Education

Research Description

Dr. Ngaile is interested in design and manufacturing, tribology in manufacturing, modeling and optimization of manufacturing processes, material characterization, and finite element analysis. Dr. Ngaile is developing new formulations of metal forming lubricants, and is studying how to tailor metal forming processes to minimize the quantity of toxic-rich lubricants needed in these processes. Also, he is studying the influence of ultrasonic vibration on microforming processes.

Publications

Weight reduction of heavy-duty truck components through hollow geometry and intensive quenching

Lowrie, J., Pang, H., & Ngaile, G. (2017), Journal of Manufacturing Processes, 28, 523-530.

A novel hybrid heating method for mechanical testing of miniature specimens at elevated temperature

Li, L., Ngaile, G., & Hassan, T. (2017), Journal of Micro and Nano-Manufacturing, 5(2).

A novel hybrid heating method for elevated temperature mechanical testing of miniature specimens

Li, L., Ngaile, G., & Hassan, T. (2016), (Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 1, ).

Analytical modeling of hydrodynamic lubrication in a multiple-reduction drawing die

Lowrie, J., & Ngaile, G. (2016), In 44th north american manufacturing research conference, namrc 44. (Procedia Manufacturing, 5) (pp. 707-723).

New punch design for the elimination of punch ejection load through manipulation of the elastic strain field in the punch nose

Lowrie, J., & Ngaile, G. (2016), Journal of Manufacturing Processes, 22, 49-59.

Preliminary investigation of the process capabilities of hydroforging

Alzahrani, B., & Ngaile, G. (2016), Materials, 9(1).

Novel extrusion punch design for improved lubrication and punch ejection

Lowrie, J., & Ngaile, G. (2015), (Proceedings of the ASME 10th International Manufacturing Science and Engineering Conference, 2015, vol 1, ).

Die-less hydroforming of multi-lobe tubular structures

Hummel, S., & Ngaile, G. (2015), Proceedings of the Institution of Mechanical Engineers. Part B, Journal of Engineering Manufacture, 229(3), 435-452.

Enhancement of tribological performance via innovative tooling design for extrusion processes

Lowrie, J. B., Ngaile, G. (2014), (Proceedings of the ASME 9th International Manufacturing Science and Engineering Conference, 2014, vol 2, ).

Development of chemically produced hydrogen energy-based impact bonding process for dissimilar metals

Ngaile, G., Lohr, P., Lowrie, J., Modlin, R. (2014), Journal of Manufacturing Processes, 16(4), 518-526.

View all publications via NC State Libraries

Grants

Enhancing Tool Life by Manipulating Punch & Die Elastic Strain Field during Forging

Forging Industry Educational and Research Foundation (FIERF)(7/15/18 - 1/14/20)

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Enhancing Tool Life by Manipulating Punch & Die Elastic Strain Field during Forging

Sponsor: Forging Industry Educational and Research Foundation (FIERF)

Start Date: 7/15/18

End Date: 1/14/20

Abstract

The overarching goal of this proposal is to establish a knowledge base for enhancing the life of forging tools by manipulating the elastic strain field induced in the die and punches during forging, such that the contact stresses at the tool-workpiece interface is minimized or eliminated during punch ejection and release of the forging from the dies. It should be noted that, the retained contact stress at the tool-workpiece interface after the forging load is released is mainly attributed by the spring back of the dies/punches. The retained contact stress has detrimental effects on the tool life as it exacerbates tool wear, increase temperature dissipation from the workpiece to the tools as well as worsening the tribological conditions. The tasks to be carried out in this project are; (a) Investigate forging tooling design set ups commonly used in the forging industry and establish loading characteristics as a function of family of products. (b) Using the loading characteristics as a base, identify potential candidates (forgings) and their respective tooling configurations that are conducive for manipulating elastic strain fields. (c) Develop tooling set up schemes for dies and punches where induced tool elastic strain during the forging cycle can be manipulated. With the aid of numerical modeling carry out a parametric study to determine optimal conditions for the tooling. (d) Develop a laboratory scale tooling set up for backward and forward rod extrusion processes with provision for manipulating tool elastic strain fields during the forging cycle. Using this tooling demonstrate the feasibility of the proposed techniques in enhancing tool life. (e) In collaboration with industrial partners, carry out field trials to determine the effectiveness of the proposed methodology in enhancing tool life.

