Department of Mechanical Engineering

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https://hdl.handle.net/11693/13680

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Open Access
Application of ultrasonic waves in bioparticle manipulation and separation
(Wiley, 2023-10-06) Özer, M. B.; Çetin, Barbaros; Özçelik, A.; Becker, R.; Huang, T. J.
The chapter starts with a brief overview of microfluidic bioparticle manipulation methods with a unifying approach for forces generated on bioparticles using different physical fields such as electrical, magnetic and acoustic fields. Later, the advantages and disadvantages of the ultrasonic bioparticle manipulation methods are discussed and the method's fundamental architectural components and theoretical background are explained. The chapter continues with different analytical approaches used for the numerical modeling of such systems. An extensive literature survey is provided detailing the method's applications on biological systems. The chapter concludes with discussions and recommendations for the successful commercialization of ultrasonic bioparticle manipulation methods.
Open Access
The variational explanation of Poisson’s ratio in bond-based peridynamics and extension to nonlinear Poisson’s ratio
(Springer International Publishing, 2021-11-24) Ekiz, Ekim; Javili, Ali
It is commonly stated that the Poisson’s ratio associated with bond-based peridynamics is 14 for three-dimensional isotropic elasticity. This manuscript critically revisits this statement from a variational perspective for both two-dimensional and three-dimensional problems. To do so, a purely geometrical description of Poisson’s ratio is considered. Unlike the commonly established treatment of the problem, the Poisson’s ratio here is calculated via minimizing the internal energy density, rather than quantifying it and comparing it to its counterpart in classical linear elasticity. The advantage of the proposed approach is threefold. Firstly, elements of Cauchy linear elasticity such as “strain”, “stress” and “elastic parameters” are entirely absent throughout the derivations here. This is particularly important since peridynamics is a non-local formulation, and therefore, using local notions such as “strain” and “stress” implies locality and is misleading. Secondly, unbound by linear elasticity, the proposed approach unlocks the limitation of the analysis to small deformations. Hence, it can be immediately applied to large deformations, resulting in a nonlinear Poisson’s ratio that is no longer constant. Thirdly, the two-dimensional analysis here is purely two-dimensional, corresponding to a two-dimensional manifold in a three-dimensional space. That is, the two-dimensional formulation is neither plane stress nor plane strain that are rather degenerate three-dimensional cases. This contribution introduces the notion of nonlinear Poisson’s ratio in peridynamics for the first time and proves that the nonlinear Poisson’s ratio at the reference configuration coincides with 14 for three-dimensional and 13 for two-dimensional problems.
Open Access
SCoReR: sensorized collision resilient aerial robot
(IEEE - Institute of Electrical and Electronics Engineers, 2023-05-15) Bakır, Alihan; Özbek, Doğa; Abazari, Amirali; Özcan, Onur
Detection and control of the physical contact/impact between micro aerial vehicles and the surrounding obstacles have become a significant issue with the rapid growth of their use in inspection and mapping missions in confined, obstacle-cluttered environments. In this work, we introduce a collision-resilient compliant micro quadcopter equipped with soft coil-spring type force sensors to passively resist and detect the physical contact/impact of the drone. The sensors act as resistive elements with a nominal resistance of 130–150 kΩ. They are manufactured from a conductive material via FDM 3D printing. We install these sensors on the protective bumpers of the collision-resilient foldable body of the drone. Any contact/impact between the bumpers and an obstacle results in deformation and buckling of the soft sensors, which results in a drastic change in their resistance, making it possible to detect the contacts/impacts of the bumpers. With a total weight of 220g and dimensions of 22cmx22cmx9cm, SCoReR successfully detects and recovers 100% of the contacts/impacts when it approaches a rigid wall with a velocity in the range of [0.1-1] m/s.
