applied to experimental models. The results show the super-retarding mortar can be applied to the actual engineering, and it can be treated as the theoretical reference for the actual project application of the new prestressed concrete system.

In suspension bridge, the main cable is the major bearing member, instead of the 1770MPa cable wire normally adopted in current design, the application of cable wire strengths up to 1960MPa can lighten the dead weight, reduce the size of tower and anchorage, and shorten the construction period, obtain economical design. In this paper, a under-construction suspension bridge with span of 1688m is taken as a case-study, Comparative analyses are performed mainly focusing on basic parameters, carrying efficiency of main cable, static behavior and dynamic properties as different high strength cable are adopted in this suspension bridge. The results show that compared with 1770MPa main cable, using 1960MPa main cable in suspension bridge is benefit for improving the carrying efficiency of main cable, the steel consumption is also saved by 13%, but the vertical stiffness of the structure is reduced partly; the changes of main cable slightly affect the natural vibration frequency of girder, but have greater influences on vibration of main cable.

This paper is part of ‘through process modelling of welded aluminium’ project. It describes experimental and numerical investigation on butt-welded specimens of aluminium alloy AA6060. In the experiments, tensile test was used with Digital image correlation (DIC) technique to obtain full field strain measurement on the transversely loaded specimens. The tensile properties of these specimens are presented in terms of response curves. A user defined material was implemented in the explicit finite element code for the numerical calculations. The concept of non-local approach for plane stress analyses and the Cockroft Latham fracture criterion were used respectively to reduce mesh dependence of strain localization and to predict ductile fracture. The numerical results were compared to the experimental data and the measured and predicted response was evaluated.

The limited lengths of reinforcing bars have been commonly found in the practical construction of most reinforced concrete structures. The required length of a bar may be longer than the available stock of steel length. For maintaining desired continuity of the reinforcement in almost all reinforced concrete structures, some reinforcing bars should be carefully spliced. In the case of long flexural beam, bar installers end up with two or even more pieces of steel that must be spliced together to accomplish the desired steel length. An experimental study was conducted to investigate flexural behavior of reinforced concrete beams utilizing a variety lap splices of reinforcing steel bars under two-point loading. Five variations of lap splices of reinforcing steel bars positioned at midspan of tensile reinforcement of the beam were investigated. Welded joints and overlapped splices were used to construct the variation of lap splices of reinforcing steel bars. The general trend in crack pattern, the load deflection characteristics and the mode of failure of flexural beams under two-point loading were also observed. The flexural strength comprising load-displacement response, flexural crack propagation, displacement ductility is briefly discussed in this paper.

Thermal buckling and postbuckling of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams are investigated in this paper based on Timoshenko beam theory within the framework of von Kármán geometric nonlinearity. The material properties of FG-CNTRCs are assumed to be temperature-dependent and vary in the beam thickness direction. The governing equations are derived by employing Hamilton’s principle then discretized by using differential quadrature (DQ) method. An iterative scheme is used to obtain the critical buckling temperature and nonlinear thermal postbuckling equilibrium path of the FG-CNTRC beam. Numerical results are presented for FG-CNTRC beams hinged or clamped at both ends, with particular focuses on the effects of the volume fraction of carbon nanotubes (CNTs), slenderness ratio, and end supports on the thermal buckling and postbuckling characteristics.

Steel storage racks, commonly assembled from cold-formed steel profiles, are braced in the cross-aisle direction, where bracing members are typically bolted between two uprights forming an “upright frame”. Especially for high-bay racks and racks supporting the building enclosure, accurately determining the transverse shear stiffness of upright frames is essential in calculating the elastic buckling load, performing earthquake design and serviceability checks. International racking specifications recommend different approaches to evaluate the said transverse shear stiffness. The Rack Manufacturers Institute (RMI) Specification conservatively uses an analytical solution based on Timoshenko and Gere's theory while the European (EN15512) and Australian (AS4084) Specifications recommend testing to be conducted. Previous studies have shown that Finite Element Analyses (FEA), solely using beam elements, fail to reproduce experimental test results and may overestimate the transverse shear stiffness by a factor up to 25. This discrepancy is likely attributed to the local deformations occurring at the bolted joints. In this paper, a commercially used upright frame configuration has been modeled using shell elements in FEA and the response is verified against published experimental test results. A good correlation is found between the FEA and test results, concluding that shell elements are able to fully capture the behaviour of the upright frame. Future studies on the use of the FE model are also presented.

