bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on optimisation processing of spatiotemporal correlation temperature and humidity data based on wireless sensor networks in cigarette factory
Authors: Liao Yusheng , Ran Jingwang , Zhou Xianjiang
Published: December 2019

The tobacco leaves have higher requirements on the environment during production and storage, especially for the temperature and humidity. In order to improve the quality of tobacco leaves, it is necessary to accurately monitor the temperature and humidity and optimise the parameters involved in the control. Based on the temperature and humidity monitoring system of cigarette factory, the authors optimised the temperature and humidity data obtained by wireless sensors. The data quality evaluation indicators were designed, and the Dixon criterion was used to eliminate gross errors in individual data instance. The abnormal data detection mechanism is designed to eliminate the fault data in multiple data instances by the similarity criteria among neighbour nodes in the area. In order to solve the problem of excessive computation caused by node explosion, extended rules of healthy node judgment were designed. Through the actual operation of the system for >6 months, the algorithm maintains good fault detection capabilities for different fault models and can provide support for temperature and humidity data processing of wireless sensor networks (WSNs).
A gravitational lensing detection of filamentary structures connecting luminous red galaxies
Authors: Xia Qianli , Robertson Naomi , Heymans Catherine , Amon Alexandra , Asgari Marika , Cai Yan-Chuan , Erben Thomas , Harnois-Déraps Joachim , Hildebrandt Hendrik , Kannawadi Arun , Kuijken Konrad , Schneider Peter , Sifón Cristóbal , Tröster Tilman , Wright Angus H.
Published: December 2019

We present a weak lensing detection of filamentary structures in the cosmic web, combining data from the Kilo-Degree Survey, the Red Cluster Sequence Lensing Survey, and the Canada-France-Hawaii Telescope Lensing Survey. The line connecting luminous red galaxies with a separation of 3 − 5 h−1 Mpc was chosen as a proxy for the location of filaments. We measured the average weak lensing shear around ∼11 000 candidate filaments selected in this way from the Sloan Digital Sky Survey. After nulling the shear induced by the dark matter haloes around each galaxy, we reported a 3.4σ detection of an anisotropic shear signal from the matter that connects them. Adopting a filament density profile, motivated from N-body simulations, the average density at the centre of these filamentary structures was found to be 15 ± 4 times the critical density.
Preliminary Study of Electrochemical Advanced Oxidation of Organic Dyes on TiO2
Authors: Banu Alexandra , Mocirla Madalina , Soylu GizemNur
Published: December 2019

Methyl orange (MO) is an environmental concern because their degradation products are highly toxic to aquatic microorganisms and carcinogenic, also their degradation products are mutagenic to humans. Electrochemical oxidation is one of the promising technologies for the dye wastewater de-pollution, which are obtained extensively attentions because it holds the advantages of total oxidization of dyes to CO2 and H2O. Titanium dioxide has emerged as the leading candidate to provide complete destruction of organic pollutants via heterogeneous photocatalysis that result in total mineralization of many organic pollutants. Though this process offers actual annihilation of the dye moleculesatavery high efficiency, thepost-treatmentrecoveryof TiO2 canbecostly. The titanium nanotubes are typically produced by anodic oxidation of the titanium foil in various electrolytes.Degradation of methyl orange (MO) was conducted by electrochemical oxidation method with Ti/TiO 2 nanotubes anodes. Were prepared samples of TiO2 nanotubes by anodizing titanium in an electrochemical bath consisting of 1:1 waterglycerol with 0.4% of HF using different conditions: 25V for 8 hours, 30V for 3 hours in the stationary state, 30V 3 hours under ultrasound stirring. The oxidation efficiency was determined by UV-VIS analysis of the electrolyte.
Positioning system for assembly and manufacturing tasks
Authors: Breaz Radu-Eugen , Racz Sever-Gabriel
Published: December 2019

The paper presents a two-axis positioning system using asynchronous motors as actuation devices. Theuse of asynchronous motors reduces the overall cost of the system, while providing actuating torques superior to the ones provided by stepping motors. The system is controlled by mean of a programmable logic controller (PLC) and two voltage-frequency inverters fitted with motion control cards. In contrasts to a stepping motor system, which works in open loop mode, the proposed system uses closed loop control on each axis. The motion loop is closed by means of an incremental encoder.
Taking brain-computer-interfacing one step further: a portable, wireless system coupled with online linear discriminant analysis for the detection of error-related potentials
Authors: Ancău Dorina , Roman Nicolae-Marius , Ancău Mihai
Published: December 2019

Recent years have witnessed extensive developments of computer science applications in medicine - assistive technologies. Among them, the concept of Brain-Computer-Interfaces, facilitating direct communication between brain and computer, has inspired numerous practical ideas on controlling an external device via neural signals. The perception of an error made by oneself, another human or a machine, triggers an error-related potential, which has already been exploited as a binary correction readout for decisions made by Brain-ComputerInterfaces. Our approach takes advantage of this technique, while taking it one step further regarding portability by using an affordable, robust and wireless headset, the Emotiv EPOC+, to recognize error-related potentials in electroencephalograms of subjects performing various on-site, dynamic tasks. We also introduce a straightforward linear-discriminant analysis classifier that extends the range of detection from offline, post-hoc analysis, to online, within-trial recordings, an essential condition towards blending machine-performed tasks with human-generated thought processes in everyday life.
Modelling and simulation of a flexible packaging system for detergents
Authors: Blaga Florin , Pop Alin , Stănăşel Iulian , Hule Voichiţa , Indre Claudiu
Published: December 2019

