bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elastoplastic Behavior of SLA Resins in Compression
Authors: Baumgarner Julia , Piovesan Davide 
Published: January 2022

Abstract
Additive manufacturing is a growing field. One of the most common types of 3d printing methods is stereolithography. While the tensile properties of many stereolithographic resins are known, the compressive properties are not publicly available. In this paper, four types of resins that from Formlabs® are tested under compression to estimate their mechanical properties. Testing was performed on Clear, Tough, Durable and High Temperature resins with and without post processing. Post processing was performed in a customized curing oven following direction from the resin manufacturer. After testing, it was found that the Tough and Durable resins performed similarly when green, but the curing process stiffened the Tough Resin. Clear and High Temperature resins performed similarly after curing, whereas the High Temperature resin behaves more like an elastomer when green.
We estimated the tangent modulus of the stress-strain curve using a Polynomial fitting and were able to separate the elastic modulus from the viscous modulus. We found that the viscous modulus is non linear and depends upon the velocity of the test.
The test presented here are the first comparison of different types of Formalab resins under compression and can shed some light on the anisotropic behavior of many of these resins.
Effect of Inlet Geometry on Flat Plate, Film Cooling Effectiveness From Shaped Holes
Authors: Wang Hanlin , Wright Lesley M. 
Published: January 2022

Abstract
Modern gas turbine engines require a sophisticated cooling system design to achieve higher power output and efficiency. In this study, systematic tests were carried out to evaluate the potential effect of non-cylindrical inlet geometries on the performance of laid back, fan-shaped film cooling holes using the pressure sensitive paint (PSP) measurement technique.
A laid-back, fan-shaped hole outlet design in open literature was selected as the basis for the film cooling holes in this study, with varying inlet geometries. “Racetrack” shaped inlet geometries with aspect ratios of 2:1 and 4:1 were tested along with traditional cylindrical inlets. The coolant flow conditions range from blowing ratios of M = 0.3–1.5 and density ratios DR = 1 and 2. The mainstream turbulence intensity is fixed at 6%.
Test results show that the shaped inlets can provide a higher area-averaged film cooling effectiveness, η, over the traditional cylindrical inlet design using the same amount of coolant. For the 2:1 inlet, an advantage of 20% higher η could be maintained for DR = 1, while for DR = 2 this advantage is reduced to 10%. For the 4:1 inlet, when the coolant momentum flux ratio I &lt; 0.5, a similar or slightly higher improvement can be obtained, but when I &gt; 1, the advantage diminishes with the growing momentum flux ratio to approximately 5%, at I = 2.25. In terms of discharge coefficients, the 2:1 inlet geometry is similar to the cylindrical inlet under most flow conditions. For the 4:1 inlet, its discharge coefficient is 2–5% lower than the fan-shaped holes with a cylindrical inlet, under the same flow conditions.
Sit to Stand Gait Trainer: Modulation of Lift Force via Elastic Network
Authors: Smith Jordan , Felmlee Robert , Crowe Mary , Piovesan Davide 
Published: January 2022

Abstract
Falls in nursing homes and hospitals are common occurrences and a significant problem in the healthcare industry. A large number of accidents occur during sit to stand transitions. Not only patients with lower limb weakness are prone to injury after falls, but the healthcare workers are prone to musculoskeletal injuries when helping individuals transitioning from sitting to a standing position. Sit to stand devices are currently being used in hospitals, but the current models are expensive and do not allow patients to use any of their lower body strength in the process. We proposed the design of a device adjustable to each user in order to maximize the use of their own strength and allow them to stand up comfortably and safely. The design is innovative, customizable, and enables the device to be used as a walker as well. We propose an actuation system that combines a set of elastic bands to modulate the force used for lifting and gravity compensation. The system comprises of two sets of rubber bands that can modulate the force profile as a function of the height of the seat. Furthermore, this device offers a potential solution to the disproportionate number of workers injured in the healthcare field during lifting and assisting patients during the sit to stand transition.
Experimental Investigation on the Effect of Condenser Length on the Heat Transfer Performance of an Ω-Shaped Cryogenic Axially Grooved Heat Pipe
Authors: Li Yongyan , Li Nanxi , Dong Deping 
Published: January 2022

