bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of shear affected zone on edge crack sensitivity in dual-phase steels
Authors: Habibi N. , Beier T. , Richter H. , Könemann M. , Münstermann S. 
Published: November 2019

Abstract
Dual phase steels offer good combination of mechanical properties which is attractive for automotive industry. However, some challenges still remain and suppress using them widely. One of these challenges is the formation of premature cracks at shear-cut edges during the subsequent forming processes, which cannot be predicted by the conventional finite element methods. Therefore, the present study aims to propose a numerical tool to predict edge cracks in DP steel components. In this regard, the hole expansion method was applied as an edge crack detection technique on DP1000 steel sheets. To elaborate the study, parallel finite element simulations were performed as well. The simulation method considered the whole hole piercing process and the following hole expansion test as a one-stroke two-step strategy. The hole piercing process was applied in the first step on the sheet and a hole was cut. The results reveal that this process forms some surface irregularities and applies a special amount of damage at the cut edge, which both could have effects on the edge crack sensitivity. To study these effects, the subsequent hole expansion test was simulated on the manufactured hole. Thus, the effects of both surface irregularities and residual damage from hole piercing process were investigated in different case studies with all possible combinations of these effects. This strategy provides possibilities to numerically separate effects of surface quality and residual damage. The contribution shows on the one hand the experimental investigations and on the other hand deals with the numerical influence analyses.
Forming behaviour of stainless steel sheets at different material thicknesses
Authors: Lehmberg A , Sunderkoetter C , Glaesner T , Brokmeier H-G 
Published: November 2019

Abstract
The austenitic stainless steel X5CrNiMo17-12-2 in thickness ranging from 0.2 mm to 1.0 mm was examined in regard to the mechanical properties and microstructure. The aim was to investigate the suitability of conventional test methods for thin material down to 0.2 mm. Within these investigations, all used thicknesses were characterized by conventional tensile tests and X-ray diffraction. The results were subsequently compared with each other. The material specific vertical anisotropy r and forming limit curve showed a strong dependence on material thicknesses. The results of anisotropy pointed out different values depending on the test methods performed. In addition, the results of microstructure analysis show a decrease of grain size with lower material thickness caused by the formation of twins and probably heat treatments during the manufacturing process.
Developing smart multi-sensor monitoring for tool wear in stamping process
Authors: Shanbhag V.V. , Pereira M.P. , Voss B. , Ubhayaratne I. , Rolfe B.F. 
Published: November 2019

Abstract
Tool wear and galling are of significant concern in the automotive stamping industry, due to the increase in use of higher strength sheet steels in automotive structures and reduced lubrication during stamping production. There are many methods explored in the literature and applied in industry to combat wear in stamping, including new die materials and coatings, alternative lubrication systems and better predictive models. However, smart condition monitoring will continue to be relevant in conjunction with these methods because it can provide further opportunities for production quality and cost improvements, despite the advancements of these other methods. This paper explores the use of multiple sensors and multiple signal processing techniques, aimed at developing a smart multi-sensor method to monitor galling wear. The three main sensors and corresponding signal processing techniques examined are: (i) measurement of punch force signatures analyzed via Principal Component Analysis (PCA); (ii) acoustic emissions signals measured via wideband sensors and examined using time and frequency domain features; (iii) measurement of audio signals in the audible frequency range analyzed via blind signal separation techniques. For all techniques, a semi-industrial stamping test was used to provide realistic production-type conditions, albeit with accelerated wear rates. The relationship between the key outputs from the three sensor/analysis methods were directly compared to a new quantitative measure of galling wear severity. Based on these results, it was observed that a multi-sensor approach for wear condition monitoring provides an opportunity for the development of a smart monitoring tool that can actively track the progression of wear.
A type of cruciform specimen applied to evaluate forming limits for boron steel under hot stamping conditions
Authors: Zhang R , Shao Z , Lin J 
Published: November 2019

