Residual stresses analysis in plasma dressed welded joints

The presence of residual stresses in a structure influences his behaviour. Fatigue strength of welded joints is significantly influenced by the presence of residual stresses, of flaws and notch sharpness at the weld toe. Plasma dressing at the weld toe is frequently used to remove flaws and to lessen the notch sharpness at the weld toe. With this re-melt, the stress field in the weld toe is also profoundly modified. The Finite Element Method (FEM) proves to be effective to simulate the stress fields generated by welding. The simplified two-dimensional models (2D) are efficient in this estimation. This paper presents a 2D finite element model to predict the residual stresses generated by Plasma dressing at the weld toe of a T-joint. The welded T-joints are made in St 52-3 steel, are obtained by covered electrode process and improved with plasma dressing. The analysis was developed with the MSC.Marc finite element code. The estimated stress field is validated with experimental stress results obtained using X-ray diffractio

Early memories of warmth and safeness and eating psychopathology: The mediating role of social safeness and body appreciation

Research on human development and functioning has highlighted the importance of early emotional and relational experiences. Particularly, an association between the absence of early positive memories and the presence of disordered eating has been evidenced by recent investigations. However, the mechanisms underlying this association remain unclear. Using a sample of 490 women, the hypothesis that early positive memories are negatively associated with disordered eating via social safeness and a positive relationship with one’s body image was tested via path analysis. The tested model explained 51% of eating psychopathology’s variance, and revealed a good adjustment to the empirical data. Additionally, social safeness and body appreciation were revealed as mediators of the impact of early warm and safe memories on disordered eating, when controlling for the effect of BMI. These findings suggest the importance of targeting social safeness and acceptance, especially when defining potentially effective programmes for the prevention of eating disorders

A finite element model using a unified formulation for the analysis of viscoelastic sandwich laminates

In this paper we present a layerwise finite element model for the analysis of sandwich laminated plates with a viscoelastic core and laminated anisotropic face layers. The stiffness and mass matrices of the element are obtained by Carrera's Unified Formulation (CUF). The dynamic problem is solved in the frequency domain with viscoelastic frequency-dependent material properties for the core. The dynamic behaviour of the model is compared with solutions found in the literature, including experimental data

Retrofitting of Welded Structures by TIG and Plasma Dressing

Due to economic and environmental constrains, the currently trend is to use the welded structures beyond their design lives. The predominant cause of in service failure of these aged structures is the fatigue of the welded joints. The use of improvement techniques in welded joints, as a repair technique, has been suggested by several authors. TIG dressing is one of the most promising of these repair techniques. However, the effectiveness of TIG remelting is closely linked to the depth of the repaired crack. The use of strain gauges can be effective to detect the presence of fatigue cracks in their initial phase of propagation, however their effectiveness in inspection programs on jobsite needs to be proven. Some TIG variants associated to recent technological innovations of fusion arc welding, are appointed to improve the penetration and the sustainability of the remelting process. In this article are presented some results of the work developed by the authors in the last years, relevant to assess the efficiency of sustainable repair, by TIG and plasma dressing, of welded structures. Relevance is given to the repair, complete or defective, of deep cracks, as well as the possible advantage of using TIG variants.info:eu-repo/semantics/publishedVersio

Simulation of crack growth in T-welded joints: residual stress field effect

In this article, a three-dimensional finite element model is used to predict the growth of cracks at the weld toe of a T-joint. The model is developed using the MSC Marc software. Fatigue life is estimated by integrating the Paris-Erdogan law and the stress intensity factors are obtained by the virtual crack closure technique. The influence of residual stresses generated by plastic deformation at the weld toe on the crack propagation speed is analyzed. The existence of residual compression stress fields causes a delay in crack growth. The obtained results are compared with the integration solutions of the Paris-Erdogan law using the stress intensity factor computed through the Mk factor proposed by Bowness and Lee, included in BS 7910 standard.info:eu-repo/semantics/publishedVersio

Experiential avoidance versus Decentering abilities: The role of different emotional processes on disordered eating

In modern Western societies, the female body is a predominantly used dimension in self and social evaluations. In fact, the perceived discrepancy between one´s current and ideal body image may act as a pathogenic phenomenon for women´s well-being. Furthermore, significant differences in the tendency to engage in disordered eating attitudes and behaviours have been verified between women sharing similar characteristics and perceptions about weight and body shape, which suggests that different emotion regulation processes may be involved in this association. This study thus aims to clarify the mediational effect of two different emotional regulation processes, experiential avoidance and decentering, on the association of weight and body shape variables and shame with disordered eating, in a sample of 760 women. The tested path model explained 44% of disordered eating attitudes and behaviours and showed an excellent model fit. Results demonstrated that Body Mass Index had a direct effect, albeit weak, on disordered eating behaviours and that body image discrepancy and shame presented indirect effects through the mechanisms of experiential avoidance and decentering. Results also revealed that experiential avoidance and decentering showed significant mediator effects on the relationship of weight and body shape and shame with disordered eating behaviors. These findings suggested that while experiential avoidance exacerbates the impact of weight and body shape and shame on disordered eating attitudes and behaviors, decentering seems to attenuate this association. Our findings appear to offer significant clinical and research implications, highlighting the importance of targeting maladaptive emotion processes through the development of decentering abilities

Compatible blends of thermoplastic starch and hydrolyzed ethylene-vinyl acetate copolymers

AbstractEthylene-vinyl acetate copolymer (EVA) with 19% of vinyl acetate and its derivatives modified by hydrolysis of 50 and 100% of the initial vinyl acetate groups were used to produce blends with thermoplastic starch (TPS) plasticized with 30wt% glycerol. The blends were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, water absorption, stress–strain mechanical tests, dynamic mechanical analysis and thermogravimetric analysis. In contrast to the blends with unmodified EVA, those made with hydrolyzed EVA were compatible, as demonstrated by the brittle fracture surface analysis and the results of thermal and mechanical tests. The mechanical characteristics and water absorption of the TPS were improved even with a small addition (2.5wt%) of hydrolyzed EVA. The glass transition temperature rose with the degree of hydrolysis of EVA by 40 and 50°, for the EVA with 50 and 100% hydrolysis, respectively. The addition of hydrolyzed EVA proved to be an interesting approach to improving TPS properties, even when very small quantities were used, such as 2.5wt%

Dilution and magnification effects on image analysis applications in activated sludge characterization

The properties of activated sludge systems can be characterized using image analysis procedures. When these systems operate with high biomass content, accurate sludge characterization requires samples to be diluted. Selection of the best image acquisition magnification is directly related to the amount of biomass screened. The aim of the present study was to survey the effects of dilution and magnification on the assessment of aggregated and filamentous bacterial content and structure using image analysis procedures. Assessments of biomass content and structure were affected by dilutions. Therefore, the correct operating dilution requires careful consideration. Moreover, the acquisition methodology comprising a 100 magnification allowed data on aggregated and filamentous biomass to be determined and smaller aggregates to be identified and characterized, without affecting the accuracy of lower magnifications regarding biomass representativeness.AGERE (Empresa de Águas, Efluentes e Resíduos de Braga – EM) and AGS(Administração e Gestão de Sistemas de Salubridade, S.A.)Fundação para a Ciência e Tecnologia (FCT