Open Access
Using micro-milled surface topography and force measurements to identify tool runout and mechanistic model coefficients
(Springer UK, 2023-02-15) Masrani, Abdulrzak; Karpat, Yiğit
Modeling the forces during micro-milling processes is directly linked to the chip load and mechanistic model parameters that are generally dependent on the tool/work combination. Tool runout, deflection, and the material’s elastic recovery mainly affect the chip load as a function of feed. Experimentally measured micro-milling forces can be employed to identify cutting force coefficients and runout parameters. However, decoupling the interplay among runout, deflection, and elastic recovery is difficult when only measured forces are considered. In this paper, machined surface topography has been considered as an additional process output to investigate the influence of runout and deflection separately. The machined surface topography was investigated using a scanning laser microscope to identify minimum chip thicknesss and runout parameters. A finite element model of tool deflection has been developed based on the end mill geometry used in the experiments. The finite element model was used to obtain a surrogate model of the tool deflection which was implemented into the mechanistic model. Nanoindentation tests were conducted on the coated WC tool to identify its material properties which are employed in the finite element model. An uncut chip thickness model is constructed by considering preceding trochoidal trajectories of the cutting edge, helix lag, tool runout, tool deflection, and the chip thickness accumulation phenomenon. The force model was validated experimentally by conducting both slot and side milling tests on commercially pure titanium (cp-Ti). The predicted cutting forces were shown to be in good agreement with the experimental cutting forces.
Open Access
Integrated vehicle control using adaptive control allocation
(John Wiley & Sons Ltd., 2023-04-28) Temiz, Ozan; Çakmakçı, Melih; Yıldız, Yıldıray
The focus of this paper is an integrated, fault-tolerant vehicle control algorithm for the overall stability of ground vehicles. The proposed scheme comprises a high-level controller that creates a virtual control input and a low-level adaptive control allocator that distributes the virtual control effort among redundant actuators. The proposed control framework distinguishes itself from earlier results in the literature by its ability to blend active suspension, steering and traction control channels, in the presence of uncertainties and time-varying dynamics, without the need for fault identification. The control structure is validated in the simulation environment using a fourteen-degree-of-freedom non-linear vehicle model. The integrated controller is compared to the case of a conventional control approach where each control problem is solved separately. Our results show that, compared to the conventional approach, the proposed method ensures that the vehicle follows driver inputs with up to % higher longitudinal maneuver velocity, despite the presence of actuator failures and slippery road conditions. Furthermore, to demonstrate the benefit of integrating active suspension control to the overall control scheme, we replaced the suspension control of the proposed approach with an independent suspension control system for comparison purposes. We then showed that the integrated case provided % lower roll angle deviation, and % lower pitch angle deviation, in the presence of actuator effectiveness loss and adverse road conditions.
Open Access
Permittivity-based classification by the integration of impedance cytometry and microwave sensing
(IEEE - Institute of Electrical and Electronics Engineers, 2023-11-07) Tefek, Uzay; Sarı, B.; Alhmoud, Hashim; Hanay, Mehmet Selim
The direct determination of the permittivity of individual micro-objects has proven challenging due to the convoluting effect of their geometric size on capacitive signals (i.e., on the electric size of a particle). To overcome this challenge, we have developed a sensing platform to independently obtain both the geometric and electric size of organic and inorganic particles, by combining impedance cytometry and microwave resonant sensing in a microfluidic chip. This way the microwave signal is normalized to yield an intrinsic parameter that depends only on permittivity. The permittivity can then be used for material classification or single-cell interrogation.
Open Access
Position-independent microparticle sensing: microwave sensors integrated with metalized, 3D microelectrodes
(IEEE - Institute of Electrical and Electronics Engineers, 2023-11-07) Alataş, Yağmur Ceren; Tefek, Uzay; Sarı, B.; Hanay, Mehmet Selim
Microfluidics integrated microwave sensors can be used for high throughput and label-free sensing with single particle resolution. For microwave sensors with coplanar electrodes, electric field is nonuniform over the height of microfluidic channel, causing position dependent sensitivity. One way to resolve positional dependency is to place electrodes on the sidewalls of microfluidic channel to obtain uniform electric field. Here, we demonstrate a novel, metal coated 3D SU8 microelectrode integrated with microwave resonator to obtain uniform electric field inside microfluidic channel and mitigate position dependent sensitivity. SU8 electrodes are positioned at the sensing region of the resonator, in contact with the microfluidic channel walls. During microparticle sensing experiments, phase and amplitude of the resonator are tracked using custom built single side band detection circuitry to detect particle induced shifts in these signals. Results of particle sensing, and size classification experiments indicate that with 3D SU8 electrode integrated microwave resonators, position-independent sensitivity can be achieved.
