In ballasted track, the wheel load is transmitted to the subgrade via sleepers commonly made of impregnated wood, prestressed concrete, steel or recently developed polymer sleepers. Mentioned material types of sleepers are characterized by different elastic moduli being a key parameter in any numerical model. Hence, this paper aims to determine the elastic modulus of sleepers subjected to a laboratory four-point bending test. Traffic resembling load level of 60 kN adopted from a typical axle load distributed by the rails to the sleeper was applied in a quasistatic and cyclic loading. The samples included sleepers made of polymers complemented with wood and pre-stressed concrete. The results of this paper are based on the elastic modulus investigation. Main conclusions are focused on the sleeper’s elastic modulus under changing loading frequencies. Wood and prestressed concrete sleepers indicated mainly elastic behaviour resulting in a constant elastic modulus. However, polymer sleepers showed a loading frequency dependent elastic modulus as a result of their viscous elastic behaviour. Moreover, the conclusions of this paper involve E-modulus measurements of impregnated beech sleepers in order to describe their piece by piece elasticity variation due to their natural origin.
. S., Elefteriades, J. A. (2006). Novel measurement of relative aortic size predicts rupture of thoracic aortic aneurysms. Ann. Thorac. Surg ., 81 , 169–177. Duprey, A., Khanafer, K., Schlicht, M., Avril, S., Williams, D., Berguer, R. (2010). In vitro characterization of physiological and maximum elasticmodulus of ascending thoracic aortic aneurysm using uniaxial tensile testing. Eur. J. Vasc. Endovasc. Surg ., 39 , 700–707. Elefteriades, J. A. (2002). Natural history of thoracic aortic aneurysms: Indications for surgery, and surgical versus nonsurgical risks
The article presents a method for optimizing technological parameters utilizing the G. Taguchi procedure. Optimization algorithm of controlled variables was presented in order to obtain the greatest value of nanohardness, microhardness and elastic modulus.
References Bulytchev, N. C. Mechanika podzemnych sooruženij. (1982) Moskva : NEDRA, 270. ALDORF, J., HRUBEŠOVÁ, E., VOJTASÍK, K., ĎURIŠ, L. Alternativní výpočet tuhosti betonového ostění vyztuženého válcovými prvky. Informace Českého svazu stavebních inženýrů. ročník XV. (2009), č. 1, 27-31. ISSN 1213-4112. VOJTASÍK, K., HRUBEŠOVÁ, E., MOHYLA, M., STAŇKOVÁ, J. Determination of development of elasticmodulus value for primary steel concrete reinforcement according to cooperative-ring-exchange theory. Proc. 11th Int. Conf. Underground Construction Prague 2010
The paper presents the results of a triaxial test conducted on stiff, consolidated clays. The standard TXCIU procedure (isotropic consolidation and undrained shearing) was applied in the laboratory soil tests. The undrained elastic modulus Eu50 was determined from each test.
The Eu50 values were determined for soil samples cut out from different depths and tested under different confining pressures. There was a significant scatter of values with depth, and no relationships between Eu50 modules or other geotechnical parameters (e.g., cu) were observed.
This work presents the concept of normalization of Eu50 modulus values using modified normalization SHANSEP (Stress History And Normalized Soil Engineering Properties). This method was first proposed for estimating the value of the undrained shear strength cu normalizing the parameter relative to the in situ effective vertical stress σ′vo and loading history (overconsolidation stress σ′p and overconsolidation ratio OCR) of the soil.
The study demonstrated that the concept of normalization of soil properties can also be used for testing elastic modulus Eu50 of consolidated natural clays and normalized values of geotechnical parameters taking into account the state of stress and load history can be correlated with the value of the overburden pressure.
Calcium manganese oxide (CaMnO3) polycrystalline was synthesized by solid state reaction (SSR) and hot-press (HP) methods. The powder of CaCO3 and MnO2 were mixed by ball milling then calcined at 850°C for 10 h and hotpressing at 850 °C for 1 h to obtain the CaMnO3 samples. The crystallography of the samples was analyzed by the X-ray diffraction (XRD). The microstructures of the samples were observed by scanning electron microscope (SEM). It was found that, the sintering process influence the crystalline perfection and have a direct impact on the mechanical properties of CaMnO3 and their aging behavior. The values of the effective elastic modulus was 6 GPa and Flexural strength was 0.417 MPa of CaMnO3 were found to be in the range of corresponding values for high performance and possibility fabricated n-type thermoelectric leg.
this study investigates the fresh and mechanical performance of concrete incorporating sintered fly ash lightweight aggregates (SFLWA) both with and without steel fibers. Comparative assessments of natural aggregates with sintered fly ash aggregates were evaluated. Mix design was obtained by the IS method for M30 grade concrete, and within the natural aggregates were replaced with 20%, 40%, and 60% amounts of SFLWA. The addition of SFLWA shows an increase in the workability of the concrete. Replacement with SFLWA increases with an increase in slump value, and decreases in strength parameters. Compressive strength of 42.6 MPa was achieved with a 40% replacement of SFLWA with steel fibers. The mechanical properties such as compressive strength, split tensile strength, flexural strength, elastic modulus, and structural efficiency of SFLWAC were examined, both with and without fibers. The incorporation of fibers drastically improved the mechanical properties of the mix.
References 1. Hartwig J. Mechanism of actin rearrangements mediating platelet activation. J Cell Biol. 1992;118:1421-42. 2. Rheinlaender J, Vogel S, Seifert J, Schachtele M, Borst O, Lang F, et al. Imaging the elasticmodulus of human platelets during thrombininduced activation using scanning ion conductance microscopy. J Thromb Haemost. 2015; 113(2):305-11. 3. Parise LV, Smyth SS, Coller BS. Platelet morphology, biochemistry, and function. In: Lichtman MA, Beutler E, Kaushansky K, Kipps TJ, Seligsohn U, Prchal J, editors. Williams Hematology. 7th ed. New York
The article presents methods to determine the peat elasticity modulus based on settlement measurement of the preloaded embankment. The author proposes two methods: the first does not take into consideration the strengthening of the soil as a result of the settlement and the second includes the strengthening process of soil related to the settlement. Based on the presented methods, computer simulations were performed in the first case for the assumed embankment in order to verify the methods and in the second case for the real conditions in the area of Szczecin, Poland.