bluuebunny/crossref_metadata_2025 huggingface dataset:
Crack growth threshold under hold time conditions in DA Inconel 718 – A transition in the crack growth mechanism
Authors: Fessler E. , Pierret S. , Andrieu E. , Bonnand V.
Published: February 2019

Aeroengine manufacturers have to demonstrate that critical components such as turbine disks, made of DA Inconel 718, meet the certification requirements in term of fatigue crack growth. In order to be more representative of the in service loading conditions, crack growth under hold time conditions is studied. Modelling crack growth under these conditions is challenging due to the combined effect of fatigue, creep and environment. Under these conditions, established models are often conservative but the degree of conservatism can be reduced by introducing the crack growth threshold in models. Here, the emphasis is laid on the characterization of crack growth rates in the low ?K regime under hold time conditions and in particular, on the involved crack growth mechanism. Crack growth tests were carried out at high temperature (550 °C to 650 °C) under hold time conditions (up to 1200 s) in the low ?K regime using a K-decreasing procedure. Scanning electron microscopy was used to identify the fracture mode involved in the low ?K regime. EBSD analyses and BSE imaging were also carried out along the crack path for a more accurate identification of the fracture mode. A transition from intergranular to transgranular fracture was evidenced in the low ?K regime and slip bands have also been observed at the tip of an arrested crack at low ?K. Transgranular fracture and slip bands are usually observed under pure fatigue loading conditions. At low ?K, hold time cycles are believed to act as equivalent pure fatigue cycles. This change in the crack growth mechanism under hold time conditions at low ?K is discussed regarding results related to intergranular crack tip oxidation and its effect on the crack growth behaviour of Inconel 718 alloy. A concept based on an “effective oxygen partial pressure” at the crack tip is proposed to explain the transition from transgranular to intergranular fracture in the low ?K regime.
Fretting fatigue crack propagation rate under variable loading conditions
Authors: Gandiolle C. , Fouvry S.
Published: February 2019

Fretting fatigue experiments aim to represent industrial problems and most of them endure variable loading. Being able to assess lifetime of assemblies, especially for low propagation rate conditions, is essential as experimental validation is often too expensive. Both experimental and numerical approaches are proposed to follow the crack propagation rate of steel on steel cylinder/plane fretting fatigue contact submitted to variable loading conditions. An original experimental monitoring has been implemented on the fretting-fatigue test device to observe crack propagation using a potential drop technique. A calibration curve relating crack length and electrical potential was established for the studied contact. It allows direct knowledge of the crack length and crack propagation rate. It was applied to mixed load test showing crack arrest for the last loading condition. To explain this behavior, a 2-dimensional FE modeling was implemented to simulate the complexes multi-axial contact stressing. The crack propagation rate was formalized using an effective stress intensity factor amplitude ?Keff coupled with Paris law of the material. The crack arrest condition for a given loading was related to ?Keff along the expected crack path crossing the material crack arrest threshold ?K0. The failure was related to ?Keff reaching the critical stress intensity factor KIC. A good correlation with experiments was observed allowing to predict the crack arrest condition although the model tends to overestimate the final crack length extension.
Crack path in liquid metal embrittlement: experiments with steels and modeling
Authors: Auger T. , Hémery S. , Bourcier M. , Berdin C. , Martin M. , Robertson I.
Published: February 2019

We review the recent experimental clarification of the fracture path in Liquid Metal Embrittlement with austenitic and martensitic steels. Using state of the art characterization tools (Focused Ion Beam and Transmission Electron Microscopy) a clear understanding of crack path is emerging for these systems where a classical fractographic analysis fails to provide useful information. The main finding is that most of the cracking process takes place at grain boundaries, lath or mechanical twin boundaries while cleavage or plastic flow localization is rarely the observed fracture mode. Based on these experimental insights, we sketch an on-going modeling strategy for LME crack initiation and propagation at mesoscopic scale.
Implementation of a damage model in a finite element program for computation of structures under dynamic loading
Authors: Oudni Nasserdine , Bouafia Youcef
Published: February 2019

This work is a numerical simulation of nonlinear problems of the damage process and fracture of quasi-brittle materials especially concrete. In this study, we model the macroscopic behavior of concrete material, taking into account the phenomenon of damage. J. Mazars model whose principle is based on damage mechanics has been implemented in a finite element program written Fortran 90, it takes into account the dissymmetry of concrete behavior in tension and in compression, this model takes into account the cracking tensile and rupture in compression. It is a model that is commonly used for static and pseudo-static systems, but in this work, it was used in the dynamic case.
Orientation of propagating crack paths emanating from fretting-fatigue contact problems
Authors: Giner Eugenio , Díaz-Álvarez José , Marco Miguel , Miguélez Mª Henar
Published: February 2019