Open Access
Effects of compliance on path-tracking performance of a miniature robot
(IEEE - Institute of Electrical and Electronics Engineers, 2023-05-15) Uğur, Mustafa; Arslan, Burak; Özzeybek, Alperen; Özcan, Onur
Path-tracking is often challenging in miniature robots because their feet or wheels tend to slip due to the low robot weight. In this work, we investigate the effect of c-leg compliance on path-tracking performance and the obstacle-climbing capabilities of our foldable and miniature robot with soft, c-shaped legs. With its 82 mm x 60 mm x 29 mm size and 29.25 grams weight, a single module of our robot is one of the smallest untethered miniature robots. Our results show that utilizing soft c-shaped legs provides smooth path-tracking performance, similar to a wheeled differential drive robot. However, modules with rigid c-shaped legs are affected significantly by the impact and slip between the leg and the ground, and they perform rather unpredictably. Additionally, modules with wheels cannot climb obstacles 1 mm or larger. We show that using soft legs enhances the obstacle climbing skills of modules by climbing a 9 mm obstacle, while the module with rigid legs can only climb a 7 mm obstacle. These path-tracking abilities and obstacle-climbing capacity support our vision to build a reconfigurable robot using these modules.
Open Access
Control and study of bio-inspired quadrupedal gaits on an underactuated miniature robot
(Institute of Physics, 2023-01-25) Askari, Mohammad; Uğur, Mustafa; Mahkam, Nima; Yeldan, Alper; Özcan, Onur
This paper presents a linear quadratic Gaussian (LQG) controller for controlling the gait of a miniature, foldable quadruped robot with individually actuated and controlled legs (MinIAQ-III). The controller is implemented on a palm-size robot made by folding an acetate sheet. MinIAQ-III has four DC motors for actuation and four rotary sensors for feedback. It is one of the few untethered robots on a miniature scale capable of working with different gaits with the help of its individually-actuated legs and the developed controller. The presented LQG controller controls each leg’s positions and rotational speeds by measuring the positions and estimating the rotational speeds, respectively. With the precise gait control on the robot, we demonstrate different gaits inspired by quadrupeds in nature and compare the simulation and experiment results for some of the gaits. An extensive simulation environment developed for robot dynamics helps us to predict the locomotion behavior of the robot in various environments. The match between the simulation and the experiment results shows that the proposed LQG controller can successfully control the miniature robot’s gaits. We also conduct a case study that shows the potential to use the simulation to achieve different robot behavior. In a case study, we present our robot performing a prancing similar to horses. We use the simulation environment to find the required motor configuration phases and physical parameters, which can make our robot prance. After finding the parameters in simulation, we replicate the configuration in our robot and observe the robot making the same moves as the simulation. © 2023 IOP Publishing Ltd.
Open Access
Driver modeling using a continuous policy space: theory and traffic data validation
(Institute of Electrical and Electronics Engineers, 2023-11-16) Yaldiz, C. O.; Yıldız, Yıldıray
In this article, we present a continuous-policy-space game theoretical method for modeling human driver interactions on highway traffic. The proposed method is based on Gaussian Processes and developed as a refinement of the hierarchical decision-making concept called “level- k reasoning” that conventionally assigns discrete levels of behaviors to agents. Conventional level- k reasoning approach may pose undesired constraints for predicting human decision making due to a limited number (usually 2 or 3) of driver policies it provides. To fill this gap in the literature, we expand the framework to a continuous domain that enables a continuous-policy-space, consisting of infinitely many driver policies. Through the approach detailed in this article, more accurate and realistic driver models can be obtained and employed for creating high-fidelity simulation platforms for the validation of autonomous vehicle control algorithms. We validate the proposed method on a traffic dataset and compare it with the conventional level- k approach to demonstrate its contributions and implications.
Embargo
Observing inter-well and intra-well oscillations in buckled nanomechanical systems enabled by image processing
(AIP Publishing LLC, 2023-12-08) Erdem, Ege; Demiralp, Berke; Pisheh, Hadi S.; Firoozy, Peyman; Karakurt, Ahmet Hakan; Hanay, Mehmet Selim
The scanning electron microscope (SEM) recordings of dynamic nano-electromechanical systems (NEMS) are difficult to analyze due to the noise caused by low frame rate, insufficient resolution, and blurriness induced by applied electric potentials. Here, we develop an image processing platform enhanced by the physics of the underlying system to track the motion of buckling NEMS structures in the presence of high noise levels. The algorithm is composed of an image filter, two data filters, and a nonlinear regression model, which utilizes the expected form of the physical solution. The method was applied to the recordings of a NEMS beam about 150 nm wide, undergoing intra- and inter-well post-buckling states with a transition rate of approximately 0.5 Hz. The algorithm can track the dynamical motion of the NEMS and capture the dependency of deflection amplitude on the compressive force on the beam. With the help of the proposed algorithm, the transition from inter-well to intra-well motion is clearly resolved for buckling NEMS imaged under SEM.
