Lower Thrust Force Research Articles

Influence of Armature Windings Pole Numbers on Performances of Linear Permanent-Magnet Vernier Machines

Linear permanent-magnet vernier (LPMV) machine has attracted more and more attention for several advantages including high power density and low cost. Both magnets and windings are located on the short mover, while the long stator is only consisting of iron, which is very suitable for long stroke applications. This paper investigates the influence of armature windings pole-pair numbers on the electromagnetic performances of LPMV machine by using an analytical method based on the finite element. The aim of this paper is to make a comprehensive comparative study of the machine with different armature windings pole-pair numbers while keeping slot number as a constant, select the topology of high performances and recommend suitable application areas. The performances of machines with the armature windings pole-pair numbers $P_{\mathrm {w}}= 1$ , 3, 6 are analyzed in detail. Finally, a new modular LPMV machine with $P_{\mathrm {w}} = 6$ , which possess higher thrust force, lower thrust force ripple, and high fault-tolerant capability, is prototyped and experiments are conducted for validation.

Experimental Investigation of Bubble-Mixed Cutting Fluid Delivery for Micro Deep-Hole Drilling

In drilling, chip-clogging results in increased drilling temperature, excessive tool wear, and poor hole quality. Especially, in microdrilling, low rigidity of the tool and inability of cutting fluid to penetrate narrower tool–workpiece interface significantly reduce the drilling performance. A novel bubble-mixed cutting fluid delivery method proposed in this research aims toward achieving a high-performance micro deep-hole drilling process with a significant reduction in the consumption of cutting fluid. Experimental results show that the bubble-mixed cutting fluid delivery method achieves lower thrust force during drilling, higher drilled depth before tool breakage, and lower dimensional and circularity errors when machining deep holes in comparison with dry cutting or conventional flood delivery method. It is also found that the smaller-sized bubbles effectively penetrate the tool–workpiece interface during the drilling producing deeper holes by better chip evacuation and cooling.

An experimental study on the effects of various drill types on drilling performance of GFRP composite pipes and damage formation

Drilling is the most commonly used machining operation among others for assembly applications. The necessity of this operation has come to the forefront in composite materials that are becoming widespread nowadays. In this study, drilling performance of glass fiber reinforced plastic (GFRP) composite pipes used in many sectors such as natural gas transmission lines, pressurized sewer lines, industrial waste transmission, defense industry, and construction industry was investigated. The GFRP pipe was produced by filament winding method with a winding angle of ±55°. Different drill types (conventional twist drill, brad and spur drill, and brad center drill) with a drill diameter of 4 mm were utilized for drilling the pipe and the effect of drill type on the drilling performance was investigated. Drilling tests were performed at a constant 5000 rpm spindle speed and six different feed rate parameters (25, 75, 125, 175, 225, and 275 mm/min). Thrust forces generated during drilling were recorded and after the drilling operations, hole exit surface damage, and borehole surface damage were examined by a digital microscope and scanning electron microscope (SEM). Results showed that the brad center drill produced lower thrust forces while the twist drill generated higher thrust forces. The severity of damages could vary depending on the tool geometry and feed rate. Especially, at lower feed rates, conventional twist drill results with increased delamination and uncut fibers as compared with other drills. The brad center drill presents better performance since it generates fewer damages. Also, it is observed that these damages formed in the winding angle direction (orientation).

Comparative study on drilling effect between conventional drilling and ultrasonic-assisted drilling of Ti-6Al-4V/Al2024-T351 laminated material

This paper investigates the performance of ultrasonic-assisted drilling (UAD) in machining of Ti-6Al-4V/Al2024-T351 laminated material by using DEFORM-3D finite element method. The effectiveness of two key parameters, frequency and spindle speed, is discussed. The purpose is to explore the effect of UAD on machining performance, to compare it with conventional drilling (CD) and to prove that the UAD technique could achieve better hole quality. To be more specific, the following aspects are taken into account: chip morphology, layer delamination, thrust force, temperature change, and effective stress. The result shows that UAD can produce fragile chips, smaller layer delamination, lower thrust force, larger maximum temperature, and lower effective stress. Both frequency and spindle speed have influence in their own way on machining process.

