Maciej S. Kumosa | |
---|---|
Born | 1953 |
Nationality | Polish and American |
Occupation(s) | Materials scientist and academic |
Known for | HVT Center and research on Extreme Materials and their Applications |
Title | John Evans Professor |
Academic background | |
Education | MS., Applied Mechanics and Materials Science PhD., Applied Mechanics and Materials Science |
Alma mater | Wrocław University of Science and Technology |
Doctoral advisor | Leszek Golaski |
Academic work | |
Institutions | University of Denver Center for Novel High Voltage/Temperature Materials and Structures (HVT) |
Maciej S. Kumosa is a materials scientist and academic. He is a professor in the Department of Mechanical and Materials Engineering at the University of Denver,and the Director of the Center for Novel High Voltage/Temperature Materials and Structures (HVT). [1]
Kumosa's research interests involve analyzing advanced materials at multiple scales,both experimentally and numerically,for applications in electrical,aerospace,and other fields under extreme operating conditions. [2]
Kumosa serves as an Editorial Board Member for Composites Science and Technology, [3] Structural Durability &Health Monitoring, [4] and Fibers. [5]
Maciej Kumosa was born on July 13,1953,in Warsaw,Poland,to a family with teaching,medicine,and farming backgrounds. His father,Dr. Stefan Kumosa, [6] was a well-respected physician in Słupca,a small town in the middle of communist Poland with approximately 5,000 residents during that period. At age five,Kumosa was relocated from Warsaw to Slupca,where he received his elementary and high school education from primary school number 1 and Marshal Józef Piłsudski High School [7] in 1968 and 1972,respectively.
Kumosa earned his Masters's degree in Applied Mechanics and Materials Science from the Technical University of Wroclaw,in 1978. He continued his studies at the same university,completing his Ph.D. in Applied Mechanics and Materials Science in 1982. [8]
In 1981,Kumosa began his career as a Senior Research Assistant in the Institute of Materials Science and Applied Mechanics at the Technical University of Wroclaw and was appointed as an assistant professor in 1983. He then served as a Senior Research Associate at the University of Cambridge from 1984 to 1990,followed by an appointment as an associate professor in the Department of Materials Science and Engineering and Department of Electrical Engineering and Applied Physics at Oregon Graduate Institute (OGI) in Portland from 1990 until 1998. In 1996,he joined the University of Denver as a research professor in the Department of Engineering and was later promoted to the roles of Associate Professor and Full Professor. Since 2006,he has been serving as a John Evans Professor at the University of Denver (DU). [1]
Kumosa was the Chair of the Mechanical and Materials Engineering (MME) Department at DU from 2007 to 2009 and later served as the Director of the Center for Nanoscale Science and Engineering from 2007 to 2012. Since 2014,he has been serving as the Center Director of the National Science Foundation Industry/University Cooperative Research Center for Novel High Voltage/Temperature Materials and Structures (the HVT Center). [9]
Kumosa's research focused on advanced materials under extreme conditions for electrical and aerospace applications,using experimental and numerical methods to optimize performance. [2] He has authored publications spanning the fields of composites,materials science,applied physics,applied mechanics,and general science,including IEEE journals,conference proceedings,engineering magazines,and national research reports. [8]
Kumosa's research has been funded by federal and private sponsors,including the National Science Foundation,the Air Force Office of Scientific Research,the Department of Energy (Headquarters),NASA,the Bonneville Power Administration,and the Western Area Power Administration. His main private research sponsors have been the Lockheed Martin Corporation,the Electric Power Research Institute,Tri-State Generation and Transmission,the Alabama Power Company,and Pacific Gas &Electric.