In this work, the orientation and propagation of cracks in fretting fatigue problems is analyzed numerically using the finite element method (FEM) and the extended finite element method (X-FEM). The analysis is performed by means of a 2D model of a complete-contact fretting problem, consisting of two square indenters pressed onto a specimen subjected to cyclic fatigue. For the simulation, we allow for crack face contact in the implementation during the corresponding parts of the fatigue cycle. The problem is highly nonlinear and non-proportional and we make use of the so-called minimum shear stress range orientation criterion, min(??), proposed by the authors in previous works. This criterion is introduced to predict the crack path in each step of the crack growth simulation. The objective of the work is to detect which is the relevant parameter affecting the crack path orientation. A parametric study of some a priori relevant magnitudes is carried out, such as normal load on the indenters, bulk load on the specimen, stress ratio and relative stiffness of the indenter and specimen materials. Contrary to previous expectations, it is shown that the relative magnitude of the applied loads has no significant effect. However, it is found that the stiffness of the indenter material with respect to the specimen material has the greatest effect. A simple explanation of this behavior is also provided.
Fatigue failure analysis of pin-loaded lugs
Authors: Boljanovic Slobodanka , Maksimovic Stevan
Published: February 2019

In the present paper, mathematical models are proposed in order to analyze the strength of pinloaded lugs with semi-elliptical crack and through-the-thickness crack. The crack growth investigation of considered crack configurations tackles the fatigue life evaluation and the crack path simulation of semi-elliptical crack. The residual strength is estimated by applying the two-parameter driving force model. The numerical and analytical approaches are employed for the stress intensity factor calculation. Experimental fatigue crack growth data are used in order to verify efficiency of the developed models. A good correlation between fatigue crack growth estimations and experimental observations is obtained.
Plasma-sprayed thermal barrier coatings: numerical study on damage localization and evolution
Authors: Slámecka K. , Skalka P. , Celko L. , Pokluda J. , Saucedo-Mora L. , Marrow T. J. , Thandavamoorthy U.
Published: February 2019

Thermal barrier coatings (TBCs) are advanced material systems used to enhance performance and in-service life of components operated at high temperatures in gas turbines and other power-generation devices. Because of complexity, numerical methods became important tools both for design of these coatings and for in-service life estimations and optimization. In this contribution, two main features that affect the TBCs’ performance, namely the roughness of the bond coat and the microstructure of the ceramic top coat, are discussed based on Finite Element Method (FEM) and Finite Element Microstructure MEshfree (FEMME) simulations that were used to calculate stresses and assess damage within the coating. Roughness data obtained from plasma-sprayed CoNiCrAlY + YSZ coated samples are supplemented to discuss assumptions and results of employed numerical models.
Multiple and non-planar crack propagation analyses in thin structures using FCPAS
Authors: Dündar H. , Ayhan A. O.
Published: February 2019

In this study, multiple and non-planar crack propagation analyses are performed using Fracture and Crack Propagation Analysis System (FCPAS). In an effort to apply and validate FCPAS procedures for multiple and non-planar crack propagation analyses, various problems are solved and the results are compared with data available in the literature. The method makes use of finite elements, specifically three-dimensional enriched elements to compute stress intensity factors (SIFs) without special meshing requirements. A fatigue crack propagation criterion, such as Paris-Erdo?an equation, is also used along with stress intensity factors to conduct the simulation. Finite element models are generated within ANSYS™ software, converted into and solved in FRAC3D program, which employs enriched crack tip elements. Having computed the SIFs for a given crack growth increment and using a growth criterion, the next incremental crack path is predicted and the fracture model is updated to reflect the non-planar crack growth. This procedure is repeated until cracks reach a desired length or when SIFs exceed the fracture toughness of the material. It is shown that FCPAS results are in good agreement with literature data in terms of SIFs, crack paths and crack growth life of the structure. Thus, accuracy and reliability of FCPAS software for multiple and non-planar crack propagation in thin structures is proven.
Fatigue life prediction of pedicle screw for spinal surgery
Authors: Major Š. , Kocour V. , Cyrus P.
Published: February 2019

This paper is dedicated to fatigue estimation of implants for spinal surgery. This article deals especially with special case of hollow pedicle screw. Implant systems utilizing specially designed spinal instrumentation are often used in these surgical procedures. The most common surgical procedure is spinal fusion, also known as spondylodesis, is a surgical technique used to join two or more vertebra. Implants are subjected to many loading cycles during their life, especially in the case of other degenerative changes in the skeleton, there are often changes in loading conditions, which often cannot be accurately determined. These changes often lead to further bending load in the thread. Hollow screws studied in this work show higher fatigue resistance than other types of implants.
Development of in-situ fatigue crack observing system for rotating bending fatigue testing machine
Authors: Lian B. , Ueno A. , Iwashita T.
Published: February 2019

To substitute for a traditional replication technique, an in-situ fatigue crack observing system for rotating bending testing machine has been newly developed. For verifying performance of this observing system, fatigue tests were carried out by using fatigue specimen having a small artificial defect. It is proved that this system can be detect a small fatigue crack and its propagation behavior.
Crack path simulation for cylindrical contact under fretting conditions
Authors: Cardoso R.A. , Araújo J.A. , Ferreira J.L.A. , Castro F.C.
Published: February 2019

