Scholarly Works, Mechanical Engineering

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https://hdl.handle.net/10919/23262

Research articles, presentations, and other scholarship

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Analysis and material tailoring of functionally graded linearly elastic orthotopic incompressible material cylinders under combined loads
Nie, G. J.; Batra, Romesh C. (Taylor and Francis, 2025-12)
Toward Sustainable Digital Infrastructure: Thermal and Economic Potential of Data Center Heat Reuse
Ashraf, Muhammad; Ibrahim, Ibrahim; Untaroiu, Alexandrina (2026-03-10)
Data centers consume large amounts of electricity, with a significant fraction dissipated as low grade heat. Generally, this waste heat is released to the environment, but growing energy demands and decarbonization targets have emphasized the interest in its recovery and reuse. This study investigates the initial technoeconomic viability of heat reuse from a modeled system with varying effeciency and other key influencing parameters. By using the thermal approximations, we quantify the available temperature ranges and heat flows for several reuse pathways, including district heating, absorption cooling, and domestic hot water production. The results will reflect on the key parameters including the thermal efficiency of direct reuse of heat for low temperature applications, while higher temperature uses necessitate auxiliary upgrades that reduce overall system performance. A comparative techno-economic analysis highlights the trade-offs between capital investment, operating cost, and key data center parameters across reuse scenarios. In particular, coupling with district heating networks emerges can be one of the most scalable option, though decentralized applications (e.g., building heating) can offer faster payback under certain operating regimes. The findings underscore that while data center heat reuse is technically feasible, its practical deployment depends strongly on local infrastructure compatibility and economic drivers. This work contributes a structured framework for evaluating reuse pathways, providing both performance metrics and cost considerations to guide decision making for sustainable data center operation.
Methodology for Real-Time Hydroplaning Risk Estimation Using an Intelligent Tire System: An Analytical Approach
Vilsan, Alexandru; Sandu, Corina; Anghelache, Gabriel; Warfford, Jeffrey (MDPI, 2025-11-30)
This study presents a real-time capable methodology for quantifying the hydroplaning risk of a passenger car tire using data from an intelligent tire system. An analytical water lift force formulation is applied to convert measured peak lift force values into longitudinal water velocity. Based on the water velocity and groove dimensions, the intake flow rate that the tire must evacuate is estimated. Hydroplaning risk is then defined as the ratio between the intake flow rate and the maximum flow capacity of the tire before total hydroplaning occurs. Experimental investigations under real-world conditions were carried out at 45 mph and 65 mph, yielding average hydroplaning risk values of 12.6% and 21.3%. The proposed model was validated by performing hydroplaning tests under a controlled water depth of 1 mm at Michelin Laurens Proving Grounds. The hydroplaning risk values computed by the intelligent tire system were compared with reference data from the literature obtained under similar test conditions. Additionally, the critical hydroplaning speed of the test tire was estimated and compared against predictions from established numerical models, such as those proposed by Gengenbach and Spitzhüttl. The methodology is confirmed as a reliable algorithm for real-time hydroplaning risk monitoring with the potential to improve vehicle safety.
Bioinspired Fano-like resonant transmission: frequency selective impedance matching
Esposito, Andrea; Tallarico, Domenico; Sayed Ahmed, Moustafa; Miniaci, Marco; Shahab, Shima; Bergamini, Andrea (IOP Publishing, 2024-04-12)
The study of the impedance mismatch between the device and its surroundings is crucial when building an acoustic device to obtain optimal performance. In reality, a high impedance mismatch would prohibit energy from being transmitted over the interface, limiting the amount of energy that the device could treat. In general, this is solved by using acoustic impedance matching layers, such as gradients, similar to what is done in optical coatings. The simplest form of such a gradient can be considered as an intermediate layer with certain qualities resting between the two media to impedance match, and requiring a minimum thickness of at least one quarter wavelength of the lowest frequency under consideration. The desired combination(s) of the (limited) available elastic characteristics and densities has traditionally determined material selection. Nature, which is likewise limited by the use of a limited number of materials in the construction of biological structures, demonstrates a distinct approach in which the design space is swept by modifying certain geometrical and/or material parameters. The middle ear of mammals and the lateral line of fishes are both instances of this method, with the latter already incorporating an architecture of distributed impedance matched underwater layers. In this paper, we develop a resonant mechanism whose properties can be modified to give impedance matching at different frequencies by adjusting a small set of geometrical parameters. The mechanism in question, like the lateral line organ, is intended to serve as the foundation for the creation of an impedance matching meta-surface. A computational study and parameter optimization show that it can match the impedance of water and air in a deeply sub-wavelength zone.