The paper presents how an automated manufacturing system for the packaging of detergents can be modelled using Petri nets. The complexity of the Detergent Packing System and the high level of automation,require the use of efficient modelling and simulation methods to verify the validity of the solutions adopted. For this purpose, a modern modelling and simulation method based on Petri nets is used. The models associated with the system are developed into a hierarchical structure: the model of some modules in a line; the model of a line; system model as a whole. The model of a packing line consists of the following sub-modules corresponding to the modules of the line: filling the bags, grouping the bags in boxes, grouping the boxes in a row, palletizing, supplying with new empty pallets, full pallets evacuation. The six lines of the manufacturing system can work in various ways: they can pack detergent bags of the same mass or of different masses. Under these conditions, the operating mode is checked step by step, and the necessary adjustments can be done as to ensure continuous operation of the system without any blockages.
Preliminary analysis of tower crane as a type of truss structure
Authors: Hric Slavomir , Tkac Jozef , Matiskova Darina , Micko Milan , Mandulak Dusan
Published: December 2019

Truss structures are part not only technical practice but also our everyday life. It is very important to be designed safely. One of the tools that help a designer to avoid errors and to make the rightdecisions about a structure material, beam profile, shape of rod construction, etc. is virtual analysis. The article deals with the preliminary study of tower crane, which can be considered as the truss structure. Various types of structures are described in the introduction. The main part of the article is devoted to static analysis of the crane. The physical 3D model was prepared in reduced scale according to standards of European model trains NEM (Normen Europäischer Modellbahnen). Axial forces, stresses in beams, as well as the maximum possible load have been specified by analytical method. The strain analysis of crane has shown that the primary design of the structure was not acceptable and the construction would not be able to lift up required weight. Results were verified by virtual simulation insoftware Robot Structural Analysis. Therefore, the truss was reinforced by additional bars and newly remodelled tower crane has been tested to specify the maximum load of external weight.
Comparison study regarding bearing performance on 3 types of air bearingsusing Dyrobes software
Authors: Becze Sigismund , Vuscan Gheorghe Ioan
Published: December 2019

The gas bearings have low load capacity and high stiffness requirements beside the high precision which all are a concern in their development. The 2 large categories of gas bearings have each of them a drawback: the static gas bearing have the performances depending by the system which maintain the pressure, while the dynamic one's performances are increasing with speed. The article creates a comparison between 3 different type of dynamic gas bearing, using air as lubricant. While all 3 types of bearing having similar performances at max speed in term of eccentricity ratio vs. rpm, minimum film thickness and equilibrium locus, the cross-coupled damping and stiffness shown a rotor destabilization tendency. The 3 lobe rotor presented the highest pressure profiles at every speed. The pressure profiles present same shapes after 80000 rpm. The results shown potentially a multilobe rotor can over perform the plain bearing also in low speed.
Use of Neural Networks in Tool Wear Prediction
Authors: Kundrík Juraj , Kočiško Marek , Pollák Martin , Telišková Monika , Bašistová Anna , Fiala Zdeněk
Published: December 2019

Modern CNC machine tools include a number of sensors that collect machine status data. These data are used to control the production process and for control of the CNC machine status. No less importantpart of the production process is also a machine tool. The condition of the cutting tool is important for the production quality and its failure can cause serious problems. Monitoring the condition of thecutting tool is complicated due to its dimensions and working conditions. The article describes how the tool wear can be predicted from the measured values of vibration and pressure by using neural networks.
Evaluation of accuracy of seamless steel tube scanning by industrial computed tomography
Authors: Kritikos Michaela , Buranský Ivan , Buranská Eva , Mojžiš Milan
Published: December 2019

Measurement by computed tomography is very useful in evaluation of dimensions and internal structure. There are still some problems which need to be solved. Scanning accuracy depends, among other things, on the part´s material. Metal parts have high density and their scanning leads many times to failure. This paper deals with evaluation of accuracy of seamless steel tube scanning by industrial computed tomography. This method of scanning can lead to substitution of destructive method for measurement,but it is necessary to have knowledge if the scan has required accuracy. The tube with different diameters in length is scanned by X-Ray beam and it is evaluated inner and outer diameter, concentricity and wall thickness in 8 sections. The accuracy of scan is compared with reference values achieved by coordinate measuring machine in the same sections.
The effect of the number of inference rules of a fuzzy controller on the quality of control of a mobile robot
Authors: Kósa Patrik , Olejár Martin , Palková Zuzana , Hrubý Dušan , Cviklovič Vladimír , Harničárová Marta , Valíček Jan
Published: December 2019

