bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ductile-to-Brittle Fracture Size Effect of Titanium Sheets in Micro/Meso-Scale Plastic Deformation
Authors: Sun Lei , Xu Zhutian , Peng Linfa , Lai Xinmin 
Published: January 2022

Abstract
With a significantly increasing demand for miniaturized titanium thin-walled products, micro forming using sheet metals is a promising approach with high productivity. However, once the sheet thickness is scaled down to a micro-scale, there are many unknowns in terms of size effect and its affected fracture behavior. In this research, the influence of grain size on the fracture behavior of commercially pure titanium sheets with a thickness of 0.1 mm was investigated by the uniaxial tensile tests combined with a digital image correlation measurement system. The ductile-to-brittle transformation of fracture behavior with the grain size increasing from 33.07 to 107.70 μm was revealed. Macroscopically, the elongation and critical fracture stress of CP-Ti samples decrease with the increase of grain size. According to the scanning electron microscopic observations, the number of dimples decreases with grain size increasing, while the cleavage planes and river patterns gradually dominate in the coarse grain fracture surface. To explore the fracture mechanism, the dislocation evolution of various grain sizes is further observed by a transmission electron microscope. The dislocation emission from crack-tips was revealed at different grain sizes. Significant dislocation pile-up at grain boundaries was observed in the specimen with a grain size of 33.07 μm. Those intense dislocations reduce the effective stress at the crack tip resulting in higher crack propagation resistance. Nevertheless, the dislocation density at crack-tip decreases strongly with the increase of grain size leading to high crack-tip effective stress and less crack plasticity. Hence cleavage fracture was dominated in coarse grain CP-Ti sheets.
Error Analysis of Models for the Forces on a Cylinder Undergoing 2-DOF Prescribed Motion in a Stream
Authors: Aktosun Erdem , Xiros Nikolaos I. , Dahl Jason M. 
Published: January 2022

Abstract
Based on experimental data, a data error estimation model is developed for an existing neural network time dependent hydrodynamic force model. The force model, based on forces measured in forced motion experiments, is used to approximate the time dependent forces on a cylinder that may undergo combined in-line and cross-flow vortex-induced vibrations. This model will be used to develop future control models to improve VIV-based energy harvesting systems. Previously, a dynamic model of appropriate complexity was created in order to approximate time dependent lift and drag forces based on force time histories measured in an expansive set of forced motion experiments. Position and velocity were used as input to the dynamic model. A feed forward neural network was trained using the force database in order to develop time dependent models of forces on the cylinder for prescribed sinusoidal motion. The time series error between the measured and feed forward Artificial Neural Network (ANN) model was found for the lift and drag force time histories. In the present study, an autoregressive error predictor is developed from the existing neural network time dependent model of forces on the cylinder for given kinematic conditions. This autoregressive (AR) error predictor is developed based on the error between the measured signal and artificial neural network model and can be used to improve predictions from the model.
Residential Appliance Usage Patterns From Overall Energy Consumption Data: A Statistical Machine Learning Approach
Authors: Bandyopadhyay Arkasama , Bhattacharya Anirban 
Published: January 2022

Abstract
Large energy-intensive domestic appliances like heating, ventilation, and air-conditioning systems, electric water heaters, refrigerators, clothes washers, dishwashers, and dryers can together comprise about 58% of annual residential electricity consumption in the US. Accurate knowledge of domestic appliance-level energy usage patterns can help energy modelers and electric utilities design optimal demand response programs in residential communities. However, while the widespread installation of residential smart meters in the US over the past decade has enabled electric utilities to collect diurnal individual household-level electricity consumption profiles, it is extremely rare to find location-specific, short-interval, disaggregated appliance-level data for individual residences. This study develops a novel methodology to reliably predict future domestic appliance energy consumption profiles based primarily on overall electricity consumption and local weather data. The model is demonstrated using fifteen-minute interval appliance-level empirical energy consumption data for a test-bed of 25 single-family detached homes in Austin, TX from Pecan Street Inc. — a non-profit entity based in Austin. Although the training of our model utilizes historical appliance profiles, the results obtained from this analysis can be used to reliably and accurately predict time-granular appliance-level energy consumption patterns (not only on/off times) using only the overall electricity consumption profile of the household. Thus, this study opens up the possibility for energy modelers to reliably forecast domestic appliance electricity consumption profiles without having appliance-level historical energy usage datasets available.
Equivalent Energy Absorption (EEA) - A Methodology for Improved Automotive Crash & Safety Design
Authors: Narayana Peddi Sai Rama , Prakash Raghu V. , Gunti Srinivas , Raghu Kanugula 
Published: January 2022