In this work different strategies to estimate crack path for cylindrical contacts under fretting conditions are carried out. The main goal is to propose and to evaluate methodologies not only to estimate the direction of crack initiation but also the subsequent propagation in its earlier stages, where the stress field is multiaxial, non-proportional and decays very fast due to the proximity with the contact interface. Such complex conditions pose a substantial challenge to the modelling of crack path. The numerical simulations are provided by a 2D Finite Element Analysis taking into account interactions between the crack faces. The results show that, under fretting conditions, models based on the critical plane method are not effective to estimate the crack initiation orientation, while models based on a so called “critical direction” applied along a critical distance provide better results. Regarding the subsequent crack propagation orientation, it was possible to see that stress intensity factor based models where one considers an infinitesimal virtual crack emerging from an original preexistent crack are powerful mechanisms of crack orientation estimation
The study of a defect evolution in iron under fatigue loading in gigacyclic fatigue regime
Authors: Plekhov O. , Naimark O.
Published: February 2019

The work is devoted to the study of the damage accumulation in iron under gigacyclic fatigue (VHCF) regime. The study of the mechanical properties of the samples with different state of life time existing was carried out on the base of the acoustic resonance method. The damage accumulation (porosity of the samples) was studied by the hydrostatic weighing method. The obtained results show the accumulation of porosity in the volume of the sample during fatigue loading and corresponding decrease of the elastic properties. A statistical model of damage accumulation was proposed in order to describe the damage accumulation process. The model describes the influence of the sample surface on the location of fatigue crack initiation
Analysis of cracking of low-alloy copper stretched at elevated temperature
Authors: Ozgowicz Wojciech , Kalinowska-Ozgowicz Elzbieta , Lenik Klaudiusz , Duda Aneta
Published: February 2019

This paper presents both mechanical and structural aspects of micro-cracking of CuNi2Si copper alloy in CNCS grade revealed during the static tensile test in the temperature range between 20ºC and 800ºC. The purpose of this paper is to determine the impact of plastic deformation temperature and structural condition of the tested alloy on the type and mechanism of its cracking under specified deformation conditions. Therefore, the subject of the detailed metallographic analysis in a microscopic scale is the location of initiation and propagation of cracking, morphology of precipitations and their impact on the cracking process, nature and type of the fractures formed during material decohesion as well as microstructural analysis of the alloy by electron diffraction method. The obtained results allow the determination of the impact of analysed factors on cracking mechanism in the tested alloy as well as the specification of effective methods for limitation of the effects of cracking and thus the improvement in plasticity of alloy and workability of its products
Multi-purpose fatigue sensor. Part 1. Uniaxial and multiaxial fatigue
Authors: Karuskevich M.V. , Ignatovich S.R. , Maslak .P. , Menou A. , Maruschak P.. , Panin S.V. , Berto F.
Published: February 2019

The paper describes the key principles and results of preliminary experiments aimed at the development of new technique for the fatigue life prediction under conditions of biaxial cyclic tension. The foundations of the method were developed early by the numerous tests with monitoring the process of surface deformation relief formation, which is proved to be an indicator of accumulated fatigue damage under uniaxial fatigue. The employed phenomenon was early applied for the development of a family of uniaxial loading fatigue sensors. The formation of strain induced relief has been recently taken into consideration as a part of damage accumulation criteria under biaxial fatigue as well. The home-made testing machine has been designed to implement combined bending and torsion loading that simulates loads experienced by an aircraft wing skin. The experimental evidences on formation and evolution of the deformation relief revealed under conditions of combined loading, supports the proposed concept of biaxial fatigue sensor.
A comparison of methods for calculating notch tip strains and stresses under multiaxial loading
Authors: Lutovinov M. , erný J. , Papuga J.
Published: February 2019

Selected methods for calculating notch tip strains and stresses in elastic–plastic isotropic bodies subjected to multiaxial monotonic loading were compared. The methods use sets of equations where hypothetical notch tip elastic strains and stresses obtained from FEM calculations serve as an input. The comparison was performed within two separate groups of methods: the first group consists of the methods intended for cases of multiaxial proportional loading and the second group deals with multiaxial non-proportional loading. Originally, the precision of the methods was validated by comparison with results obtained from elastic–plastic FEM analyses. Since computer performance at the time was lower than nowadays, verification of the proposed methods on FEM models with a finer mesh was needed. Such verification was carried out and is presented in this paper. The effect of various formulations of material stress–strain curve was also evaluated.
Fatigue life assessment of a non-load carrying fillet joint considering the effects of a cyclic plasticity and weld bead shape
Authors: Tsutsumi S. , Morita K. , Fincato R. , Momii H.
Published: February 2019

