The overarching goal of this study is to advance fundamental understanding of mechanisms for producing hydrodynamic cavitation from a fluid stream in a manufacturing process and use the cavitation as an energy source to augment the process. 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 in a form of pressure waves or high-speed micro jets enough to plastically deform metallic materials. In many systems where fluid interacts with structures (e.g., marine propellers, pumps, valves, turbines), cavitation causes pitting, severe wear, and erosion. Potential utilization of this energy in different fields is enormous, particularly, because this energy is condensed in micro bubbles making it possible to be deployed to a minute target. The specific objectives of the study are as follows: (a) Fundamental study of the mechanics of hydrodynamic cavitation and characterization of energy release under different operation conditions, (b) parametric study of hydrodynamic cavitation featuring key variables for augmenting manufacturing processes, and (c) fundamental study on the potential mechanisms for producing cavitation and deploying at target locations via flow induced vibration, vortex flow, and self-sustained fluid oscillations.

The overall objective of this study is to develop preform design schemes for flash-less die forging. The preforms are iteratively searched by backward tracing of material points in the FE models. The tasks to be carried out will include (a)Survey families of forgings that are carried out in closed die forging with and without flash. The survey will be aimed at quantifying material waste caused by forging with flash and at identifying potential candidate parts that might benefit from the proposed study.(b) Develop preform design schemes for two-dimensional (2D) problems (axisymmetric and plane strain). The schemes will be developed for use in conjunction with point tracking function in DEFORM 2D software. The mapping schemes are expected to contain algorithms for data transformation between DEFORM 2D simulations and a CAD program.(c) Develop preform design schemes for forgings that exhibit 3D deformation behavior. The schemes will be developed for use in conjunction with the point tracking function in DEFORM 3D software. The mapping schemes are expected to contain algorithms for geometric transformations between DEFORM 3D simulations and a CAD program.(d) Build a scaled-down flash-less forging test setup to validate the proposed schemes for both 2D and 3D geometries and (e) in collaboration with industry partner(s), validate the developed schemes in an industrial setup.

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.

North Carolina State University, Ohio State University, Oakland University, and University of New Hampshire are applying for a planning grant to establish a multi-university IUCRC Center for Industrial Metal Forming. The mission of the proposed Center is to perform cutting-edge, pre-competitive fundamental research in metal forming science and engineering in collaboration with industrial members to drive innovation and competitiveness in U.S. advanced manufacturing processes. CIMF will employ Industrial Internet of Things (IIoT), sensor technologies, novel numerical modeling and experimental techniques to enable advancements in material utilization, weight reduction and improved dimensional stability of formed components, extending the life of metal forming dies and increasing the productivity of industrial metal forming processes.

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.

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.

Develop three modules featuring modeling of metal forming process which will be used to train engineers at Y-12 facility. The first module will focus on fundamentals of linear finite element discretization, the second will address metal forming fundamentals with focus on input parameters in numerical modeling, and the third module will cover finite element simulation of metal forming processes. The second part of this project is to conduct research to identify optimal fabrication methods for specific products supplied by Y-12 Company. The investigation will involve numerical modeling featuring different concepts/metal forming possibilities, followed by critical analysis of the results. After narrowing down to a methodology that is optimal, the manufacturing system will be designed, fabricated and tested.

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.

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.

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.