Embargo
Textured surfaces for oil droplet transport
(Elsevier BV, 2023-08-22) Yelekli Kirici, Ecem; Naji, Mayssam; Çanakçı, Ahmet Selim; Erdem, Emine Yegân
Droplet-based microfluidic systems bring the advantage of handling samples in discrete forms and these systems can be built as a surface-based platform, eliminating the need of a carrier fluid. Droplet transport on surfaces can be achieved by creating local energy gradients by using electrowetting, thermocapillary forces, chemical gradients and surface texture. These methods are developed for aqueous droplets; while controlled transportation of oil droplets remains as a challenge due to their low surface tension. One of the major challenges in achieving controlled oil droplet manipulation is to obtain oil repellent -oleophobic- surfaces. In this work, pillar arrays with mushroom shaped profiles were designed, fabricated, and tested to study oil wetting on textured surfaces. Contact angles higher than 170° were achieved for hexadecane droplets in Fakir state. Based on these findings, surface texture ratchet tracks that are composed of an array of arc shaped pillars were built to generate local energy gradients to manipulate oil droplets in a continuous fashion. Motion of hexadecane droplets at a speed of 7 mm/s was achieved. The results of this study are crucial for applications of oil droplet transport such as in biochemistry, smart surface development, wearable device design as well as microsystem packaging.
Open Access
Safe shared control between pilots and autopilots in the face of anomalies
(Wiley, 2023-06-09) Eraslan, Emre; Yıldız, Yıldıray; Annaswamy, Anuradha M.
As societal drivers of sustainability, efficiency and quality of life become more urgent and intensive, analysis and synthesis of safety critical systems in the face of anomalies become extremely important. In applications such as fully autonomous ground or air transportation, in electrical grids, and healthcare, often there are two decision-makers, one of which is automation, and the other is a human expert. While there have been several studies undertaken to understand the role of automation, and that of human experts, how the two decision-makers can carry out a shared control in a safety-critical system in the face of anomalies has not been investigated in depth. Our focus in this chapter is on two different shared control architectures for a cyber–physical–human system (CPHS), where the decision-making of the human expert is judiciously combined with that of an advanced automation with cyber components of sensing, computation, communication, and actuation. These architectures are evaluated in the context of flight control problems when severe anomalies are present. It is argued that for a successful synthesis of CPHS a granularity assignment of task allocation and timeline has to be carried out which enables the coordination between human and automation, the specific tasks that they carry out, and the timeline associated with these tasks, all in the context of an anomaly. Models of the physical system, the automation, and the pilot using two different shared control architectures are discussed. Validation of these architectures with a simulation study with human-in-the-loop of flight control problems is reported, demonstrating the design of successful CPHS in the presence of severe anomalies.
Open Access
Real-time biosensing bacteria and virus with quartz crystal microbalance: recent advances, opportunities, and challenges
(Taylor & Francis, 2023-05-16) Bonyadi, Farzaneh; Kavruk, Murat; Uçak, Samet; Çetin, Barbaros; Bayramoğlu, Gülay; Dursun, Ali D.; Arıca, Yakup; Özalp, Veli C.
Continuous monitoring of pathogens finds applications in environmental, medical, and food industry settings. Quartz crystal microbalance (QCM) is one of the promising methods for real-time detection of bacteria and viruses. QCM is a technology that utilizes piezoelectric principles to measure mass and is commonly used in detecting the mass of chemicals adhering to a surface. Due to its high sensitivity and rapid detection times, QCM biosensors have attracted considerable attention as a potential method for detecting infections early and tracking the course of diseases, making it a promising tool for global public health professionals in the fight against infectious diseases. This review first provides an overview of the QCM biosensing method, including its principle of operation, various recognition elements used in biosensor creation, and its limitations and then summarizes notable examples of QCM biosensors for pathogens, focusing on microfluidic magnetic separation techniques as a promising tool in the pretreatment of samples. The review explores the use of QCM sensors in detecting pathogens in various samples, such as food, wastewater, and biological samples. The review also discusses the use of magnetic nanoparticles for sample preparation in QCM biosensors and their integration into microfluidic devices for automated detection of pathogens and highlights the importance of accurate and sensitive detection methods for early diagnosis of infections and the need for point-of-care approaches to simplify and reduce the cost of operation.