Abstract
In order to optimize the coupling between the heat pipe and the cold source, and to study the influence of different condenser lengths on the performance of heat pipes, a nitrogen charged Ω-shaped axially grooved heat pipe with a gas reservoir working at ambient temperature was designed based on the heat transport demand for space cryogenic applications. The supercritical startup performance of the heat pipe in the liquid nitrogen temperature zone and the heat transfer performance under different condenser heat fluxes are tested. The experimental results reveal that the heat pipe with gas reservoir starts up rapidly, and the length of the condenser has no effect on the start-up rate. When the filling rate of the heat pipe is 100%, for a given operating temperature under the same heat load, with the decrease in the condenser length, the heat pipe requires a greater degree of subcooling at the condenser to dissipate heat, so the thermal resistance of the heat pipe increases. Meanwhile, the heat transfer capacity will decrease. It is because the decrease of capillary pressure due to the increase of the contact angle of the working fluid on the wick surface. At a given operating temperature and the same length of the condenser, when the heat load increases, the heat transfer coefficient of evaporator and condenser will increase, so the thermal resistance of the heat pipe will decrease accordingly.
Damage Tolerance Analysis of Wing Fuselage Interface in BWB Aircraft Design
Authors: Bakshi Ashok K. , Dattaguru B. 
Published: January 2022

Abstract
As conventional aircraft manufactured based on tube and wing concept came to design saturation stage, aircraft industry is looking for totally new efficient configurations. In this regard the BWB (Blended Wing Body) configuration offers a paradigm shift in the aircraft design. This design provides aerodynamically efficient, low carbon emission environmentally friendly benefits and can adopt advanced technologies like laminar flow, jet flaps and distributed propulsion and ease of flight controls. However, despite these benefits, the BWB is yet to be produced for commercial use due to several challenges. To benefit the airline operators and optimize profit, both passenger and cargo options are suggested to make a multi-role version. This paper tried to bring out alternate proposition in BWB design highlighting design challenges that have hindered the actual production of a viable BWB passenger aircraft with multi-role cargo option. Even though the fully composite BWB concept is three decades old, it has not gone into production due to issues related to product quality and reliability of composite material apart from high costs in damage tolerance design which will be addressed in this paper.
Introducing Students to Cogeneration Systems Using a Design and Analysis Software in Energy Systems
Authors: Naman Yasin , Kowalski Gregory J. , Zenouzi Mansour 
Published: January 2022

Abstract
An interactive software package is presented for evaluation and design of hybrid co-generation systems. This software with user-friendly interface is introduced to replace a previous graphical summary of a simulation of a Brayton Cycle-fuel cell cogeneration system in an introductory graduate course in the Energy Systems program at Northeastern University and an advanced undergraduate course at Universidad de América. The description of the software package code and how it is implemented is outlined. The code is a MATLAB simulation of a hybrid co-generation system including the analysis of the solid oxide fuel cell and reformer. While there was a small sample of students in 2020–2 class and special circumstances related to the COVD-19 restrictions, there is evidence that the software package was an improvement over the previous methodology. A written tutorial and YouTube interactive guide for students to download the software considered as an improvement by the student feedback survey.
Design of a Carbon Fiber Ankle Foot Orthotic With Optimal Joint Stiffness
Authors: Koch Aaron , Richardson Brandon , Schell Daniel , Piovesan Davide 
Published: January 2022

Abstract
An Ankle Foot Orthosis, or AFO, is a device used in human rehabilitation to support lower extremities. The device is similar to a brace that is capable of maintaining the stability of a joint while storing some elastic energy to help lifting the legs at the ankle.
The main challenge for this design is to determine the optimal stiffness of the device and how such stiffness comes from the distribution of the stiffness at the joints. Furthermore, the device must be stiff enough for athletic play, but be comfortable for clinical scenarios.
We performed a set of experiments on a commercial AFO made of carbon fiber. The angles at the ankle and toes were measured during self-paced walking together with the interaction force between the shin and the AFO. Based on such measurements, we estimated the total rotational stiffness of the device and the distribution of stiffness at each joint. A 3-point bending test following ASTM D7264/D7264M-15 standard was used to evaluate the stiffness of the material produced by a Mark II 3D printer capable of printing long fiber composite. After the optimal printing parameters were selected to obtain the desired stiffness of the material, a finite element analysis was performed to design the AFO geometry to match each single joint stiffness.
This customized procedure can provide the design specification of a device so to produce the best athletic performances still maintaining comfort.
Conjugate Mixed Convective Flow of Gallium in a Partially Vented Square Cavity in the Presence of a Rotating Cylinder
Authors: Faiaz Abrar Nur-E , Priam Shadman Sakib , Shahriar Asif , Mamun Mohammad Arif Hasan 
Published: January 2022

