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Research Papers

J. Manuf. Sci. Eng. 2017;139(6):061001-061001-10. doi:10.1115/1.4035004.

This work presents an automated fabric layup solution based on a new method to deform fiberglass fabric, referred to as shifting, for the layup of noncrimp fabric (NCF) plies. The shifting method is intended for fabric with tows only in 0 deg (warp) and 90 deg (weft) directions, where the fabric is sequentially constrained and then rotated through a deformation angle to approximate curvature. Shifting is conducted in a two-dimensional (2D) plane, making the process easy to control and automate, but can be applied for fabric placement in three-dimensional (3D) models, either directly or after a ply kitting process and then manually placed. Preliminary tests have been conducted to evaluate the physical plausibility of the shifting method. Layup tests show that shifting can deposit fabric accurately and repeatedly while avoiding out-of-plane deformation.

Topics: Textiles , Machinery , Blades
Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061002-061002-8. doi:10.1115/1.4035185.

Composite plates have the advantages of high strength and light weight and are widely used in the field of aerospace engineering. Instability is their most common failure mode. Considerable research on the instability of composite plates under linear loads has been conducted, but there is less research on the instability of composite plates under nonlinear loads. Therefore, an instability discriminant model for a metal composite plate under a nonlinear load is established using a metal composite plate as the object of study. The influence of width, thickness, thickness ratio, and material properties on the discrimination factor of instability is analyzed. Analysis results show that, for common metal composite plates with aspect ratios four, under the same load, larger ratios of width to thickness, smaller elastic moduli, and larger Poisson's ratios of each layer of the plate make the plate more prone to instability. Under the premise of the same total load, compared with the linear uniform load, the composite plate is more and more prone to instability with the increase of the nonlinear load. These conclusions serve to supplement theoretical results.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061003-061003-6. doi:10.1115/1.4035219.

Electromagnetic forming (EMF) is a high strain rate forming technology which can effectively deform and shape high electrically conductive materials at room temperature. A field shaper is frequently used for concentrating the magnetic pressure in the desired forming area. The geometric parameters of a field shaper, as an intermediate device, affect the magnetic pressure and radial displacement in electromagnetic inside bead forming. EMF consists of electromagnetic and mechanical parts simulated using maxwell and abaqus software, respectively. The effects of geometric parameters of the stepped field shaper on magnetic pressure and radial displacement were investigated, and the best parameters were determined. Experimental tests were performed at various discharge voltages and the results were compared with simulation. The results indicated that using the stepped field shaper, the magnetic pressure concentration ratio increased from about 23–85% in comparison with using a direct coil. The maximum magnetic pressure increased by approximately 21% due to the effective concentration of magnetic pressure. Consequently, regardless of the electromagnetic energy losses because of using a field shaper, the radial displacement increased by 8% in simulation and 6% in experiment. The result of this study would be also helpful in designing field shapers in similar applications which is highly crucial and strongly recommended.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061004-061004-12. doi:10.1115/1.4035079.

The advantages of the five-axis flank milling of (developable) ruled surfaces include that (1) the machined surfaces could be very accurate and smooth and (2) the machining efficiency is high. Currently, spiral bevel gears are machined on the machine tools specially used for gear manufacturing. The disadvantages are that the cost is high for small batch, prototype, or repair. If a small group of spiral bevel gears are needed, the current methods are not valid. Thus, it is expected to machine the gears on five-axis computer numerical control (CNC) milling centers. Unfortunately, when tooth surfaces are designed based on the conventional gear manufacturing methods, they cannot be accurately machined in five-axis flank milling. This work is to develop the new technique for the five-axis flank milling of spiral bevel gears. First, a new method of designing the tooth surface of spiral bevel gears with ruled surface is proposed. Second, the cutter locations and orientations are calculated for five-axis flank milling the tooth surfaces. Third, the actual tooth surfaces are accurately represented with the cutter envelope surface in five-axis flank milling. It is confirmed that the difference of the actual tooth surface and the designed tooth surface is within the tolerance. Then, a pinion is generated to mesh with the gear, and the tooth contact analysis (TCA) is conducted. The good result demonstrates that the proposed method is valid, thus it can be used in industry.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061005-061005-9. doi:10.1115/1.4035419.