Dynamical structures in a low-thrust, multi-body model with applications to trajectory design

A key challenge in low-thrust trajectory design is generating preliminary solutions that simultaneously detail the evolution of the spacecraft position and velocity vectors, as well as the thrust history. To address this difficulty, dynamical structures within a combined low-thrust circular restricted 3-body problem (CR3BP-LT) are explored as candidate solutions to seed initial low-thrust trajectory designs. Furthermore, insights from dynamical systems theory are leveraged to inform the design process. In the combined model, the addition of a low-thrust force modifies the locations and stability of the equilibria, resulting in flow configurations that differ from the natural behavior in the CR3BP. Families of periodic solutions in the vicinity of the equilibria supply novel geometries that may be employed in initial designs. Additionally, the application of simplifying assumptions yields a conservative, autonomous system with properties that supply useful insights. “Forbidden regions” at fixed energy levels bound low-thrust motion in such a simplified system, and analytical equations are available to guide the navigation through energy space. Periodic orbits and their associated manifolds also possess useful properties and act similarly to separatrices in the simplified regime. These structures and insights are employed to design transit and capture trajectories in the Earth-Moon CR3BP-LT.

Circular cutting strategy for drilling of carbon fiber-reinforced plastics (CFRPs)

ABSTRACTThe drilling process of carbon fiber-reinforced plastics (CFRPs) is the most commonly employed machining operation due to the necessity of joining these materials. However, these materials are prone to delaminate during the process, and the presence of this defect is the most cause of rejection for CFRP products, especially those produced for the aeronautic industry. Therefore, this article aims to study a drilling strategy (named circular drilling strategy) by using dedicated tools with different diameters, in order to reduce the extension of delaminations. Holes with different diameters (6, 8, and 10 mm) were obtained both with the conventional and with the proposed drilling strategy under distinct cutting conditions that mainly differ in the feed rates (62, 125, and 250 mm/min) and cutting velocities (50, 75, and 100 m/min). The effect of the cutting parameters and tool diameter on the cutting forces and delamination factor was studied for both the conventional and circular drilling process. The results proved that the proposed technique produces better hole quality and lower thrust forces than the conventional one under the same cutting conditions.

Linear Hybrid Reluctance Motor with High Density Force

Linear switched reluctance motors are a focus of study for many applications because of their simple and sturdy electromagnetic structure, despite their lower thrust force density when compared with linear permanent magnet synchronous motors. This study presents a novel linear switched reluctance structure enhanced by the use of permanent magnets. The proposed structure preserves the main advantages of the reluctance machines, that is, mechanical and thermal robustness, fault tolerant, and easy assembly in spite of the permanent magnets. The linear hybrid reluctance motor is analyzed by finite element analysis and the results are validated by experimental results. The main findings show a significant increase in the thrust force when compared with the former reluctance structure, with a low detent force.

Analysis of double‐sided sandwiched linear flux‐switching permanent‐magnet machines with staggered stator teeth for urban rail transit

Linear flux-switching permanent-magnet (LFSPM) machines exhibit significant potential in many applications. A double-sided sandwiched LFSPM (DSSLFSPM) machine with high thrust force capability is investigated in this study. After being optimised for optimal thrust force using Maxwell 2D, this machine is found to deliver higher thrust force when compared with an optimised conventional 12/14 LFSPM machine. However, low thrust force ripple is also required in many applications. Thus, in order to reduce the thrust force ripple, the DSSLFSPM machine is improved by a staggered stator teeth structure and an end permanent-magnets method, then, two improved machines are obtained. The improved machines can reduce the thrust ripple to a very low level without thrust force density decrease. Further, the stator yoke thickness of the improved machines is optimised to reach optimal thrust force density. Finally, the performance of the DSSLFSPM-ST machines is analysed including the normal force, the efficiency and the power factor. It shows that the improved DSSLFSPM machines exhibit relatively low normal force and high thrust force density as well as low thrust ripples, indicating that they are suitable for long-stroke applications.

