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Performance degradation of gas turbine is a common phenomenon during operation. Maintenance of the degraded gas turbines and improving their performance at a low cost are important in engineering. In this paper, the maintenance method based on reassembling degraded components of existing gas turbines was studied. This research was based on a type of 2MW gas turbine engine. Blue ray scanning was carried out to rebuild the 3D flow-path geometries of the compressor and turbine of a degraded engine. Then CFD simulations were carried out to compare the characteristic maps of new and degraded components. Secondly, performance tests of six engines were carried out. A correction method was developed to get the specific component characteristics using test data, which can also analyze and quantify the degradations. Also, a gas turbine performance prediction program was used to find the promising component-exchange plan within 5 given gas turbines to improve total thermal efficiency. Finally, additional test was carried out to verify the performance of the reassembled gas turbine. Through the developed method including 3D scanning, CFD simulation, and correction of component characteristics with engine test data, the component performance degradation of a specific gas turbine can be obtained in quantity. The gas turbine performance predictions based on the acquired characteristic maps showed good agreement with test data. With the help of the method developed in this work, a new gas turbine engine was obtained through exchanging the components of degraded engines, which is at a very low cost and in a short time. The improvement in total thermal efficiency was about 0.3 percentage, which was verified by engine tests.

Nickel-Titanium (NiTi) alloy is difficult to be machined and fabricated due to its properties of rapid work-hardening and superelasticity. Traditional manufacturing methods, such as casting, vacuum arc melting, and hot-isostatic pressing, have disadvantages of high cost, time-consuming, and limitation in the complexity of parts’ fabrication. In order to reduce or solve these problems, laser additive manufacturing methods have been studied in the fabrication of NiTi alloy. Among the investigations, laser engineered net-shaping (LENS) in-situ synthesis of NiTi from blended Ni and Ti powders shows its unique advantage of cost-effectiveness and flexibility in tailoring NiTi’s phase transformation properties. In addition, it is reported that LENS in-situ synthesized NiTi parts have comparable properties with NiTi alloys fabricated from pre-alloyed powders. However, there are no existing investigations on the effects of processing parameters on the mechanical properties of the LENS in-situ fabricated NiTi parts. The processing parameters would have great influences on the properties of the LENS in-situ synthesized NiTi parts. This paper, for the first time, reports the effects of laser power, powder feeding rate, and Z increment of the deposition head on microstructure, microhardness, and Young’s modulus of the LENS in-situ synthesized NiTi parts.

To improve the accuracy of the machined surface produced by an ordinary milling machine, a system called workpiece-referred form accuracy control (WORFAC) was developed and confirmed in diamond turning. However, non-rotational symmetric surface structures, such as V-grooves, pyramid structures, F-theta lenses, and other free form surface cannot be machined by diamond turning. We proposed to improve the form accuracy of a machined surface produced by an ordinary milling machine by diamond fly cutting using controlled cutting with reference surface (CCRS), an in-process measurement and control method. Fly cutting is usually used to manufacture ultra-precision microstructures with nanometric surface roughness and submicrometric form accuracy, without the need for subsequent polishing. Nevertheless, a high level of accuracy has only recently been achieved on ultra-precision milling machines. In this study, we verified the effectiveness of fly cutting with CCRS on an ordinary milling machine. CCRS improves machined surface accuracy by controlling the relative displacement between the tool and workpiece. Diamond fly cutting using CCRS was demonstrated to reduce the table motion error on an ordinary milling machine. The experiments of curved surface machining by uncontrolled machining and control machining were conducted, and the effectiveness of improving the circular are machining accuracy of the general-purpose milling machine was confirmed.

Titanium is widely used in many industry areas (such as automotive industry, aerospace industry, and medical industry) due to its superior properties of low density, high strength to weight ratio, strong corrosion-resistance, etc. However, commercial pure titanium (CP-Ti) parts still have some disadvantages (such as relatively low hardness, and wear resistance) which limit their further applications. In order to reduce these disadvantages, some reinforcement materials (such as ceramics and nanomaterials) are involved to fabricate titanium-based parts Compared with ceramics, low content of nanomaterials could significantly improve the mechanical properties and reduce disadvantages of ceramics (such as poor wettability and low interfacial bonding between reinforcement materials and Ti). Graphene oxide (GO) is a preferable candidate of nanomaterial due to its excellent mechanical properties and low density. The GO reinforced Ti parts have been fabricated by the selective laser sintering (SLS) process. Laser additive manufacturing (LAM) process includes directed energy deposition method and powder bed fusion method. Compared with powder bed fusion method (such as the SLS and selective laser melting (SLM)), directed energy deposition method (e.g. laser engineered net shaping (LENS)) has advantages of parts repairing and gradient parts fabrication capabilities. There are no studies on the fabrication of GO-Ti parts by LENS process. In this study, GO-Ti parts are fabricated by the LENS process. The effects of GO and laser power on fabricating defects of porosity, microstructure, and mechanical properties (including microhardness, elastic modulus, wear rate) were studied, for the first time.