As part of his Ph.D. research,Kumosa investigated both numerically and experimentally the initiation of cracking by mechanical twins in silicon iron. [10] He used an anisotropic Eshelby approach to predict the stresses required to initiate cracks by terminated mechanical twins and to determine the directions of shear deformations associated with mechanical twining. [11]
Kumosa started experimenting with thin-walled Glass Reinforced Polymer (GRP) composite structures by subjecting them to internal pressure to determine the effects of multiaxial loads in the initiation of damage in the composites. His mentors at that time were Leszek Golaski and Waclaw Kasprzak. [12]
After his graduation and initial academic appointments in Poland,Kumosa pursued an academic journey abroad in 1984. After a year as a Visiting Research Fellow at the University of Liverpool,he then moved in December 1984 to Cambridge,England,where he spent over six years in the Department of Materials Science and Metallurgy at the University of Cambridge. Collaborating with Derek Hull and his research group,he focused on material science research and in particular advanced composites investigations. [13]
During his time at Cambridge,Kumosa conducted research that involved the application of Finite Element Methods (FEM) to predict failures in advanced composite structures under multiaxial loading conditions. [14] His investigations extended to the examination of stress corrosion cracking (SCC) in Glass Reinforced Polymer (GRP) composites, [15] along with the analysis of mixed-mode failure and fracture in both GRP and Carbon Fiber Reinforced (CFRP) composites. [16] Moreover,he evaluated the potential use of Acoustic Emission (AE) for monitoring composite structures and contributed to research on the crashworthiness of composites. [13]
Kumosa contributed to the development of the Iosipescu shear test,demonstrating its uniqueness through FEM [17] including the consideration of axial splits and their impact on composite failure predictions. [16] Collaborating with W. Broughton,he further redesigned the test to incorporate biaxial shear-dominated conditions,a seminal modification at that time. [18] In addition,his FEM research supported multiaxial testing of filament-wound composite cylinders,accounting for the presence of hoop cracks in thin-walled composite tubes. [19]
Kumosa,along with Sigalas and Hull,proposed the first numerical model of a composite tube subjected to axial crashing,resulting in a highly cited paper. [19] Additionally,he demonstrated the precise counting of fractured fibers in the stress corrosion cracking of Glass Polymer Composites using AE monitoring. [20]
In May 1990,Kumosa relocated to the Oregon Graduate Institute of Science and Technology (OGI) in Portland,Oregon. His SCC and shear testing of composites projects transitioned to OGI,forming the basis for two research programs:the study of biaxial failures in high-temperature polyimide composites [21] and the investigation of in-service failures of High Voltage transmission composite insulators. [22]
Kumosa’s key graduate students at OGI who helped him build the foundation of his future NSF HVT Center were Kevin Searles,Qiong Qiu,Anurag Bansal and Jun Ding [23] [24]
At OGI from 1990 to 1995,Kumosa,together with Korusiewicz and Ding,worked on the failure analysis and design of advanced metallic alloys,contributing to the GE90 project. [25] Focused on jet engine applications,his research group focused on studying nickel-based superalloys and titanium aluminides used in the GE90 engine for their resistance to high-temperature fracture and fatigue. [25]
From 1992 to 2006,Kumosa supervised research on High Voltage (HV) composite insulators,also known as Non-Ceramic Insulators (NCIs). He directed initiatives addressing the challenges faced by these insulators used in transmission lines and substations globally. These insulators,subjected to intense mechanical,electrical,and environmental stresses,presented operational life challenges. One of his significant contributions has been to provide an explanation for various large HV transmission line insulator failures attributed to brittle fractures. Notably,he addressed the 14 energized line drops on the Western Area Power Administration's 345 kV Craig Bonanza line in Colorado and has elucidated the causes behind five catastrophic 500 kV line drops at Pacific Gas &Electric in California in 1995/1996 as well. [26]
Working initially with his graduate students Bansal and Qiu at OGI and then at DU with Lucas Kumosa Jr,Tom Ely,Paul Predecki,Dwight Smith,and Daniel Armentrout,Kumosa made contributions by identifying the specific type of acid responsible for brittle fracture failures in California,Colorado,and other global regions. [27] [28] Moreover,he conducted simulations of brittle fractures in insulator (GRP) composites under high voltage conditions,shedding light on critical failure mechanisms. [29]