Drilling studies on particle board composite using HSS twist drill and spade drill

Composites materials are finding increased application in different engineering fields due to its favorable properties such as light weight, high strength, stiffness, etc. Among the composites, wood based composites are natural composites in which particle board (PB) and medium density fiberboard (MDF), etc., are extensively used in domestic and commercial purposes mainly in wood based furniture. Among different machining processes, drilling is the most generally used machining process in wood working industry for assembly operations and also affects the surface quality, aesthetic appearance and performance of the final product. Delamination at entry and exit sides of a hole, edge chipping, surface damage, etc are the major damages occurs during drilling of PB composites. The surface defects and delamination damages are significantly influenced by different machining particularly drilling parameters and machining environment. Therefore, study of effect of drilling parameters and machining environment on PB composite is an important area and it needs a detailed analysis. Twist drill is a most commonly used drill bit for drilling all materials however spade drill is specially used in drilling PB composite with lower thrust force and torque and spade drills is commonly used drill bit for rough drilling of particle board composite [5].

Drilling CFRP Laminates by Dual-Axis Grinding Wheel System With Copper/Diamond Functionally Graded Grinding Wheel

This study aims to investigate the drilling performance of a copper/diamond functionally graded grinding wheel (FGGW) fabricated by centrifugal sintered-casting for carbon fiber-reinforced plastic (CFRP) laminates by originally designed dual-axis grinding wheel (DAGW) system. The copper/diamond FGGW was also originally designed and fabricated by the centrifugal sintered-casting to suppress abrasive-grain wear and reduce the consumption of abrasive grains in our previous study. Drilling tests were carried out over 50 holes in dry machining. Thrust force was evaluated with force sensor during drilling test. Hole diameter, roundness, and roughness were measured to assess hole quality. Drill chips were observed by scanning electron microscope (SEM) to investigate chip morphology. Precision drilling without burring and delamination was achieved in CFRP laminates. Good hole-quality was still obtained over 50 holes due to the low thrust force during drilling. Specific three-dimensional (3D) drilling process of the DAGW system enabled stable and precision drilling with low thrust force in CFRP laminates continuously.

Drilling studies on carbon fiber-reinforced nano-SiC particles composites using response surface methodology

ABSTRACTPolymer-based composites offers better mechanical, thermal, and physical properties which make them a potential material in the field of manufacturing and aerospace sectors. This paper investigates the influence of machining parameters on drilling of carbon fiber epoxy composites. The composites are fabricated by hand-lay technique with various weight fractions of nano-SiC (silicon carbide) particles. Experiments are performed by response surface methodology (RSM) for various machining parameters such as feed rate, spindle speed, and weight fraction of nano-SiC particles. Analysis of variance table is presented to study the dominant factors that affect the thrust force and delamination factors. Further RSM-based desirability approach is used to optimize the machining parameters which yield lower thrust force and delamination.

Wet Core Drilling of CFRP with an Electrodeposited Diamond Core Drill - Effects of Cutting Conditions on Chip Evacuation and Core Jamming

This study investigated the cutting characteristics of electrodeposited diamond core drill when used to drill a CFRP under wet condition. The effects of different tool shapes, grain sizes and feed rates were examined. A normal core drill, an eccentric with slits core drill (E.S.), and an eccentric with slits and chamfers core drill (E.S.C.) were used. The normal core drill had the shape of a hollow cylinder. The E.S. core drill had the inner cylinder shifted from the center of this tool and slits in the bottom of this tool. The E.S.C. core drill had chamfers on the periphery of this tool. The normal core drill caused severe workpiece core jamming even at 1st hole drilling, and its electro-deposited area was covered entirely by adhered chips. In the case of the E.S. core drill and E.S.C. core drill, the workpiece core did not jam and the thrust force was smaller than that of the normal core drill. The effect of chamfers was little. The E.S.C. core drill with #200 caused smaller surface roughness than that with #100. However, the thrust force was two times larger, and the delamination was observed at the exit point of the hole. In the lower feed rate per revolution the better surface roughness and the lower thrust force were obtained irrespective of the tool shape while the cutting speed showed little effect.