Surface machining of carbon fiber reinforced plastic (CFRP) using rotary ultrasonic machining (RUM) with vertical ultrasonic vibration was effective in reducing many issues, including high cutting force, high torque, and high tool wear rate. The vertical ultrasonic vibration also induced damages to machined CFRP surfaces and then resulted in increased surface roughness. To simultaneously decrease surface roughness and cutting force, the direction of ultrasonic vibration needed to be parallel with the surface generation direction (horizontal feeding direction). The horizontal ultrasonic vibration was then developed and applied for RUM surface machining of CFRP. The application of horizontal ultrasonic vibration in RUM surface machining produced simultaneously decreased surface roughness and cutting force. However, there were no investigations on delamination in such a process, and delamination was considered as one of the major factors to reject the machined CFRP products. This investigation would study the delamination under different machining-variable groups, the delamination generation mechanisms, and the relationships between delamination and cutting forces through the experimental method in surface machining of CFRP using RUM with horizontal ultrasonic vibration. Smaller cutting force and delamination thickness would be produced by the smaller depth of cut, smaller feedrate, or larger tool rotation speed. Smaller indentation depth was generated by larger tool rotation speed or smaller feedrate. Smaller material removal rate and abrasive-grain number taking part in the cutting process were produced by the smaller depth of cut. The delamination initiation at larger uncut CFRP thickness would be induced by higher cutting force.

We are investigating the impact on 3D printed part strength when the extruder is positioned using articulated robotic arms in place of a traditional x-y gantry-style system. One of our printer designs is called the DeXter printer [1] which uses two selective compliance assembly robotic arms (SCARA) to position dual extruders. An advantage of using dual robotic arms is that two extruders can move independently drastically reducing build times, or the second arm can perform additional operations like segment stimulation during the build process [2]. In either case the arms require a collision avoidance process to prevent them from colliding in the part space. A possible drawback of the collision avoidance requirement is that it can result in a time delay along some sections of the layer which, due to cooling, could have adverse effects on the part strength. This research aims to determine how this cooling time will affect the strength of ABS extruded parts. We performed tensile tests on 3D printed part samples for which we altered the g-code to produce a variable time delay during the printing process. Our control sample had a zero-dwell time, and as we increased dwell time we found that the ultimate tensile strength (UTS) did decrease.

Additive manufacturing processes, especially those based on fused filament fabrication (FFF) mechanism, have relatively low productivity and suffer from production scalability issue. One solution is to adopt a collaborative additive manufacturing system that is equipped with multiple extruders working simultaneously to improve productivity. The collaborative additive manufacturing encounters a grand challenge in the scheduling of printing path scanning by different extruders. If not properly scheduled, the extruders may collide into each other or the structures built by earlier scheduled scanning tasks. However, there existed limited research addressing this problem, in particular, lacking the determination of the scanning direction and the scheduling for sub-path scanning. This paper deals with the challenges by developing an improved method to optimally break the existing printing paths into sub-paths and assign these generated sub-paths to different extruders to obtain the lowest possible makespan. A mathematical model is formulated to characterize the problem, and a hybrid algorithm based on an evolutionary algorithm and a heuristic approach is proposed to determine the optimal solutions. The case study has demonstrated the application of the algorithms and compared the results with the existing research. It has been found that the printing time can be reduced by as much as 41.3% based on the available hardware settings.

Carbon fiber reinforced plastic (CFRP) composites have been widely used in many applications due to their superior properties of high strength-weight ratio, high stiffness, and high wear resistance. For assembly purposes, hole making is necessary for different applications of CFRP composites. Rotary ultrasonic machining (RUM) has been proposed and investigated for hole making of CFRP composites. Studies on the effects of machining variables, tool variables, workpiece orientation, and cooling conditions on output variables in RUM of CFRP composites have been investigated. The carbon fiber reinforcement structures of CFRP composites also affect the machining performances and part’s quality. However, there is no reported investigation on studying carbon fiber reinforcement structures’ influences in RUM of CFRP composites. Experiments were conducted for this paper to investigate the effects of carbon fiber reinforcement structure on cutting force, torque, and surface roughness. Three major conclusions can be drawn from the results of this experimental investigation. First, CFRP composites with unidirectional structure led to the smallest cutting force and torque, followed by CFRP composites with plain woven structure and twill woven structure. Second, the surface roughness on CFRP composites with plain woven structure was the smallest, followed by the CFRP composites with unidirectional structure and twill woven structure. In addition, CFRP composites with different reinforcement structures have the same tendencies of output variables with different machining variables.