Fatigue life depends strongly on irreversible contributions that accumulate during cyclic loading and unloading of structures. However, the correct identification of the loading path in terms of uniaxial or multi-axial stress states, proportional or non-proportional loading is essential because these factors can significantly alter the material response. In this study, finite element analysis was conducted to assess the fatigue crack initiation life of a non-load carrying fillet joint by considering weld bead shape and a cyclic plasticity accumulation during fatigue loading, which is a main cause of crack initiation. Cyclic plasticity behaviour including cyclic hardening and softening together was investigated with an unconventional plasticity model called the subloading surface model and extended to include both elastic boundary and cyclic damage concepts. The cyclic plasticity model can capture realistic plastic strain accumulation during high cycle fatigue under macroscopically elastic stressing conditions. KEYWORDS. Unconventional plasticity; Fatigue; Loading path; Crack initiation.
Random non-proportional fatigue tests with planar tri-axial fatigue testing machine
Authors: Inoue T. , Nagao R. , Takeda N.
Published: February 2019

Complex stresses, which occur on the mechanical surfaces of transport machinery in service, bring a drastic degradation in fatigue life. However, it is hard to reproduce such complex stress states for evaluating the fatigue life with conventional multiaxial fatigue machines. We have developed a fatigue testing machine that enables reproduction of such complex stresses. The testing machine can reproduce arbitrary in-plane stress states by applying three independent loads to the test specimen using actuators which apply loads in the 0, 45, and 90 degree directions. The reproduction was tested with complex stress data obtained from the actual operation of transport machinery. As a result, it was found that the reproduced stress corresponded to the measured stress with an error range of less than 10 %. Then, we made a comparison between measured fatigue lives under random non-proportional loading conditions and predicted fatigue lives. It was found that predicted fatigue lives with , stress on critical plane, were over a factor of 10 against measured fatigue lives. On the other hand, predicted fatigue lives with, stress in consideration of a non-proportional level evaluated by using amplitude and direction of principal stress, were within a factor of 3 against measured fatigue lives.
Not available
Authors: Not available
Published: February 2019

Not available
Fatigue assessment of steel rollers by means of the local energy
Authors: Chebat F. , Cincera M. , Razavi S.M.J. , Berto F. , Welo T.
Published: February 2019

This paper aims to analyses the fatigue behavior of steel rollers using the average strain energy density (SED) criterion. Considering the variability of the V-notch opening angle, a simple scalar quantity, i.e. the value of the strain energy density averaged in a control volume surrounding the notch tip, has been introduced to overcome the complexities in failure assessment of this component. The strain energy is obtained using close form solutions based on the relevant Notch Stress Intensity Factors (NSIF) for modes I, II and III. Referring to the conventional arc welding processes, the radius of the control volume is carefully identified with reference to conventional arc welding processes being equal to 0.28 mm for welded joints made of steel. In this paper firstly the employed methodology for the fatigue assessment is described and then the first synthesis of fatigue data by means of local SED for a specific geometry is shown.
Creep behavior of V-notched components
Authors: Gallo P. , Razavi S.M.J. , Peron M. , Torgersen J. , Berto F.
Published: February 2019

Geometrical discontinues such as notches play a significant rule in structural integrity of the components, especially when the component is subjected to very severe conditions, such as the high temperature fatigue or creep. In this paper, a generalized form of the existing notch tip creep stressstrain analysis method developed by Nuñez and Glinka, is developed and extended to a wide variety of blunt V-notches. Assuming the generalized Lazzarin-Tovo solution that allows a unified approach to the evaluation of linear elastic stress fields in the vicinity of both cracks and notches is the key in getting the extension to blunt V-notches. Numerous cases have been analysed and the stress fields obtained according to the proposed method were compared with proper finite element data, showing a very good agreement.
Cracked components under anti-plane loading: recent outcomes and future developments
Authors: Berto F.
Published: February 2019

The existence of three-dimensional effects at cracks has been known for many years, but understanding has been limited, and for some situations still is. Understanding improved when the existence of corner point singularities and their implications became known. Increasingly powerful computers made it possible to investigate three-dimensional effects numerically in detail. Despite increased understanding, three-dimensional effects are sometimes ignored in situations where they may be important. The purpose of the present investigation is to study by means of accurate 3D finite element (FE) models a coupled fracture mode generated by anti-plane loading of a straight through-the-thickness crack in linear elastic plates. An extended version of the present work has recently been published in the literature. The results obtained from the highly accurate finite element analyses have improved understanding of the behaviour of through cracked components under anti-plane loading. The influence of plate bending is increasingly important as the thickness decreases. It appears that a new field parameter, probably a singularity, is needed to describe the stresses at the free surfaces. Discussion on whether KIII tends to zero or infinity as a corner point is approached is futile because KIII is meaningless at a corner point. The intensity of the local stress and strain state through the thickness of the cracked components has been evaluated by using the strain energy density (SED) averaged over a control volume embracing the crack tip. The SED has been considered as a parameter able to control fracture in some previous contributions and can easily take into account also coupled three-dimensional effects. Calculation of the SED shows that the position of the maximum SED is independent of plate thickness. Both for thin plates and for thick ones the maximum SED is close to the lateral surface, where the maximum intensity of the coupled mode II takes place.
Analysis of longitudinal cracked two-dimensional functionally graded beams exhibiting material non-linearity
Authors: Rizov Victor
Published: February 2019