The extrusion of polymer profile products with complex microcross section is difficult due to the extrudate deformation, especially for the profile with multihollow lumens and inner ribs. In order to investigate the effect of die lip geometry on extrudate deformations, three-dimensional simulations have been undertaken for typical small profile extrusions both inside and outside the die using finite-element method (FEM). The Carreau model was used to describe the shear-thinning behavior of polymer melt. The systematic definitions of the die lip geometric parameters and evaluations of the extrudate deformations were proposed. It was found that the thickness and profile deformations happen asynchronously, and the existence of the inner rib changes the global deformation, which cannot be predicted by a deformation combination of the basic geometries. Among the investigated die lip geometric parameters, the wall thickness ratio has the most pronounced effect on both thickness and external profile deformations of the extrudates, with the maximum variation of more than 80%. The decrease of the hollow ratio significantly reduces the extrudate deformation extent, especially the extrudate external profile and the extrudate thickness of the thin-wall region. Even with uniform thickness, the location and shape of the inner rib also generate extrudate deformations not only on the inner rib but also on the thickness of the outer ring at the region not connected with it, by a minor variation level of 5–25%. Comprehensive understandings on the mechanism of extrudate deformations and effects of die lip geometry were obtained. Some hints for small profile die design were provided accordingly. Numerical results showed qualitative and quantitative agreement with the experiments.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061006-061006-8. doi:10.1115/1.4035182.

There are many scientific and engineering applications of transparent glass including optics, communications, electronics, and hermetic seals. However, there has been minimal research toward the additive manufacturing (AM) of transparent glass parts. This paper describes and demonstrates a filament-fed technique for AM of transparent glass. A transparent glass filament is melted by a CO2 laser and solidifies as the workpiece is translated relative to the stationary laser beam. To prevent thermal shock, the workpiece rests on a heated build platform. In order to obtain optically transparent parts, several challenges must be overcome, notably producing index homogeneity and avoiding bubble formation. The effects of key process parameters on the morphology and transparency of the printed glass are explored experimentally. These results are compared to a low-order model relating the process parameters to the temperature of the molten region, which is critical to the quality of the deposited glass. At lower temperatures, the glass is not fully melted, resulting in index variations in the final part, while at higher temperatures, phase separation introduces bubbles and other defects into the part. The correct process avoids these issues and deposits optically transparent glass.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061007-061007-14. doi:10.1115/1.4035216.

Additive manufacturing (AM) processes are used to fabricate complex geometries using a layer-by-layer material deposition technique. These processes are recognized for creating complex shapes which are difficult to manufacture otherwise and enable designers to be more creative with their designs. However, as AM is still in its developing stages, relevant literature with respect to design guidelines for AM is not readily available. This paper proposes a novel design methodology which can assist designers in creating parts that are friendly to additive manufacturing. The research includes formulation of design guidelines by studying the relationship between input part geometry and AM process parameters. Two cases are considered for application of the developed design guidelines. The first case presents a feature graph-based design improvement method in which a producibility index (PI) concept is introduced to compare AM friendly designs. This method is useful for performing manufacturing validation of pre-existing designs and modifying it for better manufacturability through AM processes. The second approach presents a topology optimization-based design methodology which can help designers in creating entirely new lightweight designs which can be manufactured using AM processes with ease. Application of both these methods is presented in the form of case studies depicting design evolution for increasing manufacturability and associated producibility index of the part.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061008-061008-10. doi:10.1115/1.4035183.

This paper deals with localized necking in stretched metal sheets using the initial imperfection approach. The first objective is to study the effect of kinematic hardening on the formability of a freestanding metal layer. To this end, the behavior of the metal layer is assumed to follow the rigid-plastic rate-independent flow theory. The isotropic (respectively, kinematic) hardening of this metal is modeled by the Hollomon (respectively, Prager) law. A parametric study is carried out in order to investigate the effect of kinematic hardening on the formability limits. It is shown that the effect of kinematic hardening on the ductility limit is noticeably different depending on the strain path considered. The second aim of this paper is to analyze the effect of an elastomer substrate, perfectly bonded to the metal layer, on the formability of the whole bilayer. It is found that the addition of an elastomer layer substantially enhances the formability of the bilayer, in agreement with earlier studies.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061009-061009-11. doi:10.1115/1.4035418.

The stability lobe diagrams predicted using the tool frequency response function (FRF) at the idle state usually have discrepancies compared with the actual stability cutting boundary. These discrepancies can be attributed to the effect of spindle rotating on the tool FRFs which are difficult to measure at the rotating state. This paper proposes a new tool FRF identification method without using noncontact sensor for the rotating state of the spindle. In this method, the FRFs with impact applied on smooth rotating tool and vibration response tested on spindle head are measured for two tools of different lengths clamped in spindle–holder assembly. Based on those FRFs, an inverse receptance coupling substructure analysis (RCSA) algorithm is developed to identify the FRFs of spindle–holder–partial tool assembly. A finite-element modeling (FEM) simulation is performed to verify the validity of inverse RCSA algorithm. The tool point FRFs at the spindle rotating state are obtained by coupling the FRFs of the spindle–holder–partial tool and the other partial tool. The effects of spindle rotational speed on tool point FRFs are investigated. The cutting experiment demonstrates that this method can accurately identify the tool point FRFs and predict cutting stability region under spindle rotating state.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061010-061010-8. doi:10.1115/1.4035371.

