The firm delocalization decision: an empirical investigation

In the current paper, the determinants of firm international relocation decision in twenty-six European countries during the period 2004-2014 are analyzed. We demonstrate, at light of three different but complementary theories that neoclassical, behavioural and institutional „push‟ factors have an impact in a firm decision-making process. Findings support that firm size, access to a global network, foreign capital, and negative internal growth in the workforce induce firm relocation. On the other hand, the degree of sunk assets has a negative effect on the probability of relocation. Delocalization decisions are also sector-dependent with low-tech manufacturing firms paying high salaries relocating abroad with a greater likelihood

Stress Intensity Factor - Simple Solution for a Complex Problem

This research explores the modeling of a cracked structure using a linear elastic finite element method (FEM) analysis with the objective of determining the stress intensity factor (SIF) for complex geometries. The analysis uses a mapping of the stress concentration area ahead of the crack tip to asymptotically determine the SIF. For model calibration, Irwin’s approximation method was used in two known crack case solutions subjected to a uniform tensile loading (Mode I – Opening) with fixed geometric dimensions. With focus on aircraft airworthiness application, two more complex geometries with irregular stress distributions were analyzed and the results were extracted for future use in crack growth simulation

Influence of Cold Expansion and Aggressive Environment on Crack Growth in AA2024-T3

This research aims to establish the effect of hole cold expansion on fatigue life of pre-cracked material under aggressive environment. A relationship between crack propagation and secondary crack initiation was established for AA2024-T3 cold worked holes subjected to cyclic loads to determine the impact on fatigue life of joints in presence of saline solution. Galvanic corrosion of a steel fastener/aluminum plate assembly was investigated assuming the presence of cracks in the aluminum plates, whose growth will be monitored in-situ with a digital microscope throughout the fatigue process. The cold expansion treatment improved the fatigue life fourfold under a corrosive environment, and 11.3 times in a clean environment when compared to a plain hole. Corrosion revealed the possibility of a location shift in critical stress intensity factor, causing growth of the critical crack happening outside of the region where benefits of cold expansion can be achieved. The benefits of cold work expansion could be applied for pre-cracked materials for an improved inspection interval, but also calls for reevaluation of inspection area to prevent secondary crack initiation that could lead to ultimate failure of the structural component

Evaluation of Strain Distortion Correction Protocol using Scanning Electron Microscopy and Digital Image Correlation

Scanning electron microscopy in combination with digital image correlation (SEM-DIC) is a useful technique for measuring strain in materials at the micro-scale. In particular, it can be used to identify micro-scale strain localizations that are the precursor to material failure. While SEM produces high resolution images of the microstructure, the images also contain a large amount of distortion that, during DIC, will result in distorted strain values that require correction. In this project, a nickel-based alloy underwent cyclic mechanical fatigue at three different high temperatures to a targeted maximum strain. Scanning electron microscopy imaging was done on a 200x150μm area sectioned into nine of the specimen before and after testing for digital image correlation, and electron backscatter diffraction (EBSD) was also used to image the grain boundaries within the sample area. Digital image correlation was done using the software Vic-2D, and corrections were done by following the protocol previously developed. The images were then stitched together and the EBSD images were overlaid the strain maps in MATLABTM. Results show that with the use of this protocol, corrected strain measurements are approximately equal to the macroscopic strain values obtained from testing, but allows for spatial strain fields relative to the microstructure. The accuracy with which this protocol is able to correct strain bias due to SEM makes it a useful tool for measuring strain value for this material, and can be used to estimate the strain values at which strain localization begin

The Effect of Pre-Thermal and -Load Conditions on IN-718 High Temperature Fatigue Life

Ni-based superalloys are largely used in the aerospace industry as critical components for turbine engines due to their excellent mechanical properties and fatigue resistance at high temperatures. A hypothesis to explain this atypical characteristic among metals is the presence of a cross-slip mechanism. Previous work on the role of thermal activation on cubic slip has shown strain accommodation in two sets of slip planes, which resembled the activation of {100} cubic slip systems along of the octahedral slip planes {111} in Ni-based superalloys under high strain and temperature, exhibiting a more homogeneous strain distribution and less strain localization. Following those previous literature evaluations of initial conditions that can potentially activate cubic-slip planes and provide the level of accommodation and strain homogenization within the grain, this paper presents some experimental procedures and results of Ni-based superalloy (IN-718) tested at 500˚C under operational loading condition, without and after being submitted to an overload and overtemperature. The experiments have shown that a pre-condition of 1% strain at 700˚C would increase the fatigue life of the IN-718 at 500˚C by four times when compared to pristine tested samples. The present results bring up the potential of improving this material fatigue performance, opening the need to further investigate the microstructure as the precondition is applied