An analytical study of longitudinal fracture in two-dimensional functionally graded cantilever beam configurations is carried-out with taking into account the non-linear behavior of material. A longitudinal crack is located arbitrary along the beam cross-section height. The material is functionally graded along the width as well as along the height of beam. The external loading consists of a bending moment applied at the free end of lower crack arm. Fracture is studied in terms of the strain energy release rate by considering the beam complementary strain energy. The solution derived is verified by analyzing the longitudinal crack with the help of the J-integral. The distribution of J-integral value along the crack front is studied. The effects of crack location, material gradients and non-linear behavior of material on the fracture are elucidated. The analysis reveals that the material non-linearity has to be taken into account in fracture mechanics based safety design of structural members and components made of two-dimensional functionally graded materials.
Acoustic Emissions versus Pressure Stimulated Currents during bending of restored marble epistyles: Preliminary results
Authors: Kourkoulis Stavros K. , Dakanali Ioanna , Pasiou Ermioni D. , Stavrakas Ilias , Triantis Dimos
Published: February 2019

The efficiency of two modern sensing techniques, namely the “Acoustic Emissions” and the “Pressure Stimulated Currents” ones, when they are used as Continuous Structural Health Monitoring tools, is assessed experimentally. The protocol includes multi-point bending of an accurate copy of a fractured marble epistyle of the Parthenon’s Temple on the Acropolis of Athens, under a scale of 1:3. The integrity of the epistyle is restored with three pairs of bolted titanium bars, according to the pioneering technique developed by the scientists of the “Committee for the Conservation of the Acropolis Monuments”. The data provided by the above techniques are considered in juxtaposition to each other and also in comparison to data provided by the “Digital Image Correlation” technique. It is concluded that, at least from a qualitative point of view, the data of all three techniques are in good mutual agreement. Combined exploitation of the various sets of experimental data enlightens interesting aspects concerning the succession of failure mechanisms activated during the loading procedure, revealing the critical role of the internal interfaces characterizing the restored epistyle. Moreover it is definitely indicated that both the “Acoustic Emissions” and the “Pressure Stimulated Currents” techniques provide clear signs of upcoming failure well before macroscopically visible damages are detected at the external surface of the specimen.
Fatigue crack growth of composite patch repaired Al-alloy plates under variable amplitude loading
Authors: Seriari Fatima Zohra , Benachour Mustapha , Benguediab Mohamed
Published: February 2019

In this paper, fatigue crack growth of edge crack in 2024 T351 aluminum alloy plate repaired with bonded composite patch under constant and variable amplitude loading (VAL) was predicted. The Al-alloy plate was repaired with symmetric patch “Boron/Epoxy”. Additionally to constant amplitude loading (CAL), the effects of single overload and band overload were investigated for repaired and unrepaired Al-alloy plates. The obtained results confirm the improvement in repair performances by composite patch on fatigue lives and crack growth rates for all applied cycles (CAL and VAL) compared to unrepaired plates. A retardation effect was observed in application of single overload compared to band overload with the same stress ratio (R=0.2) for unpatched plate and characterized by instantaneous delays. However, this retardation effect is increased by the presence of the patch repair which leads to the higher fatigue life. Retardation effect was neglected for lower overload ratio (ORL>1.8). Comparison in fatigue life and crack growth rates under the same overload ratio (ORL=2.4) between repaired and unrepaired plates show the supplementary beneficial effects in combination of overloading and patch repair
Characterization of uniaxial fatigue behavior of precipitate strengthened Cu-Ni-Si alloy (SICLANIC(TM))
Authors: Saadouki B. , Elghorba M. , Pelca PH. , Sapanathan T. , Rachik M.
Published: February 2019

Fatigue tests were conducted on cylindrical bars specimens to understand the fatigue behavior of SICLANIC®. Although it displays good resistance in monotonic tension, this material weakens and shows a softening in repeated solicitation. This has been verified through a SEM observation, the Cu-Ni-Si alloy presents transgranular failure by cleavage. The MansonCoffin diagram exhibited the plastic deformation accommodation. The plastic deformation becomes periodic and decreases progressively as the cycle number increases. The approximations of Manson Coffin give fatigue parameters values which are in good agreement with the experience.
Investigation on the static and dynamic structural behaviors of a regional aircraft main landing gear by a new numerical methodology
Authors: Caputo F. , De Luca A. , Greco A. , Maietta S. , Marro A. , Apicella A.
Published: February 2019