Owing to its high stiffness and strength, low density, and excellent flexibility, nano-sized graphene oxide (GO) is considered as a competitive material to reinforce metallic materials. Conventional manufacturing methods for GO reinforced metal matrix fabrication include casting and powder metallurgy, both of which demonstrate disadvantages of high reinforcement agglomeration, high cost, and difficulty in fabrication of complex structures. To reduce these problems, it is important to investigate a finely-controlled, cost-saving, and near-net-shaping process for GO reinforced metal matrix manufacturing. Laser additive manufacturing is such a process that mainly includes selective laser sintering / melting (SLS / M) and laser deposition-additive manufacturing (LD-AM). Compared with SLS / M, LD-AM demonstrates parts remanufacturing capability and is capable of fabricating functionally gradient materials. In this investigation, GO reinforced Inconel 718 (IN718) parts, for the first time, are fabricated using LD-AM processes. The effects of GO on flatness, surface roughness, microstructure, microhardness, and wear resistance of LD-AM fabricated GO reinforced IN718 parts are studied. Experimental results show that the introduction of GO is beneficial for enhancing both microhardness and wear resistance but harmful to surface quality of fabricated parts. In addition, the presence of GO has little influence on microstructures.

Carbon fiber reinforced plastic (CFRP) composites were widely used in machinery, automobile, and aerospace industries due to the superior properties of high stiffness, high strength-to-weight ratio, high fatigue resistance, and good wear resistance. In these applications, hole making on CFRP composites was needed for assembly purpose. In different hole making processes, delamination was considered as a crucial issue, leading to premature failure of products. Compared with the conventional CFRP hole making processes (such as twist drilling, milling, grinding, etc.), rotary ultrasonic machine (RUM) had advantages of low cutting force and torque, low surface roughness, and long tool life. Therefore, numbers of researchers worked on RUM processes. The reported investigations mainly focused on the effects of input variables (including machining variables, tool variables, and workpiece properties) on cutting force, torque, surface roughness, and tool life, etc. In addition, effects of cutting tool variables on delamination were also reported. However, there were no reported investigations on effects of machining variables on delamination in RUM of CFRP composites. This investigation, for the first time, reported the effects of ultrasonic power, tool rotation speed, and feedrate on delamination as well as its associated cutting force. Based on the experiments, the results showed that delamination decreased with ultrasonic power increasing, tool rotation speed increasing, or feedrate decreasing. The relationships between cutting force and delamination were also studied.

As the exploitation of oil and gas gradually enters the deep sea, the low-temperature and high-pressure deep-sea environment poses a huge challenge to the flow protection of pipelines (2014a). In this paper, the phase change material sandwich pipeline which uses phase change heat storage and exothermic to maintain the pipeline temperature is taken as the research object, the heat transfer characteristics of the deep-water phase change material sandwich pipe are studied through the combination of theoretical analysis and numerical simulation (2014b). The main contents include: Firstly, through the establishment of two-dimensional and three-dimensional pipe models, analyzed the temperature distribution along the pipeline and the radial temperature distribution of the pipeline under steady oil flow conditions. Secondly, by using transient heat transfer, the effects of phase change material parameters, the proportion of phase change material in the insulation layer, and the difference in the ratio of phase change materials in the insulation layer on the insulation performance are analyzed to obtain the best results. Insulation material and optimal insulation layer layout; finally, the thermal storage and the phase change conditions of the phase-change material sandwich pipe is studied under the re-starting condition. The results show that the effective holding time of the phase change material insulation layer is close to 1.4 times that the non-phase change material insulation layer, and the melting point size has little effect on the insulation material. The closer the phase change material is to the inner tube, the better the insulation effect. This study provide guidance for the design and utilization of phase change material sandwich pipe.

Carbon fiber reinforced plastic (CFRP) composites have many excellent properties, which make them be widely used in many applications. After demolding processes, CFRP composites still need additional machining processes to achieve final shape with desired tolerances. Edge trimming is the first machining process performed on composites after their molding processes. Because of carbon fibers’ abrasive properties as well as CFRPs’ properties of inhomogeneity and anisotropy, CFRPs are regarded as the difficult-to-cut materials. Many problems are generated in traditional machining processes. To reduce and solve the problems, edge trimming using rotary ultrasonic machining (RUM) is reported in this manuscript. This paper, for the first time, makes the comparisons on machining performance (cutting forces, torque, and surface roughness) between edge trimming processes with and without ultrasonic vibration assistance. To better understand effects of ultrasonic vibration on such a process, machining mechanisms are also obtained and analyzed. This paper will provide guides for RUM edge trimming of CFRP composites.