The application of intelligent control algorithms in the field of autonomous mobile robotics enables effective control of mobile robots with a minimal possible error. At present, most of commonly used systems to control an autonomous mobile robot are, however, too complicated to design. Our goal was to design a fuzzy controller with an optimal number of inference rules in a way to achieve the best possible level of quality of mobile robot control. The proposed controller was implemented in the mobile robot EN20, where the time of regulation and the absolute and the quadratic control surface were used to evaluate quality parameters. The analysis of the quality of control was performed with the use of a fuzzy controller with 9, 25 and 49 inference rules. We found from the results of modelling that the greatest influence on the quality of control of a mathematical model of the mobile robot had the number of inference rules of the fuzzy controller. Mathematical and graphical dependence of the quality of control on the number of inference rules was calculated from the parameters of the quality of control. The results of the research are equations of the curves of the individual parameters of control of quality, which show that for the control of the autonomous mobile robot EN 20, that the optimal fuzzy controller has 49 inference rules, triangular functions of the pertinence of individual linguistic values and it is defuzzificated by Centroid method.
Industrial Intelligent Software Applications of the Overall Equipment Effectiveness (OEE) in Manufacturing
Authors: Hörmann Bernd Otto , Bizubac Dan , Popa Marcel Sabin
Published: December 2019

This paper aims to evaluate the solution behaviour of the “Overall Equipment Effectiveness” to determine the performance in innovative manufacturing environments. OEE literature categorizes six major losses: “Equipment failures and breakdowns”, “Setup/Adjustments”, “Idling and minor Stops”, “Reduced Speed Losses”, “Reduced Yields and Quality Defects and Rework”. The technical implementation method used by the authors to achieve their scope has been described using a hybrid of software development programs such as: SAP MII, SAP PCo and SAP ME in relation to the theoretical existing principles. The results presented conclude that losses in practice can occur at both high rates and low rates and therefore, an innovative manufacturing concept must be further enhanced. In terms of performance related to equipment utilization, the specific stoppages and downtimes need to be taken in consideration and adjust the OEE results accordingly. The actual situation in a real–life environment has increased in efficiency, but as technology improves, opportunities for further development appear at a high rate.
Effect of thermal degradation on rheological properties of polymeric materials
Authors: Dobránsky Jozef , Doboš Zigmund
Published: December 2019

The aim of this paper is to monitor the melt volume index of thermoplastic materials and other rheological properties such as shear rate and viscosity. The aim is to compare and assess whether several times ground and subsequently re-melted samples of pure polymer granulate will have the same or similar rheology properties and whether adjustment of the injection molding machine will be required or willneed to reduce or increase production times. Thermo Scientific with HAAKE Meltflow MT software was used to determine the melt flow rate index (MVR) of thermoplastic materials. Based on the melt flow rate (MVR), shear rate and viscosity evaluation, it has been found that, although the selected materials have undergone multiple changes in the rheology of the polymeric materials, there is no problem in the molding process, and MVR does not change significantly. In this case, no changes in the settings of theinjection molding machines and reduction or increase in production times will be necessary. When re-melting the granulate samples, no excess waste was generated, which would then need to be disposed of and the samples could be re-used for further measurement after grinding.
Study on the design and execution of a short fiber reinforced polyamide part
Authors: Bocăneț Vlad , Popescu Adrian , Fenișer Cristina , Tamba Iulian
Published: December 2019

This article presents the stages and problems that can arise from the design to the realization of a part obtained through the process of injection. The model part used in the research is a part used in the automotive industry made on a large scale. The material from which the workpiece is made is a polymer that is part of the Polyamide class namely Polyamide 6.6 armed with short fiberglass (SGFR-PA 6.6). The fiberglass arming was made at a 30% rate, resulting in a significant increase in the mechanical characteristics of the workpiece. The validation of the flow in the injection mold was done using Moldflow Adviser™. Due to the contraction of the material, different problems of the injected parts may occur, which endanger their proper functioning. Measurements were done by using a GOM ATOS™optical scanner. The scanned part was compared with the CAD model and the deviations were observed.
Defect sensitivity in additively manufactured aluminium alloys: contribution of CAD artificial defects
Authors: Bonneric Matthieu , Brugger Charles , Saintier Nicolas
Published: December 2019

The prediction of the fatigue resistance of additively manufactured parts is a current issue for the materials and process qualification in aerospace industry. Despite a continuous improvement of AM process, the presence of defects cannot yet be completely avoided, and the latter are still one of the main causes of fatigue damage in AM materials. In this framework, the present work focused on the influence of defects on the uniaxial fatigue behavior of AlSi7Mg0.6 alloy produced by Selective Laser Melting (SLM). Uniaxial fatigue tests have been performed. Fatigue specimens were subjected to a T6 treatment, and then machined in order to avoid the influence of surface roughness. Besides, for some specimens, artificial defects were directly introduced through CAD. The introduction of artificial defects, whose sizes and positions are precisely controlled, aims to provide a proper assessment of defect sensitivity. X-ray tomography was used to characterize both natural and artificial defects. Finite-element calculations of the local stress fields in the vicinity of defects were conducted, accounting for the real defect geometries obtained with CT scans. The application of a non-local multiaxial fatigue criterion then allowed to analyze defect criticity.
Determination of optimal residual stress profiles for improved rolling contact fatigue resistance
Authors: Mahdavi Hamidreza , Poulios Konstantinos , Niordson Christian F.
Published: December 2019