Kumosa's work improved the understanding of insulator failure mechanisms and contributed to global advancements in High Voltage transmission system reliability. A notable development was the establishment of the first ranking system for commonly used GRP rod materials,evaluating their resistance to High Voltage brittle fracture and other in-service failures. [26] He and his research teams also proposed the inaugural comprehensive model explaining insulator failures arising from improper crimping,which provided insights into failure modes. [30]
From 1992 to 2004,Kumosa's High-Temperature Polymer Matrix Composite research aimed to understand fundamental failure mechanisms in High-Temperature (HT) composites. Using medium and high-stiffness carbon fibers with various HT polyimide resins,the research explored the impact of aging on composite strength properties,focusing on temperature variations and biaxial shear-dominated loading conditions. He advanced multidisciplinary technologies for affordable propulsion components,aiming for optimal performance and durability at elevated temperatures with reduced cooling needs. [31]
In the course of this research,Kumosa,in collaboration with Benedikt and Predecki,developed experimental and numerical techniques to assess manufacturing stresses in propulsion engine components. These techniques,which are based on embedded aluminum inclusions,X-ray diffraction,and non-linear multiple inclusion Eshelby models,played a crucial role in predicting residual manufacturing stresses in High-Temperature Polymer Matrix Composites (HT PMCs) used in a composite combustion chamber with substantially reduced weight. [32] [33]
Additionally,Kumosa's collaborative efforts with Odegard,Rupnowski and Gentz led to the prediction of the failure properties of these composites under High-Temperature,multiaxial shear-dominated conditions. [34] [35] [36] An unprecedented evaluation of the aging resistance of the composites in nitrogen (physical aging) and air (chemical aging) at temperatures as high as 400 °C was undertaken for the first time. [37] The culmination of this research manifested in the optimization of High-Temperature (HT) combustion chamber composites,achieved through the meticulous selection and integration of fibers and matrices tailored to exhibit superior performance under high-temperature conditions. [38]
Kumosa and his team of graduate students have directed their research toward High-Temperature High-Voltage Polymer Core Composite Conductors (PCCC) for use in High-Voltage (HV) transmission lines. Between 2008 and 2010,he and Burks were the first to determine the critical bend radius of the most popular HTLS PCCC. [39] Additionally,from 2009 to 2012,they demonstrated the sensitivity of PCCC rods to transverse loading under aeolian vibrations. [40] Their findings also suggested that bearing stresses due to crimping the conductor at a dead-end connection could be considered for effective fatigue life design. This effect was evaluated for the first time for PCCC rods at various stages of environmental aging,using a unique combined experimental/numerical approach. [41]
Kumosa and Middleton conducted life predictions for PCCC conductors,indicating that exposure to high temperatures appeared to be more damaging to PCCC rods than the impact of highly concentrated ozone. Taking into account potential environmental conditions such as high temperature and ozone pollution,it was predicted that PCCC rods could endure in service for many years if the operating temperature did not exceed 120°C with an ozone concentration of no more than about 1%. [42] Subsequently,he and Hoffman demonstrated that the in-service life of the conductors could be significantly extended (by 75%) through the application of special Teflon coatings on the rods. [43]
Considering the prevalent issue faced by utilities using traditional steel/aluminum designs,especially in coastal environments,Kumosa,Håkansson,Hoffman and others conducted research to evaluate the resistance of the current PCCC design to corrosion on transmission lines. They proposed a potent analytical model of atmospheric galvanic corrosion of PCCC conductors,which was subsequently numerically and experimentally verified. [44] He and his research teams have presented insights into the in-service performance of the next generation of High-Voltage High-Temperature Low Sag Polymer Core Composite Conductors,akin to their previous work on HV composite insulators. Their efforts have led to numerous potential improvements in design,as highlighted in various publications,including a feature in the Denver Business Journal,where he also discussed how the new transmission line product could save lives. [45]
Kumosa has led a research initiative funded by the National Science Foundation (NSF) and directed the HVT Center.