As the market demand becomes more diversified and dynamic, the requirements for manufacturing systems feature a high degree of flexibility, low cost, low volume, and short delivery times. One emerging way for such flexible manufacturing is so-called “factory-in-a-box,” by which production modules are installed in a container and transported by a vehicle. The factory-in-a-box manufacturing poses a unique challenge to manufacturing supply chain network since the ease of supply chain reconfiguration when the vehicle moves to a different production site has become a major concern in addition to transportation cost and delivery time. The supply chain design is further complicated by the fact that it is coupled with subassembly planning in manufacturing, which determines appropriate subassembly modules assigned to suppliers. As such, it is critical to understand the interaction between supply chain network reconfigurability and subassembly planning. This paper develops a model using a set of decision variables to jointly characterize the topology of supply chain network and subassembly planning. A binary nonlinear programming model has been developed for the concurrent optimization of subassembly planning and supply chain network with the consideration of reconfiguration of the supply chain structure. One numerical case study was conducted to demonstrate the proposed model by providing a quantitative guideline of reconfiguring supply chain network when the final production site (on a vehicle) changes locations.

The zirconia toughened alumina (ZTA) parts fabricated by laser engineered net shaping (LENS) process demonstrate problems resulted from poor surface quality. To improve surface quality and to reduce related problems, rotary ultrasonic machining (RUM) process, which combines both grinding process and ultrasonic machining process, has been introduced. In this investigation, the effects of ZrO2 content and ultrasonic vibration on flatness, surface roughness, microhardness, and cutting force in feeding direction of LENS-fabricated ZTA parts have been studied. Results showed that with the ZrO2 content increasing, the flatness value increased, the surface roughness value decreased, and the microhardness value firstly increased then decreased. Compared with LENS-fabricated parts, the parts processed by RUM machine exhibited better surface quality with significantly reduced flatness value and surface roughness value. In RUM process, the introduction of ultrasonic vibration was beneficial for reducing cutting force.

BK7/K9 glass is regarded as a difficult-to-machine material due to its high hardness and high brittleness properties as well as high tool wear rate during machining. Facing to these challenges, an efficient and effective rotary ultrasonic machining (RUM) process, consisting of grinding process and ultrasonic machining process, was provided to process BK7/K9 glass. In this investigation, the effects of ultrasonic power on cutting forces, torque, and edge chipping of surface grinding in RUM of BK7/K9 glass were studied. Results showed that, by introducing ultrasonic vibration to surface grinding process, both cutting forces in feeding direction and in axial direction as well as torque values were reduced. The higher the ultrasonic power was, the lower the forces and torque values would be. Edge chipping, which was detrimental to the qualities of machined slots and would cause high machining cost, was significant reduced with the help of ultrasonic vibration.

Carbon fiber reinforced plastic (CFRP) composites have superior properties, including high strength-to-weight ratio, high modulus-to-weight ratio, high fatigue resistance, etc. These properties make CFRP composites being popular in many kinds of industries. Due to the inhomogeneous and anisotropic properties, and high abrasiveness of the reinforcement in CFRP composites, they are classified as difficult-to-cut materials in surface grinding processes. Many problems (including high cutting force and low machining efficiency) are generated in conventional surface grinding processes. In order to reduce and eliminate these problems, rotary ultrasonic machining (RUM) surface grinding of CFRP composites is conducted in this investigation. Effects of ultrasonic power in different machining levels are of great importance in RUM surface grinding processes. However, no investigations on effects of ultrasonic power in different machining levels are conducted in such a process. This investigation, for the first time, tests the effects of ultrasonic power on output variables, including cutting force, torque, and surface roughness in different machining levels. This paper will provide guides for future research on effects of ultrasonic power in different combinations of machining variables on output variables.

Increased demand on product variety entails a flexible assembly system for product families which can be quickly configured and reconfigured in a responsive manner to deal with various product designs. Development of such a responsive assembly system requires an in-depth understanding of the impact of product family design on assembly system performance. In this paper, the linkage between the product family design and assembly systems is characterized by an assembly hierarchy model, which reflects a hierarchical relationship among all possible sub-assemblies and components, assembly tasks, and material flow among the tasks. Our prior research developed a recursive algorithm to generate all assembly hierarchy candidates for one single product based on its liaison graph without redundancy. These generated assembly hierarchies provide a structure to help efficiently explore optimal assembly system designs with reduced computational load. In this paper, the application of the assembly hierarchy generation algorithm will be extended to a product family by developing joint liaison graph model. Taking the advantage of the modular design of the product family, we proposed a concept of multi-level joint liaison graphs to overcome the computational challenge brought by assembly hierarchy generation for joint liaisons. Two case studies were conducted to demonstrate the algorithm.

