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The Quality Assurance of Cast and Wrought Aero Jet Engine Components Made from Ni-base Superalloys with Using of Quantitative Metallography Methods and Alloys Lifetime Prediction

Abstract

The Ni-base superalloys are used in the aircraft industry for the production of aero engine most stressed parts, turbine blades or turbine discs. Quality of aero jet engine components has a significant influence on the overall lifetime of a jet engine as itself as well as the whole airplane. From this reason a dendrite arm spacing, grain size, morphology, number and value of γ′-phase are very important structural characteristics for blade or discs lifetime prediction. The methods of quantitative metallography are very often used for evaluation of structural characteristics mentioned above. The high-temperature effect on structural characteristics and application of quantitative methods evaluation are presented in this paper. The two different groups of Ni-base alloys have been used as experimental material: cast alloys ZhS6K and IN713LC, which are used for small turbine blades production and wrought alloys EI 698VD and EI 929, which are used for turbine disc production. Selected alloys have been evaluated in the starting stage and after applied heat-treatment at 850°C for 24 hrs. This applied heat-treatment causes structural changes in all alloys groups. In cast alloy dendritic structure is degraded and gamma prime average size has grown what has a negative influence on turbine blade creep rupture life. Wrought alloys show partially grain boundary melting and grain size changed due to recrystallization what causes mechanical properties decreasing – ultimate tensile strength mainly.

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Multiaxial Fatigue Experimental Analysis of 6063-T66 Aluminum Alloy of the Base Material and the Welded Material

., Riboli, M., Spagnoli, A., 2018, Full-model multiaxial fatigue life calculations with different criteria , Procedia Engineering, 213, 126-136, DOI: 10.1016/j.proeng.20118.02.014 Uhríčik, M., Kopas, P., Palček, P., 2015, Experimental and numerical analysis of aluminium alloy fatigue lifetime under combined cyclic bending-torsion loading , 32 th International Colloquium – Advanced manufacturing and repair Technologies in vehicle industry, Svojanov, Czech republic, 45-52. Yu, Z.-Y., Zhu, S.-P., liu, Q., Liu, Y., 2017, Multiaxial fatigue damage parameter and

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Local Corrosion of AISI 304 Stainless Steel in Acidic Chloride Solution

., Oravcová, M., Palček, P., Sapieta, M., Chalupová, M., 2016. The stress detection and the fatigue lifetime of stainless steel AISI 316L during three-point bending cyclic loading. (Conference Paper) EAN 2016 - 54th International Conference on Experimental Stress Analysis. www.italinox.sk (15.03.2019). Zatkalíková, V., Markovičová, L., Belan, J., Liptáková, T., 2014. Variability of local corrosion attack morphology of AISI 316Ti stainless steel in aggressive chloride environment. Manufacturing Technology, 14, 3, 493–497.

Open access
Life Cycle of a Military Product

Abstract

Romania’s membership of the select group of states belonging to the North Atlantic Treaty Organization brings, in addition to the expected security benefits and assurances and commitments and obligations that we have to assume. The participation of politicians, militaries and Romanian experts in the decision-making within the specialized committees of the NATO structures is an extremely important element for the assertion of Romania as a security guarantor in the area, a hypostasis that was only a vision a few years ago. This role of our country must be supported by strong and powerful military capabilities, capabilities that are hard to reach for many of the countries in Eastern Europe. The economically advantageous and technologically viable solution for a period of time is to acquire advanced military technical systems that are equipped with the great economic powers of NATO, systems used and verified by these armies, revitalized and upgraded, a second life goal.

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Influence of the interface conditions on flexible pavement structures life

Abstract

This paper aims to establish the interface conditions influence on the flexible pavement structures life. The methodology consists in using the interface constitutive model available in the Alizé calculation program to calculate the stresses and strains in the flexible pavement structures.

The design criteria related to limiting fatigue cracking of asphalt layers and permanent deformations at the subgrade level from the road bed are used to estimate the flexible pavement structures lifetime.

When calculating the critical stresses and strains, most mechanical design methods of the flexible pavement structures considers that the road layers at interfaces are perfect bonded or total unbonded.

Proper modeling of the interface binding condition is an important aspect in understanding the real behaviour of in-service flexible pavement structures.

Open access
EU Refugee Crisis Impact on the European Labor Market

Abstract

The advent and increasing wave of refugees arrived through various channels in Europe last year produce anxiety both in the EU leadership and in the management and organization of European states. Assessing the impact on the local labor market, on the human resources available and on the cost of insertion on the labor market in the EU it is difficult to quantify at present as long as it is not known what will be the final number of these refugees, the level of training them, and not the least the desire for integration into the European system of life and work. Prospects for reducing the number of active population in the EU in the coming years and increasing the lifetime rate require management organizations to carry out careful studies and to analyze and find solutions to integrate the active refugees in the domestic workforce, to assess the increased level training costs and integration in the local organizational culture and, not the least, the impact on the effectiveness of performed activities.

Open access
Secular Trends in BMI and Waist Circumference and the Prevalence of Overweight and Obesity in Austrian Candidates for Conscription from 2007 To 2016

Abstract

The increase of prevalence of overweight and obesity progressed worldwide and is associated with lifetime diseases. Operational readiness of armed forces is depending on anthropometric data and physical fitness of soldiers. The aim of the study was the investigation of temporal and regional trends of BMI and waist circumference of Austrian conscripts.Data came from the Ministry of Defence of Austria. Mean of body mass (BM, kg), body mass index (BMI, kg/m2,) and waist circumference (WC, cm) across age, urbanity and regions were analysed, effect size was checked by Cohen’s d and f eta. Significance was selected at p values <0.05.Mean of BM, BMI and WC showed significant differences, effect sizes were trivial. A significant high correlation was ascertained by BM (r = 0.78 – 0.82) and BMI (r = 0.77 – 0.81) to WC in all age cohorts. Regional differences were detected in BM, BMI and WC. The results show a significant increase of BM, BMI and WC in the years 2007 to 2010 and a stabilisation during the rest of investigation period. Prevalence of overweight and obesity in young men has reached a worrying level for public health in Austrian society.

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Competence of Older Employees

., & Willis, S. L. (2010). The Seattle Longitudinal Study of adult cognitive development. ISSBD Bulletin, 1(57), 1-10. Smart, E. L., Gow, A. J., & Deary, I. J. (2014). Occupational complexity and lifetime cognitive abilities. Neurology, 83(24), 2285-2291. Sturman, M. C. (2003). Searching for the inverted U-shaped relationship between time and performance: Meta-analyses of the experience/performance, tenure/performance, and age/performance relationships. Journal of Management, 29, 609-640. Swift H. J., Lamont, R. A., & Abrams

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