Uncertainty Analysis for Ferromagnetic-Paramagnetic Phase Transition Behavior of Magnetic Materials
Eger, Zekeriya Ender; Acar, Pinar (Springer, 2024-06-01)
This study aims to model the phase transition of ferromagnetic materials using two- (2D) and three-dimensional (3D) Ising models, incorporating long-range magnetic spin-to-spin interactions and the influence of an external magnetic field. The 2D Ising model is investigated mainly for a 4 x 4 domain, while its extension to larger domains is also explored. For the 3D Ising model, the selection of representative volume element is discussed in terms of free energy. An uncertainty quantification formulation is integrated into the Ising model to capture the uncertainties related to the external magnetic field and evaluate their effects on the phase transition from a ferromagnetic to a paramagnetic state. Despite the common use and known effectiveness of the Ising model, there is still no universally accepted exact solution for the 3D domains, making it an ongoing research focus. The research also acknowledges the complexities and limitations arising from experimental methods, despite the insights they provide on the microscopic dynamics of ferromagnetic materials during phase transitions.
Continuous non-invasive measurement of tidal volume and minute ventilation using a smart nasal cannula
Dogan, Alan B.; Patel, Neel; Gottschalk, Carter; Blankenship, Rae L.; Young, Valerie K.; Wicks, Alfred; Sofi, Umar F. (2025-11-27)
The Flow Regulated Nasal Delivery System (FRNDS) is a novel smart nasal cannula platform developed to enable noninvasive, continuous monitoring of tidal volume (VT) and detection of abnormal breathing events. Combined with peripheral capillary oxygen saturation (SpO₂) data modulation of oxygen flow can be accomplished. In a cohort of 57 adults, FRNDS-derived VT and minute ventilation were compared to reference measurements from respiratory inductance plethysmography (RIP) across a range of oxygen flow rates. While the cannula system tended to overestimate inspiratory and underestimate expiratory VT—especially at higher flow rates—these errors were substantially reduced by applying machine learning regression models trained on anatomical and physiological features, achieving strong agreement with RIP averaging a 53.5 mL error, 78.2 mL root-mean error, and is within ~ 11% of the actual value. The system also demonstrated robust performance in classifying clinically relevant breathing patterns, including apneic spells and mouth breathing, suggesting utility for real-time respiratory surveillance and sleep apnea detection. These results support FRNDS as a promising, adaptable solution for individualized respiratory monitoring in both clinical and home environments.
Enhancing Electrical Conductivity of Stretchable Liquid Metal-Silver Composites through Direct Ink Writing
Zu, Wuzhou; Carranza, Hugo E.; Bartlett, Michael D. (American Chemical Society, 2024-04-30)
Structure-property-process relationships are a controlling factor in the performance of materials. This offers opportunities in emerging areas, such as stretchable conductors, to control process conditions during printing to enhance performance. Herein, by systematically tuning direct ink write (DIW) process parameters, the electrical conductivity of multiphase liquid metal (LM)-silver stretchable conductors is increased by a maximum of 400% to over 1.06 x 10(6) Sm(-1). This is achieved by modulating the DIW print velocity, which enables the in situ elongation, coalescence, and percolation of these multiphase inclusions during printing. These DIW printed filaments are conductive as fabricated and are soft (modulus as low as 1.1 MPa), stretchable (strain limit >800%), and show strain invariant conductivity up to 80% strain. These capabilities are demonstrated through a set of electromagnetic induction coils that can transfer power wirelessly through air and water, even under deformation. This work provides a methodology to program properties in stretchable conductors, where the combination of material composition and process parameters leads to greatly enhanced performance. This approach can find use in applications such as soft robots, soft electronics, and printed materials for deformable, yet highly functional devices.