Controlling surface shape variations plays a key role in high-precision manufacturing. Most manufacturing plants rely on a number of multi-resolution measurements on manufactured surfaces to evaluate surface shapes and resultant quality. Conventional research on surface shape modeling focused on interpolation and extrapolation of spatial data using sampled measurements based on presumed spatial relationship over entire surface locations. However, the prediction accuracy is heavily restricted by the density of sampled measurements, preventing cost-effective evaluation of surface shape in high precision. New opportunities emerge for cost-effective high-precision surface manufacturing when the industry begins to extensively collect in-plant process information. This paper explores the opportunity by investigating strategies for fusing surface measurement data with multiple process variables. The fusion is achieved by characterizing the relationships between surface height and process variables using (1) linear regression based co-Kriging and (2) fuzzy if-then rules as well as considering spatial correlations. Under (3) Bayesian sequential updating frameworks, a generic surface variation model is updated sequentially using different process information. Case studies are conducted for comparisons and demonstrate the advantages of the fuzzy inference based spatial model.

Commercially pure titanium (CP-Ti) attracts a large number of attentions in biomedical, astronautical, and auto industrial areas due to its superior properties of good biocompatibility, excellent corrosion resistance, and high strength-to-weight ratio. Comparing with the conventional manufacturing processes (such as casting along with machining), laser additive manufacturing (LAM), mainly including selective laser sintering/melting (SLS/M) and laser engineered net shaping (LENS), has many advantages, such as complex shaped parts producing, more capability of shorter design-to-market time, energy consumption reducing, etc. It was reported that SLS/M has been successfully used in fabricating of CP-Ti components. Comparing with SLS/M processes, LENS has many advantages, including lower labor intensity, higher fabrication efficiency, and more capabilities for parts repairing and rebuilding. It is reported that LENS process was only used in CP-Ti coating and porous parts fabrication, there are no reported investigations on CP-Ti three-dimensional (3D) solid parts using LENS process. The investigations in this paper are going to conduct preliminary studies on effect of fabricating variables. In order to evaluate powder efficiency and parts’ quality, heights of fabricated parts and hardness on the top surface of the parts will be tested.

Follow the holism concept of traditional Chinese medicine (TCM), the pulse wave system is considered as an entire system of life energy propagating within the blood in the form of wave. A corresponding mechanics model is established, showing that a pulse phenomenon includes both the blood flow and the energy wave propagating within the blood. The former is a visible matter-flow with lower velocity, while the latter is an invisible energy-flow with much higher velocity, corresponding respectively to the “blood” and the “Qi” in TCM. Moreover the method of inverse analysis in the wave propagation theory is generalized to deal with the pulse wave signals. Once anyone form of pulse wave, e.g. the pressure wave, is measured, the other forms of pulse wave such as the particle velocity wave, the specific volume wave and the internal energy wave can all be deduced, and finally the constitutive equation of the system can be determined. The propagating characters of pulse wave are mainly determined by the constitutive equation of the system, which may correspond to the “body constitution” in TCM. Some intrinsic relationship may exist between them and should be further investigated.

Unsteady numerical simulation was performed with both single blade passage model and 4-blade passage model with ANSYS CFX software. Grid independence and turbulence model were verified by comparison with the experimental results. By transient numerical simulation, the time dependent parameters in tip area were analyzed. The typical vortex region was found near the blade suction side by relative vorticity strength. The pressure distributions at 90% span of the blades were compared. The mixing of tip leakage flow and the main flow was studied. 4-blade passage model simulation can capture circumferential difference in the centrifugal impeller. Periodic flow structures can be observed. Frequency analysis was performed on the pressure fluctuation in the blade tip. The effectiveness of 4-blade passage model in capturing the unsteady flow structures in the centrifugal impeller was demonstrated. The conclusion can provide guidance for stability analysis on the centrifugal impeller.

Abnormal wall thinning of elbows were detected in the economizer at waste heat boiler system. In the failure analysis, material analysis, metallographic examination, macro- and microstructure analysis and composition analysis were conducted. We analyzed the causes and mechanisms of abnormal wall thinning. The failure causes were found to be sulfuric dew point corrosion. Finally, corresponding countermeasures were suggested.Copyright © 2015 by ASME

Currently the reliability of rotating equipments in typical petrochemical plants, such as turbo machineries, centrifugal compressors, reciprocating compressors, fans, pumps, etc. plays an important role in a long-term operation of the plants. The important tasks for management technology research of rotating equipments are to build a new type of maintenance management platform and take an advantage of the reliability analysis technique for fault diagnosis and maintenance strategy optimization. In this paper, firstly, the development of maintenance management technology in China and overseas was introduced. The problems of traditional reliability analysis techniques were pointed out. Secondly, the key technologies of the new type of maintenance management system were introduced. Furthermore, the structure and work process of the new type of maintenance management system were proposed. Finally, the key contents and functions of this system were given.Copyright © 2015 by ASME

