bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Metal-Composite Layer Thickness on Springback After U-Bending
Authors: Nikhare Chetan P. 
Published: February 2021

Abstract
A sudden increase in the usage of automotive vehicles results in sudden increases in the fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. To save from the environmental regulation penalty vehicle industry is researching innovation which would reduce vehicle weight and decrease the fuel consumption. Thus, the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease fuel consumption. To achieve this target, the industry has been looking at fabricating components from high strength to ultra-high strength steels or lightweight materials. With the usage of advanced high strength steels, the lightweight was achieved by reducing a gage thickness without compromising the strength aspect. However due to their high strength property often challenges occurred are higher machine tonnage requirement, sudden fracture, geometric defect, etc. The geometric defect comes from the elastic recovery of a material, which is also known as a springback. Springback is commonly known as a manufacturing defect due to the geometric error in the part, which would not be able to fit in the assembly without secondary operation or compensation in the forming process. It is learned that the springback of the material increases with an increase in the material strength and/or decrease in material thickness. In advanced high strength steels, higher strength and lower gage thickness options make the part prone to higher springback. Due to these many challenges, other research route involved is composite material, where light materials can be used with high strength material to reduce the overall vehicle weight. This generally includes, tailor welded blanks, multilayer material, mechanical joining of dissimilar material, etc. Due to substantial use of dissimilar materials, these parts are also called as hybrid components. It was noted that the part weight decreases with the use of hybrid components without compromising the integrity and safety. In the previously published paper in IMECE2017 the study was focused on equal layer thickness of metal and composite in bilayer material. In this paper, a springback analysis was performed considering bilayer metal by varying the thickness of the metal as well as the composite. For this two dissimilar materials aluminum and composite was considered as bonded material. This material was then bent on a free bend die. The bilayer springback was compared with different layer thickness of metal and composite and in different condition like aluminum layer on punch side and then on die side. These results were then compared with the baseline springback of only aluminum thin and thick layer.
Force Controlled Electrical Pulse Assisted Forming
Authors: Grimm Tyler J. , Deshpande Amit B. , Mears Laine , Hu Jianxun 
Published: February 2021

Abstract
Electrically-assisted manufacturing refers to the direct application of electrical current to a workpiece during a manufacturing process. This assistance results in several benefits such as flow stress reduction, increased elongation, reduced springback, increased diffusion, and increased precipitation control. These effects are also associated with traditional thermal assistance. However, for over half a decade it has been argued whether or not these observed effects are due to electroplasticity, a term which describes effects that cannot be fully explained through resistive heating. Several theories have been proposed as to the mechanism responsible for these purported athermal effects. Conflicting results within literature have enabled this debate over electroplasticity since its discovery in the mid 20th century.
While the effects of electrically-assisted manufacturing are clearly characterized throughout literature, there is a lack of research related to control systems which may be used to take advantage of its effects. Typically, control systems are developed using an empirical approach, requiring extensive testing in order to fully characterize the stress-strain behavior at all conditions. Additionally, current research has primarily focused on reducing flow stresses during electrically-assisted processes without regard for the strength of the material subsequent to forming. Therefore, there is a strong need for a control system which can quickly be deployed for new materials and does not significantly reduce the subsequent strength of the material.
Herein, a novel control approach is developed in which electrical pulses are triggered by a predetermined stress level. This stress value would be set according to the manufacturer’s stamping die strength. Once the material reaches this stress value, current is deployed until a minimum stress level is reached. At that point, the electricity is turned off and the material allowed to cool; at that stage the stress begins to elevate and the cycle continues. This approach does not require extensive pre-testing and is robust to a range of strain rate. This type of implementation can also be adapted to different levels of capability. For example, since the current is controlled by force and not by time, a low-current power supply will stay on for each pulse longer than a power supply with higher capabilities; however, each will achieve a similar effect. This study investigates the effect of several different minimum stress levels and strain rates. The strain rates chosen are relatively similar to common stamping process. This system was experimentally tested using 1018 CR steel. This control approach was found to be a successful method of maintaining a desired stress level.
Displacement of the Residual Limb Within Transfemoral Sockets: A Literature Review
Authors: Salazar-Salgado Sara , Rendón-Vélez Elizabeth 
Published: February 2021