In this paper, a new methodology supporting the design of landing gears is proposed. Generally, a preliminary step is performed with simplified FE model, usually one-dimensional, to achieve the reaction forces involving each component during all aforementioned aircraft operations. Though this approach gives a valid support to the designer, it is characterized by several problems, such as the related approximations. So, it is important, by a numerical point of view, to develop an isostatic FE model equivalent to the real one. In fact, if the landing gear is modelled as hyperstatic, the static equilibrium equations are insufficient for determining the internal forces and reactions on each sub-component; so, the modelled material properties and geometries assume an increasing importance, which gets the model too approximating. The proposed methodology consists of achieving the reaction forces by means of multibody simulations, by overcoming such problems, since each component is modelled as rigid. In this paper, also a FE model for the investigation of the structural response is proposed. Aimed to Certification by Analysis purposes, the developed multibody and the FE models have been assessed against an experimental landing gear drop test carried out by Magnaghi Aeronautica S.p.A., according to the EASA CS 25 regulations.
Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases
Authors: Tocci Marialaura , Pola Annalisa , Montesano Lorenzo , Marina La Vecchia G.
Published: February 2019

In the present paper, the influence of eutectic and intermetallic phases on cavitation resistance of Al-Si alloys was studied. In fact, Al-Si alloys are commonly used for the production of components, such as cylinders, pistons, pumps, valves and combustion chambers, which in service may incur in cavitation phenomenon. Samples of AlSi3, AlSi9 and AlSi9CuFe were characterized from the microstructural point of view. Hardness measurements were also performed. Subsequently, cavitation tests were carried out according to ASTM G32 standard and the erosion mechanism was examined by scanning electron microscope. It was found the both eutectic and intermetallic phases enhance cavitation resistance, expressed in terms of mass loss. Particularly, intermetallic particles with complex morphologies provide a positive contribution, exceeding that of other microstructural features, as grain size. The effect of T6 heat treatment was also evaluated. It was confirmed that the precipitation of fine strengthening particles in the Al matrix successfully hinders the movement of dislocations, resulting in a longer incubation stage and a lower mass loss for heat-treated samples in comparison with as-cast ones. Finally, the relationship between cavitation resistance and material hardness was investigated.
Undergraduate paramedic student experiences working in snow resort medical clinics: a non-traditional interprofessional clinical placement model
Authors: Devenish Anthony Scott , Mckay Glenn , Long Davd Nicholas , Horrocks Peter David , Smith Michael
Published: February 2019

Abstract

This study investigates the experiences of undergraduate paramedic students completing interprofessional clinical placements in snow sport injury clinics. Qualitative methods were used to investigate the experiences of participants (n=6) undertaking a non-traditional ambulance clinical placements as part of a multidisciplinary healthcare team.  Ethical approval was obtained through X University. Data were collected via one-on-one face-to-face interviews and analysed using holistic and focused coding. Results were divided into three main categories, namely pre-placement, intra-placement and post placement phases. As it was a new placement, student capabilities were not initially known by clinic staff. Nevertheless the workplace culture was inclusive and supportive, and paramedic skills were applicable in the clinic environment.  Despite the placement costs being excessive, participants viewed it as an investment in their future careers. Benefits of the placement included improved maturity levels, acquisition of professional networks, an understanding of interprofessional practice and an exposure to clinical skills not normally practiced on traditional ambulance placements. The interprofessional clinical placement appears to be a valid alternative to traditional ambulance placements. However, using this model to replace mainstream placements is problematic due to the costs involved, the limited number of spots available and the seasonal occurrence of snow sports. 
ANALISIS KEBUTUHAN UNTUK PROGRAM MULTI MEDIA INTERAKTIF SEBAGAI MEDIA PEMBELAJARAN
Authors: Waldopo Nfn
Published: February 2019

Multi media interkatif adalah sebuah program media pembelajaran yang memadukan secara serasi antara unsur suara, visual dan teks. Di samping itu program Multi media interkatif juga bisa berinteraksi dengan penggunanya. Interkasi di sini dalam arti dapat memberkan umpan balik (feed back) atas tugas-tugas yang dikerjakan ataupun pertanyaan-pertanyaan dijawab oleh penggunanya. Karena adanya ketiga unsur tersebut, program multi media dianggap sebagai media pembelajaran yang banyak memiliki kelebihan jika dibandingdengan media lainnya. Penelitian ini bertujuan untuk memperoleh informasi apakah program multi media interaktif dibutuhkan sebagai media pembelajaran. Jika dibutuhkan jenis mata pelajaran apa saja yang perlu ditunjang dengan program multi media, serta jenis format sajian yang disenangi. Populasnyai siswa, guru dan kepala sekolah SLTA, Sedangkan pengambilan sampel dilakukan secara acak (random). Dari hasil pengacakan ditetapkan 5 lokasi yang akan disurvey yaitu Padang, Balik Papan, Makassar, Semarang dan Surabaya. Dari 5 lokasi terpilih 6 SLTA yaitu SMAN 1 Solok, MAN 2 Padang, SMAN 5 Semarang, SMAN 6 Surabaya, SMAN 1 Samarinda dan SMAN 3 Makssar. Subyek penelitian adalah para siswa, guru dan Kepala Sekolah, Peneltian dilaksanakan selama 4 bulan yaitu dari bulan Mei hingga September 2005. Hasil penelitian menunjukkan bahwa Program Multi Media Interaktif dibutuhkan, terutama untuk menunjang beberapa jenis mata pelajaran tertentu di SMA/MA. Beberapa mata pelajaran yang perlu ditunjang dengan Program Multi Media Interaktif adalah: Matematika, Fisika, Biologi, Kimia, Bahasa Inggris, Sejarah, Geografi dan Akuntansi. Sedangkan format sajianyang disenangi adalah Games dan Tutorial. Sehubungan dengan temuan tersebut, maka dikemukakan beberapa saran yaitu Pustekkom secara berkelanjutan perlu mengembangkan program-program multi media interaktif untuk kegiatan pembelajaran, Dalam mengembangkan program-program multi media perlu melibatkan berbagai pakar agar program-program yang dikembangkan menarik dan dapat meningkatkan kualitas hasil pembelajaran peserta didik. Pustekkom juga perlu menyusun sistem pemanfaatannya yang terintegrasi dengan kegiatan pembelajaran di sekolah.
Complicaciones post-anestésicas y procederes de enfermería en pacientes postquirúrgicos
Authors: Noguera Jaramillo Alexander Arcesio , Chapi Chandi Mayra Maribel
Published: February 2019