Torsional vibration control of a rotating mechanical system which incorporates a Hooke’s joint is investigated by pole assignment techniques. Linearized analytical models for the torsional system are established for the purposes of controller design. The resulting two-degree-of-freedom rotational system which contains time varying coefficients is parametrically excited due to an inherent non-linear velocity ratio across the Hooke’s joint. The controller is designed via full state feedback and observer based feedback in the transformed domain, using Lyapunov transformation. This transformation reduces the original time-varying system to a form suitable for controller design. A dual-system approach is employed to calculate the observer gain matrix for the time-varying system. Numerical simulation results show that the proposed control method is effective for suppressing torsional vibration of a Hooke’s joint driven system.Copyright © 2014 by ASME

A life management approach on in-service device in refining unit was presented in this paper. By means of this method, corporate resources can reasonably be allocated. And a long-term operation of the equipment can be ensured. First, according to the type of the equipments, statistical analysis of equipments was carried out to obtain the life stages: early life stage, middle life stage, late life stage, extended life stage. Then, based on damage mechanism residual life of the equipments was calculated out. At the same time, the recommended maintenance cycle was given. If the operational life of the equipments cannot meet the expected life, the cause analysis should be done. The subsequent processing steps, such as maintenance, repair and renewal were proposed. Next, the equipments in the corporation were classified. For different class of the equipments, the different management methods were given. Finally, a re-evaluation of life was conducted.Copyright © 2014 by ASME

This paper presents a method to reduce surface variation in face milling processes based on high-definition metrology (HDM) measurements. Our previous research has found and established the relations between surface variation patterns, cutting forces, and process variables. The findings revealed that varying feed rate and proper cutter path planning are the most feasible and cost-effective approaches for reducing variation along the feed direction. This paper explores the HDM data pattern that reflects surface tilting along the circumferential direction induced by cutter-spindle deflection. It is found that such a tilt is caused by the cutting load imbalance between the two sides of the cutter path. Cutting force modeling is then conducted to estimate such cutting load imbalance. Based on the model, a cutter load balancing algorithm is developed to reduce surface variations by adjusting cutter path and/or feed rate. A case study based on a cutting experiment is conducted to demonstrate that the proposed method can improve the surface flatness by 25%.Copyright © 2014 by ASME

By application of CFD codes, 3D complex flow field and temperature field in the transfer canal are simulated. It indicates that there is obvious cross-flow in the complex flow path of spent fuel container, and the natural circulation flow brings an inhomogeneous heat-transfer condition to the spent fuel assembly. A model of typical unit of canal is built, and local flow field and temperature field are analyzed with CFD code. The results of thermal hydraulics analysis could be a good reference for nuclear safety research on spent fuel assembly. Considering a conservative operating condition, a case with conservative boundary conditions is investigated by CFD code with 3D model. The result shows that fuel rods in the local region, which are in the container upside and far from holes of wall and roof, get the worst cooling effect, and even maybe boiling occurs in clad surface. Based on the thermal-hydraulics analysis, optimized mechanical designs of container are suggested, the new design would optimize the local flow field, and increase the flow velocity of water, to construct more unhindered convection there, as a result, make spent fuel rods in the bad cooling region get better cooling.Copyright © 2013 by ASME

The steady-state phase distribution and the structural parameters have been taken as the input for the nuclear physics calculation in the ADS windowless spallation target. The distribution of the extreme large power density of the heat load is imported back as the source term in the energy equation. Then temperature distribution is obtained based on the flow process and heat transfer. The preliminary results show that the temperature distribution reaches the steady-state and its shape is like the broken wings of the butterfly. This is very important for the further design and optimization of the ADS windowless spallation target. So the two-way coupling simulation of the heat transfer process is successfully performed between the computational fluid dynamics and the nuclear physics simulation.Copyright © 2013 by ASME

A large-scale earthquake simulation experiment about the unanchored cylindrical steel liquid storage model tanks has been completed. The self-vibration characteristics of the model tanks with liquid inside were investigated based on the experimental data of the acceleration dynamic response. The seismic table test, the analysis methods are designed and conducted, and experimental results of the model tanks were carefully measured. Furthermore, ANSYS finite element software was used to simulate and calculate the low order natural frequency and fundamental frequency of the model tank systems according to the national design standard. The reasons for the existence of consistency and differences among the results obtained from experiments, numerical simulation and national design standard were discussed.Copyright © 2013 by ASME