Abstract
According to the World Health Organization and the International Society for Prosthetics and Orthotics, between 0.5 to 0.8 percent of the global population has suffered limb amputations. In the last years, Colombia, Angola, Afghanistan, and Chechenia are the countries that have held the first places with the highest amount of landmine victims. In Colombia, this weapon has left more than 10.000 affected people, many of which have suffered traumatic lower limb amputation To recover some of the lost function, amputees are generally prescribed with a prosthesis. However, the adaptation of the user with this element depends on the comfort felt when using it and consequently, on the fit between the socket and the residual limb. The fit between these two elements is highly influenced by the relative motion between them (i.e. displacement, slip). Both excess of displacement or complete absence, have several negative consequences for the amputee. Thus, measuring displacement could be an important indicator of the quality of the socket and the suspension system, and could provide critical information to improve surgical interventions, the prescription of prosthetic elements and the design and development of new prosthetic components. Several authors have investigated this topic; however, the studies have been mostly conducted on transtibial amputees. Therefore, this review aims to summarize the gathered information about the displacement between the socket and residual limb in transfemoral amputees.
A computer-aided systematic literature search was performed by two independent reviewers using three databases. The selected papers were evaluated with regards to: sample characteristics, displacement measurement instrument, measured activity, displacement axis, surfaces in contact, type of socket and type of suspension system used.
Most of the studies were performed on less than five individuals with mature residual limbs and trauma caused amputation. The most common aspects of displacement were: imaging techniques (measurement instrument), gait (measured activity), vertical direction (displacement axis), bone/socket (surfaces in contact), quadrilateral (type of socket) and suction-based (suspension system).
The optimal range of motion is still unknown for transfemoral amputees. A marker-based optical tracking system is promising for research purposes, while electronic sensors would be optimal for clinical use. Volume change may be an indirect and, more straightforward option to measure displacement. Further research is needed to determine the effect of using a modified socket, to find a way to measure relative motion inside the socket using marker-based optical tracking systems and to define the influence of subject-specific characteristics in the amount of displacement. A better understanding of what happens inside the socket helps to optimize prosthetic designs and to improve the amputee’s quality of life.
Effect of the Number of Stages on the Performance of Savonius Vertical Axis Wind Turbines: Part I — Using Straight Semicircular Blades
Authors: Saad Ahmed S. , Ookawara Shinichi , Elwardany Ahmed , El-Sharkawy Ibrahim I. , Ahmed Mahmoud 
Published: February 2021

Abstract
The Savonius vertical axis wind turbine offers several benefits as simple construction, low manufacturing, installation and maintenance costs, low operating wind speed, and independence of wind direction. However, the conventional single-stage Savonius rotors have negative torque values at a certain range of rotor angles and large torque variation over the complete cycle which led to reduction of the power coefficient and the self-starting abilities. To overcome these drawbacks, a multi-stage Savonius wind rotor is proposed to obtain the optimum number of stages that enhances both the power coefficient and the self-starting capabilities. In the current study, one-, two-, three-, and four-stage Savonius wind rotors with straight semicircular blades are investigated. In two stages rotor, one single-stage rotor is mounted over another single stage with a phase shift of 90°. In the three stages rotor, the three singlestage rotors are mounted one above the other with a phase shift of 60° relative to one another while with a phase shift of 45° for the four stages. All rotors have overall rotor diameter (D) of 200 mm, a thickness of 2 mm, a stage aspect ratio of 1.0, and an overlap ratio (δ) of 0.0. The diameter of the circular end plates (Do) attached to the rotor tips is 1.1 of the rotor diameter (D). All studies are performed at a wind speed (V) of 6 m/s.
The variations of torque and power coefficients are estimated for all the studied multi-stages rotors. Therefore, 3D incompressible unsteady Reynolds-Averaged Navier-Stokes equations along with the k-ω shear-stress transport turbulence model is developed and numerically simulated using ANSYS Fluent. The numerical model is validated using the available measurements and numerical results.
The predicted flow field characteristics such as streamlines and pressure fields around the studied rotors with various numbers of stages are presented and analyzed. Accordingly, results indicated that with the increase in the number of stages, a significant enhancement of the torque and the power coefficients is attained. In addition, the rate of percentage gain in the torque and the power coefficients is higher for two stages rotor than that of three and four stages rotors. The maximum torque and power coefficients for the two stages rotor are 0.336 and 0.194, respectively. The power coefficient gain obtained by using the two stages Savonius rotor is 17.5 % compared to the conventional single stage which has a power coefficient of 0.165 at a wind velocity (V) of 6 m/s. Furthermore, using a multi-stage rotor significantly smooths the variations in the torque coefficient and produces positive static torque values at all rotational angles resulted in enhancing the self-starting capabilities of the Savonius rotor.
Investigating the Sensitivity of Particle Size Distribution on Part Geometry in Additive Manufacturing
Authors: Ramesh Sagar Vaishak , Lorin Samuel , Göhl Johan , Quist Johannes , Cromvik Christoffer , Mark Andreas , Jareteg Klas , Edelvik Fredrik , Wärmefjord Kristina , Söderberg Rikard 
Published: February 2021