El tema propuesto en esta investigación es de crucial interés a nivel local, nacional y mundial ya que cubre la imperiosa necesidad de mejorar los procederes de enfermería en el área de centro quirúrgico, ya que el personal que labora en esta área debe contar con amplios conocimientos y habilidades técnico-científicas especializadas, además deben desarrollar una amplia capacidad de juicio crítico basado en las habilidades intelectuales, científicas, humanistas con calidad y calidez pero sobre todo con responsabilidad como defensores de la salud de nuestros pacientes. El objetivo de esta investigación es determinar la existencia de complicaciones post-anestésicas en pacientes postquirúrgicos de nuestra institución, por error u omisión de algún procedimiento en el postoperatorio inmediato hasta que el paciente es dado de alta en el área quirúrgica del Hospital General Luis Gabriel Dávila (HLGD) en el periodo Marzo – septiembre 2015, Cantón Tulcán, Provincia del Carchi. Se atendió 180 pacientes en el área de recuperación postquirúrgica, la prevalencia de complicaciones en estos pacientes fue 32.8% que presentaron algún tipo de signo o síntoma relacionado como complicación. Además, se evaluaron a 18 profesionales de enfermería las cuales laboran en esta área y se tomó en cuenta el trabajo realizado en el pre y trans-operatorio para clasificar a los pacientes con algún tipo de complicación, datos que fueron analizados para determinar conclusiones en el área y que vayan acorde al problema e hipótesis planteada.
Relación entre edad ósea y edad cronológica de futbolistas de la provincia de Imbabura
Authors: Hidrobo Coello Juan Fernando
Published: February 2019

Actualmente el campeonato ecuatoriano de fútbol mantiene sus actividades entre la división mayor y divisiones formativas; sin que exista un correcto control entre las edades a las cuales los futbolistas ecuatorianos se desempeñan a nivel profesional. Esto dado por múltiples factores como son: lejanía de lugares de registros de nacimiento, partos domiciliarios, alteración de documentos. Creando desigualdades en la competición tanto en divisiones formativas como a nivel profesional. Haciendo que repetidamente en encuentros deportivos, en divisiones inferiores se noten muchos desequilibrios en la composición física de los futbolistas, que se traduce como inequidad de edades. Y que ha causado problemas y sanciones a nivel nacional e internacional por la no concordancia de las edades. La edad cronológica registrada en el Registro Civil está expuesta a muchos errores y dudas. Por lo que es necesario controlar de manera adecuada la edad biológica, la edad cronológica y la edad civil, un examen no invasivo es el carpograma que determina la edad ósea con un mínimo margen de error que servirá constantemente para valorar la maduración y desarrollo de los futbolistas.
Percepciones de las personas vinculadas a servicios de cuidados a largo plazo. Una revisión panorámica
Authors: Juanillo-Maluenda Hugo
Published: February 2019