A theoretical framework is developed for the evaluation of favorable residual stress profiles, suppressing fatigue damage initiation in rolling contact fatigue. Non-metallic inclusions at the microstructure of bearings are one of the most important reasons for fatigue damage initiation since they act as stress risers. In order to evaluate the stress state around such inclusions at the micro-scale, macroscopic stress histories are determined by Hertzian contact theory at different depths below the raceway for a typical roller bearing. These stress distributions are then used as far-field stresses for a micro-scale model accounting for single inclusions of different geometries and orientations. Eshelby’s method is used to relate far-field and local stresses in the vicinity of inclusions. The von Mises stress criterion is then used as a conservative estimator of crack initiation due to micro-scale plasticity. The effect of compressive residual stresses added to the axial and circumferential normal stress components at different depths is analyzed. The von Mises stress field around different inclusions at different depths is investigated in order to determine the most critical case in terms of micro-scale plastic deformation. Finally, an optimization process is carried out in order to determine the residual stresses that minimize the maximum observed von Mises stress as a function of depth.
High temperature bi-axial low cycle fatigue behaviour of railway wheel steel
Authors: Nikas Dimitrios , Ahlström Johan
Published: December 2019

One of the most important aspects in railway operation is the interaction between rail and wheel. Railway wheels are commonly made from medium carbon steels (∼ 0.55 wt.% C), heat treated to a near pearlitic microstructure with some 5–10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads are evolved because of recurring braking and occasional slippage. Thus the combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of the current investigation is to evaluate the mechanical behaviour of wheel material (UIC ER7T) subjected to non-proportional biaxial fatigue loading, as this simulates the actual working conditions in a better way than uniaxial loading. Axial-torsional low cycle fatigue tests were performed at room temperature and elevated temperatures using thin walled specimens to study the cyclic stress-strain properties of this material. The results showed large influence of temperature on the ratcheting behaviour of the material. Biaxial non-proportional loading gave much higher strain hardening as compared to uniaxial loading. Hardening due to dynamic strain ageing can be seen in the biaxial tests at temperatures around 300°C.
Creep Damage Evaluation using Uniaxial Miniature Specimens for Multiaxially Damaged Components
Authors: Kosaka Rui , Ogawa Fumio , Itoh Takamoto , Sakane Masao
Published: December 2019

This study discusses a method of evaluating multiaxial creep damage for high temperature components subjected to multiaxial creep damage utilizing a miniature creep testing. A new model of the damage evaluation is proposed based on a linear creep damage accumulation and von Mises equivalent stress being a measure of multiaxial creep damage. The model clearly indicates that conventional creep damage evaluation methods utilizing a unidirectional miniature creep testing give an unconservative estimate in some cases for multiaxially creep damaged components. To verify the appropriateness of the proposed model, multiaxial creep tests were performed using cruciform specimens of a Mod.9Cr-1Mo steel. Miniature specimens in two directions were machined from a pre-damaged cruciform specimen and the uniaxial creep rupture lifetimes of the miniature specimens demonstrate the validity of the proposed model.
Low-cycle fatigue behaviour of an aero-engine disk alloy under non-proportional loading
Authors: Sahadi Cavalheiro João Vitor , Nowell David
Published: December 2019

The quest for higher efficiency and fuel economy has pushed aeroengines to challenging levels. In order to become more efficient, engines must run at higher bypass ratios and temperatures, resulting in extreme operating conditions for their hottest section. Nickel based superalloys have been used for this application for the past 50 years due to high fatigue strength at elevated temperatures. This paper investigates the deformation behaviour and fatigue lives of a powder metallurgy Nickel-based superalloy developed for discs of high-pressure turbines, i.e. the most demanding section of aeroengines. For that six different non-proportional load paths were carefully selected, where five of them present the same degree of load non-proportionality, to explore load path dependency and the effects of non-proportional multi-axial loading on fatigue lives. Results confirm an additional cyclic hardening caused by load non-proportionality and its detrimental effect on fatigue life. Lives for non-proportional tests were around three times shorter than fatigue lives for proportional tests at comparable stress levels.
A cloud-based fatigue analysis tool with interactive Neuber’s master curve
Authors: Kujawski Daniel
Published: December 2019

A cloud-based fatigue analysis and life prediction tool is presented. Users around the globe may access it via Internet by means of multiple platforms such as desktop and laptop computers, tablets and/or smart-phones. It is an intuitive educational software, aimed also to assist designers in the pre-prototyping stage in fatigue life estimation for smooth or notched parts subjected to constant amplitude, block loading, and spectrum loading histories. For spectrum amplitude loading a dedicated spectrum software package is provided, which is essential for a potential clean-up and/or desired modifications of a raw spectrum data. Subsequently, a rainflow method is utilized and the corresponding hysteresis loops at the notch-root or critical “hot spot” location are determined and plotted. For notched components, an interactive Neuber’s master curve is utilized and discussed. It is shown, that the Neubers’s master curve is only material dependent and is applicable for both monotonic and cyclic loading situations.
Mixed-mode crack tip fields in a polycrystalline aluminum alloy
Authors: Wicke Marcel , Brueckner-Foit Angelika
Published: December 2019