Abstract
The aim of this research is to investigate mixed convection heat transfer properties in a ventilated square cavity with a heated cylinder. The cylinder is positioned in the cavity’s middle. The cylinder has been observed in both stationary and rotating (counter-clockwise and clockwise rotating directions) conditions. Furthermore, the cavity’s wall is believed to be thermally insulated along with a solid wall on the left side. Flows (Liquid Gallium) enter the cavity through the inlet at the top of the right wall and exit the cavity through the bottom of the right wall. The current research simulates a real-world device, such as liquid-cooled electronic equipment with a heating part or a heated oven. The effects of the cylinder diameter and rotational direction of the cylinder in the cavity are highlighted. The coupled equations of mass, momentum, and energy govern the mathematical model, which is solved using a Galerkin weighted finite element formulation. The current study takes into account a broad range of relevant parameters, including Richardson number, cylinder diameter, and cylinder rotation direction. Divers kinds of results are simulated using these parameters such as streamlines, isotherms as well as heat transfer rate by calculating the average Nusselt number on the hot cylinder wall and bulk fluid temperature of the cavity. For pure mixed convection (Ri = 1), the clockwise spin direction gives 10% more heat transfer rate than the counter-clockwise spin direction. The heat transfer rate is an increasing function of Hartman number and a decreasing function of cylinder diameter. In the case of pure mixed convection (Ri = 1), increasing cylinder diameter from o.1L to 0.3L causes the heat transfer rate to reduce at a rate of 57.7%, and increasing the Hartman number from 0 to 100 causes the heat transfer rate to increase at a rate of 11.1%.
Multiscale Modelling of Multifunctional Composites: A Review
Authors: Suresh Babu Sandeep , Mourad Abdel-Hamid I. 
Published: January 2022

Abstract
Multi-scale modelling is a cornerstone for the relatively new class of hierarchical materials which can perform multifunctional tasks, owing to their electrical, magnetic or thermal properties. Careful design strategies are to be devised, in-order to maintain their multi-functionality over the expected range of operation. In this study, we focus on these materials, which can be manufactured using a specialized technique of additive manufacturing, known as fused deposition modelling (FDM), owing to its flexibility and compatibility, working with polymer based materials. A review has been made on the various parameters affecting the manufacturing process, and how these variations can affect the properties of the end product. Future research directions are also pointed out, including stimuli responsive printing technique, popularly known as 4D printing and integration of neural networks into the manufacturing process which can improve the overall design lifecycle efficiency. This can involve autonomous production of test specimen, and revert back the data for model improvement, thereby enhancing predictive capabilities. The major focus of this work is on how we can use our current knowledge and techniques in the design of efficient and effective multifunctional composite materials from the bottoms-up approach.
A Study on the Onset of Secondary Hydriding in Defective Zr-2 Fuel for Boiling Water Reactors
Authors: Enivweru Doctor , Wang Qingyu , Ayodeji Abiodun , Moussa Hassane Ayouba 
Published: January 2022

Abstract
One of the most common threats to the integrity of reactor fuel cladding is the geometric imperfections such as the missing pellet surface (MPS) that produces a remarkable surge in the local fuel-clad gap. The cooling water could occupy this gap leading to secondary hydriding (SH) and hydrogen embrittlement. Most studies on this subject have identified extensive radiolysis in boiling water reactors (BWRs) to be responsible for hydrogen evolution during accident conditions. However, the quantitative determination of hydrogen and how it affects zircaloy-2 during normal reactor operation has not been given adequate attention. To bridge this gap and to better predict the onset of cladding failure, this study investigates secondary hydriding and its characteristic phenomenon in a fuel cladded with zircaloy-2. Multiphysics model is used to model diffusion of heat and hydrogen, then the effect of an intermediary porous/non-protective oxide layer and the impact of dose rate from different types of radiation are studied. The contributions of the source term due to radiolysis of neutrons (n), gamma (γ), alpha (α) and beta (β) radiations are also considered. Results showed that neutrons, having a maximum dose rate of 39.9 kGy/s accounts for over 99% of ZrH precipitation in a UO2 fuel with MPS. The effect of oxide (ZrO2) thickness in SH, and the derivative of oxide thickness are also discussed.
Structural Reliability Estimation of Steel Hall Exhibiting Random Mechanical Parameters
Authors: Bredow Rafał , Kamiński Marcin 
Published: January 2022

Abstract
The main idea behind this work is computational verification of the FORM reliability indices for industrial steel halls with the use of Stochastic Finite Element Method. This approach is implemented in the computer algebra software thanks to an application of the iterative generalized stochastic perturbation method. Structural static and dynamic responses of typical steel hall are numerically determined in the context of Serviceability and Ultimate Limit States. They are computed using BFGS algorithm for large deformations, HHT method in case of structural vibrations and Euler-Bernoulli beam theory available all in the FEM system ROBOT. Expected values, coefficients of variations as well as reliability indices are found while randomizing Young modulus of the steel according to Gaussian distribution. This randomness is selected due to the fact that arbitrary value is recommended for all steel types by most of designing codes while material engineering results show that this parameter exhibit remarkable differences due to the alloy components and their processing. Static equivalent of the wind pressure in civil engineering design of such structures is found to be quite efficient not only in deterministic approach but also in the context of reliability analysis.
An Exploration of X-Vectors for Damage Detection and Identification
Authors: Hom Kyle , Beigi Homayoon , Betti Raimondo 
Published: January 2022