Despite recent advances in the finite element method, mesh distortion due to large deformations may still occur in some problems such as footings subjected to deep penetration or objects penetrating into a soil layer. In order to overcome mesh distortion, robust remeshing techniques are required. In this paper the performance of four remeshing methods is studied by analysing a free falling penetrometer penetrating into an undrained layer of soil. These techniques are implemented within the framework of the Arbitrary Lagrangian-Eulerian method and include the refinement based on an elastic relocation, a technique based on the Radial Basis Functions, the Spring Analogy method, and the Elastic Hardening method. Since one of the challenging problems in a large deformation analysis is dealing with complex boundary shapes, a scheme based on the B-Splines used in isogeometric analysis is also presented here.

Mechanical properties of the laminates reinforced with steel wires based on UHTS (Ultra High Tensile Strength) steel are only slightly worse than popular carbon strips. Thanks to competitive price they become popular strengthening material for concrete structures. The paper presents the results of laboratory tests of beams not efficiently reinforced in shear zone and strengthened along its side surfaces by the L-type overlays made of SRP tape. In addition, in order to ensure a high load-bearing capacity, beams were strengthened against bending. The effectiveness of reinforcement in a comparative test of unreinforced model was analyzed including ultimate capacity, deflection, failure model and strains. The results were used to evaluate the efficiency of SRP shear strengthening.

This paper describes the nonlinear probabilistic analysis of the failure pressure of the shielding plate of the reactor box of the nuclear power plant under a high internal overpressure and temperature. The scenario of the hard accident in Nuclear power plant (NPP) and the methodology of the calculation of the fragility curve of the failure overpressure using the probabilistic safety assessment PSA 2 level is presented. The fragility curve of the failure pressure was determined using 45 probabilistic simulations using the response surface method (RSM) with the Central Composite Design (CCD) for 106 Monte Carlo simulations for each model and 5 level of the overpressure.

Longitudinally welded steel pipe piles are not as commonly used as seamless steel pipe piles in offshore platform. Although longitudinally welded steel pipe piles are considerably cheaper than seamless steel pipe piles, yet many feared that longitudinally welded steel pipe piles are prone to fail because of non-uniformity in the heat affected zone (HAZ), especially when receiving impact loads during the installation process. In this paper, a finite element model is developed to study the deformation and failure of the longitudinal welded piles. Two modelling cases are performed: single and double piles, with two different failure parameters: maximum stress and maximum plastic displacement.

Regenerative shock absorber is designed to convert the vibration energy losses from the vehicle suspension into electricity. This paper presents an experimental study on the dynamic characteristics of hydro-magneto-electric-regenerative shock absorber (HMERSA). Study was carried out by developing a prototype of HMERSA and testing its dynamic characteristics. The results were analyzed and discussed. Prototype of the HMERSA consists of hydraulic system and electric generator. The HMERSA was tested using a quarter car suspension test rig with input displacement in various frequency (1.3Hz, 1.5Hz, 1.7Hz) and for HMERSA’s various oil viscousity (ISO VG 10, 32, 46). Sprung mass acceleration and the generated electric power representing the dynamic characteristics of HMERSA were measured. Maximum power 2.5 watt and root mean square acceleration 0.172 m/s2 gained for HMERSA with oil viscousity ISO VG 10 at all excitation frequency.

The paper deals with an assessment of blade tip movements based on precise time measurement known under abbreviation BTT - Blade Tip Timing. In addition to the common way of BTT data processing, a new Residual Fatigue Lives of Blades system (RFLB) proceeds further up to estimation of blade damages by processing output files generated by BTT systems.