Abstract
Safety norms across the world are becoming more and more stringent posing new challenges to achieve lightweight vehicle structures. Structures made of Advanced/Ultra high strength steels (AHSS) play a vital role in meeting the vehicle safety targets, by absorbing large amounts of impact energy, as well as by withstanding higher impact loads that occur due to vehicle collisions.
Safety simulations usually take longer solution times due to their complexity and nonlinear nature. Engineers often encounter with a problem of quick evaluation of safety performance by using different grades of materials to optimize the weight & cost. In this paper, a new methodology - Equivalent Energy Absorption (EEA) has been proposed to do a quick trade-off study on performance vs weight for various thickness and material combinations. A relationship is established between the gauge and grade of a component to derive an equivalent safety performance so that engineers can make quick decisions by conducting minimal number of simulations. a simple rectangular crush box was considered for study to assess the Energy Absorption (EA) with various material and thickness combinations. A Design of Experiments (DOE) study was done using simulations with many numbers of material grades and gauges to construct a 3D Response Surface between gauge, grade & EA parameters to understand the relationship between each of these parameters.
A case study has been discussed in the paper about application of this methodology on a vehicle to evaluate its safety performance. It has been found that more than 80% evaluation time is reduced by using this methodology.
Towards Development of 3D Printed Swimming Robot Using Soft Electromagnetic Actuation
Authors: Garcia Martin , Rouse Ciaphus , Estrada Benjamin , Tekes Coskun , Moghadam Amir Ali Amiri , Tekes Ayse 
Published: January 2022

Abstract
Success of emerging field of soft robotics relies on the development of efficient soft actuators. Most of these actuators suffers from disadvantages such as limited blocking force, lifetime, high actuation voltage, and slow response time. Swimming robots in particular utilizes single or multiple soft actuators to mimic the dynamic of a fish during motion. In this study we used 3D printing to fabricate soft electromagnetic actuators based swimming robot. The mechanism consists of soft actuator legs, compliant paddle and floatation. We designed a hybrid propulsion mechanism by using double soft leg actuators as caudal fins and side paddles as pectoral fins. This increases the thrust and efficiency to overcome the water drag as well as providing stability. We 3D printed the soft actuator using thermoplastic polyurethane (TPU) filament to reduce the manufacturing cost as well as to simplify the process. The main body is also 3D printed using polylactic acid (PLA). The infill percentage of the soft body is adjusted to increase the bending performance without yielding under actuation. The prototype of the swimming robot was tested in water. The body velocity of the robot is measured as 0.106 BL/s. Motion analysis was made MSC Adams by simulating the deformation of flexible beams.
A Numerical Study on Springback of a Channel Through the Oscillation of Punch
Authors: Nikhare Chetan P. , Buddi Tanya , Kotkunde Nitin , Singh Swadesh Kumar 
Published: January 2022