La presente revisión panorámica examina las percepciones de los servicios de cuidados a largo plazo desde la perspectiva de distintos actores. La actual preocupación de esta temática se sustenta en el creciente envejecimiento demográfico que viven los países alrededor del mundo, ya que este incremento poblacional implica una mayor demanda de servicios de cuidados, especialmente en personas mayores. Pese a la atención que existe en torno a los servicios de cuidados a largo plazo, es escasa la evidencia que permita reconocer cómo las personas que están de alguna manera vinculadas a este tipo de servicios, perciben las prestaciones que se otorgan según la oferta de servicios que presenten los países. En consecuencia, la justificación de realizar una revisión panorámica se basa en detectar los vacíos de conocimiento en torno al tema con el propósito de continuar las líneas de investigación para cerrar estas brechas de conocimiento. La pregunta de revisión que orientó este estudio fue ¿qué se conoce en la literatura publicada acerca de las percepciones que tienen las personas mayores, personas cuidadoras, personas voluntarias, personas trabajadoras, tomadores de decisiones e investigadores sobre los servicios de cuidados a largo plazo? La revisión se dividió en seis secciones, con lo que permite sugerir que existe un conocimiento limitado de la oferta de servicios y las barreras implicadas en el acceso, además de avanzar en el estudio de las distintas variantes de financiamiento que las personas perciban que sea el más adecuado conforme a su situación, y finalmente estudiar los actores sobre-presentados en la prestación de cuidados, como es el caso de las personas voluntarias. En tal sentido, es necesario realizar más estudios que permitan establecer distintas perspectivas socio-culturales de las personas involucradas en los cuidados, independiente si pertenecen a países con políticas de cuidados ya instauradas o no.
DAWUD AL-DHAHIRI DAN ALIRAN AL-DAHIRIYAH
Authors: Tihami M. A.
Published: February 2019

Dawud al-Dhahiri dan Aliran al-Dhahiriyah
REFORMASI HUKUM DAN POSISI PERADILAN AGAMA DI INDONESIA
Authors: ARIPIN JAENAL
Published: February 2019

The Religious Court has changed in the way of the law paradigm change applied in Indonesia by applying the concept of separation of power, not distribution of power. Its status and position as the administrator of judicial power, has the independency at the moment because it is not under the executive power any longer. Its competence, has also changed with new competencies: syari'ah economy, the enactment of ancestry and adoption, and of hisab and rukyah. But the material law is not changed in either old or new competency. Because there is no change in law material, the judges perform not only as the law administrator but also as the law interpreter/ rechstvinding on law in book, law in concretto, and/or living law like in legal culture. This is meant that justice seekers will ftel the pure justice.
HUKUM HUMANITER INTERNASIONAL
Authors: Danial Danial
Published: February 2019

This pape tries to explain the difference and the similarty of the law system that regulates the war law stated both in the International humanitarian law and in the Islamic law. This article will answer two main problems. First, what are the difference and the similarity of the regulation of the war law between International humanitarian law and the Islamic law? Second, to what extent is the. implementation of both International humanitarian law and the Islamic law when the war occurs?Based on the research the writer conducted, it could be concluded that: first, the similarity of the war regulation between International humanitarian law and the Islamic law covers the regulation of the beginning and the ending of the war, the method and the means used in the war time, the regulation of the war prisoner protection, the regulation of the civil society protection. In addition, both of these laws aims at humanizing the war. Moreover, the difference between International humanitarian law and the Islamic law are that while Islamic law clearly regulates the prohibition of war, the qualifications as prerequisites of war and the principle of balance, International humanitarian law do not do it so clearly that it enables a conflict tends to be a potential for war. Hence, the principles of Islamic law are appropriate to apply in, modern war condition. Second, the use of nuclear, biological and chemical weapons, ill-treatment toward war prisoners, cruel treatment and ravishment toward civil society during wars show us that the implementation of International humanitarian law has not applied completely by the parties of lawsuit in wars. Different from the implementation of Islamic law both in the Prophet era and in caliph era, in every war, the Muslim soldiers much appreciated the human values such as a very human treatment to those who did not take part in wars, the war prisoners, even to animals.
La política como debate temático o estratégico. Framing de la campaña electoral mexicana de 2012 en la prensa digital
Authors: Muñiz Carlos
Published: February 2019

Los medios juegan un papel crucial durante las campañas electorales al transmitir información que será utilizada por los ciudadanos en su toma de decisiones. Con el objetivode detectar qué tratamiento informativo ofreció la prensa digital de las elecciones a la Presidencia deMéxico de 2012, se realizó un análisis de contenido (n = 1287) de la campaña electoral. El estudio detectó un uso predominante del encuadre de juego estratégico (strategic game frame) durante toda la campaña, en detrimento del encuadre de asunto o temático (issue frame).
Estudiar en Internet 2.0. Prácticas de jóvenes universitarios de la ciudad de Buenos Aires
Authors: Linne Joaquín
Published: February 2019

Este artículo explora las transformaciones en el estudio de jóvenes de la Universidad de Buenos Aires a partir de la masificación de Internet. La metodología consistió en una encuesta (n = 204) y 120 entrevistas. Entre los resultados, los estudiantes destacan la amplia disponibilidad de lecturas. Como aspectos negativos, señalan la dispersión ante la abundancia de opciones.
Un filosofar desde el cuerpo para la sociedad de la información
Authors: Rico Bovio Arturo
Published: February 2019

El autor examina la sociedad de la información y propone su crítica a través de la categoría de “cuerpo”, reconceptualizado como la totalidad de los aspectos físicos, biológicos, sociales y personales que somos. Incluye la noción de “cuerpos sociales” y cuestiona la era de la comunicación mediante recursos epistemológicos, ontológicos y axiológicos aplicados al estudio de la virtualidad informativa y sus alcances en el mundo actual.