Lengthwise Fracture of Two-Dimensional Functionally Graded Non-Linear Elastic Beam

Non-linear elastic analysis of lengthwise fracture in functionally graded single leg four-point bending beam configuration is performed. The material is functionally graded along the height as well as along the width of the beam. A lengthwise crack is located arbitrary along the beam height. The mechanical behaviour of beam is described by power-law stress-strain relation. The fracture is studied analytically in terms of the strain energy release rate. The solution derived is verfied by analysing the fracture with the help of the J-integral. The influences of crack location, material gradient along the height as well as along the width of beam and the nonlinear behaviour of material on the fracture are investigated. It is found that the material non-linearity has to be taken into account in fracture mechanics based safety design of functionally graded structural members and components. The analysis revealed also that the strain energy release rate can be regulated effectively by employing appropriate material gradients in functionally graded structures

Mode II Delamination Analysis of Asymmetrical Four Point Bend Layered Beams with Considering Material Non-linearity

An analytical study is performed of mode II delamination fracture in the asymmetrical Four Point Bend (FPB) beam configurations with considering non-linear material behavior. The beam mechanical behavior is described by using two non-linear constitutive models (ideally elastic-plastic model and model with power law stressstrain relation).The crack is located arbitrarily along the beam height. Fracture is analyzed by applying the Jintegral approach. By using the classical beam theory, analytical solutions of the J-integral are obtained at characteristic levels of the external load. The solutions derived are compared with the strain energy release rate. The influence of material non-linearity and crack location along the beam height on the fracture behaviour is evaluated. The J-integral solutions derived are very useful for parametric investigations, since the simple formulae obtained capture the essentials of fracture in asymmetrical FPB beams that have non-linear material behaviour

Multilayered Functionally Graded Non-linear Elastic Beams with Logarithmic Material Gradient: A Delamination Analysis

The delamination fracture in a multilayered functionally graded cantilever beam configuration that exhibits material non-linearity is analyzed in terms of the strain energy release rate. The beam under consideration has an arbitrary number of adhesively bonded horizontal layers of different thicknesses and material properties. The delamination crack is located arbitrary along the beam height. The material non-linearity is described by a stress-strain relation that involves two material properties. It is assumed that the two material properties are functionally graded in both width and thickness directions in each layer. Logarithmic laws are used to describe the variation of the material properties in the cross-sections of the layers (the material properties are distributed non-symmetrically with respect to the centroidal axes of the beam cross-section). The balance of the energy is analyzed in order to derive the strain energy release rate. The J-integral approach is applied for verification. Parametric investigations are carried-out in order to evaluate the influence of the gradients of the two material properties in both width and thickness directions of the layers on the delamintion fracture behaviour. The results obtained show that the strain energy release rate can be controlled by using appropriate material gradients in the design stage of multilayered functionally graded structural members exhibiting material non-linearity

Application of the Classical Beam Theory for Studying Lengthwise Fracture of Functionally Graded Beams

The present paper deals with analysis of lengthwise cracks in linear-elastic functionally graded beam configurations. A general approach for deriving of the strain energy release rate is developed by applying the classical beam theory. A crack located arbitrary along the beam thickness is considered, i.e. the crack arms have different thicknesses. The approach holds for beams which are functionally graded in the thickness direction (the modulus of elasticity can be distributed arbitrary along the thickness of the beam). The approach is applied to analyze the strain energy release rate for a lengthwise crack in a functionally graded cantilever beam. The beam is loaded by one concentrated force applied at the free end of the upper crack arm. An exponential law is used to describe the continuous variation of the modulus of elasticity along the beam thickness. The solution to the strain energy release rate in the cantilever beam is verified by applying the Jintegral approach. The solution is verified further by using the compliance method for deriving the strain energy release rate. The effects of crack location along the beam thickness, crack length and material gradient on the strain energy release rate in the functionally graded cantilever beam are analyzed by applying the solution derived

Applications of Two-Body Dirac Equations to the Meson Spectrum with Three versus Two Covariant Interactions, SU(3) Mixing, and Comparison to a Quasipotential Approach

In a previous paper Crater and Van Alstine applied the Two Body Dirac equations of constraint dynamics to the meson quark-antiquark bound states using a relativistic extention of the Adler-Piran potential and compared their spectral results to those from other approaches, ones which also considered meson spectroscopy as a whole and not in parts. In this paper we explore in more detail the differences and similarities in an important subset of those approaches, the quasipotential approach. In the earlier paper, the transformation properties of the quark-antiquark potentials were limited to a scalar and an electromagnetic-like four vector, with the former accounting for the confining aspects of the overall potential, and the latter the short range portion. A part of that work consisted of developing a way in which the static Adler-Piran potential was apportioned between those two different types of potentials in addition to covariantization. Here we make a change in this apportionment that leads to a substantial improvement in the resultant spectroscopy by including a time-like confining vector potential over and above the scalar confining one and the electromagnetic-like vector potential. Our fit includes 19 more mesons than the earlier results and we modify the scalar portion of the potential in such a way that allows this formalism to account for the isoscalar mesons {\eta} and {\eta}' not included in the previous work. Continuing the comparisons made in the previous paper with other approaches to meson spectroscopy we examine in this paper the quasipotential approach of Ebert, Faustov, and Galkin for a comparison with our formalism and spectral results.Comment: Revisions of earlier versio