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Advancements towards ASME nuclear code case for compact heat exchangers

US Dept. of Energy (DOE)(10/01/17 - 9/30/18)

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Advancements towards ASME nuclear code case for compact heat exchangers

Sponsor: US Dept. of Energy (DOE)

Start Date: 10/01/17

End Date: 9/30/18

Abstract

A group of investigators from several universities and industrial organizations (with University of Wisconsin as the lead) proposes to advance the state of the ASME section III code (nuclear service) for compact heat exchangers (CHXs). This proposed project will advance the technical knowledge of CHXs and lay the foundation necessary for of CHXs to be certified for use in nuclear service. During the course of this project the investigators will advance the understanding of the performance, integrity and lifetime of the CHXs for use in any industrial application making their use more attractive and accessible to industry. This will be achieved by developing qualification and inspection procedures that utilize non-destructive evaluation (NDE) and advanced in service inspection techniques, with insight from an industrial utility leader, EPRI. ASME Code experts on section III from MPR associates will direct the testing and help to develop a series of documents that define the rules and regulations for use of the CHX with input from members of the ASME section III committee. Currently, CHXs are covered by design rules in the ASME Code, Section VIII, Division 1, which is limited to the maximum temperature of 427oC, hence cannot be applied to the intermediate and secondary heat exchangers in Sodium Fast Reactors (SFRs) and High Temperature Gas-Cooled Reactors (HTGRs) with maximum outlet temperatures 550oC and 950oC, respectively. No detailed design strategies for the CHXs in the temperature range 550-950oC have been published. Through this IRP and earlier CHX projects sponsored by the US DOE, the investigators at NC State University (NCSU) will develop high temperature material properties of diffusion welded laminated structures for Alloys 617 and 800H, and Stainless Steel (SS) 316H. A set of isothermal tension, creep, fatigue and creep-fatigue tests on diffusion welded Alloy 800H will be performed and combined with the diffusion welded Alloy 617 and SS316H data from earlier CHX projects to determine the elevated temperature material properties of these ASME Code approved materials. NCSU will perform isothermal burst, and steady and cyclic pressure experiments on diffusion bonded small CHX cores of Alloy 800H, and again will combine with the earlier CHX test results on Alloy 617 and SS316H to explore the influence of sharp channel corners and thermal stresses on the failure modes. NCSU will implement a recently developed advanced unified constitutive model (UCM) in performing full inelastic analyses of CHX to provide insight on the failure responses observed in the CHX experiments to be performed through this proposed IRP. The primary outcomes of the NCSU tasks will include, i) a set of high temperature fatigue, creep, and fatigue-creep properties of three ASME Code approved materials, ii) a set of fatigue, creep and fatigue-creep test data of diffusion welded CHX cores of these materials, iii) experimentally validated UCMs and corresponding model parameters of the ASME Code approved materials, and finally iv) insight on the influence of sharp channel corners and thermal stresses on the failure modes of CHXx. These outcomes will facilitate the development of an elastic perfectly plastic (EPP) analysis based design methodologies for CHXs, background document for incorporating the EPP based structural design methodologies as an ASME Code case in Section III, Division 5, and NDE and service inspection methodologies. The project tasks will be accomplished through integrated efforts of one PhD and one undergraduate students, and two NCSU faculty members. The PhD and undergraduate students will perform the analysis and experimental tasks under the supervision of the faculty members. Through performing the research tasks and interacting with other university researchers and industry experts, graduate and undergraduate students will be trained for the future work force of the nuclear power industry.

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Development of a Manufacturing Process for High-Power-Density Hollow Shafts

FIA (Forging Industry Association)(7/15/16 - 7/14/18)

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Development of a Manufacturing Process for High-Power-Density Hollow Shafts

Sponsor: FIA (Forging Industry Association)

Start Date: 7/15/16

End Date: 7/14/18

Abstract

Lightweighting is being actively researched worldwide. The motivation to reduce the weight of a vehicle is largely driven by government regulations. For example, the fuel mileage requirement for cars in the US will increase to 35 mpg in 2020 [1]. For heavy duty trucks, the US is expected to cut carbon pollution by 17% from 2005 levels by 2020 [2]. The power train for cars and trucks carries a significant percentage of the total weight of a vehicle. For example, the power train in Classes 1–3 accounts for 36% of the total weight, whereas in Class 8 the power train accounts for 48%.The majority of power transmission systems used in the automotive, aerospace, maritime, and other industries employ solid shafts. Utilization of hollow shafts can drastically reduce weight, thus improving fuel efficiency. Although there are different ways that hollow shafts could be produced (e.g., machining), to meet the demand in the above-mentioned industries, any new manufacturing process must meet the following criteria: mass production potential, short cycle time, structural integrity, and cost effectiveness. We seek to devise a fabrication process that will combine (a) an innovative forming concept based on differential heating, (b) geometric optimization, and (c) multi-functional heat treatment.