Frequency lock-in control and mitigation of nonlinear vortex-induced vibrations of an airfoil structure using a conserved-mass linear vibration absorber
Basta, Ehab; Gupta, Sunit K.; Barry, Oumar (Springer, 2024-06-01)
We investigate the effectiveness of a vibration absorber on the vortex-induced vibration response of turbine blades during the frequency lock-in phase. A reduced-order model of a turbine blade and van der Pol oscillator is used to represent the fluid-blade interaction caused by the vortex shedding. A spring-mass-damper system is considered to model the vibration absorber. The advantage of the vibration absorber is demonstrated by simulating the nonlinear coupled four-degree-of-freedom aeroelastic system for the different sets of system parameters. We observe the dominance of a nonlinear vibration absorber over the linear vibration absorber only for the higher coupling parameter values. The analytical solution of the nonlinear coupled system is obtained through the method of multiple scales for the case of 1:1 internal resonance to identify the critical design parameters of the vibration absorber. We observe the high sensitivity of the system's frequency response to the distance of the vibration absorber from the elastic axis, along with the absorber's damping, stiffness, and mass. Finally, we perform a parametric analysis on the lock-in of the stability region to better understand the effect of the vibration absorber on the instability region.
Bandgap formation in topological metamaterials with spatially modulated resonators
LeGrande, Joshua; Malla, Arun; Bukhari, Mohammad; Barry, Oumar (AIP Publishing, 2024-05-28)
Within the field of elastic metamaterials, topological metamaterials have recently received much attention due to their ability to host topologically robust edge states. Introducing local resonators to these metamaterials also opens the door for many applications such as energy harvesting and reconfigurable metamaterials. However, the interactions between phenomena from local resonance and modulation patterning are currently unknown. This work fills that gap by studying multiple cases of spatially modulated metamaterials with local resonators to reveal the mechanisms behind bandgap formation. Their dispersion relations are determined analytically for infinite chains and validated numerically using eigenvalue analysis. The inverse method is used to determine the imaginary wavenumber components from which each bandgap is characterized by its formation mechanism. The topological nature of the bandgaps is also explored through calculating the Chern number and integrated density of states. The band structures are obtained for various sources of modulation as well as multiple resonator parameters to illustrate how both local resonance and modulation patterning interact together to influence the band structure. Other unique features of these metamaterials are further demonstrated through the mode shapes obtained using the eigenvectors. The results reveal a complex band structure that is highly tunable, and the observations given here can be used to guide designers in choosing resonator parameters and patterning to fit a variety of applications.
Electrostatic Defrosting
Lolla, Venkata Yashasvi; Zhang, Hongwei; Socha, Beckett Z.; Qiao, Rui; Boreyko, Jonathan B. (Wiley-VCH, 2025-11-11)
Electrification of ice has been studied for over half a century, mostly in the context of atmospheric science. Here, the polarizability and natural thermovoltage of a substrate-bound frost sheet are exploited for frost removal by placing an actively charged electrode overhead. This new technique, which we term electrostatic defrosting (EDF), can remove up to 75% of the frost’s mass from its substrate over a time scale of only minutes. A one-dimensional numerical model is developed to rationalize the effective electrostatic force exerted by the electrode on the warm end of the frost sheet. Experimentally, the effectiveness of EDF is shown to depend on the applied voltage, relative humidity of the ambient air, the gap height between the frosted substrate and the electrode plate, and the type of substrate. Although EDF primarily removes the dendritic frost structures rather than the underlying frozen condensate, this selective removal can still offer significant advantages for applications requiring improved visibility or reduced surface roughness. EDF can effectively remove frost without the application of heat, chemicals, or mechanical forces, rendering it a promising new construct for defrosting.