Principle and Modeling of a Novel Moving Coil Linear-Rotary Electromagnetic Actuator

This paper presents a novel electromagnetic actuator that adopts an air-core coil mover to deliver decoupled linear and rotary motions. It uses light-weight moving coil to achieve high speed and dynamic response, and single-phase Lorentz-force driving scheme to realize direct and noncommutation actuation. To overcome the low thrust force of such driving scheme, unique magnetic circuits are used to enhance the thrust force and torque of the proposed actuator. Closed-form analytical solutions for modeling the magnetic field within the coil operating regions of these unique magnetic circuits are presented together with the complete thermal analyses. A prototype was developed and it delivers 10 mm stroke and 90 $^{\circ }$ angular displacement. Using commercially available drivers, it achieved a high throughput of 8000 units/h with 20 $\mu$ m, and 0.66 $^{\circ }$ tracking accuracy.

Mechanical Properties and Machinability Studies on the Human Hair-Coconut Coir-Glass Fibre Hybrid Composite

Natural Fiber-reinforced epoxy composites have a potential of lightweight structural materials used in various engineering applications owing to its excellent properties. Present paper investigates the mechanical properties of glass fibre, coconut fibre and human hair reinforced epoxy hybrid composite. In this work, epoxy resin with various layers of reinforcement added by using hand layup technique. The composite is subjected to mechanical testing. Machinability studies were performed based on the drilling experiments. TiAlN coated solid carbide (SC) and High speed steel (HSS) drills were used in the drilling experiments and made a comparative study on the output parameter. Solid carbide tool has a lower thrust force with feed rate being the most influential parameter on thrust force.

Preparation, Properties and Machinability Study of Luffa Fiber - Groundnut Shell Reinforced Epoxy Composite

The need for eco-friendly materials and non-polluting processing techniques has made natural fibre reinforced polymer composites as potential candidates to replace GFRPS and CFRPS in semi structural applications. Ground nut shell and luffa fibre are easily available in the market at low cost. Polymer composites consisting of 30%, and 40% volume fractions of a hybrid reinforcement containing groundnut shell and luffa fibre in epoxy resin were fabricated by hand lay-up technique with varying process parameters, the variation in the mechanical properties such as tensile, compressive, flexure and impact strength are studied. The optimum mechanical properties were obtained in 40% of fiber volume fraction of treated fiber composites the machinability study was performed by drilling experiments using a drilling machine with drill tool dynamometer. Two input parameters, cutting speed and feed rate and the one output parameter, thrust force, were used for the drilling process. TiAlN coated solid carbide and hss drills were employed in the drilling experiments and a comparative study was made based on the output parameters. Solid carbide resulted in lower thrust force values and feed rate proved to be the most influential parameter on thrust force.

Analysis of thrust ripple harmonics on different electric loadings in PM linear synchronous machines with skewed PMs

Purpose – Permanent magnet linear synchronous machines (PMLSMs) have large thrust ripple due to the longitudinal end effect caused by the finite length of the armature compared with rotary machines. The purpose of this paper is to analyze the influence of electric loading on thrust ripple performances based on a 12 slots/14 poles (12S/14P) PMLSM. Furthermore, the method of skewed PMs to reduce thrust ripple is investigated based on multi slices 2D finite element (FE) models. Design/methodology/approach – The thrust ripple of PMLSM under open-circuit condition results from the slotting and the longitudinal end effects. Therefore, periodical model has been designed to clarify the effect of the longitudinal end effect. Under on-load condition, the thrust ripple increases and exhibits an effective component of thrust force. To analyze the thrust ripple under on-load condition, frozen permeability (FP) technique is employed. In addition, the method of skewed PMs is analyzed in this paper to obtain more smooth thrust force performance. The effectiveness of skewing accounting for skew angles, step skew numbers and slot/pole number combinations was highlighted. Findings – The longitudinal end effect dominates the thrust ripple of PMLSM in both cases, i.e., open-circuit and on-load conditions. Under on-load condition, the second harmonic component of thrust ripple related to flux linkage harmonics increases significantly. Moreover, the effectiveness of skewed PMs is largely reduced with the increase of magnetic saturation. At last, a proper skew angle and step skew number are obtained for the conventional PMLSM with fractional-slot winding. Originality/value – By 60 electrical degrees and two or three step skewed PMs, the thrust ripple can be decreased to a tolerable limite for conventional PMLSM. The thrust ripple harmonics contributed by longitudinal end effect and flux linkage harmonics are analyzed, respectively, which is beneficial to exploring other techniques such as adding end auxiliary teeth to obtain lower thrust force pulsation.

