Prognostics and health management design for rotary machinery systems—Reviews,methodology and applications

Much research has been conducted in prognostics and health management (PHM), an emerging field in mechanical engineering that is gaining interest from both academia and industry. Most of these efforts have been in the area of machinery PHM, resulting in the development of many algorithms for this particular application. The majority of these algorithms concentrate on applications involving common rotary machinery components, such as bearings and gears. Knowledge of this prior work is a necessity for any future research efforts to be conducted; however, there has not been a comprehensive overview that details previous and on-going efforts in PHM. In addition, a systematic method for developing and deploying a PHM system has yet to be established. Such a method would enable rapid customization and integration of PHM systems for diverse applications. To address these gaps, this paper provides a comprehensive review of the PHM field, followed by an introduction of a systematic PHM design methodology, 5S methodology, for converting data to prognostics information. This methodology includes procedures for identifying critical components, as well as tools for selecting the most appropriate algorithms for specific applications. Visualization tools are presented for displaying prognostics information in an appropriate fashion for quick and accurate decision making. Industrial case studies are included in this paper to show how this methodology can help in the design of an effective PHM system.     

Dynamics of mechanical systems with Coulomb friction,stiction, impact and constraint addition-deletion—III Spatial systems

The general theory and computational algorithms presented in Part I of this paper are implemented for spatial systems. A spatial Cartesian generalized coordinate formulation is used to obtain the explicit form of equations and transformations that are derived in Part I. Algorithms are implemented in the DADS 3D Computer Code, which is used to solve examples in this part of the paper.     

Drilling of woven glass fiber-reinforced plastic—an experimental and finite element study

Drilling in woven fiber-reinforced plastics is a well-known practice in modern-day manufacturing. The high fracture toughness of woven fiber-based composites over unidirectional counterparts is increasing demand in aviation and electronics industries. Hence, failure of these materials at harsh environments is a matter of concern. Very few numerical studies on drilling of these composites have been carried out; hence, the present scope may be considered as a trial de novo. Delamination was studied in the present work at different feed–speed combinations. Drilling responses were estimated using finite element as a numerical simulation tool. An equivalent elastic macromechanical model was assumed for the woven composite workpiece. A 3D drill bit was modeled using commercial CAD package Pro-Engineer and Ansys Autodyn was used as the solver environment. The simulation and validation experiments were carried out at planned feed–speed combinations. The effect of process parameters on exit and entry delamination is also documented. The thrust determined by finite element techniques showed good prediction with the experimental results.     

Contributions in medical needle technologies—Geometry,mechanics, design,and manufacturing

This article summarizes the contributions in research on tissue cutting with needles. The geometry of the needle's cutting edges was analytically defined and expressions for the inclination and rake angles of hollow and solid needles and trocars have been derived. Based on the semi-empirical method, finite element model and the fracture mechanics approach, force models of needle insertion were developed. The relationship between the needle's tip geometry and insertion force was established and used in several applications. It was shown, for example, that the cutting edge of the lancet needle can be optimally designed to minimize insertion force or bevel length. The cutting mechanics in rotary needle insertion was investigated along with the exploration of improvements of needle biopsy performance by decreasing the needle cutting and friction forces. The deflections of the needle during insertion were measured to develop a strategy for guiding the needle to the right position in brachytherapy and drug delivery. From an overall perspective, fundamental advances and application problems based on the cutting mechanics of soft tissue for needle were highlighted to lay the foundation for developments of biomedical device and improvements of healthcare procedures.     

Comments on “enhancement of an efficient liveness-enforcing supervisor for flexible manufacture systems”

Region theory can synthesize maximally permissive supervisors by solving a set of inequalities based on the marking/transition-separation instances (MTSIs). It is infeasible to solve these inequalities for either a sizable net or a small net with a sizable initial marking. Huang et al. [1] propose novel crucial MTSIs to reduce the number of MTSIs. Experimental results show that the proposed control policy is the most efficient algorithm among the closely related approaches. One example shows that it not only reaches all live states but also employs fewer control arcs than that by Li et al. Huang et al. offer no hints on why it employs fewer control arcs. This paper develops theory to explain the physics behind.     

Dynamics of mechanical systems with Coulomb friction,stiction, impact and constraint addition-deletion—I theory

This paper presents a unified formulation of the equations of motion for constrained multibody systems with Coulomb friction, stiction, impact and constraint addition-deletion. Cartesian generalized coordinates are employed, and basic variational principles of mechanics are used for derivation of the governing equations of each of the physical modes of behaviour considered. It is shown that the apparently different physical phenomena considered are in fact closely related mathematically. Computational algorithms to implement the formulations are presented in matrix form in Part I of the paper and are implemented for planar and spatial systems in Parts II and III.     