Using High Resolution Images to Investigate Fatigue Crack Initiation of Alloys at the Microstructural Level

Microstructural features within a material dictate the material’s mechanical behavior and lead to localized strains as the sample is deformed. In order to further understand structural failure, an improved understanding of how microstructural features influence failure is necessary. Fatigue is one common mode of failure for aerospace applications, and a better understanding of the conditions of crack initiation can provide information that ultimately may increase longevity of aerospace systems. This paper investigates the hypothesis that fatigue crack initiation for a cyclically loaded sample is correlated to areas of higher localized strain. The experiment was conducted using a Ti-6Al-4V sample subjected to low amplitude fatigue ratio. For sample preparation, a titanium nanopowder solution is applied to an area of interest. The titanium particles on the sample are then imaged in an optical microscope, and the displacement of each particle is measured after loading the sample. The resultant displacement field is converted into a strain field, which will indicate locations on the sample with higher localized strains. When comparing sites of crack initiation to the strain field map, there is a tendency for cracks to initiate near locations with high localized strains. This knowledge can lead to an improved ability to predict fatigue crack initiation locations, and can also be used to improve structural designs at the microstructural level

Considerações sobre a importância da turma no desempenho dos alunos em escolas municipais

O processo de distribuição dos alunos entre as turmas de uma mesma série, conhecido como enturmação, acarreta conseqüências para o desempenho dos alunos. Neste trabalho, oferecemos evidências do efeito turma sobre o desempenho, utilizando dados de uma amostra de escolas municipais de três municípios do Estado do Rio de Janeiro. Os dados referem-se ao teste de português, aplicado a 2254 alunos da 4ª série, distribuídos em 103 turmas de 53 escolas. O escopo do trabalho é o de contribuir para um melhor entendimento do efeito turma de três maneiras. Primeiro, para verificar a importância relativa da turma no desempenho dos alunos, são comparadas as variâncias explicadas pela turma e por três grupos de variáveis: alunos, professores, e diretores. Segundo, é visto como três fatores ligados à enturmação, (idade média da turma, rodízio de professores e tamanho da turma) afetam o desempenho médio das turmas. Finalmente, tendo a turma como unidade de análise, observa-se a relação entre a desigualdade do desempenho, medida pelo seu desvio padrão, e a eficiência, medida pela média desse desempenho

Reliability prediction for structures under cyclic loads and recurring inspections

This work presents a methodology for determining the reliability of fracture control plans for structures subjected to cyclic loads. It considers the variability of the parameters involved in the problem, such as initial flaw and crack growth curve. The probability of detection (POD) curve of the field non-destructive inspection method and the condition/environment are used as important factors for structural confidence. According to classical damage tolerance analysis (DTA), inspection intervals are based on detectable crack size and crack growth rate. However, all variables have uncertainties, which makes the final result totally stochastic. The material properties, flight loads, engineering tools and even the reliability of inspection methods are subject to uncertainties which can affect significantly the final maintenance schedule. The present methodology incorporates all the uncertainties in a simulation process, such as Monte Carlo, and establishes a relationship between the reliability of the overall maintenance program and the proposed inspection interval, forming a “cascade” chart. Due to the scatter, it also defines the confidence level of the “acceptable” risk. As an example, the damage tolerance analysis (DTA) results are presented for the upper cockpit longeron splice bolt of the BAF upgraded F-5EM. In this case, two possibilities of inspection intervals were found: one that can be characterized as remote risk, with a probability of failure (integrity nonsuccess) of 1 in 10 million, per flight hour; and other as extremely improbable, with a probability of nonsuccess of 1 in 1 billion, per flight hour, according to aviation standards. These two results are compared with the classical military airplane damage tolerance requirements

Manejo da obesidade infanto-juvenil

The issue addressed here was presented at the Parallel Symposium: “Clinical management of obesity and NAFLD in children“, coordinated by: Anil Dhawan (UK) and Mary Fewtrell (UK). Here are presented some aspects highlighted in the presentation of Cristina Campoy (Granada, Spain), entitled “Nonsurgical Management of childhood obesity.