Abstract
Selective laser melting process is a powder bed fusion additive manufacturing process that finds applications in aerospace and medical industries for its ability to produce complex geometry parts. As the raw material used is in powder form, particle size distribution (PSD) is a significant characteristic that influences the build quality in turn affecting the functionality and aesthetics aspects of the end product. This paper investigates the effect of PSD on deformation for 316L stainless steel powder, where three coupled in-house simulation tools based on Discrete Element Method (DEM), Computational Fluid Dynamics (CFD), and Structural Mechanics are employed. DEM is used for simulating the powder distribution based on the different particle size distribution of the powder. The CFD is used as a virtual test bed to determine thermal parameters such as density, heat capacity and thermal conductivity of the powder bed viewed as a continuum. The values found as a stochastic function of the powder distribution is used to test the sensitivity of the melted zone and distortion using Structural Mechanics. Results showed significant influence of particle size distribution on the packing density, surface height, surface roughness, the stress state and displacement of the melted zone. The results will serve as a catalyst in developing geometry assurance strategies to minimize the effect of particle size distribution on the geometric quality of the printed part.
Fuel Consumption Reduction of Off-Road Vehicles by Improving the Efficiency of the Hydromechanical Variable Transmission’s Lubrication and Actuation Systems
Authors: Milani Massimo , Montorsi Luca , Terzi Stefano , Mario Gelmini , Panizzolo Fabrizio , Profumo Giovanni 
Published: February 2021

Abstract
The paper investigates the efficiency of a hydro-mechanical variable transmission combining experimental and numerical approaches in order to develop operating strategies for power transmission losses reduction due to hydraulic circuits design. Two operating regions, characterized by high working time, have been detected analyzing the telescopic boom handler load spectral map of a real off-road vehicle transmission; the first one characterized by high output speed and the second one by low speed and torque transmission.
The efficiency of the former region has been increased by improving the fluid dynamic behavior of the lubrication system, which is greatly affected by the high flow rate generated by the fixed displacement pump operating at high speed, while the latter has been improved regulating the flow pressure of the actuation system with a controlled relief valve. The power losses of the system are experimentally determined testing an instrumented transmission on an ad-hoc test rig.
CFD dynamic models are adopted for the lubrication circuit optimization, addressing its real geometrical features as well as the actual operating conditions. Furthermore, the influence of the hydrodynamic resistance of the reverse and first wet clutches on the transmission power losses is investigated regulating the lubrication flow through an on/off valve. Tests demonstrated that up to 6.5 kW can be saved at high transmission ratios.
Finally, the effect of the two regulating strategies have been estimated in terms of energy saving and C02 emission reduction on the total vehicle life. Results proved that 5600 kWh and 7250 kWh saved energy can be achieved for the two strategies corresponding to 3.7 tons and 4.6 tons of avoided CO2 respectively.
Risk Analysis of Live Fire Shoot House Containment Systems Against Multiple Projectile Impacts
Authors: Andreen Steven D. , Davis Brad G. 
Published: February 2021

Abstract
Many analytical and numerical models exist that can describe the effect of single projectile impacts on steel targets. These models are not adequate for the evaluation of live fire shoot house containment systems, which are subjected to repeated impact loading from small caliber projectiles over the lifetime of the structure. Models assuming perfectly rigid projectiles over-predict penetration depths. Models assuming rigid targets cannot predict any penetration, and hydrodynamic models are best suited to high velocity impacts well above the ranges of conventional ordinance. Development of sufficient analytical or numerical tools using traditional techniques would be either intractable, empirically based and unique to a given scenario, require unique material properties that are not commonly available, or require significant computational effort. Due to the limited amount of empirical data on multiple impact failure, classical reliability methods are not suitable for assessing the probability of containment system perforation. Using existing experimental results of .223 caliber ammunition against AR500 steel panels with 2-inch ballistic rubber, a commonly found protective system in these facilities, the cumulative effects of multiple projectiles were quantified to estimate the number of impacts required to perforate the target material. Impacts were simulated from normal distributions of the x and y coordinates describing the impact point using a cartesian coordinate plane. The impact resistance of the steel was also simulated from a triangular distribution to account for the variability of the experimental results. Monte Carlo Simulation was then used to estimate the expected number of impacts to cause failure at a single point on the target. Using this collective model, it was possible to determine that the distribution of the number of rounds to cause target failure approached a normal distribution. The results indicated that the mean impacts at failure was 11800 with a standard deviation of 800 impacts. Finally, targeting the allowable risk level for structural failure from the JCSS probabilistic model code from the simulated normal distribution, it was determined that the safe number of impacts was approximately 7996. Decision makers can utilize the safe number of impacts to inform training guidance for the future use of facilities and to develop effective inspection requirements. This model can also be adapted to evaluate similar training facilities and to assess how other small caliber projectile impacts would affect live fire shoot house containment systems, providing a useful tool for the design and analysis of future and the assessment of existing facilities for use with ammunition that did not exist during its design.
Study on Model-Based Systems Engineering Method for Modeling of Thermal Power System
Authors: Chen Jinwei , Li Yuanfu , Hu Zhenchao , Zhang Huisheng 
Published: February 2021