Abstract
To meet the demand of light weighting, environmental regulation, increase fuel economy, many innovations are underway. Options are light weighting the part to reduce the fuel consumption or decrease the gage in high strength dense material. In both cases during or after deforming the part these challenges occur like higher tonnage machine for deformation, sudden fracture, geometric defect, etc. One of the geometric defects which is very common in sheet metal forming is springback. Springback is the deviation of the part from the desired shape after the part is shaped and then load is released. It is the material tendency to relaxed back based on the accumulated strain and its elasticity. In lighter material or higher strength steels, the springback phenomena is very common due to lower elasticity or higher strength value. In this paper springback is analyzed by conceptualizing an innovative process. The innovative process is oscillation of the punch after the forming process is done. The 2D channel strip of the aluminum 2024 high strength alloy was used in the bending process. The process of bending with punch die and the blank was modeled in the ABAQUS finite element software. First, the conventional channel deformation was performed, and the deformation was studied and springback was compared with the desired shape. Then the oscillation of the punch was set either in the longitudinal or lateral direction. The frequency of the punch was also been changed to see the effect on the deformation behavior of the material and springback after the punch release. The residual stress during the process was studied and compared. Further the maximum stress, deformation of the channel and springback was analyzed and presented. It was found that the punch oscillation contributes in reducing the springback.
A Novel Mean Stress-Independent Fatigue Model for Bonded Joints With Ductile Adhesives
Authors: Gerini-Romagnoli Marco , Nassar Sayed A. 
Published: January 2022

Abstract
A mean stress-independent lap shear fatigue model is proposed for Aluminum 2024 alloy Single Lap Joints (SLJ) that are bonded with ductile, polyurethane-based, adhesive. Fatigue data is generated in the High Cycle Fatigue range, for 4 values of mean stress and multiple levels of alternating load. Individual S-N curves are constructed, for each value of mean stress, and the results are statistically analyzed. A separate logarithmic regression of the entire pool of data is performed, considering maximum stress and fatigue life of the samples. The test data align along the same regression line. As a result, the amount of tests to perform for durability characterization of single lap joints bonded with ductile adhesive can potentially be reduced.
High sampling frequency information of the displacement of the specimens during fatigue tests is periodically acquired and filtered. The creep-like curve describing the evolution of the mean displacement during the fatigue tests suggests that cold flow phenomena could trigger fatigue failure, rather than the propagation of a crack.
Profile Loss of a Printed Transonic Turbine Cascade
Authors: Hake Leander , aus der Wiesche Stefan 
Published: January 2022

Abstract
Profile losses of turbine blades are one of the main problems in turbine technology. Besides the occurring aerodynamic effects, it is well known that the surface roughness has a significant influence on these losses. It is generally known that a better surface quality leads to lower profile losses. Many studies for this topic are given in open-source literature, but the investigations were mainly performed in an ideal gas atmosphere (air). The present contribution presents the results of an experimental study of profile losses of an additive manufactured linear turbine cascade placed in the test section of a closed-loop organic vapor wind tunnel, or CLOWT for short. The investigations are carried out under an organic superheated steam atmosphere. For this organic vapor atmosphere, the of carbon based liquid Novec™ 649 has been used. In addition, measurements were also realized in an air atmosphere. To get different point of views, three different approaches are chosen to determine the profile losses.
Improved Tensile Strength and Electrical Conductivity of the Electrical Conductor Aluminum Alloy 6201
Authors: Allamki Alyaqadhan , Al-Maharbi Majid , Arunachalam Ramanathan , Zahid Qamar Sayyad 
Published: January 2022

Abstract
The aluminum-magnesium-silicon alloy 6201-T81 is a popular electrical conductor, widely used for overhead and distribution lines. Its light weight makes its mass conductivity twice that of copper. Aluminum conductors however experience creep, corrosion, power loss, and other drawbacks. Therefore, it has become a necessity for manufacturers to improve mechanical and electrical properties. The alloy 6201-T81 is an age hardenable alloy, in which a controlled precipitation of Mg2Si is performed through two different successive heat treatments: Solution heat treatment and precipitation heat treatment. ∅ 3.5 mm wires of the alloy were solution heat treated at 510 °C for an hour, quenched in ice water, and precipitation heat treated at the temperature range 150–200°C for the time range 2–24 h. Results show that strength and hardness increase with aging time at the precipitation heat treatment temperatures 150 °C, 165 °C, and 175 °C, but decreased with aging time at 185 °C and 200 °C. The increase was due to the precipitation of finely and uniformly coherent needle-like Mg2Si precipitates, β″. The decrease was due to the precipitation of the semi-coherent and incoherent rod-like Mg2Si precipitates β′ and β, respectively. Electrical conductivity increases with the aging temperature and time. Maximum conductivity was 60 %IACS obtained after treatments (185°C, 18h), (200 °C, 13h), and (200 °C, 24h. Optimum mechanical properties were obtained after the treatment (165 °C, 18 h) (313 MPa, 8%, 95 HV, and 57.7 %IACS). Optical micrographs verified the correlation between the microstructural grain size and both the mechanical and electrical properties.
Comparison of Clustering Techniques for Feature-Based Toolpath Generation in Dieless Manufacturing
Authors: Nagargoje Aniket , Kankar Pavan Kumar , Jain Prashant Kumar , Tandon Puneet 
Published: January 2022

