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

A novel gripper for multiaxial mechanical testing of microtubes at elevated temperatures

Li, L., Chan, Y.-C., Ngaile, G., & Hassan, T. (2020), REVIEW OF SCIENTIFIC INSTRUMENTS, 91(5). https://doi.org/10.1063/5.0007150

Formulation of SiO2/oil nanolubricant for metal forming using hydrodynamic cavitation

Pang, H., & Ngaile, G. (2020), PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE. https://doi.org/10.1177/0954405420933120

Development of a non-isothermal forging process for hollow power transmission shafts

Pang, H., & Ngaile, G. (2019), JOURNAL OF MANUFACTURING PROCESSES, 47, 22–31. https://doi.org/10.1016/j.jmapro.2019.08.034

Development of scanning electron microscope-compatible multiaxial miniature testing system

Rahman, F., Ngaile, G., & Hassan, T. (2019), MEASUREMENT SCIENCE AND TECHNOLOGY, 30(10). https://doi.org/10.1088/1361-6501/ab1ca6

High injection pressure diesel sprays from a piezoelectric fuel injector

Wang, L., Lowrie, J., Ngaile, G., & Fang, T. (2019), APPLIED THERMAL ENGINEERING, 152, 807–824. https://doi.org/10.1016/j.applthermaleng.2019.02.095

Investigation of energy storage in bolted joint components and the development of a geometry selection design tool for Belleville washers

Carcaterra, B., & Ngaile, G. (2019), ENGINEERING STRUCTURES, 178, 436–443. https://doi.org/10.1016/j.engstruct.2018.10.049

Development of a Non-isothermal Forging Process for Hollow Power Transmission Shafts

Pang, H., & Ngaile, G. (2018), Procedia Manufacturing, 26, 1509–1516. https://doi.org/10.1016/J.PROMFG.2018.07.087

Punch design for floating based micro-tube hydroforming die assembly

Ngaile, G., & Lowrie, J. (2018), Journal of Materials Processing Technology, 253, 168–177. https://doi.org/10.1016/J.JMATPROTEC.2017.10.049

Scalability of conventional tube hydroforming processes from macro to micro/meso

Lowrie, J., & Ngaile, G. (2018), PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE, 232(12), 2164–2177. https://doi.org/10.1177/0954405416683736

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). https://doi.org/10.1115/1.4035954

View all publications via NC State Libraries

Grants

Dynamic Digital Twin for Enhancing Forging Part Quality and Control

Forging Industry Educational and Research Foundation (FIERF)(7/15/20 - 1/14/22)

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Dynamic Digital Twin for Enhancing Forging Part Quality and Control

Sponsor: Forging Industry Educational and Research Foundation (FIERF)

Start Date: 7/15/20

End Date: 1/14/22

Abstract

Manufacturing of the 21st century is rapidly changing due to the advent of high speed computers, availability of interconnectivity of machines or systems (internet of things IoT), cloud computing, artificial intelligence (IE), and the like. This paradigm shift lead to the introduction of Digital manufacturing (DM), which can be defined as an integrated approach to manufacturing that is centered on a computer system. DM integrates modeling, simulation, visualization, data analytics, manufacturing, and supply chain by a digital link to define, manage and collaborate the overall product life cycle. Some of the benefits of digital manufacturing include, (a) increase productivity across the entire value chain, from design and engineering to sales, production and service, (b) faster time-to-market, (c) potential to optimize part manufacturing processes within a managed environment, and (d) enables faster creation of factory models and ensure that they are operating under optimal layout, material flow and throughput before production ramp-up. Forging involves shaping a billet to conform to the die cavity, largely via compressive loading. To transform the billet to a quality forged product, several subsystems are needed: (i) billet shearing/sizing, (ii) lubrication, (iii) billet heating, (iv) billet handling, (v) forging, (vi) secondary/finishing operations. All these subsystems exhibit inherent variances/disturbances that have a direct influence on the quality of the forgings and process economics. The overarching goal of this proposal is to develop a digital twin architecture for enhancement of forging part quality and control. By mapping numerically simulated data consisting of thermo-mechanical field variables of the tooling and billet deformation to thermal-mechanical loading response of the press, near real-time feedback and process control can be achieved, thus optimizing the process.

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MRI: Acquisition of a Large High-Temperature Vacuum Press for Advanced Materials Research, Manufacturing and Training at NC State University

National Science Foundation (NSF)(8/01/20 - 7/31/23)

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MRI: Acquisition of a Large High-Temperature Vacuum Press for Advanced Materials Research, Manufacturing and Training at NC State University

Sponsor: National Science Foundation (NSF)

Start Date: 8/01/20

End Date: 7/31/23

Abstract

It is proposed to acquire and install a Diffusion Bonding Hot Press Furnace for processing advanced materials such as ceramics, composites, refractory metals and composite metal foams for research and training on various topics of materials processing, evaluation and treatment. The system will be used to perform processing of panels of various sizes up to 1ft x 1ft. Currently the only system similar to this unit in the entire area is an old (over 50 years old) hot press with a very small chamber size and malfunctioning hydraulic press that is in PI’s lab. Due to the lack of capacity of this machine, the PIs are unable to process large parts or advanced materials that require higher temperature or pressure for manufacturing (such as ceramics and refractory metals). This press can be a valuable tool not only to support all PIs’ research, but also to support all users of NCSU on-campus Center for Additive Manufacturing and Logistics (CAMAL) and other universities in the area such as Duke university. CAMAL center currently houses five metal additive manufacturing machines that are used for a variety of research projects. However, it is lacking such large chamber press with high temperature capabilities for processing and post processing treatments of advanced ceramics, metallic and composite materials. Since the unit will housed in a shared facility, it will be easy for access both as an educational tool and a research tool for users not only at the college of engineering, but also all other colleges across the campus as well as outside users from both academia and industry. The advantages of this system over all other units are the distinctly larger chamber along with higher service temperatures and clean, efficient, and fast heating and cooling rate with a simultaneous heating and pressing. Additionally, it may be used in vacuum and in partial pressure inert gas atmosphere. Moreover, proper operation of the furnace may be mastered in a few hours which is necessary for such equipment that is going to be used by various users and students both as an educational and a research tool.