Kumosa's previous projects,including the PCCC conductor research,were integrated into the HVT Center,and new projects were initiated. Within the PCCC conductor project,his research performed in collaboration with Waters and Hoffman focused on the conductors' resilience to low-velocity excessive transverse impacts using unique fixtures and simulating impact behavior through Finite Element Method (FEM) analysis. The conductors exhibited superiority over their Al/steel counterparts in this regard. [46]
The group also demonstrated the successful monitoring of PCCC conductors for various static and dynamic loads using Fiber Bragg Grating (FBG) sensors. These sensors proved effective in monitoring conductors during installation and in-service for both small and large deformations. [47]
Among the new projects in the HVT Center,Kumosa studied the "Effect of Oxygen Aging on Ti/Al/V Powders used in Additive Manufacturing" with Billy Grell,Zach Loftus,and others. [48] Along with Lu,Yi,Solis-Ramos and other researchers,he also investigated the "Synergistic Aging of Polymers and their Composites." [49] The extreme aging of silicone rubbers used in HV voltage applications was another research conducted by him and Bleszynski in the Center,resulting in the design,manufacture,and testing of an HV silicone rubber with improved resistance to extreme aging by about 50%. [50]
Henderson,Predecki,and Kumosa's project "Prevention of Ballistic Damage to HV Transformer Bushings" tested the use of ballistic polymer coatings on HV porcelain transformer bushings to protect them against high-power rifle damage,demonstrating for the first time that the bushings could be safeguarded against vandalism with properly designed and applied coatings. [51] His collaborative project with Waters,Hoffman,and Predeck titled,"Polymerization in Single Fiber Composites using FBG Sensors" introduced a novel technique using FBG sensors within the HVT Center. [52] This technique evaluated the responses of modeled polymer and metal composites to manufacturing conditions,using FBG sensors to identify the beginning and end of curing,the gel point,cooling strains,and stresses for polymers such as epoxies,and was later applied successfully to monitor the solidification of metals. [53]
More recently in 2023,Kumosa's research teams studied both the "Modernization of Large Power Transformer (LPT) Tanks" [54] and the "Development of Next-generation Graphene and Graphene Oxide Epoxy Base Nanocomposites".[ citation needed ] In the LPT project,he,Jide Williams,Hoffman,and Predecki demonstrated for the first time that heavy LPT tanks could be replaced with advanced PMCs for weight reduction,superior resistance to rifle damage,and improved performance in other adverse in-service conditions. [55] In the Graphene Oxide Project,Matt Reil and others discovered a new powerful toughening mechanism in an epoxy resin with embedded graphene oxide nano-particles which was subsequently explained through extensive numerical and experimental simulations and verifications. [56]
A composite material is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from mixtures and solid solutions. Composite materials with more than one distinct layer are called composite laminates.
Carbon fibers or carbon fibres are fibers about 5 to 10 micrometers (0.00020–0.00039 in) in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages: high stiffness, high tensile strength, high strength to weight ratio, high chemical resistance, high-temperature tolerance, and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military, motorsports, and other competition sports. However, they are relatively expensive compared to similar fibers, such as glass fiber, basalt fibers, or plastic fibers.
Fiberglass or fibreglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic.
In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.
Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycle, including during their initial processing, use, disposal into the environment and recycling. The rate of this degradation varies significantly; biodegradation can take decades, whereas some industrial processes can completely decompose a polymer in hours.
Polyimide is a polymer containing imide groups belonging to the class of high-performance plastics. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, such as high temperature fuel cells, displays, and various military roles. A classic polyimide is Kapton, which is produced by condensation of pyromellitic dianhydride and 4,4'-oxydianiline.
Pre-preg is a composite material made from "pre-impregnated" fibers and a partially cured polymer matrix, such as epoxy or phenolic resin, or even thermoplastic mixed with liquid rubbers or resins. The fibers often take the form of a weave and the matrix is used to bond them together and to other components during manufacture. The thermoset matrix is only partially cured to allow easy handling; this B-Stage material requires cold storage to prevent complete curing. B-Stage pre-preg is always stored in cooled areas since heat accelerates complete polymerization. Hence, composite structures built of pre-pregs will mostly require an oven or autoclave to cure. The main idea behind a pre-preg material is the use of anisotropic mechanical properties along the fibers, while the polymer matrix provides filling properties, keeping the fibers in a single system.