Abstract
The ultra-high strength boron steel has been intensively used in the hot stamping process to produce complex-shaped structural components in transportation industries. Forming limit diagram (FLD) is a fundamental and useful tool to evaluate the formability of metallic materials under various forming conditions. Since the standardized Nakajima test and Marciniak test are not applicable to perform formability tests for hot stamping applications due to the complex heating and cooling processes required, an in-plane testing method, in which cruciform specimens are deformed under hot stamping conditions in a Gleeble materials simulator combined with a multi-axial tensile rig to convert an input force to an output biaxial force, has been successfully applied to assess the formability of aluminium alloys at elevated temperatures. However, it is challenging to apply this in-plane testing method for boron steel due to higher nonuniformity of temperature distribution in gauge region of the cruciform specimen at a higher temperature. In this paper, a new type of cruciform specimen, together with a new specimen heating strategy, has been proposed to improve the temperature distribution in the gauge region. The dimensions of the newly-designed cruciform specimen have been optimised by a thermo-electrical finite element model embedded with a UAMP subroutine in ABAQUS to improve the uniformity of temperature distribution in the gauge region. In order to validate the new design of cruciform specimen, biaxial tensile tests were conducted under hot stamping conditions by using the in-plane testing method.
New Multiphase CP and DP 1000 MPa strength level grades for improved performance after hot forming
Authors: Lahaije C T W , Rana R , Sunderkoetter C , Pérez Iñaki , Arribas Maribel , Aranguren Iñigo , Caro Daniele De 
Published: November 2019

Abstract
Pure martensitic steels have after hot forming limited performance in terms of rest ductility which limits the application in crash relevant parts. New steel grades were designed in the EU project HOTFORM including the corresponding process routes. These steel grades have ferritic-martensitic dual phase (DP) and martensitic-bainitic complex phase (CP) microstructures after hot forming process. The laboratory tests show an improved formability after hot forming. The basic concepts of the new alloys are explained. Furthermore, for validation of upscaling purposes a semi-industrial test is carried out and the results are discussed. The main application is for vehicle safety. This is evaluated by comparing the crash performance of these hot formed grades with cold rolled DP1000 and CP1000 for crash cans in a drop tower test.
Formability study on stamping an engine hood with aluminum alloy sheet
Authors: Lin Chien-Wei , Chen Fuh-Kuo 
Published: November 2019

Abstract
The formability of stamping an engine hood with aluminum alloy sheet was examined in the present study. In the stamping process, except that aluminum alloy would crack easily, a small elastic modulus makes the aluminum alloy easier to produce a significant springback defect, which would lead to variation of accuracy and is hard to grapple with. In the present study, the cyclic tension-compression reversal tests were first conducted to obtain the stress-strain relations and the Bauschinger effect exhibited in the aluminum alloy sheet was noted. The finite element simulations were then preformed for V-bending and U-hat drawing of aluminum alloy sheet, and the results of springback and side-wall curl were compared with those obtained from experiments. It is concluded from the comparison that the material model which includes the Bauschinger effect renders a more consistent result with the experimental data. In order to investigate the difference of forming characteristics between conventional steel and A6181-T4 in the stamping process of an engine hood, the effects of process parameters on the stamping formability were systematically analyzed by the finite element simulations. The finite element simulation results were validated by the production engine hood and the characteristics of A6181-T4 formability investigated in this study were confirmed.
Comprehensive understanding of effective parameters on edge cracking sensitivity of hot-rolled complex phase steels
Authors: Goncalves J , Alibeigi S , Sarkar S 
Published: November 2019