Feasibility study on the rotary ultrasonic elliptical machining for countersinking of carbon fiber–reinforced plastics

Carbon fiber–reinforced plastics have been widely applied in aerospace industry as aircraft structural components due to their excellent mechanical and physical properties. The countersinking process of the carbon fiber–reinforced plastic hole is indispensable for the assembly of countersunk head screw. In conventional countersinking process of carbon fiber–reinforced plastics, it is prone to produce the delamination, fiber pullout, poor surface levelness and dimensional accuracy of countersunk hole. As a new technology, the rotary ultrasonic elliptical machining for countersinking of carbon fiber–reinforced plastics is employed, which is a non-traditional process that can effectively improve the surface levelness, surface integrity and machining accuracy of carbon fiber–reinforced plastic countersunk hole. This article reported a feasibility study on the rotary ultrasonic elliptical machining for countersinking of carbon fiber–reinforced plastics without coolant for the first time. The processing principle of rotary ultrasonic elliptical machining for countersinking was illustrated according to the countersinking models and the equations of motion locus. Based on the principle analysis, the surface levelness, tool blades’ path and countersunk hole surface morphology in rotary ultrasonic elliptical machining of the separated and unseparated types were analyzed compared to that in conventional countersinking. In addition, the rotary ultrasonic elliptical vibration transducer was designed and fabricated, as well as the experimental platform was set up. The experimental results demonstrated that the rotary ultrasonic elliptical machining achieved much better results than that in conventional countersinking, such as lower thrust force, torque, cutting temperature, better surface levelness, hole dimensional accuracy, surface integrity and chip-removal effect. The experimental results also verified the feasibility of rotary ultrasonic elliptical machining for countersinking of carbon fiber–reinforced plastics.

Experimental Study on Ultrasonic Vibration-Assisted Grinding of High Volume Fraction SiCp/Al Composites Micro-Hole

Aiming at the difficulty of 65% volume fraction SiCp/Al composites micro-hole machining and the problem of exit defects, the ultrasonic vibration-assisted grinding (UVAG) method for micro-hole machining was experimental studied taking Φ2-3mm hole for example. Results indicated that the thrust force was reduced by 79.8% through UVAG with lower fluctuation and the tool wear was much less than conventional drilling (CD). Lower thrust force and better exit quality were obtained with the increasing of the ultrasonic amplitude.

Effect of Chisel Edge in Ultrasonic Assisted Drilling of Carbon Fibre Reinforced Plastics (CFRP)

Ultrasonic assisted drilling (UAD) has been reported effective for thrust force reduction during drilling of CFRP resulting in lower exit delamination. However, this process is not fully understood in relation to machining theory. This work focused on understanding the separate effects of chisel and cutting edges during UAD in comparison with conventional drilling (CD). Experiments were performed at 100 m/min cutting speed and 0.05mm/rev feed rate. UAD produced 36% lower thrust force with a chisel edge, similar torque and 35% lower wear on chisel edge compared to CD, suggesting forces from chisel edge specifically, being reduced in UAD.

Novel linear switched-flux PM machine with 9/10 primary/secondary pole number combination

Purpose – Due to linear structure, linear switched flux permanent magnet machines (LSFPMMs) also may have odd pole primary, such as 9, 15, 21, etc., without unbalanced magnetic force in equivalent rotary machines. The paper aims to discuss these issues. Design/methodology/approach – In order to increase the thrust force density, the influence of some major design parameters, including split ratio, PM thickness, primary slot width and secondary pole width, are investigated by finite element analysis. For reducing the thrust force ripple under on-load condition, the end auxiliary teeth are adopted and their positions are also optimized. Findings – This novel 9/10 primary/secondary poles LSFPMM has high average thrust force and low thrust force ripple by optimization. The results demonstrate that the odd pole primary may be a good candidate for long-stroke linear direct drive application. Originality/value – A novel 9/10 primary/secondary poles linear switched flux permanent magnet machine is developed in this paper. The similar conclusions could be obtained for other LSFPMMs with odd pole primary.