Airborne Acoustic Vortex End Effector-Based Contactless, Multi-Mode, Programmable Control of Object Surfing
Li, Teng; Li, Jiali; Bo, Luyu; Brooks, Michael R.; Du, Yingshan; Cai, Bowen; Pei, Zhe; Shen, Liang; Sun, Chuangchuang; Cheng, Jiangtao; Pan, Y. Albert; Tian, Zhenhua (Wiley, 2024-09-01)
Tweezers based on optical, electric, magnetic, and acoustic fields have shown great potential for contactless object manipulation. However, current tweezers designed for manipulating millimeter-sized objects such as droplets, particles, and small animals exhibit limitations in translation resolution, range, and path complexity. Here, a novel acoustic vortex tweezers system is introduced, which leverages a unique airborne acoustic vortex end effector integrated with a three-degree-of-freedom (DoF) linear motion stage, for enabling contactless, multi-mode, programmable manipulation of millimeter-sized objects. The acoustic vortex end effector utilizes a cascaded circular acoustic array, which is portable and battery-powered, to generate an acoustic vortex with a ring-shaped energy pattern. The vortex applies acoustic radiation forces to trap and spin an object at its center, simultaneously protecting this object by repelling other materials away with its high-energy ring. Moreover, The vortex tweezers system facilitates contactless, multi-mode, programmable object surfing, as demonstrated in experiments involving trapping, repelling, and spinning particles, translating particles along complex paths, guiding particles around barriers, translating and rotating droplets containing zebrafish larvae, and merging droplets. With these capabilities, It is anticipated that the tweezers system will become a valuable tool for the automated, contactless handling of droplets, particles, and bio-samples in biomedical and biochemical research. A novel acoustic vortex tweezers system is reported, which leverages a unique acoustic vortex end effector based on a portable, battery-powered, cascaded circular acoustic array. The system enables contactless, multi-mode, programmable object surfing, as demonstrated in experiments involving trapping, repelling, and spinning particles, translating particles along complex paths, guiding particles around barriers, and translating and rotating droplets containing zebrafish larvae. image
Scale modeling of thermo-structural fire tests of multi-orientation wood laminates
Gangi, Michael J.; Lattimer, Brian Y.; Case, Scott W. (Springer, 2024-07-01)
The stacking sequence of laminated wood significantly impacts the composite mechanical behavior of the material, especially when scaling down thermo-mechanical tests on plywood. In previous research, we developed a scaling methodology for thermo-structural tests on samples with similar cross sections, however this paper focused on testing plywood samples with different stacking sequences between the scales. Plywood samples at 1/2 -scale and 1/4 -scale were subjected to combined bending and thermal loading, with the loading scaled to have the same initial static bending stresses. While the 1/4 -scale 4-layer [0 degrees/90 degrees]s laminate and the 1/2 -scale 8-layer [0 degrees/90 degrees/90 degrees/0 degrees]s laminate had an equal number of 0 degrees and 90 degrees layers, as the char front progresses, the sections behave differently. Thus, modeling becomes essential to extrapolating the data from the smaller 1/4 -scale test to predict the behavior of the larger 1/2 -scale test. Reduced cross-sectional area models (RCAM) incorporating classical laminated plate theory were used to predict the mechanical response of the composite samples as the char front increased. Three methods were proposed for calibrating the RCAM models: Fourier number scaling, from detailed kinetics-based pyrolysis GPyro models, and fitting to data from fire exposure thermal response tests. The models calibrated with the experimental char measurements produced the most accurate predictions. The experimental char models validated to predict the behavior of the 1/4 -scale tests within 2.5%, were then able to predict the 1/2 -scale test behavior within 4.5%.
Influence of fuel inhomogeneity on detonation wave propagation in a rotating detonation combustor
Raj, P.; Meadows, Joseph (Springer, 2024-10-01)
Rotating detonation combustor (RDC) is a form of pressure gain combustion, which is thermodynamically more efficient than the traditional constant-pressure combustors. In most RDCs, the fuel-air mixture is not perfectly premixed and results in inhomogeneous mixing within the domain. Due to discrete fuel injection locations, local pockets of rich and lean mixtures are formed in the refill region. The objective of the present work is to gain an understanding of the effects of reactant mixture inhomogeneity on detonation wave structure, wave velocity, and pressure profile. To study the effect of mixture inhomogeneity, probability density functions of fuel mass fractions are generated with varying standard deviations. These distributions of fuel mass fractions are incorporated in 2D reacting simulations as a spatially/temporally varying inlet boundary condition. Using this methodology, the effect of mixture inhomogeneity is independently investigated to determine the effects on detonation wave propagation and RDC performance. As mixture inhomogeneity is increased, detonation wave speed, detonation efficiency, and potential for pressure gain all decrease, ultimately leading to the separation of the reaction zone from the shock wave.