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North Carolina Consortium for Manufacturing Data Science (NC-CMDS)

University of North Carolina System Office (formerly UNC - General Administration)(8/01/16 - 6/30/17)

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North Carolina Consortium for Manufacturing Data Science (NC-CMDS)

Sponsor: University of North Carolina System Office (formerly UNC - General Administration)

Start Date: 8/01/16

End Date: 6/30/17

Abstract

This effort lead by University of North Carolina at Charlotte and in collaboration with UNC chapel hill and NCSU aims at establishing a North Carolina multi-university/industry consortium for improving manufacturing capabilities through the application of data science tools. The application domain is process optimization, where data analytic and decision-support tools will be applied to manufacturing process models and data to converge on optimal operating conditions. The innovative concept is that every part produced represents a new experiment. This leads to the final vision of data-driven machining in which an Intelligent Manufacturing Advisor continuously adjusts process parameters to maintain optimal performance at the machine level, maximize productivity at the factory level, and balance system output at the enterprise level.

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Optimization of DuraForce Fastening System via Numerical Modeling

DuraForce Fastener Systems, LLC (5/16/16 - 5/30/17)

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Optimization of DuraForce Fastening System via Numerical Modeling

Sponsor: DuraForce Fastener Systems, LLC

Start Date: 5/16/16

End Date: 5/30/17

Abstract

One of the most concerning problems with a threaded fastener is the tendency to loosen over time, creating a joint failure. The main cause for bolt loosening is the side sliding of nut or bolt head relative to the joint. This movement causes relative motion between the threads of the nut and bolt. The self-loosening causes a reduction in the clamp force which results in joint slip. As a consequence of this, the bolt is subjected to bending loads and finally fails by fatigue. The main reasons of relative motion are: bending of parts that causes induction of forces at the friction surface, differential thermal effects cause by temperature or material difference, applied forces on the joint can lead to shifting of the joint surfaces leading to relative motion and hence loosening. To address this problem of self-loosening, Allied Industrial Corporation has developed a mechanism where the bottom part of a nut is made such that it has a conical shape that is used to transmit the force to a conically shaped collar. When the nut advances towards the collar, the annulus cone will deflect inward while the collar would deflect outward. In this way, both the annulus cone and the collar will store strain energy. Any tendency of bolt loosening can therefore be prevented by the stored energy. The goal of this study is to investigate the influence of various parameters (geometry, friction, materials) on the robustness of the new fastening system. The results are expected to provide Allied Industrial Corporation with design guidelines for the new bolt-nut fastening system. The investigation will be carried out with the aid of numerical simulations.

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ASME Code Application of the Compact Heat Exchanger for High Temperature Nuclear Service

US Dept. of Energy (DOE)(10/01/16 - 9/30/19)

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ASME Code Application of the Compact Heat Exchanger for High Temperature Nuclear Service

Sponsor: US Dept. of Energy (DOE)