Carefully performed experiments with long cracks in the near-threshold regime have shown that the crack tip field of these cracks significantly deviate from the expected mode-I butterfly-shaped ones and resemble strongly to mixed-mode crack tip fields. A simulation study using a crystal plasticity (CP) approach has been utilized in order to understand this phenomenon. To this end, a digital twin of an aluminum sample fatigued in the near-threshold regime was generated with the help of electron backscatter diffraction (EBSD) and X-ray tomography. Once set-up, the digital twin was loaded in uniaxial tension using the fast spectral solver implemented in the Düsseldorf Advanced Material Simulation Kit (DAMASK). The versatility of this experimental-computational approach for studying the strain partitioning at the crack tip is demonstrated in this work.
Residual strength evaluation under mixed mode loading
Authors: Boljanović Slobodanka , Maksimović Stevan , Carpinteri Andrea
Published: December 2019

This work explores the failure resistance of fatigue damages with random orientation through a new computational framework. Such analytical model aims to enable designers to properly and quickly assess stress state and residual life under cyclic loading with constant amplitude and overload, employing suitable fracture mechanics-based concepts. The efficiency of estimates obtained is discussed by means of relevant mixed-mode tests available in the literature.
Effect of triaxial stress distribution upon roughness of brittle fracture surface
Authors: Nakamura Noritaka , Kawabata Tomoya , Takashima Yasuhito , Nishizono Yuki , Yanagimoto Fuminori
Published: December 2019

To observe the effect of stress triaxiality upon brittle fracture surface, we performed two types of experiments which differ in stress triaxiality. As a result, crack branch starting speed changes in two specimens and the speed was affected by stress triaxiality. In bending condition, branch starting speed is around 0.86 cr (cr: Rayleigh wave speed), which is higher than that in tensile condition, 0.59 cr. It was realized that in higher stress triaxiality, branching is easy to occur because in bending condition stress triaxiality is said to be lower. On the other hand, mirror-mist transition speed is not affected by stress triaxiality. By fracture surface observation, we proposed that branch occurs when microbranch grew. This proposition was supported by FEM calculation with microbranch model, it was proved that in bending condition microbranch is difficult to grow. Additionally, we proposed a qualitative explanation that microbranch is easy to grow when stress triaxiality is higher because growth of microbranch is affected by T-stress. It is since the phenomena is not on the main crack propagating plane.
Fatigue behavior of Nitinol medical devices under multi-axial non-proportional loads
Authors: Berti Francesca , Wang Pei-Jiang , Spagnoli Andrea , Guala Carlo , Migliavacca Francesco , Pennati Giancarlo , Edelman Elazer R , Petrini Lorenza
Published: December 2019

Nickel-Titanium alloys (Nitinol) are widely used for biomedical applications. Peripheral stents are almost exclusively composed of Nitinol, as its superelasticity is suited for minimally-invasive insertion and durable effect. After crimping and deployment stents undergo cyclic multi-axial loads imposed by vascular and lower-limb motion (e.g. axial compression, bending, and torsion). This complex mechanical environment could lead to metal fatigue and device fracture, with possible severe consequences (e.g. in-stent restenosis). Standard regulations require experimental verification of stent fatigue behaviour for preclinical assessment, but no exact indications are provided to direct the load combination. Moreover, different fatigue criteria were developed for common metals to predict fatigue endurance, but no criteria were specifically defined for the unique thermo-mechanical properties of Nitinol. This study investigated the role of cyclic multi-axial loading conditions on different stent geometries, looking at how they affect the stress/strain distribution along the device and how different criteria may affect the fatigue prediction (e.g. the standard Von Mises alternate approach and other critical plane approaches). Then, a preliminary experimental fatigue campaign was performed in agreement with the numerical simulations in order to compare the numerical predictions with the experimental results. The result suggest that the critical plane approaches are more reliable than the standard Von Mises criterion.
Characterising Fatigue Behaviour of Nodular Cast Iron Using Micromechanical Simulations
Authors: Lukhi Mehul , Kuna Meinhard , Hütter Geralf
Published: December 2019

Elastic-plastic porous materials experience an increase in the mean void volume fraction when they are subjected to cyclic loading. This behavior is known both from the experiments and simulations in the literature. The authors have first time used this mechanism for the evaluation of the fatigue life in nodular cast iron. In this contribution, the stress-life approach is presented for the characterization of fatigue failure. For this purpose, micromechanical finite-element simulations are carried out using the axisymmetric cell model. The cell model having isotropic/non-linear kinematic hardening behavior is subjected to fully reversed cyclic stress controlled loading. The finite element simulations are carried out cycle by cycle until the final failure of the cell model. The numbers of cycles to failure are extracted from the simulations. The stress-life curves are shown for spherical and elliptical graphite particle cell models. The results of the micromechanical simulations are in qualitative agreement with the typical experimental stress-life curves.
Fatigue behaviour of selected materials under multiaxial asynchronous loadings
Authors: Pejkowski Łukasz , Skibicki Dariusz , Seyda Jan
Published: December 2019