Abstract
The aim of the current research is to compare the data clustering techniques for the geometrical feature extraction. The CAD models of the geometries are sliced to generate the data sets for clustering. This paper presents the comparison of K-means, Spectral, Density-based spatial clustering of applications with noise (DBSCAN) and Single Linkage Hierarchical (SLH) clustering techniques for arbitrary shaped contour clustering and formation of the groups based on the means of the contours. The factors considered for the comparison include, the inputs desired by the clustering techniques; time taken for contour clustering; ability to identify the arbitrary shaped contours; and the ability to form the features in feature-based toolpath generation in dieless manufacturing. The paper discusses three different approaches designed to accomplish the task. From the comparative analysis, it is found that the Spectral, DBSCAN and SLH can identify the arbitrary shaped contours. Further, DBSCAN and SLH clustering techniques can form the groups that can be used for feature-based toolpath generation in dieless manufacturing, whereas the other two fails to perform the same. The DBSCAN performs the contour clustering faster than the Spectral and SLH clustering.
Development of an Automatic Detection and Regulation Model of Brush Wire Pressure for a Micro Aerospace Components
Authors: Kang Yonggang , Ren Haodi 
Published: January 2022

Abstract
Micro-component brush wires are important parts of many conductive structures. The pressure of the brush wires has a crucial influence on product performance. Testing and adjusting the pressure of the brush wires is a key step to improve product performance. The existing measurement and adjustment schemes are poor in accuracy and low in automation, and rely heavily on the experience of workers. This study has developed a set of high-precision automatic brush-pressure testers, obtained the rule of brush-wire pressure adjustment through simulation calculations, and realized the high-precision, automatic measurement, and adjustment of brush pressure.
A Novel Fractional Fixed-Time Sliding Mode Control Method for Spherical Robot Linear Motion Speed Control
Authors: Ting Zhou , Yugong Xu , Bin Wu 
Published: January 2022

Abstract
This paper studies the linear motion speed control problem of an underactuated spherical robot under unknown disturbances. A novel fractional fixed-time terminal sliding mode control with a nonlinear disturbance observer is proposed for the spherical robot to achieve fast stabilization and robust control performance. First, a novel fixed-time terminal sliding surface is proposed by adding a fractional differential operator in the traditional integer order fixed-time terminal sliding surface. A nonlinear disturbance observer is designed to estimate the unknown disturbances. Then a fractional hierarchical sliding mode speed controller is designed based on the novel fractional fixed-time terminal sliding surface and the nonlinear disturbance observer. Through the Lyapunov stability theorem, the boundedness of each sliding surface is achieved, and the stability of the whole system is guaranteed. The effectiveness of the proposed controller has been verified via simulation work. The simulation results show the fractional sliding mode controller has a shorter settling time and lower overshoot compared to an integer order sliding controller. When subjected to the abrupt changes of rolling friction, the fractional hierarchical sliding mode controller shows stronger robustness than the integer order one.
Evaluating Bicep Stiffness in Increasing Age Groups
Authors: Salman Muhammad , Contois Zachary , Tanveer M. Hassan 
Published: January 2022