Start Date: 10/01/16

End Date: 9/30/19

Abstract

The proposed project will implement the recently developed elastic-perfectly plastic (EPP) analysis methodologies in accordance with the ASME Code, Section III, Division 5 for diffusion welded compact heat exchangers (CHXs) in high temperature nuclear service. Burst, and cyclic pressure and thermal experiments on diffusion bonded CHX specimens of SS316L and Alloy 617 will be performed for investigating stress concentrations at sharp channel corners and determining possible failure modes. Hybrid and printed circuit heat exchangers (H2X and PCHE) meet the requirements of space and weight savings, high thermal effectiveness, low pressure drop and high design pressure capability. These attributes improve cost and efficiency of advanced reactors and thereby advances DOE’s goal of carbon-free energy production. Currently, CHXs are covered by design rules in the ASME Code, Section VIII, Division 1 along with Section IX procedures for diffusion welding. But the Section VIII rules are limited to the maximum temperature of 427oC, hence cannot be applied to the intermediate and secondary heat exchangers (IHXs and SHXs) in Sodium Fast Reactors (SFRs) at 550oC and in high temperature gas-cooled reactors (HTGRs) at 950oC). No detailed design strategies for the CHX at the temperature range (550-950oC) have been published. For the IHXs in SFR and HTGR, thermal stresses, fatigue and creep deformation and rupture life limits must be considered for Section III, Division 5, Class A applications, and these are not covered in the Section VIII design methodology. Some IHX and SHX applications are anticipated to operate at significant pressure differentials in addition to cyclic thermal conditions. Hence, determination of thermal stresses in addition to primary stresses is essential for the calculation of creep strains, thermal deformations and peak stresses for fatigue and creep/fatigue usage estimates. It is anticipated that the thermal stresses in the diffusion bonded core will be large, especially during transients. Also high thermal strain concentrations are expected in the core near sidewalls, as well as at header attachment welds. On some scales, these concerns may be best addressed by the recently introduced EPP analysis methodology proposed for the evaluation of primary loads, strain limits and creep-fatigue in Division 5 of the ASME Code. Current Division 5 rules using simplified elastic, and decoupled creep and plasticity analyses have been deemed inappropriate for elevated temperature applications. Hence, EPP methodologies which considers creep-plasticity interactions will allow limit to various stress measures and strain limits. This project will perform a systematic set experiments on stainless 316L and Alloy 617 ASTM coupons and CHX specimens to develop structural design methodology based on EPP analysis in order to provide assessment of the elevated temperature failure modes of two types of CHXs under sustained and cyclic thermal and pressure loads. The research will be performed in consultation with the industry and ASME Code experts such that the outcomes can be used as technical basis for Section III, Division 5 ASME Code Case for CHXs in high temperature nuclear service.

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Novel Multi-Functional Hybrid Drawing Process (Area: Material Processes)

US Army - Army Research Office(6/20/16 - 11/19/18)

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Novel Multi-Functional Hybrid Drawing Process (Area: Material Processes)

Sponsor: US Army - Army Research Office

Start Date: 6/20/16

End Date: 11/19/18

Abstract

Novel Multi-functional Hybrid Drawing Process The overarching goal of this proposal is to explore new multi-functional hybrid manufacturing processes, where several operations which are complementary to each other are carried out simultaneously. To gain fundamental knowledge pertaining to this new class of manufacturing processes we focus on a novel multi-functional hybrid drawing operation. The conceived system is comprised of multiple segmented dies with provision for high pressure fluid supply. The dies are conceived to generate hydrodynamic cavitation energy at the tool-workpiece interface which is instantly harnessed to carry out several operations aimed at enhancing metal drawing capabilities. Hydrodynamic cavitation can occur in a flowing fluid region where the pressure of the liquid falls below its vapor pressure. It is a result of gas bubble formation, growth, and finally bubble burst, resulting in energy release sufficient to plastically deform metallic materials. In this multi-functional drawing process, three manufacturing operations that would have otherwise been carried out independently can be realized: (1) real-time surface texturing via cavitating fluid which in turn generates lubricant pathways (micro pool lubrication), (2) real-time alteration of physicochemical properties of fluid (in-situ lubricant formulation) due to local adiabatic temperature rise during bubble implosion, (3) altering local and global state-of-stress thus increasing the shear stress τs, which in turn increases material formability, and (4) hydrodynamic “pseudo shot peening” via high velocity liquid micro-jets from cavitation, thus enhancing part surface integrity. The specific objectives of the study are (a) fundamental study of the mechanics of hydrodynamic cavitation and accompanied energy release that can be used to trigger other operations in real time, (b) study of real-time texturing of a blank/workpiece via hydrodynamic cavitation in a manufacturing process, where the produced micro-texture is instantaneously used to transport lubricant, thus enhancing tribological performance, (c) parametric study of the major variables that influence hydrodynamic cavitation, with focus on geometries that induce cavitation, physicochemical properties of fluid, fluid pressure gradient responsible for initiation of cavitation, vapor bubble size and bubble growth, (d) study of the potential of hydrodynamic cavitation in enhancing surface properties through imploding gas bubbles on the surface of manufactured products, and (d) explore the potential of altering the chemical characteristics of cavitating fluid, with a goal of increasing its lubricity; In situ lubricant formulation and the potential for producing nano-lubricants using shear energy emanating from high velocity micro jets.