Four types of materials: PA38 aluminium alloy, E235 steel, E355 steel and 1.4301 austenitic steel were subjected to low-cycle multiaxial loadings. All tests were strain-controlled and typical, thin-walled, hollow specimens were used. Various synchronous and asynchronous loadings were applied. The analysis of experimental results involved: cyclic stress-strain response, fatigue life and observation of microcracks behaviour on the surfaces of fatigued specimens. Obtained results indicate that the difference in the strain components frequency of the asynchronous loadings has a significant influence on the fatigue behaviour of the materials.
Determination of critical plane and assessment of fatigue durability for multiaxial cyclic loading and arbitrary shift of phases
Authors: Stratula Boris A. , Burago Nikolai G. , Nikitin Alexander D. , Nikitin Ilia S.
Published: December 2019

An analytical solution for the well-known fatigue criterion proposed by Papadopoulos was obtained. An arbitrary shift of phases was taken into account. Comparison between analytical, numerical solutions with experimental data was made. Computation results based on FEM were compared with assessments by the mentioned above criterion.
Interaction Between Normal and Shear Stresses and Its Effect on Multiaxial Fatigue Behavior
Authors: Sharifimehr Shahriar , Fatemi Ali
Published: December 2019

Interaction between normal and shear stresses plays an important role in multiaxial fatigue damage. The aim of this study was to investigate this interaction effect on fatigue behavior of shear failure mode materials under multiaxial loading conditions. In order to model the influence of normal stress on fatigue damage, the present study introduces a method based on the idea that the normal stress acting on the critical plane orientation causes two types of influence, first by affecting roughness induced closure, and second, by a fluctuating normal stress affecting the growth of small cracks in mode II. The summation of these terms could then be used in shear-based critical plane damage models, for example FS damage model, which use normal stress as a secondary input. In order to investigate the effect of the method, constant amplitude load paths with different levels of interaction between the normal and shear stresses were designed for an experimental program. The proposed method was observed to result in improved fatigue life estimations where significant interactions between normal and shear stresses exist.
Mean shear stress effect built into the multiaxial fatigue strength estimation method of an integral type
Authors: Papuga Jan , Suchý Lukáš , Růžička Milan
Published: December 2019

The effect of mean shear stress is implemented into the PIR criterion [1-2]. Results of the new solution are only slightly worse than the similarly improved PCN criterion described in [3]. Five methods of the integral type known to the author (PIR + new PIN, the Fogue method, the Liu & Zenner method, the Papadopoulos method) are evaluated here on a large set of experimental data (286 items). Because the integral solution is easier to handle, the simplified reduced formulas of each criterion for the case of purely axial loading are presented. Their relations each to other, and also to other common uniaxial mean stress effect methods are then studied and small numerical benchmark convening this load condition is prepared.
A fast algorithm to racetrack filter multiaxial histories preserving load shape
Authors: Meggiolaro Marco Antonio , Pinho de Castro Jaime Tupiassú , Wu Hao
Published: December 2019

A fast algorithm is presented to implement a multiaxial version of the racetrack amplitude filter, improved upon the authors’ previous works. The algorithm only requires a single user-defined scalar filter amplitude to eliminate noise and potentially non-damaging events from arbitrary non-proportional multiaxial stress or strain histories, while preserving all key features of the load path. It can be applied as a pre-processing step to both invariant-based and critical-plane multiaxial damage models, highly decreasing the computational cost in assessments involving oversampled or noisy data, much improving the usefulness of computationally-intensive multiaxial models. Since load path shape is well preserved (within the chosen filter resolution), peaks and valleys from subsequent candidate plane projections are not filtered out. Moreover, path-equivalent stress or strain calculations can still be applied after the filtering process, without precision loss beyond the filter resolution. The algorithm is synchronous and preserves load order, becoming suitable for strain-based multiaxial damage models involving plastic memory, as well as for mixed-mode crack propagation calculations. The filter efficiency is validated from oversampled tension-torsion experimental data in 316L stainless steel tubular specimens, following complex non-proportional histories. Finally, a fully-tested computer implementation of the algorithm is presented.
Establishment of damage estimation rule for brittle fracture after cyclic plastic prestrain in steel
Authors: Kosuge Hiroaki , Kawabata Tomoya , Okita Taira , Murayama Hideaki , Takagi Shunsuke
Published: December 2019

Material damage caused by complicated prestrain like cyclic prestrain and various direction prestrain. It is so important to understand the mechanism of material damage for high-precision lifetime evaluation of steel structure. Material damage depends on not only equivalent plastic strain but the order of pestrain loaded. Also, material damage can be expressed by effective damage strain from back stress uploading and total dislocation density calculated from conventional mechanism based on strain gradient plasticity (CMSGP). These ideas can be extended to multiaxial problems and material damage can be estimated by these parameters as well as uniaxial problems.
Crack growth and microstructural changes in AISI 52100: white etching cracks (WEC) and fine granular area (FGA)
Authors: Averbeck Stefan , Spriestersbach Daniel , Kerscher Eberhard
Published: December 2019