Inorganic materials and organic salts are usually used as phase change materials (PCMs) for thermal energy storage. Some of these materials have high latent heat of fusion; however one major drawback of these materials is the low thermal conductivity, which limits the rate of charging and discharging process. In this paper, we studied metallic alloys (eutectic alloys or alloys with a narrow melting temperature range) as phase-change materials, which have both high thermal conductivity and high latent heat of fusion. A formula was presented from entropy change to predict the latent heat of fusion of metallic alloys. We found that the latent heat of fusion of alloys can be expressed from three different contributions: the latent heat from each element, the sensible heat, and the mixing entropy. From the theory we also showed that latent heat of fusion could be greatly increased by maximizing the entropy of mixing, which can be realized by introduce more elements in the alloys, i.e., form ternary alloys by adding elements to binary alloys. This idea is demonstrated by the synthesis and measurement of the binary alloy 87.8Al-12.2Si (at%) and ternary alloy 45Al-40Si-15Fe (at%). The metallic alloy is synthesized by hot pressing method. The latent heat of fusion of 45Al-40Si-15Fe (at%) is about 865 kJ/kg with melting temperature from 830 °C to 890 °C from the differential scanning calorimetry (DSC) measurement, comparing with 554.9 kJ/kg and 578.3 °C for the binary alloy 87.8Al-12.2Si (at%). From the binary to the ternary alloy, the contribution to the latent heat from mixing entropy increases by 17%.Copyright © 2013 by ASME

The fitness-for-service assessment is widely used to demonstrate whether identified defects or in-service deterioration threaten the structure integrity of the pressure equipment. This article introduces the development of the Chinese national safety assessment standard. The assessment procedure and assessment techniques of current Chinese national safety assessment standard GB/T 19624-2004 are demonstrated, and the improvement is proposed. In order to maintain availability of aging equipment and enhance the long-term economic performance of in service pressure equipment, a new Chinese national safety assessment standard system is methodology proposed based on the analysis of some international structure integrity procedures or standards. A new national standard fitness-for-service which focuses on the evaluation of in-service damage and degeneration will be established while GB/T 19624 is applicable for general defects.Copyright © 2013 by ASME

Equipment integrity management technology is to take a combination of technical improvement measures and standardizing the equipment management, to ensure the operating status integrity for critical equipments in the entire device. It is a device risk management philosophy. Equipment integrity management technology is playing a more and more important role in raising the standard of business management, reducing the cost of production, ensuring the long period safe operation of plants. In this paper, firstly, the concept of equipment integrity management was provided. Secondly, the content and implementation of equipment integrity management system was given. Furthermore, an Equipment Integrity Management System Based on Predictive Maintenance built by China Special Equipment Inspection & Research Institute (CSEI) is introduced. The scheme and the thoughts of the system are introduced in details. And the characteristics and functions of the proposed system have been demonstrated.Copyright © 2013 by ASME

In multistage manufacturing processes, the machined surface shape of a part changes as it goes through each stage. Process monitoring at multiple stages is necessary for root cause diagnosis and surface variation reduction. However, due to measurement time and capacity constraints, it is challenging to collect sufficient surface measurements at all intermediate stages for monitoring. This paper proposes a functional morphing based algorithm to monitor the surface variation propagation using end of line multi-resolution measurements supplemented with low resolution measurements at intermediate stages. The surface changes over multiple stages are captured by a functional morphing model which integrates geometric transformations with engineering insights. The model estimates a morphed surface prediction at an intermediate stage of interest using end-of-line surface measurements. This morphed surface is combined with the low-resolution measurements at that stage to improve the surface prediction accuracy. The model can be further improved by incorporating the effects of correlated process variables. Based on the model, abnormal surface variations can be detected and located by a single-linkage cluster monitoring algorithm as developed in our previous work. The case study of a two-stage machining process demonstrates that the method successfully monitors multistage surfaces using reduced measurement resolution at intermediate stages.Copyright © 2013 by ASME

Using high-hydrogen fuels in industrial gas turbines is an effective way to achieve near-zero carbon emission power generation. Lean premixed combustion can effectively reduce NOx emission. However, due to the strong flashback and auto-ignition tendencies during fuel-air mixing, it is a challenge to use lean premix combustion mode of high hydrogen fuels under gas turbine operation conditions. An innovative conceptual design of arrayed-vanes premixer was proposed to achieve safe and uniform mixing of fuel and air. Inside the arrayed-vanes premixer, a cascade of mixing vanes is arranged in the axial annular air flow passage. Fuel-air mixing and flow field stretch are improved and well controlled by the arrayed vanes. The conditions of auto-ignition and flame stabilization inside the vanes are unsatisfied. Meanwhile the upstream flow disturbance will be inhibited by the arrayed vanes, which benefits combustion stability. The arrayed-vanes premixer was designed and its flow field was numerically simulated under the operation condition of F class gas turbine combustors. The flow and fuel-air mixing behavior was analyzed and compared with a typical swirl-based premixer now widely used in DLN combustors of F class gas turbines. The results show that the non-uniformity index of fuel concentration distribution at the exit plane of the arrayed-vanes premixer is 50% lower than that of the swirl-based premixer. The responses of flow field at the exit plane to the inlet flow disturbance was calculated and compared for the two types of permixer. The inlet flow disturbance includes the velocity distortion and the oscillation of the pressure. The results show that the arrayed-vanes premixer absorbs and damps the inlet flow disturbance better than the swirl-based premixer. And it exhibits highly monochromatic characteristic through the acoustic signature analysis. Furthermore, the tendencies of auto-ignition and flashback were investigated by examining the flow field and the flammability of hydrogen. The results show that there is a low risk of auto-ignition or flashback due to the short residence time and the high discharge velocity. The present study indicates that the arrayed-vanes premixer achieves ultra uniform fuel-air mixing, good adaptability to inlet flow disturbance and anti auto-ignition and flash back, which is benefit to DLN combustor designed for high-hydrogen fuels. This design will be possibly used in DLN combustors after future developments.