Embargo
Surface elasticity and area incompressibility regulate fiber beading instability
(Elsevier, 2023-04-26) Bakiler, A. D.; Javili, Ali; Dörtdivanlıoğlu, B.
A continuum body endowed with an energetic surface can exhibit different mechanical behavior than its bulk counterpart. Soft polymeric cylinders under surface effects become unstable and form surface undulations referred to as the elastic Plateau–Rayleigh (PR) instability, exclusively driven by competing surface and bulk properties. However, the impact of surface elasticity and area compressibility, along with bulk compressibility, on the PR instability of soft solids remains unexplored. Here we develop a theoretical, finite deformations framework to capture the onset of the PR instability in highly deformable solids with surface tension, surface elasticity, and surface compressibility, while retaining the compressibility of the bulk as a material parameter. In addition to the well-known elastocapillary number, surface compressibility and a dimensionless parameter related to the surface modulus are found to govern the instability behavior. The results of the theoretical framework are analyzed for an exhaustive list of bulk and surface parameters and loading scenarios, and it is found that increasing surface elasticity and surface incompressibility preclude PR instability. Theoretical results are compared with high-fidelity numerical simulation results from surface-enhanced isogeometric finite element analysis and an excellent agreement is observed across a broad range of material parameters and large deformation levels. Our results demonstrate how surface effects can be used to (i) render stable soft structures and prevent PR instability when it occurs as an unwanted by-product of manufacturing techniques or (ii) tune the instability behavior for possible applications involving polymer fibers.
Open Access
Microwave resonators enhanced with 3D liquid-metal electrodes for microparticle sensing in microfluidic applications
(Institute of Electrical and Electronics Engineers , 2023-11-22) Alataş, Yağmur Ceren; Tefek, Uzay; Sari, B.; Hanay, Mehmet Selim
In electrical sensing applications, achieving a uniform electric field at the sensing region is required to eliminate the compounding effect of particle location on the signal magnitude. To generate a uniform electric field in a microfluidic platform, 3D electrodes based on conductive electrolyte liquids have been developed before, where the ionic conductivity of the electrolyte was sufficient for impedance measurements at low frequencies (typically lower than 50 MHz). However, electrolyte liquids cannot be used as electrodes at microwave frequencies (>1 GHz) due to the low mobility of ions. Here, we used Galinstan, a room-temperature liquid metal, to microfabricate 3D liquid electrodes connected to a microwave resonator — and all integrated within a microfluidic system. By generating a highly uniform electric field, a mixture of 20 μm and 30 μm diameter polystyrene particles were measured and analyzed without any calibration for particle position. The results demonstrate the utility of liquid electrodes in enhancing the electrical characteristics of microwave resonant sensors.
Open Access
Atmospheric-pressure mass spectrometry by single-mode nanoelectromechanical systems
(American Chemical Society, 2023-09-08) Kaynak, Batuhan Emre; Alkhaled, Mohammed; Kartal, Enise; Yanık, Cenk; Hanay, Mehmet Selim
Weighing particles above the megadalton mass range has been a persistent challenge in commercial mass spectrometry. Recently, nanoelectromechanical systems-based mass spectrometry (NEMS-MS) has shown remarkable performance in this mass range, especially with the advance of performing mass spectrometry under entirely atmospheric conditions. This advance reduces the overall complexity and cost while increasing the limit of detection. However, this technique required the tracking of two mechanical modes and the accurate knowledge of mode shapes that may deviate from their ideal values, especially due to air damping. Here, we used a NEMS architecture with a central platform, which enables the calculation of mass by single-mode measurements. Experiments were conducted using polystyrene and gold nanoparticles to demonstrate the successful acquisition of mass spectra using a single mode with an improved areal capture efficiency. This advance represents a step forward in NEMS-MS, bringing it closer to becoming a practical application for the mass sensing of nanoparticles. © 2023 The Authors. Published by American Chemical Society.
