Periodica Polytechnica (Budapest University of Technology and Economics)
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Limit State of Bake Hardened Stamped Interstitial-free Steel Automotive Parts Caused by Local Thickness Reduction
Get PDFCurrent trends in the complex shapes of modern automobiles lead to the need for extremely formable materials for deep drawing applications. In general Interstitial–Free (IF) steels present the solution for this purpose. In addition, the cold stamping process is influenced by a variety of input factors that must be correctly adjusted. An imperfection in one of the inputs may cause stamping defects even with deep drawing materials. Limit states may then appear in the form of cracks or unacceptable thinning in the critically stressed areas of the stamped parts. For this reason, a general focus is placed on the use of non-destructive methods and inspection of stamped parts after stamping for potential subsequent modification of the stamping process. The presented work deals with the material analyses of stamped parts made of Bake-Hardened Interstitial-Free steel, including the local thickness reduction of the material, leading to the occurrence of crack propagation. The focus of the work was placed on the critical influencing factors resulting from the limit states presented. The evaluation of the material flow and the local plastic response was carried out using a cylindrical indentation method. In addition, the SEM analyses showed the importance of the deformation capacity of the surface coating which proved to be one of the decisive parameters for the occurrence of limit states
Aerodynamic Study of Different Types of Wingtip Devices
Get PDFThe economic system of the 21st century requires technological solutions that ensure economical and sustainable passenger and freight transport, also by air. To this end, aircraft manufacturers are constantly working to make their aircraft as economical as possible.The aim of the research is to examine the effectiveness of the CFD simulation programs by conducting wind tunnel tests. This research also studies different types of wingtip devices then compares the results to determine the most effective one in terms of aerodynamical drag reduction. In the course of the research, we test wingtip devices of various designs in a self-built wind tunnel, and then compare the measured data with the results of the computer simulation
A szociológia országos szakkönyvtára új szerepben: A Szociológiai Gyűjtemény mint híd
No full textThe Sociological Collection of the Szabó Ervin Library of Budapest was founded 50 years ago, so it is worth briefly reviewing where it started and where it is now. The article first traces the history of the delegation of the special library function and then distinguishes between the concepts of function and collection. Afterwards it takes stock of the functions that the Collection has performed in the past and present. In doing so, it will be seen that, both in response to the challenges facing special libraries as a result of social change, and in response to its specific position within its own institution (special library within the public library), the Sociological Collection has charted its own role as a bridge – a decisive factor for its future plans.A Fővárosi Szabó Ervin Könyvtár Szociológiai Dokumentációs Osztályát 50 évvel ezelőtt alapították, ebből az apropóból érdemes röviden áttekinteni, hogy honnan indult és hol tart most utódja, a Szociológiai Gyűjtemény. A szakkönyvtári funkció delegálásának története, a funkció és a gyűjtemény kifejezés fogalmi elkülönítése, valamint az abból adódó következtetések levonása után a Gyűjtemény múltban és jelenben ellátott feladatait vesszük számba. Ennek során láthatóvá válik, hogy egyfelől a társadalmi átalakulásból következő, szakkönyvtárakat érő kihívásokra reagálva, másrészt a saját intézményén belüli speciális helyzetére (szakkönyvtár a közkönyvtáron belül) való válaszként a Szociológiai Gyűjtemény a maga útját a híd szerepében jelölte ki – ami meghatározó jövőbeli terveire nézve is
Investigation on Key Influencing Factors Affecting Temperature Distribution in Concrete
Get PDFConcrete is an unavoidable composite material used in buildings and structures. The behavior of concrete under the effect of fire is always critical, causing more structural damage. This research proposes experimental investigation on various factors that affect temperature distribution in concrete when exposed to fire. Water cement ratio, grade of concrete, curing period, type of admixtures, and fibers are the factors taken into consideration. The test was carried out in the temperature range of 100 °C to 600 °C. The temperature was measured at various depths of the specimen and then compared. Results from experiments show that grade of concrete, water-cement ratio, curing period and admixture type significantly influences the temperature distribution in concrete whereas contribution of fiber type is negligible. Comparison of temperature distribution at 25 mm from the bottom of specimen at 600 °C for M20 grade with 0.5 and 0.4 water cement ratio was done. It is found that temperature distribution in concrete goes higher as water cement ratio goes higher. There is an increase of 22.6% of temperature distribution for 0.5 water cement ratio than 0.4. Concrete samples which were cured for 14 days, and 28 days were tested, temperature distribution in concrete cured for 14 days is higher than that cured for 28 days. It is because of the curing time of calcium silicate hydrate (CSH) gel, and it was not fully matured and there was no moisture to finish the hydration process of cement