Inhibiting Shuttle Effect and Dendrite Growth in Sodium-Sulfur Batteries Enabled by Applying External Acoustic Field
Zhang, Qipeng; Bo, Luyu; Li, Hao; Shen, Liang; Li, Jiali; Li, Teng; Xiao, Yunhao; Tian, Zhenhua; Li, Zheng (American Chemical Society, 2024-08-21)
The room-temperature sodium-sulfur (RT Na-S) battery is a promising alternative to traditional lithium-ion batteries owing to its abundant material availability and high specific energy density. However, the sodium polysulfide shuttle effect and dendritic growth pose significant challenges to their practical applications. In this study, we apply diverse disciplinary backgrounds to introduce a novel method to stimulate polarized BaTiO3 (BTO) nanoparticles on the separator. This approach generates more charges due to the piezoelectric effect under stronger driving forces produced by applying a controllable acoustic field at the outer edge of the cell. The acoustically stimulated BTO attracts more polysulfides, thus reducing the shuttling effect from the cathode to the anode and ultimately enhancing the battery performance. Meanwhile, the acoustic waves create additional streaming flows, improving the uniformity of the sodium ion dispersion, enhancing the sodium ion transport and reducing the possibility of sodium dendrite development. We believe that this work offers a new strategy for the development of high-performance Na-S batteries.
Integrated Fatigue Evaluation of As-Built WAAM Steel Through Experimental Testing and Finite Element Simulation
Gothivarekar, Sanjay; Brains, Steven; Raeymaekers, Bart; Talemi, Reza (MDPI, 2025-10-11)
Additive Manufacturing (AM) has attracted considerable interest over the past three decades, driven by growing industrial demand. Among metal AM techniques, Wire and Arc Additive Manufacturing (WAAM), a Directed Energy Deposition (DED) variant, has emerged as a prominent method for producing large-scale components with high deposition rates and cost efficiency. However, WAAM parts typically exhibit rough surface profiles, which can induce stress concentrations and promote fatigue crack initiation under cyclic loading. This study presents an integrated experimental and numerical investigation into the fatigue performance of as-built WAAM steel. Fatigue specimens extracted from a WAAM-fabricated wall were tested under cyclic loading, followed by fractography to assess the influence of surface irregularities and subsurface defects on fatigue behaviour. Surface topography analysis identified critical stress-concentration regions and key surface roughness parameters. Additionally, 3D scanning was used to reconstruct the specimen topography, enabling detailed 2D and 3D finite element (FE) modelling to analyze stress distribution along the as-built surface and predict fatigue life. A Smith-Watson-Topper (SWT) critical plane-based approach was applied for multiaxial fatigue life estimation. The results reveal a good correlation between experimental fatigue data and numerically predicted results, validating the proposed combined methodology for assessing durability of as-built WAAM components.
Parameter Identification of Soil Material Model for Soil Compaction Under Tire Loading: Laboratory vs. In-Situ Cone Penetrometer Test Data
Shokanbi, Akeem; Jasoliya, Dhruvin; Untaroiu, Costin D. (MDPI, 2025-10-15)
Accurate numerical simulations of soil-tire interactions are essential for optimizing agricultural machinery to minimize soil compaction and enhance crop yield. This study developed and compared two approaches for identifying and validating parameters of a LS-Dyna soil model. The laboratory-based approach derives parameters from triaxial, consolidation, and cone penetrometer tests (CPT), while the optimization-based method refines them using in-situ CPT data via LS-OPT to better capture field variability. Simulations employing Multi-Material Arbitrary Lagrangian–Eulerian (MM-ALE), Smoothed Particle Hydrodynamics (SPH), and Hybrid-SPH methods demonstrate that Hybrid-SPH achieves the optimal balance of accuracy (2% error post-optimization) and efficiency (14-h runtime vs. 22 h for SPH). Optimized parameters improve soil–tire interaction predictions, including net traction and tire sinkage across slip ratios from −10% to 30% (e.g., sinkage of 12.5 mm vs. 11.1 mm experimental at 30% slip, with overall mean-absolute percentage error (MAPE) reduced to 3.5% for sinkage and 4.2% for traction) and rut profiles, outperforming lab-derived values. This framework highlights the value of field-calibrated optimization for sustainable agriculture, offering a cost-effective alternative to field trials for designing low-compaction equipment and reducing yield losses from soil degradation. While sandy loam soil at 0.4% moisture content was used in this study, future extensions to different soil types with varied moisture are recommended.