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Study on Weight Reduction of Forged Parts Used in Heavy-Duty Truck Vehicles via Innovative Forging Techniques and Material Substitution

Forging Industry Educational and Research Foundation (FIERF)(10/12/15 - 5/31/17)

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Study on Weight Reduction of Forged Parts Used in Heavy-Duty Truck Vehicles via Innovative Forging Techniques and Material Substitution

Sponsor: Forging Industry Educational and Research Foundation (FIERF)

Start Date: 10/12/15

End Date: 5/31/17

Abstract

The major goal of this study is to investigate the potential of innovative forging technologies, materials substitution, and part/design modifications to reduce weight in forged parts used in light- and heavy-duty truck vehicles, without diminishing the structural integrity of any component. This study will focus on vehicles falling in Classes 1, 2, 7, and 8, which consume 93% of the total fuel used in trucks in the US [1]. Classes 1 and 2 belong to the light-duty vehicle category, weighing less than 10,000 lb. Classes 7 and 8 represent heavy-duty vehicles, weighing over 26,000 lb [2]. The specific objectives are to (a) conduct a study on forged components used in power train, chassis, and suspension systems, and thereby identify families of parts with high potential for weight reduction through innovative forging technologies or material substitution, (b) evaluate the feasibility and economic practicability of forging components that are currently produced by casting or other manufacturing techniques, (c) carry out preliminary investigation on effective forging technologies that could be used in lightweight manufacturing. This might include hybrid forging/forming operations, and (d) carry out preliminary investigation on the energy flow path/maps that forged parts are subjected to during service life. Systematically assess from mechanical and metallurgical point of view, the potential for weight reduction in specific components.

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Study on Weight Reduction of Forged Parts Used in Light-and Heavy-Duty Truck Vehicles via Innovative Forging Techniques and Material Substitution

Forging Industry Educational and Research Foundation (FIERF)(11/30/-1 - 5/31/17)

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Study on Weight Reduction of Forged Parts Used in Light-and Heavy-Duty Truck Vehicles via Innovative Forging Techniques and Material Substitution

Sponsor: Forging Industry Educational and Research Foundation (FIERF)

Start Date: 11/30/-1

End Date: 5/31/17

Abstract

The major goal of this study is to investigate the potential of innovative forging technologies, materials substitution, and part/design modifications to reduce weight in forged parts used in light- and heavy-duty truck vehicles, without diminishing the structural integrity of any component. This study will focus on vehicles falling in Classes 1, 2, 7, and 8, which consume 93% of the total fuel used in trucks in the US [1]. Classes 1 and 2 belong to the light-duty vehicle category, weighing less than 10,000 lb. Classes 7 and 8 represent heavy-duty vehicles, weighing over 26,000 lb [2]. The specific objectives are to (a) conduct a study on forged components used in power train, chassis, and suspension systems, and thereby identify families of parts with high potential for weight reduction through innovative forging technologies or material substitution, (b) evaluate the feasibility and economic practicability of forging components that are currently produced by casting or other manufacturing techniques, (c) carry out preliminary investigation on effective forging technologies that could be used in lightweight manufacturing. This might include hybrid forging/forming operations, and (d) carry out preliminary investigation on the energy flow path/maps that forged parts are subjected to during service life. Systematically assess from mechanical and metallurgical point of view, the potential for weight reduction in specific components.

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Reactive Supersonic Diesel Jets Under Extreme High Injection Pressure

National Science Foundation (NSF)(8/01/14 - 1/31/16)

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Reactive Supersonic Diesel Jets Under Extreme High Injection Pressure

Sponsor: National Science Foundation (NSF)

Start Date: 8/01/14

End Date: 1/31/16

Abstract

High-speed (supersonic) liquid jets have wide applications in engineering for propulsion and power generation. The underlying hypothesis for this proposal is that under supersonic conditions shock waves are induced around liquid jets leading to significant enhancement in the atomization, mixing, ignition, and combustion. We propose to study a transient supersonic diesel jet under injection pressures of up to 1,000 MPa. The goals are to exploit the induced shock waves during liquid penetration, identify their effects on atomization, mixing, and combustion, and determine the effectiveness of extreme high injection pressures in mixing and combustion enhancement. Specifically, in this proposal, we will: a) study the liquid penetration, breakup, and interaction with the induced shock waves; b) study the influence of shock waves on the liquid atomization and the mixing with ambient air; c) study the influence of shock waves on ignition and combustion development; and d) gather fundamental knowledge pertaining to supersonic liquid jet with controllable dispensing pressures up to 1,000 MPa that can be disseminated to designers and developers of highly efficient, high power density, and clean next-generation internal combustion engines. Successful application of this phenomenon in internal combustion engines will lead to breakthroughs in engine design, allowing significant reductions in fuel consumption, thereby diminishing our dependence on foreign oil and reducing pollutant emissions.

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