The ability to forecast equipments failure is vital to reducing maintenance costs, operation downtime and safety hazards. In this paper, first, RBI application status in China is discussed. Through analyzing the existing condition of RBI technology on equipments, the necessary of dynamic risk management based on RBI is pointed out. After that, the development Status of RBI Software in China is put forward. Considering the shortcoming of these pieces of software, Static Equipment Predictive Maintenance Intelligent Management System is built by China Special Equipment Inspection & Research Institute (CSEI). The system integrates 8 core modules, including corrosion monitoring and management module, the remaining life evaluation calculation module, damage mode discrimination module, material upgrade management module, the analysis and prediction of erosion areas of the pipes module, risk analysis and dynamic updates module, safe operation of warning based on GIS module, the generation of the inspection scheme module. It provides timely the equipments operation condition information for the plant management departments, realizes the combination with plant management and condition monitoring. Finally, the scheme and the thoughts of the system are introduced in details. And the characteristics and functions of the proposed system have been demonstrated.Copyright © 2012 by ASME

The cracking reason of ethylene oxide evaporator in one petrochemical company was studied by means of metallographic examination, fracture analysis of the failure samples, energy spectrum analysis of the corrosion product and so on. The results showed that the microstructure near the welding heat affected zone was sensitized due to the welding process, which led to the precipitation of chromium carbide along grain boundary and the lack of Cr precipitation near grain boundary. Furthermore, under the combined action of the stress and corrosive medium, the intergranular stress corrosion cracking took place in welding heat affected zone of ethylene oxide evaporator.Copyright © 2012 by ASME

In recent years, the coal chemical industry project which can replace the petrochemical products is an investment hot spot. The Syngas-purification Unit is a main part of the coal chemical industry. Its role is: purify the syngas obtained from the gasification reaction (absorb the hydrogen sulfide and carbon dioxide). Yet, there is no research and the summary about the corrosion, failure mechanism and risk level of this unit. In this paper, the syngas-purification equipment of Sinopec Qilu Corporation were quantified by RBI analysis, and investigated the corrosion of the syngas-purification equipment, and discussed the device typical failure mechanism, and proposed the recommendations of the corrosion and on-line monitoring, etc. In last few years, the production of clean energy and alternative oil chemical products from the new coal chemical projects become of great interest[1]. Because the purification of the syngas is necessary, the syngas-purification unit is one of the main equipment of coal chemical industry. In the country, there is no systematic study or summary about the corrosion, failure mechanism and risk level of the device. The RBI analysis of the Syngas-purification unit is necessary, and has some guiding significance for the routine maintenance and periodic inspection of the device. This paper introduces the corrosion and the typical failure mechanism of Syngas-purification unit followed by the risk assessment results. Then the paper puts forward the suggestion on line monitoring.

This paper develops a face milling planning method to reduce surface height variation based on the high definition metrology (HDM). HDM provides high-lateral resolution data over an area up to 300×300 mm2. The measurement results on production engine head surfaces reveal a strong correlation between the surface height and the effective material removal rate (eMRR) along the cutting path. Such a correlation can be explained by a cutting force model which verifies that the surface variation is attributed to the axial cutting force variations, and the axial force is proportional to the eMRR. This paper proposes a machining algorithm that minimizes eMRR to reduce the cutting force variation by altering the feed rate and cutter path, thereby reducing the surface height variation. The varying feed approach can eliminate one surface pattern in the case study without significantly changing the cycle time. The optimized cutter path results in 25% reduction in zone flatness on the other surface pattern. This improvement demonstrates the potential of the eMRR based approach in attaining cost-effective high-precision machining. The method may also be extended to a wide range of face milling applications.

High-definition metrology (HDM) systems with fine lateral resolution are capable of capturing the surface shape on a machined part that is beyond the scope of measurement systems employed in manufacturing plants today. Such surface shapes can precisely reflect the impact of cutting processes on surface quality. Understanding the cutting processes and the resultant surface shape is vital to identifying opportunities for high-precision machining process monitoring and control. This paper presents modeling and experiments of a face milling process to extract surface patterns from measured HDM data and correlate these patterns with cutting force variation. A relation is established between instantaneous cutting forces and the observed dominant patterns along the feed and circumferential directions. Potential applications of such relationship in process monitoring, diagnosis, and control are also discussed.Copyright © 2012 by ASME