Abstract
Good stretch-flangeability is an essential property for forming complex press-formed automotive parts such as chassis, suspension and control arm components. Continuous research is ongoing in developing materials that could improve the performance of Advanced High Strength Steels (AHSS) during industrial stretch-flangeable operations. Consequently, there is a great interest in investigating the sheared edge stretchability and determining the factors, critically influencing the product edge formability. The objective of the present research is to obtain a comprehensive understanding of effective parameters on the cut-edge behaviour of Hot-Rolled (HR) stretch-flangeable Complex Phase (CP) steels. The role of microstructural damage on the edge stretchability of CP steels was evaluated employing hole punching and Hole Expansion (HE) tests. The influence of product microstructure and inclusions were highlighted. A correlation between the Lankford coefficients (‘r’ value), strain hardening exponent (‘n’ value) and Hole Expansion Rate (HER) was investigated. Finally, a new specific testing procedure combining a shearing test followed by tensile test is proposed to correlate with hole punching and HE operations and to develop in-depth understanding.
Formation of the properties of nano-modified concretes
Authors: Sharanova A V , Dmitrieva M A , Zakharov A A 
Published: November 2019

Abstract
Nanomodified concrete is obtained from multicomponent dry building mixes based on Portland cement containing nanoscale filler particles. This paper examines the cement-sand mixture activated in a high-energy mill as a nanomodifier. The result is the gain in strength of concrete in the initial hardening time. The influence of fractional characteristics of sand on the activation process is analyzed. Three sand samples of different deposits of the Kaliningrad region characterized by different size and content of dust and clay particles were studied. The results of tests of samples of fine-grained concrete with activated and non-activated components for the initial compressive strength at the age of 0-90 minutes after the preparation of the mixture are presented. It is noted that the mechanical activation of cement-sand mixture is most effective when there are large fractions in the activated sand.
Weak adhesion and delamination of hydrogenated diamond like carbon coating on a rough surface of tappet valve substrate
Authors: Kolawole F O , Varela L B , Kolawole S K , Ramirez M A , Tschiptschin A P 
Published: November 2019

Abstract
DLC(a-C:H) film are known for their excellent tribological properties however, possess poor adhesion on metallic substrate causing film delamination. Introduction of adhesive silicon interlayer has showed improvement in the adhesion of DLC-H on metallic substrate. In the present study DLC-H was deposited on tappet valve and silicon wafer using PECVD. The as-deposited DLC-H was characterized using XRD, EDS and Raman spectroscopy. SEM was also used to measure the thickness of the DLC-H coating and the average surface roughness (Ra) was measured using 3D Profilometry. Scratch test was used to determine the COF, adhesion and hardness of the DLC-H coating. The DLC-H coating on tappet valve had weak adhesion compared with DLC-H coating deposited on silicon substrate, which had good adhesion. The result of the Raman spectroscopy revealed a sp3 fraction of 0.43 for the DLC-H deposited on silicon substrate. The thickness of the as-deposited DLC-H film was 1.78 µm, which was measured using SEM to view the cross-section of the as-deposited DLC-H coating on the silicon substrate. The surface roughness of the as-deposited DLC-H coating on silicon substrate was 26.59 nm. Silicon substrate coated with DLC-H had the lowest COF, ranging from 0.06 to 0.09.
Fast Switching Valve Utilization to Control Pneumatic Cylinder Speed
Authors: Adel Elkashef M. , Aly Mohamed , Mahmoud Osama E. , Hossamel-din Yehia H. 
Published: November 2019

Abstract
The position and speed of the piston of pneumatic cylinder are very important parameters in evaluating the pneumatic system performance. Utilization of Pulse Width Modulation (PWM) technique to control the Fast Switching Valve (FSV) usually causes fluctuation in the piston motion and accordingly, the system performance deteriorates. The objective of this work is to introduce a novel PWM control technique considering the suitable duty cycles according to the switching frequency in order to improve the FSV characteristics and reduce piston speed fluctuation. A test rig for a simple pneumatic circuit with an FSV as a control element has been designed and realized. The displacement of the piston is measured using a Linear Wire Potentiometer Transducer (LWPT), while its derivative is used to estimate the speed considering a low pass filter to reduce the effect of piston position signal noise. A nonlinear mathematical model is introduced and experimentally validated. The results of both computer simulation and experimental measurements show that the integration between fast switching valve and PWM control signal leads to a quasi-linear relationship between duty cycle and piston speed. Moreover; results proved the successful control of piston speed based on the correct duty cycle and valve switching frequency.
The performance of structured and unstructured grids on wind simulations around a high-rise building
Authors: Hågbo T-O , Giljarhus K E T , Qu S , Hjertager B H 
Published: November 2019