Holographic thermal mapping in volumes using acoustic lenses
Cengiz, Ceren; Shahab, Shima (IOP Publishing, 2024-09-13)
Acoustic holographic lenses (AHLs) show great potential as a straightforward, inexpensive, and reliable method of sound manipulation. These lenses store the phase and amplitude profile of the desired wavefront when illuminated by a single acoustic source to reconstruct ultrasound pressure fields, induce localized heating, and achieve temporal and spatial thermal effects in acousto-thermal materials like polymers. The ultrasonic energy is transmitted and focused by AHL from a transducer into a particular focal volume. It is then converted to heat by internal friction in the polymer chains, causing the temperature of the polymer to rise at the focus locations while having little to no effect elsewhere. This one-of-a-kind capability is made possible by the development of AHLs to make use of the translation of attenuated pressure fields into programmable heat patterns. However, the impact of acousto-thermal dynamics on the generation of AHLs is largely unexplored. We use a machine learning-assisted single inverse problem approach for rapid and efficient AHLs' design to generate thermal patterns. The process involves the conversion of thermal information into a holographic representation through the utilization of two latent functions: pressure phase and amplitude. Experimental verification is performed for pressure and thermal measurements. The volumetric acousto-thermal analyses of experimental samples are performed to offer a knowledge of the obtained pattern dynamics, as well as the applicability of holographic thermal mapping for precise volumetric temperature control. Finally, the proposed framework aims to provide a solid foundation for volumetric analysis of acousto-thermal patterns within thick samples and for assessing thermal changes with outer surface measurements.
Simultaneous optimal system and controller design for multibody systems with joint friction using direct sensitivities
Verulkar, Adwait; Sandu, Corina; Sandu, Adrian; Dopico, Daniel (Springer, 2025-05-01)
Real-world multibody systems are often subject to phenomena like friction, joint clearances, and external events. These phenomena can significantly impact the optimal design of the system and its controller. This work addresses the gradient-based optimization methodology for multibody dynamic systems with joint friction using a direct sensitivity approach. The Brown-McPhee model has been used to characterize the joint friction in the system. This model is suitable for the study due to its accuracy for dynamic simulation and its compatibility with sensitivity analysis. This novel methodology supports codesign of the multibody system and its controller, which is especially relevant for applications like robotics and servo-mechanical systems, where the actuation and design are highly dependent on each other. Numerical results are obtained using a software package written in Julia with state-of-the-art libraries for automatic differentiation and differential equations. Three case studies are provided to demonstrate the attractive properties of simultaneous optimal design and control approach for certain applications.
Origami-/kirigami-inspired structures: from fundamentals to applications
Li, Suyi; Daqaq, Mohammed (Royal Society, 2024-10-07)
The Scutulum and the Pre-Auricular Aponeurosis in Bats
Pedersen, Scott C.; Snipes, Chelsie C. G.; Carter, Richard T.; Muller, Rolf (Wiley, 2024-11-01)
The external ear in eutherian mammals is composed of the annular, auricular (pinna), and scutellar cartilages. The latter extends between the pinnae, across the top of the head, and lies at the intersection of numerous auricular muscles and is thought to be a sesamoid element. In bats, this scutulum consists of two distinct regions, (1) a thin squama that is in contact with the underlying temporalis fascia and (2) a lateral bossed portion that is lightly tethered to the medial surface of the pinna. The planar size, shape, and proportions of the squama vary by taxa, as does the relative size and thickness of the boss. The origins, insertions, and relative functions of the auricular muscles are complicated. Here, 30 muscles were tallied as to their primary attachment to the pinnae, scutula, or a pre-auricular musculo-aponeurotic plate that is derived from the epicranius. In contrast to Yangochiroptera, the origins and insertions of many auricular muscles have shifted from the scutulum to this aponeurotic plate, in both the Rhinolophidae and Hipposideridae. We propose that this functional shift is a derived character related primarily to the rapid translations and rotations of the pinna in high-duty-cycle rhinolophid and hipposiderid bats.

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