A stationary apparatus of magnetic abrasive finishing using a rotating magnetic field

The precision and efficient surface finishing processes have recently become highly demanded by industries. Magnetic Abrasive Finishing (MAF) is studied as an effective method for a surface finishing. The MAF process can produce a smoothly finished surface by means of relative motion between a magnetic abrasive and the workpiece surface. To successfully finish the surface, it is critical to control the magnetic abrasive motion on the workpiece surface. The magnetic abrasive is suspended in a magnetic field generated by the electromagnets located underneath the workpiece. In this paper, a finishing system using a rotating magnetic field, with stationary electromagnets and workpiece, has been developed for the surface finishing. This system utilizes a rotating magnetic field to control the force and dynamic motion of the Magnetic Abrasive Particles (MAPs). This approach eliminates any mechanical motion of the electromagnets and the workpiece, to make the system more controllable, reliable, and cost-effective. The mechanism and characteristics of this system are summarized in this paper. The finite element method with COMSOL Multiphysics^® Simulation software was used to analyze the magnetic flux distribution, magnetic flux density, and magnetic forces in the working area.

     

A NEW LOW-REYNOLDS-NUMBER TURBULENCE MODEL FOR PREDICTION OF TRANSITION ON GAS TURBINE BLADES

A new low-Reynolds-number (LRN) turbulence model is developed for the prediction of transition. In the definition of the LRN functions in the new model, only local quantities are used so that the model potentially can be used for a wide range of flows. The performance of the new model in predicting boundary layer transition is demonstrated by reference to a wide range of experimental data for boundary layers with free-stream turbulence and pressure gradient.     

Constant rate of strain consolidation of resedimented Class F fly ash

Although the utilization of fly ash has increased over the last several decades, more than 60 percent of the fly ash produced each year in the United States continues to be disposed in ash ponds and landfills. Many disposal facilities are now or will soon be filled to their design capacity. As a result, there is an increasing interest in reclaiming existing fly ash pond areas. One possible use is as foundation for new disposal facilities, parking lots or even buildings. Before these facilities could be constructed on former fly ash ponds, the response of the fly ash to imposed loads must be determined. In the current study, constant rate of strain (CRS) consolidation tests as per ASTM D4186 were performed on medium-scale resedimented Class F fly ash samples. The compressibility behavior of the fly ash tested was found to be similar to published results for inorganic sandy silt and poorly graded sand. The value of secondary compression coefficient was found to be small.     

A new multi-objective approach in order to balancing and sequencing U-shaped mixed model assembly line problem: a proposed heuristic algorithm

The International Journal of Advanced Manufacturing Technology - Mixed model production is the practice of assembling different and distinct models in a line without changeovers responding to...     

Scale effect on the behavior of geocell-reinforced soil

Existing studies confirmed that the response of geocell-reinforced beds is directly affected by contributory factors, including soil's grains, geocell's characteristics, and surface loading geometries. In this paper, a series of plate load tests has been carried out for the further understanding of the behaviour of geocell-reinforced soil. Four different soil grains sizes, two different geocell's opening sizes and three different loading plate sizes were the considered variables. During the tests, the applied loading and soil surface settlements were recorded to evaluate the systems' response. As it was expected, the geocell-reinforced soil exhibited higher bearing capacity than the unreinforced status, up to 524%. The results further focused on the important role of scale effect on the response of reinforced foundations. The optimum nominal cells size of geocells was obtained about 15 times of medium grain size of soil. Also, it was found that in order to obtain the highest reinforcement benefits, the footing's width should be in the range 13–27 (20 in average) times of medium grain size of the backfill. Finally, to provide more stable and reliable geocell-reinforced backfill, it is recommended that the cells size of geocells should be selected smaller than 0.67 times of footing width.     

Design and analysis of a polymeric photo-thermal microactuator

This paper presents the modeling, simulation and characterization of a photo-thermally actuated bent-beam microactuator. The microactuator consists of a single polymeric layer (SU-8) fabricated with conventional photolithography techniques. The principle of operation is based on the thermal expansion of the bent-beams that absorb the required heat by laser illumination. This provides an effective non-contact actuation mechanism by laser beam focusing. A theoretical model of the microactuator is derived and verified by finite element simulations and experiments. The experiments show that a bent-beam actuator with 800 m long, 40 m wide, 100 m thick and 6° bent arms achieves a tip displacement of 16 m with an incident laser beam of 50 mW power while keeping the maximum temperature less than 125 °C. This study merges the advantages of photo-thermal actuation with practicality of polymeric materials. To verify the effectiveness of the proposed microactuator mechanism, a microgripper with bent-beam actuator was fabricated and characterized. It has been demonstrated that the opening of the gripping fingers can be increased from 20 to 50 m for a microgripper with 1000 m long fingers with an incident laser power of 50 mW. This polymeric microgripper with photo-thermal actuation provides a way of gentle grasping with electrical isolation, high repeatability and low temperature operation that is particularly crucial for biomanipulation applications. The polymeric photo-thermal actuator described in this study expands the practical applications of microactuators/microgrippers which are critical tools in bioMEMS devices.