AbstractIn this study, computational fluid dynamics has been applied to analyze the performance of both structured and unstructured meshes when used in steady-state simulations of wind in an urban area. This case specifically examines the wind environment around a single high-rise building with the geometry of 1: 1: 2 (length, width, height) within the atmospheric boundary layer.The Reynolds-averaged Navier-Stokes simulations were conducted using OpenFOAM, with grids generated withblockMesh, snappyHexMesh,andPointwise.A set of coarse meshes and a set of fine meshes were used for comparison.Minor differences in the flow pattern were observed depending on the mesh type used, including the reattachment lengths, the drag coefficients, the velocity profiles, and the positioning of the vortex leeward of the high-rise building. However, the main flow features were the same, indicating that for simulations where overall flow features are of importance there is high flexibility in choice of meshing technique.
Analysis of the alkali-activated fly ashes from electrostatic precipitators by impedance measurements
Authors: Walter J , Mierzwiński D , Kosiba K 
Published: November 2019

Abstract
Curing the fly ash materials with addition of sand activated by 8 M sodium hydroxide (NaOH) was analysed by impedance spectroscopy. The measurements were carried out for 6 hours from the moment the samples were put into the oven at 75 °C. It was found characteristic similar shape of impedance curves recorded versus time of solidification process. Starting from the curve obtained after 52 min to longer times impedance curve crossed at about 30 Hz. The first lower than 30 Hz frequencies range showed continues decreasing of impedance values with increasing the time. Changes in impedance curve versus time looks different for second frequencies higher than 30 Hz. Temperature of the material increases slightly over temperature of the oven as a result of exothermic reactions which can be seen at impedance vs. time curve as a bulge. The starting of these reactions can be seen more precisely in the second range of the frequency as a continuous increase of impedance value preceded by its initial fast decline. The main purpose of the article is the possibility of using the described method, it can be particularly useful for assessing the starting point of an exothermic reaction and its progress in the case of different masses of heated material.
Development of a stabilized natural fiber-reinforced earth composite for construction applications using 3D printing
Authors: Silva G , Quispe L , Kim S , Nakamatsu J , Aguilar R 
Published: November 2019

Abstract
The application of additive manufacturing technologies to the construction industry has a wide range of advantages from the economic, social and design flexibility point of view. However, most of up to date research studies have been performed using ordinary Portland cement (OPC)-based mortars and concretes. Therefore, the objective of this article is to explore the development of an eco-friendly earth composite reinforced with natural sisal fibers and chemically stabilized with a hydraulic binder. Analysis of the workability by shear vane tests was performed on fresh earth samples to find the optimum water content in sisal fiber-reinforced earth stabilized with OPC. Afterward, the effect of the addition of OPC on the hardening process was evaluated through shear vane and Vicat needle tests from 0 to 180 min after mixing. The results indicate that water content, fiber addition and OPC replacement have a strong influence on the shear yield strength. Furthermore, the presence of chemical stabilizers as OPC accelerates the hardening process allowing a faster layer-by-layer deposition. This low cost and eco-friendly preliminary earth-based composite can be used for 3D printing applications in the construction industry.
Genesis of non-uniformity of plasma fluxes over emissive wall in low-temperature plasmas
Authors: Schweigert I V , Walker M L R , Keidar M 
Published: November 2019