The service life of rolling element bearings can usually be predicted with good accuracy. However, the damage phenomenon „white etching cracks” (WEC) can lead to premature and unforeseeable failures. The formation of zones with strongly decreased grain sizes at the crack faces is a characteristic of this type of failure. An earlier study showed that it is possible to reproduce this type of failure by multiaxial fatigue experiments with superposed cyclic compression and torsion. The present study shows the analysis of the stress state of those multiaxial fatigue tests with stress-based critical plane criteria. Using the critical plane results as a basis for a fracture mechanical analysis, a correlation is found between the crack length, the associated plastic zone size, and the extent of the transformed microstructure. This correlation is very similar to our results of the study of fine granular areas (FGA), a very high cycle fatigue phenomenon in bearing steels. It is argued that a plasticity-driven mechanism similar to the one proposed for FGA formation is responsible for WEC formation, too. Additional factors that are often cited as promoting WEC formation could explain the shift from very high cycle fatigue in the case of FGA to the early failures due to WEC.
Ultrasonic fatigue experiments with biaxial cruciform specimens
Authors: da Costa Pedro R. , Montalvão Diogo , Freitas Manuel , Reis Luis
Published: December 2019

Fatigue studies of materials in simple or complex loading systems for any given lifetime is object of continuous research. This is due to the advancements on mechanical and structural components, as well as for new and innovative materials, which implies the knowledge of a materials response to all dynamic loads. The fatigue failure regime beyond what was once considered to be the fatigue limit (infinite life) is characterized between 107 and 109, known as Very High Cycle Fatigue regime. Due to the time consuming and wide energy consumption of conventional fatigue testing for such regime, fatigue tests under ultrasonic actuators are being used, capable of applying the dynamic loads at around 20 kHz. Nowadays, several variants of ultrasonic fatigue tests were already proposed and tested but it is still a somewhat limited fatigue test if compared to the conventional servo-hydraulic fatigue testing machines of general use. In this study, biaxial in plane stresses are induced in specially designed cruciform specimens with ultrasonic fatigue testing resonant principals. Two geometries were numerically analysed, manufactured and experimentally tested, the in-phase tension-tension (T-T) specimen and the out-of-phase compression-tension (C-T) specimen. All specific designed geometries go under a thorough numerical and several experiments analysis for their validation. The specimens showing a correct and as intended behaviour are led to failure.
Clinical risk evaluation of medical device software: an axiomatic design-based methodology
Authors: Rolli Fernando , Pecoraro Fabrizio , Luzi Daniela , Ricci Fabrizio L. , Pourabbas Elaheh , Parretti Chiara
Published: December 2019

The increasing complexity of medical device (MD) management software requires the adoption of new methodological approaches that pay particular attention to safety issues. The risk analysis is one of the key activities to be carried out by the manufacturer before the development of the software application as it determines the type of documentation to be provided as well as the activities to be performed to place the MD on the market. After the definition of software requirements and their iterative transformation into architectural items and/or units, the manufacturer defines the safety class of each item. The adoption of an axiomatic design approach facilitates this process. This combination of techniques helps to focus the design of medical device software on non-conformities with a clear link to clinical risk. This objective can be achieved by assessing the complexity of the system to be designed, both in terms of its functional size, and as a level of overall clinical risk. In this multi-dimensional perspective, the software effort expressed in function points provides an estimate of the development cost. While the clinical risk analysis allows to quickly identify critical areas, to intervene with the same promptness and to draft a management plan according to the regulations of the various control authorities.
Generic Production System Model of Personalized Production
Authors: Foith-Förster Petra , Bauernhansl Thomas
Published: December 2019

Manufacturing companies are operating in a turbulent business ecosystem that calls for product variety, product mix flexibility, volume scalability and high efficiency. Personalized production arises as new production paradigm to replace mass personalization. The paper proposes a generic model for the design of production systems for the paradigm of personalized production. The model applies the system design methodology Axiomatic Design and uses the notation of Axiomatic Design Theory for Systems combined with the product precedence graph for product structure modeling. The model represents the static system structure, decomposed into its subsystems, and explains the dynamic behavior of the system during operation, depending on the product’s architecture. It is intended as a reference model for production system planning.
Chancen und Risiken von Metaproteomik in der Mikrobiomforschung
Authors: Haange Sven-Bastiaan , Jehmlich Nico , Jacobi Thomas , Bergen Martin von
Published: December 2019

Die Erforschung des menschlichen Darmmikrobioms in den letzten 15 Jahren führte zu neuen Erkenntnissen wodurch Korrelationen und sogar Kausalitäten vieler Erkrankungen mit der Veränderungen der Mikrobiota beschrieben werden konnten. Wegbereitend für die Analyse der Mikrobiota von in vivo Proben war dabei die Entwicklung der sogenannten Meta-omics Methoden, insbesondere die 16 S rRNA Gensequenzierung und die Metagenomik. Jedoch hat die taxonomische Zusammensetzung der Darmmikrobiota aufgrund der hohen funktionellen Redundanz und Vielfältigkeit des Stoffwechselpotentials einzelner Bakterienarten nur geringe Vorhersagekraft bezüglich ihrer tatsächlichen Funktionalität. Aus diesem Grund wurden metaproteomische und metabolische Markierungsmethoden mit stabilen Isotopen (Protein-SIP) entwickelt. Wenn man die Gesamtanzahl der Proteine einer mikrobiellen Gemeinschaft betrachtet, können somit Informationen zur taxonomischen Verteilung, metabolischer Funktion, metabolischer Aktivität sowie für die Funktion der Mikrobiota Schlüsselarten identifiziert werden.