MNEs and flexible working practices in Mauritius

We compare how far companies based in Africa, India and the 'global North' operating in Mauritius adopt high-trust flexible working practices, and how these are linked to different clusters of wider labour management practice. Using comprehensive firm-level data collected in late 2011, we find that African/Indian company practices are closer to those of indigenous firms than to those of Northern companies. The different company groups operate in quite different ways but regional MNEs operate in a similar way to indigenous companies. We therefore conclude that Rugman and Verbeke’s ‘regionalization’ theory also applies to the HR field. We further find that both a relatively strategic approach to HRM and measures to develop employer-employee interdependence are, respectively, linked directly and indirectly to flexible working incidence

Уровень глюкозы крови при поступлении у больных с острым инфарктом миокарда и без сахарного диабета: прогностическое значение

Department of Emergency and Cardiac Rhythm Disorders, Institute of Cardiology, Chisinau, Congresul III al Medicilor de Familie din Republica Moldova, 17–18 mai, 2012, Chişinău, Republica Moldova, Conferinţa Naţională „Maladii bronhoobstructive la copii”, consacrată profesorului universitar, doctor habilitat Victor Gheţeul, 27 aprilie, Chişinău, Republica MoldovaAims. Hyperglycemia (HG) is common among patients with acute myocardial infarction (AMI) and is associated with high risk of mortality and morbidity. The aim of this study was to investigate the relationship between admission plasma glucose level and AMI outcomes in patients without diabetes (DM). Materials and results. 224 consecutive AMI patients without DM were included in the study. Patients were stratified into 4 groups (Gr) defined by admission plasma glucose: Gr1 – 11 mmol/l. The mean follow-up was 26 ± 6 months. Patients with HG were older and more often female. More frequently, at admission, they presented with atypical symptoms, ventricular arrhythmias, in Killip class > 2, developed more often Q wave AMI (p < 0.05), reduced EF% (p < 0.05), progression of heart failure. HG was associated in nondiabetics with increased in-hospital morbidity and mortality (p < 0.0001). Long-term mortality didn’t differ among the groups, but survival term was lower in subjects with HG on admission. Conclusion. Hiperglycaemia on admission could identify high risk AMI patients and is associated with high risk of mortality and morbidity among subjects without diabetes.Цель исследования: изучение взаимосвязи уровня глюкозы при поступлении (УГП) и исходов острого инфаркта миокарда (ОИМ) у больных без сахарного диабета (СД). Материал и методы. В исследование включили 224 больных ОИМ без СД. В зависимости от УГП больных разделили на 4 группы: I гр. – 11,0 ммол/л. Длительность наблюдения составила 26 ± 6 месяцев. Лица с гипергликемией (ГГ) при поступлении были старше и чаще женского пола. Пациенты с повышенным УГП чаще имели атипичную клинику, явления сердечной недостаточности > 2 класса по Killip, ОИМ с зубцом Q (p < 0,05), сниженную ФВ% (p < 0,05), прогрессирование сердечной недостаточности за время госпитализации. У больных без СД с ГГ при поступлении была отмечена самая высокая внутрибольничная смертность. Смертность при длительном наблюдении не отличалась в изучаемых группах. Выводы. Гипергликемия при поступлении является маркером неблагоприятного прогноза и ассоциируется с высоким риском осложненного течения и смертельного исхода ОИМ у больных без СД

Gauging kinematical and internal symmetry groups for extended systems: the Galilean one-time and two-times harmonic oscillators

The possible external couplings of an extended non-relativistic classical system are characterized by gauging its maximal dynamical symmetry group at the center-of-mass. The Galilean one-time and two-times harmonic oscillators are exploited as models. The following remarkable results are then obtained: 1) a peculiar form of interaction of the system as a whole with the external gauge fields; 2) a modification of the dynamical part of the symmetry transformations, which is needed to take into account the alteration of the dynamics itself, induced by the {\it gauge} fields. In particular, the Yang-Mills fields associated to the internal rotations have the effect of modifying the time derivative of the internal variables in a scheme of minimal coupling (introduction of an internal covariant derivative); 3) given their dynamical effect, the Yang-Mills fields associated to the internal rotations apparently define a sort of Galilean spin connection, while the Yang-Mills fields associated to the quadrupole momentum and to the internal energy have the effect of introducing a sort of dynamically induced internal metric in the relative space.Comment: 32 pages, LaTex using the IOP preprint macro package (ioplppt.sty available at: http://www.iop.org/). The file is available at: http://www.fis.unipr.it/papers/1995.html The file is a uuencoded tar gzip file with the IOP preprint style include