Abstract
Origins of spatial modulation of stationary electron and ion currents to the wall in discharge plasma with/without magnetic field at low gas pressure are studied in the experiments and 2D PIC MCC simulations. It is shown that a non-uniformity of ion and electron fluxes to the wall is induced by (a) a non-planar topology on the emissive wall, (b) a difference in the secondary electron emission yields of materials in segmented wall or (c) an inclination of the external magnetic field. The transition in the sheath structure over the grooved emissive surface from a developed sheath to a collapsed one caused by the increase of electron energy enlarges the alteration of the ion and electron currents over the grooved or segmented surfaces. The experimental study of the plasma-emissive wall sheath transition was carried out with hexagonal boron nitride wall samples grooved with the characteristic size of 1 mm and 5 mm, which is about of the Debye length. In kinetic simulations, this phenomenon is analyzed in terms of the electron and ion energy distribution functions. An external oblique magnetic field applyed to the dc discharge is found to redistribute the plasma and the periodical structure with the spikes of electron and ion densities forms This phenomena causes the non-uniform spatial distribution of electron and ion currents to the wall. The spikes in electron and ion densities became more pronounced with an increase of magnetic field incidence angle.
Sonographic Analysis of the Upper Labial Orbicularis Oris and Its Clinical Implications
Authors: Park Hyun Jin , Lee Kyu-Lim , Gil Young-Chun , Lee Ji-Hyun , Hu Kyung-Seok , Kim Hee-Jin 
Published: November 2019

Abstract

Background
Purse string lips, which include the vertical wrinkles over the lips, are frequently observed in aged individuals. Botulinum toxin and fillers are routinely injected into these areas to remove the wrinkles; however, the anatomy of the orbicularis oris muscle (OOr) near the vermilion border area has not been well defined.

Objectives
The aim of this study was therefore to identify any morphological differences of the upper OOr via sonographic imaging.

Methods
The upper lip muscles as observed utilizing an ultrasound device were divided into 2 muscles (pars peripheralis and pars marginalis) that were subsequently divided into a further 2 types (Type I and Type II) associated with the development of the pars marginalis. Type II was further divided into Type IIa and Type IIb depending on whether the muscle fibers were well developed and connected.

Results
On the midline of the lip, Type I, in which the pars marginalis was rarely observed and only appeared in traces, was observed in 20.0% of the volunteers. Type IIa, in which the pars marginalis was well-developed and appeared continuous, was observed in 42.9% of the volunteers. Type IIb, in which the pars marginalis was observed but appeared discontinuous, was observed in 37.1% of the volunteers.

Conclusions
The shapes of the upper pars marginalis of the OOr varied markedly between volunteers. Type classification of the OOr based on its shape and the lip appearance serves as a reliable source of reference information to be utilized when injecting botulinum toxin into the upper lip.
MotifCNN-fold: protein fold recognition based on fold-specific features extracted by motif-based convolutional neural networks
Authors: Li Chen-Chen , Liu Bin 
Published: November 2019

AbstractProtein fold recognition is one of the most critical tasks to explore the structures and functions of the proteins based on their primary sequence information. The existing protein fold recognition approaches rely on features reflecting the characteristics of protein folds. However, the feature extraction methods are still the bottleneck of the performance improvement of these methods. In this paper, we proposed two new feature extraction methods called MotifCNN and MotifDCNN to extract more discriminative fold-specific features based on structural motif kernels to construct the motif-based convolutional neural networks (CNNs). The pairwise sequence similarity scores calculated based on fold-specific features are then fed into support vector machines to construct the predictor for fold recognition, and a predictor called MotifCNN-fold has been proposed. Experimental results on the benchmark dataset showed that MotifCNN-fold obviously outperformed all the other competing methods. In particular, the fold-specific features extracted by MotifCNN and MotifDCNN are more discriminative than the fold-specific features extracted by other deep learning techniques, indicating that incorporating the structural motifs into the CNN is able to capture the characteristics of protein folds.