Der Fokus des Artikels liegt auf der Methode Metaproteomik sowie der proteinbasierten Stabil-Isotopen-Markierung (Protein-SIP), weil diese Ansätze funktionelle und taxonomische Ergebnisse vereinen. Zusätzlich werden Chancen aber auch Risiken betrachtet, mit denen die Methoden naturgemäß einhergehen.
Fäkaler Mikrobiom-Transfer (FMT) – eine Übersicht
Authors: Lübbert Christoph
Published: December 2019

Die humane intestinale Mikrobiota hat wichtige metabolische und immunologische Funktionen für das Individuum und ist Bestandteil der Abwehr gegenüber pathogenen Erregern im Gastrointestinaltrakt. Antibiotika, Probiotika, diätetische Maßnahmen wie Präbiotika sowie als relativ neu etablierte Methode der fäkale Mikrobiom-Transfer (FMT, auch fäkale Mikrobiota-Transplantation) können die Zusammensetzung des intestinalen Mikrobioms beeinflussen. Als FMT wird die Übertragung von Stuhlmikroorganismen, vornehmlich Bakterien, aber auch Bakteriophagen, Pilzen und Viren eines gesunden humanen Spenders in den Gastrointestinaltrakt eines Patienten bezeichnet. Diese Maßnahme soll der Wiederherstellung einer normalen Darmmikrobiota bei Patienten mit einer Dysbiose-assoziierten Erkrankung dienen. Die bislang einzige Indikation für einen FMT ist die multipel rezidivierende Clostridioides difficile-Infektion (CDI). Über 85 % betroffener Patienten können in dieser Situation durch eine „Stuhltransplantation“ erfolgreich und dauerhaft geheilt werden. Als mögliche weitere Anwendungsgebiete werden chronisch-entzündliche und funktionelle Darmerkrankungen, nicht-alkoholisch bedingte Fettlebererkrankung, Insulinresistenz, morbide Adipositas, multiple Sklerose (MS) oder idiopathische thrombozytopenische Purpura (ITP) diskutiert. Die Evaluation in klinischen Studien ist noch unvollständig. Die Durchführung des FMT unterliegt in Deutschland dem Arzneimittelgesetz (AMG) als individuelle Heilmittelzubereitung, an deren Herstellung und Durchführung der behandelnde Arzt verantwortlich und persönlich beteiligt sein muss. Notwendig ist eine sorgfältige Spenderselektion durch genaue Anamnese, klinische Untersuchung, Blut- und Stuhluntersuchungen.
Rezidivtherapie beim Eierstockkrebs
Authors: Arnheim Katharina
Published: December 2019

Die Rezidivtherapie beim Ovarialkarzinom gelingt auch ohne Zytostatika: Die Biological-Doublette aus Niraparib und Bevacizumab bewies in einer Phase-II-Studie ihre hohe Effektivität bei guter Verträglichkeit.
Frühes kolorektales Karzinom
Authors: Krome Susanne
Published: December 2019

Während die Inzidenz und Mortalität bei älteren Patienten mit kolorektalem Karzinom (CRC) abnehmen, beobachtet man bei jüngeren Erkrankten einen Anstieg. Bislang lag eine zusammenfassende molekulare Charakterisierung der Early-Onset-Karzinome nicht vor. Die retrospektive Analyse von mehr als 36 000 Patienten zeigte auch innerhalb der Patientengruppe < 50 Jahre heterogene Ergebnisse.
ICML 2019: Asymptomatische CLL
Authors: Schmale Ine
Published: December 2019

Bisher konnte nicht nachgewiesen werden, dass Patienten mit Chronisch Lymphatischer Leukämie (CLL) in einem frühen, asymptomatischen Stadium von einer Intervention profitieren. Die Deutsche CLL-Studiengruppe untersuchte in der doppelblinden, multizentrischen Phase-III-Studie CLL12 den frühen Einsatz von Ibrutinib versus Placebo.
Lungenkarzinom
Authors: Kretzschmar Alexander
Published: December 2019

Ist die Tumormutationslast beim nicht-kleinzelligen Lungenkarzinom (NSCLC) kein Outcomemarker? Die auf dem WCLC 2019 vorgestellten Ergebnisse von 3 Studien mit den Checkpoint-Inhibitoren Pembrolizumab, Nivolumab und Ipilimumab zeigten keine Assoziation mit dem Gesamtüberleben (OS).