A study on the energy efficiency improvement of greenhouses — with a focus on the theoretical and experimental analyses

Most greenhouses in Korea are made according to European weather conditions, which leads to very low solar energy efficiency under the domestic weather conditions. Thus, greenhouses in Korea should be adapted to the regional weather conditions to improve their energy efficiency. This paper investigates the current greenhouses in Korea. It also analyzes the problems arising from the greenhouses and offers alternatives for improving their energy efficiency based on measurements and a theoretical analysis. The elements of greenhouses were also investigated. When using a partially non-transparent insulation with heat storage mass between the indoor and outdoor air, the temperature difference became greater than 20°C during the daytime and greater than 5°C during the night, which will reduce the cost of fossil fuels.     

Comments on “Efficient deadlock prevention policy in automated manufacturing systems using exhausted resources”

As reported by Hu and Li (International Journal of Advanced Manufacturing Technology 40:566-571, 2009), in order to design liveness-enforcing supervisors for automated manufacturing systems (AMS), a deadlock prevention policy was proposed based on the exhausted resources. The proposed policy exploits a special structure of Petri nets for the liveness of a specific system. In order to show the applicability of this method, two examples were considered. One of the examples involves an AMS with a large-state space. Unfortunately, the liveness-enforcing supervisor containing seven monitors (control places) computed as reported by Hu and Li (International Journal of Advanced Manufacturing Technology 40:566-571, 2009) to enforce liveness on this system does not provide a live behaviour. This paper reports this fact.     

Dynamic performance of a cable with an inspection robot — analysis, simulation, and experiments

A special cable inspection robot is designed to inspect automatically the cables of a cable-stayed bridge. The free vibration equation of the cable-robot system is derived firstly to study the dynamic characteristics and safety performance of the system. Then, the effect of the robot on the cable natural frequency is discussed, and the dynamic response equation when a robot is climbing at a constant speed is deduced. Furthermore, the effect of the cable vibration on the robot’s climbing ability is studied. The natural frequency characteristics of the robot are analyzed and optimized to avoid the resonance between the cable and the robot, using a finite element model. Additionally, dynamic cable responses are simulated under different conditions wherein the robot mass are 10 and 200 kg, and the speeds are 0.2 and 0.3 m/s, respectively. At last, to demonstrate further the dynamic characteristics of the cable-robot system experimentally, cables are set up on the Junshan highway bridge over the Yangtze river. Similar experimental models of these cables are constructed, and vibration experiments are conducted to validate the theoretical calculation. The results show that a light robot has little effects on the cable vibration amplitude and vibration acceleration; this confirms the safety of the cable.     

Production, identification, and use of nanocarbon in vehicles’ frictional systems

Nanocarbon production by the decomposition of hydrocarbon gas at atmospheric pressure is considered; no catalysts are employed. The role of nanocarbon in improving the antifrictional, antiwear, and antiscratch properties of lubricants is studied.     

Experimental research and analysis of three-finger micro-tweezers

1Introduction Withthedevelopmentofmicro electro me chanicalstructure(MEMS),grasping,manipu latingandassemblingofmicroobjectsarequite fascinating.Newtoolsforthesepurposeshave beendevelopedrapidly.However,mostofthese researchesarefocusedontwo fingermicro tweezers[1～3].Thestabilityandapplicationof two fingermicro tweezersinmanipulationand assemblyareverylimitedingraspingsphere,co lumnarorcomplicatedmicroobjects[4].Inorder tograspparticlesmoresteadily,carbonfibers areusedtocreatethethreefingers…     

Influence of milling on surface integrity of Ti6Al4V—study of the metallurgical characteristics: microstructure and microhardness

The quality of titanium alloy parts in the aeronautical field demands high reliability, which is largely related to surface integrity. Surface integrity is generally defined by three parameters: a geometric parameter, a mechanical parameter and a metallurgical parameter. The present article addresses the influence of milling on the metallurgical parameter for a surface milled in Ti6Al4V material, focusing in particular on the microstructure and microhardness. Observation of the machined surface from a macroscopic perspective highlight an orange peel phenomenon. This effect is the combined result of redeposition and crushing of the milled material. No plastically deformed layer or lengthening of the grains was observed under the milled surface. As far as microhardness is concerned, a slightly softened region was observed under the milled surface. A diffusion of vanadium from the β phase to the α phase was also noted, but with no change in microstructure.     

Organic optoelectronics ： materials, devices and applications

1Introduction Beforethediscoveryofelectricallyconduc tivepropertiesthroughdoping,polymerswere widelyusedaselectricalinsulatorsduetothesu periorinsulatingpropertiestheyexhibited.In1977,thediscoveryofthefirsthighlyconductive polymer,chemicallyandelectrochemicallydoped polyacetylene,wasreported[12].Thediscovery ofdopedpolyacetylenehasopenedanentirenew fieldforpolymersandorganicmaterialsintheir applicationstobothconductorsandsemiconduc tors.Althoughtheinitialemphasiswasonthe conductivepropertiesob…