Abstract
Thermal power systems, particularly with large capacity and high operating parameters, are more and more complicated nowadays, which include machinery, electronics, electrical, hydraulic, thermal, control, and process-oriented subsystems. The traditional development method based on documents has the problems of difficulty to reuse the designed elements, weak traceability of requirements, and lack of top-level logic verification. Moreover, there is a large gap because different models, tools and terminology are used during design process. The gap results in inefficiencies and quality issues that can be very expensive. In this paper, a model-based systems engineering (MBSE) approach is introduced for the top-down design flow of thermal power systems. The MBSE method can perfected the requirement definition, complete the mapping of the requirements to the system elements, realize the function logic verification, and support requirements verification at all stages. A GOPPRR (graph, object, point, property, role, relationship) meta-modeling method is proposed to support the MBSE formalisms. An Architecture Analysis and Design Integrated Approach (Arcadia) framework is adopted to capture the complex architecture, which is a standardized modeling method including requirement analysis, function analysis, logic analysis, and architecture design. Based on the architecture-driven algorithm and code generation, the standardized modeling process can establish a traceable relationship at each design stage and can verify the availability of initial requirements. Moreover, the designed elements of previous work can be reused in other relative design processes. The proposed MBSE method in this paper is applied to establish a gas turbine performance simulation model. The entire modeling process is enhanced by managing the relative design information consistently. The performance of the design process with MBSE method is analyzed and compared from different aspects. The results show that the performance simulation model of the power system established by the MBSE method can effectively describe the requirements, functions, logic, and architecture during design process. Based on the MBSE method, the requirements of the system are refined, traced and verified.
Development of a Low-Cost Sensor Network for Community-Made Measurements of Air Pollution
Authors: Sandoval Campos Sebastian , Ballesteros Higuera Fabián A. , Roa Prada Sebastián , Cáceres Becerra Claudia I. , Díaz Claro Alfredo A. 
Published: February 2021

Abstract
The levels of pollution present in the air have been dramatically increasing over the years due to the continuous emission of greenhouse gases such as CO2, CO, NOx and H2S, among others. The main source of these emissions is from burning fossil fuels for electricity, heat, and transportation. This represents a tremendous risk to the populations located near the emission sources where people get exposed to dangerous concentrations of such gases on a daily basis. The lack of open real-time monitoring tools makes people unaware of the damage these pollutants cause to their health.
This research proposes the development and implementation of a low-cost independent solution to keep the members of a community informed about concentration levels of air pollution due to local emissions. This tool must be easily accessible to the users so that the data about the number of particulates per million of a specific gas within a zone of interest can be viewed at any time. The proposed solution consists of a sensor network, covering the widest possible area, with respect to the point of interest. The collected data is sent to a cloud server, which operates as storage center and in which the data can be latter accessed for subsequent analysis. The measurements are sent to the server by means of a wireless communication protocol, carried out by a General Packet Radio Service, GPRS, communication module connected to each station. In this way, the coverage of the network is not limited by issues such as the use of local area networks which at the same time facilitates the transportation and installation of the stations at any desired measurement site.
Since each station can collect large amounts of data during a given period of time, it was necessary to implement techniques such as Big Data in order to extract important information and to identify patterns from the data such as the areas having the highest concentration of gases and possible correlations with other variables such as local weather conditions. This information could be used to support the making of decisions that benefit the communities impacted by air pollution, for example the early triggering of bad air quality alarms or the development of policies to regulate industry operation that can potentially impact the health of neighboring communities. A pilot case study was implemented in the city of Floridablanca, Colombia, to demonstrate the monitoring of the emissions of hydrogen sulfide of a big wastewater processing plant.