This paper provides time domain simulation and experimental results for surface location error (SLE) and surface roughness when machining under both stable (forced vibration) and unstable (period-2 bifurcation) conditions. It is shown that the surface location error follows similar trends observed for forced vibration, so zero or low error conditions may be selected even for period-2 bifurcation behavior. The surface roughness for the period-2 instability is larger than for stable conditions because the surface is defined by every other tooth passage and the apparent feed per tooth is increased. Good agreement is observed between simulation and experiment for stability, surface location error, and surface roughness results.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061011-061011-11. doi:10.1115/1.4035721.

Maintenance and its cost continue, over the years, drawing the attention of production management, since the unplanned failures decrease the reliability of the system and the return of investments. Maintenance services of manufactured products are among the most common services in the industry; they account for more than half of the total costs and influence the environmental impact of the product. In order for manufacturers to increase their productivity, by performing accurate and quick maintenance, advanced monitoring systems should be considered in order to easily detect machine tool failures before they occur. Toward that end, a cloud-based platform for condition-based preventive maintenance, supported by a shop-floor monitoring service and an augmented reality (AR) application, is proposed as a product-service system (CARM2-PSS). The proposed AR maintenance service consists of algorithms of automated generation of assembly sequences, part movement scripts, and improved interface that aim to maximize existing knowledge usage while creating vivid AR service instructions. Moreover, the proposed monitoring system is supported by a wireless sensor network (WSN), and is deployed on a Cloud environment together with the AR tool. The monitoring system monitors the status of the machine tools, calculates their remaining operating time between failures (ROTBF), and identifies the available windows of the machine tools in order to perform the AR remote maintenance. In order to validate the proposed methodology and calculate its impact, it is applied in a real-life case study of a white-goods industry.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061012-061012-13. doi:10.1115/1.4034279.

The use of magnesium (Mg) alloy has been continuously on the rise with numerous expanded application in transportation/aerospace industries due to their lightweight and other areas, such as biodegradable medical implants. It was shown recently that machining can be used to improve the functional performance of Mg-based products/components, such as corrosion resistance, through engineered surface integrity. In this paper, the behavior of AZ31B Mg alloy in cryogenic machining was discussed firstly. The surface integrity can be significantly improved by introducing the ultrafine grained (UFG) layer due to the severe plastic deformation (SPD) effect during cryogenic machining. The mechanisms of microstructure evolution and plastic deformation were analyzed based on the experimental findings in literature. A physics-based constitutive model involving material plasticity and grain refinement is developed based on both slip and twinning mechanisms and successfully implemented in a finite-element (FE) analysis with multiple cutting passes to predict the microstructure evolution by nanocrystalline grain refinement and other improvement of the surface integrity in the cryogenic machining of AZ31B Mg alloy. With a more quantitative assessment, the FE model results are further discussed for grain refinement, changes in microhardness, residual stresses, and slip/twinning mechanism with the apparent SPD taking place due to rapid cryogenic cooling.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061013-061013-9. doi:10.1115/1.4035124.

This study aims at exploring the potentialities of cold orbital forming in forming complex sheet metal. Aiming at a complex mobile phone shell component of aluminum alloy, two technical schemes for cold orbital forming are first presented. Then, the optimized one, i.e., the more complex inner surface of mobile phone shell is arranged to be formed by the rocking punch with a complex motion, is determined by analyzing the nonuniform plastic deformation laws and punch filling behaviors. On the basis of the optimized technical scheme, the blank geometry in cold orbital forming of mobile phone shell is also optimized based on the forming status of the most difficult forming zone. The consistent finite element (FE) simulated and experimental results indicate that under the optimized technical scheme, not only the bosses in the mobile phone shell are fully formed but also the obtained flow lines are reasonable, which proves that the technical scheme presented in this study is feasible and cold orbital forming exhibits huge potentialities in forming complex sheet metal.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061014-061014-12. doi:10.1115/1.4035417.

Abrasive flow finishing (AFF) is one of the advanced finishing processes used mainly for finishing of complex surface features. Nano finishing of aluminum alloys is difficult using conventional finishing processes because of its soft nature. So, in this work, aluminum alloys are finished using AFF process. Since the finishing is carried out using polymer rheological abrasive medium (medium), the finishing forces on aluminum alloy workpieces are too low compared to conventional finishing processes. Thus, this process generates nano surface roughness on aluminum alloy. By using the theoretical model, change in surface roughness (ΔRa) with respect to various AFF input parameters is studied. A new simulation model is proposed in this paper to predict the finishing forces and ΔRa during AFF process. Modeling of finishing forces generated during the AFF process is carried out using ansys polyflow. These forces are used as input in the simulation model to predict ΔRa. Medium rheology decides the magnitude of the generated finishing forces in AFF process. Therefore, to predict the forces accurately, rheological properties of the medium are measured experimentally and used as input during modeling. Further, to make the simulation more realistic, abrasive particle bluntness with respect to extrusion pressure and number of strokes is considered. Because of considering these realistic conditions, simulation and experimental results are in better agreement compared to theoretical results.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):061015-061015-11. doi:10.1115/1.4035422.