Electrospinning is a fiber production method that uses electric force to draw charged threads of polymer solutions or polymer melts up to fiber diameters in the order of some hundred nanometers. Electrospinning shares characteristics of both electrospraying and conventional solution dry spinning of fibers. The process does not require the use of coagulation chemistry or high temperatures to produce solid threads from solution. This makes the process particularly suited to the production of fibers using large and complex molecules. Electrospinning from molten precursors is also practiced; this method ensures that no solvent can be carried over into the final product.
Carbon nanofibers (CNFs), vapor grown carbon fibers (VGCFs), or vapor grown carbon nanofibers (VGCNFs) are cylindrical nanostructures with graphene layers arranged as stacked cones, cups or plates. Carbon nanofibers with graphene layers wrapped into perfect cylinders are called carbon nanotubes.
Nanocomposite is a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nanometers (nm) or structures having nano-scale repeat distances between the different phases that make up the material.
Carbon nanotubes (CNTs) are cylinders of one or more layers of graphene (lattice). Diameters of single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) are typically 0.8 to 2 nm and 5 to 20 nm, respectively, although MWNT diameters can exceed 100 nm. CNT lengths range from less than 100 nm to 0.5 m.
In the theory of composite materials, the representative elementary volume (REV) is the smallest volume over which a measurement can be made that will yield a value representative of the whole. In the case of periodic materials, one simply chooses a periodic unit cell, but in random media, the situation is much more complicated. For volumes smaller than the RVE, a representative property cannot be defined and the continuum description of the material involves Statistical Volume Element (SVE) and random fields. The property of interest can include mechanical properties such as elastic moduli, hydrogeological properties, electromagnetic properties, thermal properties, and other averaged quantities that are used to describe physical systems.
A thermoset polymer matrix is a synthetic polymer reinforcement where polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the Space Shuttle.
In materials science ceramic matrix composites (CMCs) are a subgroup of composite materials and a subgroup of ceramics. They consist of ceramic fibers embedded in a ceramic matrix. The fibers and the matrix both can consist of any ceramic material, including carbon and carbon fibers.
Carbon fiber-reinforced polymers, carbon-fibre-reinforced polymers, carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic, also known as carbon fiber, carbon composite, or just carbon, are extremely strong and light fiber-reinforced plastics that contain carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.
Thermoplastics containing short fiber reinforcements were first introduced commercially in the 1960s. The most common type of fibers used in short fiber thermoplastics are glass fiber and carbon fiber . Adding short fibers to thermoplastic resins improves the composite performance for lightweight applications. In addition, short fiber thermoplastic composites are easier and cheaper to produce than continuous fiber reinforced composites. This compromise between cost and performance allows short fiber reinforced thermoplastics to be used in myriad applications.
Transfer molding is a manufacturing process in which casting material is forced into a mold. Transfer molding is different from compression molding in that the mold is enclosed rather than open to the fill plunger resulting in higher dimensional tolerances and less environmental impact. Compared to injection molding, transfer molding uses higher pressures to uniformly fill the mold cavity. This allows thicker reinforcing fiber matrices to be more completely saturated by resin. Furthermore, unlike injection molding, the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding process.
In materials science, a polymer matrix composite (PMC) is a composite material composed of a variety of short or continuous fibers bound together by a matrix of organic polymers. PMCs are designed to transfer loads between fibers of a matrix. Some of the advantages with PMCs include their light weight, high resistance to abrasion and corrosion, and high stiffness and strength along the direction of their reinforcements.
Structural composite supercapacitors are multifunctional materials that can both bear mechanical load and store electrical energy. That when combined with structural batteries, could potentially enable an overall weight reduction of electric vehicles.
Gregory M. Odegard is a materials researcher and academic. He is the John O. Hallquist Endowed Chair in Computational Mechanics in the Department of Mechanical Engineering – Engineering Mechanics at Michigan Technological University and the director of the NASA Institute for Ultra-Strong Composites by Computational Design.