Abstract
Over many years muscle tissue is continuously broken down and reformed through hypertrophy, where the muscle is damaged and then the fibers are fused together to increase muscle in mass and size. As a person ages muscle tissue makeup changes based on 2 significant factors: lifestyle and genetics. Diagnosing significant injuries in this tissue requires the use of expensive technology (magnetic resonance imaging or electromyography) and invasive techniques. The focus of the study is to find an accurate, cost effective method to analyze muscle stiffness, and to observe a trend between age and muscle stiffness. The devices used in the study are a Modally Hand Impact Hammer, and three miniature PCB accelerometers. In order to capture data, the Impact Hammer is used to excite a shear wave across the Bicep Brachii. From there, the data is collected in a Signal Express software and evaluated for accuracy within MATLAB figures. The data was collected from 10 subjects. There was no clear indication that age affected the stiffness. However, this could be disproved by collecting data from a larger subject pool. The data collected was validated by other studies using tried methods.
An Experimental Investigation Onto the Effect of Two Design Methods of Leading-Edge Tubercles on the Aerodynamic Performance of a High Lift Airfoil at Low Reynolds Number
Authors: Khedr Amr A. , Adam Ihab , Ookawara Shinichi , El-Wardany Ahmed , Hassan Hamdy 
Published: January 2022

Abstract
Inspired by the tubercles on the pectoral flipper leading-edge of the humpback whale, the most acrobatic of baleen whales, sinusoidal leading-edge have been used as a passive flow control method to enhance the stall characteristics of lifting surfaces in different applications. They are supposed to reduce the lift gradually during the stall with an increase in the post-stall lift, however, their enhancement ability in pre- and post-stall is highly dependent on the geometrical parameters and the flow regime. Two different design schemes: nonlinear shear transformation design scheme (NLST) and channelled-like scheme, of the sinusoidal leading edge of the high lift airfoil S1223 are tested and compared with the unmodified airfoil at angles of attack of −6 to 30 degrees experimentally inside a wind tunnel at low Reynolds number Re = 100,000. Experimental data show that Tubercles implemented on S1223 at such a flow regime with either design scheme enhance the post-stall characteristics as much as a 42% increase in lift at some angles for NLST with pre-stall lift penalties. NLST, compared with baseline and channelled models, exhibit a significant increase in aerodynamic efficiency which make it more preferable for wind turbines applications.
Kinematic and Dynamic Modelling and Simulation of Soft Continuous Arm Based on Modal Method
Authors: Kong Qingfeng , Bai Zhengfeng 
Published: January 2022

Abstract
Inspired by the muscle structures of elephant’s trunk, octopus’ arm and tongue, the soft continuous arm developed based on bionics can extend, contract and bend along any point of its structure. Compared with the rigid manipulator, it has the characteristics of high flexibility, complex environment adaptability and safe human-machine interactivity. In this work, a three-dimensional (3D) kinematic and dynamic model of the soft continuous arm based on the modal method is presented and analyzed. The spatial kinematics model of the soft continuous arm is established based on the modal method first, in which the deformation of the soft continuous arm is assumed to be an arc without torsion, and the complex nonlinear function is approximated by a simple mathematical function. The accurate, singularity free and unique modal transformation matrix can be deduced conveniently. Also, it overcomes the limitations of the previous models in which the curve parameters are used and the curvature of the cross section assumes to be not zero as well as the dynamic model does not include the pure linear motion. The modal method can be used to simulate the spatial bending motion, but also effectively overcome the singularity problem caused by using the curve parameters for simulating the pure linear motion. Then, the dynamics model of the soft continuous arm is established using the Lagrange method. Due to large number of complex nonlinear integral operations is inevitably involved, and the computational efficiency is low in the numerical solution, the modal method is used in the numerical simulation, which greatly simplifies the complex nonlinear integral operation and improves the efficiency of numerical calculation. The simulation results of the pure elongation and bending of the soft continuous arm show that the modal method has the characteristics of fast and accurate response.