Open Access
Configurational peridynamics
(Elsevier B.V., 2023-07-31) Steinmann, P. ; de Villiers, A.M. ; McBride, A.T. ; Javili, Ali
Configurational forces that drive the evolution of material structures such as defects are introduced into a geometrically-exact peridynamics framework. The concept of bond-number double-density facilitates the definition of a peridynamic potential energy functional that inherits the key features of its conventional (local) continuum and discrete counterparts. The spatial and material variations of the peridynamic potential energy functional give rise to familiar Piola- and Cauchy-type bond-wise interaction forces that enter the pointwise force balance in the spatial and material setting, respectively. It is shown that the point-wise material body force density is a result of a non-local pull-back of the bond-wise spatial interaction force, and thereby captures non-local contributions. Several key features of configurational peridynamics are demonstrated via a computational example and a comparison to conventional configurational continuum mechanics.
Open Access
Understanding the role of interfacial mechanics on the wrinkling behavior of compressible bilayer structures under large plane deformations
(2022-03-28) Bakiler, A. Derya; Javili, Ali
Layered soft structures under loading may buckle in order to release energy. One commonly studied phenomenon is the wrinkling behavior of a bilayer system consisting of a stiff film on top of a compliant substrate, which has been observed ubiquitously in nature and has found several applications. While the wrinkling behavior of the incompressible bilayer system has been explored thoroughly, the large deformation behavior of a compressible bilayer system had been virtually unexplored until very recently. On the contrary, it is well established where more than one material is concerned, there always exists an interphase region between different constituents whose mechanical modeling has presented itself as a long-lasting challenge. To address these gaps in the literature, herein we first propose a theoretical, generic, large deformations framework to capture the instabilities of a compressible domain containing an interface. The general interface model is employed such that at its limits, the elastic and the cohesive interface models are recovered. The instability behavior of a compressible bilayer domain undergoing large deformations for a wide range of cohesive stiffness values, stiffness ratios, compressibilities, and film thicknesses is systematically explored. In particular, it is shown that delamination of the film can also be captured via this interface model. In addition, this generic framework is examined for a coated beam and a coated half-space too. The results of the theoretical framework are thoroughly compared to numerical results obtained via finite element method simulations enhanced with eigenvalue analysis, and an excellent agreement between the two sets of results is observed. It is found that varying substrate Poisson’s ratio has a significant effect on the bifurcation behavior for higher cohesive stiffnesses. Remarkably, while in classical bilayers the critical stretch at wrinkling is independent of the film thickness, herein we discover a significant dependence of the critical stretch to the film thickness in the presence of the interface.
Embargo
Modeling polymeric lubricants with non-linear stress constitutive relations
(Elsevier, 2023-09-16)
Lubricating oils are used to minimize the friction and wear of mechanical components by virtue of a thin lubricant film separating the sliding surfaces. The film’s characteristics, under high pressure, can exhibit non-Newtonian effects, such as viscoelasticity and shear thinning. The strength of these effects are measured using the Weissenberg (Deborah) number 𝑊 𝑖 (𝐷𝑒), i.e., the ratio of the polymer relaxation time to the shear (residence) time scale. Modeling these effects is computationally challenging, especially when relying on the direct numerical simulation (DNS) of the Cauchy momentum and the mass conservation equations. However, the viscoelastic Reynolds (VR) approach (Ahmed & Biancofiore, Journal of Non-Newtonian Fluid Mechanics, 292, 104524, 2021.) has been shown to be effective in modeling (i) the pressure distribution and (ii) the load carrying capacity of a viscoelastic lubricating film for mechanical contacts for the Oldroyd-B constitutive relation, since these contacts operate within the small 𝐷𝑒 limit (but no constraint in 𝑊 𝑖). In this work, we have extended the VR approach to the finitely extensible non-linear elastic (FENE) type constitutive relations that account for the (i) finite extension of the polymer chains and (ii) shear thinning. We have validated the VR approach against DNS, showing an excellent agreement over a wide range of the Weissenberg number 𝑊 𝑖, and finite extensibility parameter 𝐿, using FENE-CR and FENE-P models. Following a thorough validation, the pressure distribution and the load carrying capacity of a journal bearing, whose channel height is governed by the journal eccentricity ratio 𝑒, is considered. It is observed that the load carrying capacity of the film portrays a strongly non-linear dependence on 𝑊 𝑖, 𝐿 and 𝑒: while it increases for small values of 𝑊 𝑖, limited greatly by the capacity of the polymer to stretch, a saturation and a subsequent decline is observed for high 𝑊 𝑖 regimes. Additionally, a weakly (strongly) eccentric configuration plays an important role in promoting (hindering) the growth in load versus both 𝑊 𝑖 and 𝐿. These effects are significant and have to be considered when modeling thin contacts lubricated with a strongly viscoelastic fluid.