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Development of an In-Situ Testing Laboratory for Research and Education of Very High Temperature Reactor Materials

US Dept. of Energy (DOE)(10/01/20 - 9/30/21)

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Development of an In-Situ Testing Laboratory for Research and Education of Very High Temperature Reactor Materials

Sponsor: US Dept. of Energy (DOE)

Start Date: 10/01/20

End Date: 9/30/21

Abstract

A novel thermo-mechanical fatigue (TMF) testing system, referred by miniature TMF (MTMF) system has been developed at NCSU for in-situ testing of miniature specimens within Scanning Electron Microscopes (SEM). The MTMF is capable of prescribing axial-torsional loading to solid specimen and axial-torsional-internal pressure loading to tubular specimen of 1 mm diameter at elevated temperatures (up to 1000oC) to investigate deformation of microstructure and failure mechanism in real time. Currently, in-situ SEM testing with the MTMF is performed at the Analytical Instrumentation Facility (AIF) at NCSU. This poses a serious restriction to investigate failure mechanisms of very high temperature reactor (VHTRs) materials primarily because with a user facility, such as AIF, we can only perform short-term tests that span over few days. However, fatigue, creep and creep-fatigue tests for VHTR materials may span from few days to several weeks. Hence, existing SEMs on campus are not available for long-term in-situ testing of VHTR materials. Currently, fatigue, creep and creep-fatigue failure mechanisms of new and existing alloys are mostly investigated through ex-situ testing or short duration in-situ uniaxial testing within SEM. Consequently, initiation and propagation of many failure mechanisms, especially interactions between creep and fatigue mechanisms in reducing high temperature component lives remain unknown. Hence, developing a shared in-situ testing laboratory (ISTL) is essential to allow NCSU researchers to perform novel research on nuclear materials addressing issues of fatigue, creep and creep-fatigue failure mechanisms. The proposed ISTL dedicated to performing long-term fatigue, creep and creep-fatigue tests is in critical need to develop design criteria of VHTR materials for ASME Code Sec III Div 5. However, existing facilities at NCSU or any other universities or national labs in the nation do not have a facility dedicated to perform long term tests representing realistic loading conditions of VHTR. Therefore, a suitable SEM compatible with the MTMF system at NCSU is proposed to be acquired to develop an ISTL to address high temperature nuclear materials and ASME Code issues. With the availability of such a ISTL, uniaxial and multiaxial cyclic experiments prescribing realistic thermo-mechanical fatigue (TMF), creep and creep-fatigue loading can be performed on specimens of VHTR materials, such as Alloy 617, 316H, 800H, Grade 91 steel, for addressing the high temperature component design and development issues. Finally, because of the size of commercially available TMF systems, these cannot be used for in-situ SEM testing, which is essential for investigating existing alloys and developing new alloy for VHTRs. Hence, acquisition of a SEM will give the NCSU research community unprecedented capability to perform fundamental research and educate next generation scientists in studying real-time long-term microstructure evolution of nuclear materials under uniaxial and multiaxial loading. In addition, the proposed equipment will allow training undergraduate and graduate students and postdocs in performing material characterization using advanced techniques and provide hands on experiences to students in various undergraduate and graduate courses.

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Increasing Participation of U.S. Students to the 3rd World Congress on Micro-Nano Manufacturing (WCMNM); Raleigh NC, 10-12 September 2019

National Science Foundation (NSF)(4/01/19 - 3/31/20)

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Increasing Participation of U.S. Students to the 3rd World Congress on Micro-Nano Manufacturing (WCMNM); Raleigh NC, 10-12 September 2019

Sponsor: National Science Foundation (NSF)

Start Date: 4/01/19

End Date: 3/31/20

Abstract

The proposal seeks funding to provide partial support for 20 selected students studying in U.S. institutions to participate in the 3 rd World Congress on Micro-Nano Manufacturing (WCMNM) that will be held in Raleigh NC, 10-12, September 2019. WCMNM is a premiere global conference on micro-nano manufacturing which draws attendance of 150-300 people each year from America, Europe and Asia. WCMNM serves as a platform for exchange of ideas in the field of micro-nano manufacturing and engineering. The NSF financial support will provide the student participants with opportunities to exchange ideas with leading researchers and engineers from worldwide industrial and governmental facilities, as well as the opportunity to visit companies involved with micro-manufacturing in Research Triangle Part (RTP) in North Carolina. In addition to nurturing a global micromanufacturing vision, participants will learn the latest research areas and results in the fields of micro-nano- manufacturing. Each recipient of NSF financial support to attend WCMNM2019 must be author or co-author of a paper that is accepted for the conference.

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

Forging Industry Educational and Research Foundation (FIERF)(7/15/18 - 12/31/20)

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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: 12/31/20

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 - 12/31/20)

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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: 12/31/20

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 - 5/01/19)

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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: 5/01/19

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 - 9/30/21)

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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: 9/30/21

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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