Abstract
Damage identification for structural health monitoring (SHM) is explored through applying the x-vector speaker recognition technique in the structural domain. Using the progressive damage tests from the Z24 Bridge Benchmark dataset, a time-delay neural network (TDNN) is trained as an acoustic model to classify the provided global damage scenarios. The outputs of a pre-final layer, called x-vectors, are used as damage-sensitive features for identification of damage presence and mechanisms. Since the developed TDNN has learned the underpinning dynamics of the damage mechanisms in the Z24 tests, we apply it as a basis for damage identification problems tangential to the Z24 progressive damage classification task. Transfer learning and domain transfer are investigated via application of the developed TDNN towards local damage identification of the Z24 Bridge, and global and local damage identification for the unseen LANL SHM Alamosa Canyon Bridge, UC-Irvine Bridge Column, and Bookshelf studies. Supervised and unsupervised classification techniques are explored to assess this method, and strong results in damage detection are obtained for these SHM problems.
Design the Future Activities (DFA): Framework to Develop Case Studies to Incorporate Deep Understanding of the Coupling Between Technology, Society and the Future
Authors: Ali Hadi 
Published: January 2022

Abstract
Although engineering education research is concerned with preparing future engineers, the integration of future trends in technology with the engineering curriculum has been limited. This paper utilizes the Design the Future Activities (DFA) framework to provide guidelines for developing case studies in engineering design education to address the need for design for the future. The DFA as a framework systematically identifies and integrates emerging areas of research and technologies, such as artificial intelligence, into the teaching of engineering design. It links the contents of its three levels (Understanding technology analysis and system integration; Making a value chain, and Developing responsible innovations) with effective pedagogy for each level. Here, case studies are discussed in depth as an effective pedagogy for the second and third levels of the DFA framework. While engineers continue to be creators and influencers of such technologies, the lack of understanding of the impact of their own technologies continues to cause an imbalanced innovation landscape, in education and in the workplace. The new, revived design education approach should be attempted, assuming that educators will systematically anticipate the future and recalibrate the curriculum.
Effect of Heat Stabilization and Solid Lubricants on High Strain Rate Response of Polyamide 6
Authors: Rodriguez Luis Rafael Miranda , Shah Neel , Haynes Aisha S. , Lim Calvin , Stout Christopher G. , Recchia Stephen S. , Pelegri Assimina A. 
Published: January 2022

Abstract
In this research, high strain rate impact testing of polyamide 6 composites (PA6) with different inclusions and processes is performed to assess the material response to increasing impact loads. Testing groups are divided into four categories depending on their inclusions and process: no inclusions, heat stabilized with no inclusions, oil & Molybdenum disulfide (MoS2), and glass fiber solid lubricant. Computational analysis is performed to obtain material properties such as dynamic modulus and stress-strain behavior from Split Hopkinson Pressure Bar (SHPB) tests. Out of the four groups, it was concluded that oil & MoS2 and glass fiber solid lubricant were more capable of maintaining dynamic modulus. In contrast, PA6 without any inclusions experienced a rapid decrease in dynamic modulus with increasing strain rate. Microscopic imagery is taken to evaluate crack formation in samples and sample deformation. Multiple side and edge cracks were developed from the specimens starting from a strain rate of 1900s−1; however, shattering of specimens was not experienced until above 2300s−1 strain rates were achieved. It is concluded that tested specimens experienced hardening trends at higher testing pressures and strain rates. A computational analysis is underway to establish the effect of heat stabilization and lubricant inclusions in PA6 strain rate-dependent mechanical response.
Infrared Radiometry Based Steady-State Method for Thermal Conductivity Measurement
Authors: Wang Dihui , Ban Heng 
Published: January 2022

Abstract
This study develops an infrared radiometry-based steady-state technique (SSIR) that combines the benefits of transient pump technique, steady-state method, and infrared radiometry. The method uses a continuous wave (CW) laser as the pump source and a high-speed infrared camera system to capture temperature-time maps as the probe system. Instead of the thermoreflectance measurement, the advanced infrared camera system eases the theoretical model and experiment. The infrared camera system enables straightforward temperature versus time reading with a good spatial resolution. For demonstration, material with thermal conductivity over two orders of magnitude (1∼150Wm−1K−1) are measured. This technique enables measuring thermal conductivity independently from volumetric heat capacity, and by using reference sample, the sensitivity to most input parameters is effectively reduced. Therefore, SSIR shows lower uncertainty to standard FDTR and TDTR.