The tool orientation of a flat-end cutter, determined by the lead and tilt angles of the cutter, can be optimized to increase the machining strip width. However, few studies focus on the effects of tool orientation on the five-axis milling process stability with flat-end cutters. Stability prediction starts with cutting force prediction, and the cutting force prediction is affected by the cutter-workpiece engagement (CWE). The engagement geometries occur between the flat-end cutter and the in-process workpiece (IPW) are complicated in five-axis milling, making the stability analysis for five-axis flat-end milling difficult. The robust discrete vector method (DVM) is adopted to identify the CWE for flat-end millings, and it can be extended to apply to general cutter millings. The milling system is then modeled as a two-degrees-of-freedom spring-mass-damper system with the predicted cutting forces. Thereafter, a general formulation for the dynamic milling system is developed considering the regenerative effect and the mode coupling effect simultaneously. Finally, an enhanced numerical integration method (NIM) is developed to predict the stability limits in flat-end milling with different tool orientations. Effectiveness of the strategy is validated by conducting experiments on five-axis flat-end milling.

Topics: Stability , Cutting , Milling
Commentary by Dr. Valentin Fuster

Technical Brief

J. Manuf. Sci. Eng. 2017;139(6):064501-064501-7. doi:10.1115/1.4035123.

In the present investigation, an analysis using three-dimensional upper-bound method based on continuous velocity filed has been carried out for the extrusion of circular, square, and rhomboidal sections from round billets. The die surface representation in the present work could easily be applied to the extrusion of many different shapes just by defining the functions that describe the entry and exit sections and putting them into the general formulation. The die profile was tested for the third- and fifth-order polynomial functions. The extrusion process is also simulated using the finite element code, ansys (V 14.0), in order to assist the mathematical solution and to show the stress and strain distributions for the products when the strain hardening effect is taking into the account. Effects of friction, shape complexity, reduction of area, and die length on the extrusion pressure were also investigated. The results obtained in this work were compared with the theoretical results of other workers and found to be in highly compatible.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):064502-064502-12. doi:10.1115/1.4035125.

This technical brief is the extension of our previous work developed by Zhang et al. (2016, “Effects of Process Parameters on White Layer Formation and Morphology in Hard Turning of AISI52100 Steel,” ASME J. Manuf. Sci. Eng., 138(7), p. 074502). We investigated the effects of sequential cuts on microstructure alteration in hard turning of AISI52100 steel. Samples undergone five sequential cuts are prepared with different radial feed rates and cutting speeds. Optical microscope and X-ray diffraction (XRD) are employed to analyze the microstructures of white layer and bulk materials after sequential cutting processes. Through the studies we first find out the increasing of white layer thickness in the sequential cuts. This trend in sequential cuts does work for different process parameters, belonging to the usually used ones in hard turning of AISI52100 steel. In addition, we find that the white layer thickness increases with the increasing of cutting speed, as recorded in the literature. To reveal the mechanism of white layer formation, XRD measurements of white layers generated in the sequential cuts are made. As a result retained austenite in white layers is identified, which states that the thermally driven phase transformations dominate the white layer formation, rather than the severe plastic deformation in cuts. Furthermore, retained austenite contents in sequential cuts with different process parameters are discussed. While using a smaller radial feed rate, the greater retained austenite content found in experiments is attributed to the generated compressive surface residual stresses, which possibly restricts the martensitic transformation.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;139(6):064503-064503-5. doi:10.1115/1.4035370.

In this paper, joining of Hastelloy has been successfully carried out by microwave hybrid heating process. The joints were developed by using a microwave oven at a frequency of 2.45 GHz and 900 W. A thin layer of slurry consisting of nickel-based powder and epoxy resin was introduced between the faying surfaces. The joints obtained by microwave hybrid heating were characterized by XRD, SEM–EDS, Vicker's microhardness, and tensile tests. Microstructure analysis revealed the formation of equiaxed grains, and results of XRD analysis revealed formation of some intermetallics and suppression of carbide formation. This can be attributed to the volumetric heating nature of microwaves. The microhardness study revealed 320 ± 25 HV hardness on grain surfaces and 680 ± 40 HV on grain boundaries. The tensile strength of the microwave processed joints was∼82% of base Hastelloy strength. The fractographic analysis of the fractured samples revealed a ductile fracture coupled with the shearing of brittle carbides in the joint region. An overall study revealed the potential of microwaves in joining of bulk metallic materials.

Topics: Microwaves , Joining , Heating
Commentary by Dr. Valentin Fuster

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