Papers by Keyword: Elastic Modulus

Abstract: Bulk metallic glasses (BMGs) are an important class of materials with unique set of properties. A bulk metallic glass with composition of (Fe_0.6Co_0.4)₇₁Nb₄Si₅B₂₀ was cast in the form of a 1 mm thick strip in a water cooled copper mold. The BMG produced was characterized for structure, thermal and mechanical properties. The X-ray diffraction performed on the as cast alloy has shown completely amorphous structure. The glass transition and crystallization peak temperatures obtained through differential scanning calorimetry scan were 542 °C and 588.4 °C, respectively. Some cast amorphous alloy sample was annealed below glass transition (450 °C for 30 mi93nutes) and others above glass transition (580 °C for 5 minutes) temperatures. Nano- indentation hardness of 13.3 GPa was obtained for as cast alloy while a hardness values of 12.8 and 15.84 GPa were measured for heat treated alloys at temperature of 450 °C and 580 °C, respectively. Increase in hardness was attributed to formation of crystals in an amorphous matrix whereas decrease in hardness was due to relaxation of quenching residual stresses. The maximum value of elastic modulus obtained through indentation was 255 GPa for 580 °C heat treated sample.

Abstract: The modulus of elasticity is an important parameter for an accurate prediction of the springback in sheet metal forming processes. With increasing plastic deformation, this modulus behaves nonlinearly and declines, which leads to an unpredictable springback behavior. The most cited reason for this nonlinearity is the dislocation movement during plastic deformation that especially occurs with multiphase steels. The present contribution investigates the nonlinear unloading behavior and the resulting decrease of the elastic modulus from a differently heat treated DP980 steel. The heat treatments set five different microstructures with martensite volume fractions in the range of 42 to 95 %. By means of the tensile test, a decline of the elastic modulus according to pre-strain was examined by evaluating the chord-modulus during unloading at different strain levels. In addition, a nano-hardness test was performed. It turned out that in all heat treatment conditions, a pronounced decrease in the modulus of elasticity up to 25% from the initial value occurred. With decreasing annealing temperature and lower martensite volume fraction, respectively, the martensite hardness increased, leading to higher hardness differences between the ferrite and the martensite phase in the microstructure. This led to an increase of strain hardening, i.e. to an increased formation of fresh mobile dislocations in the vicinity of the harder martensite phase during plastic deformation. As a result, the modulus of elasticity decreased more sharply. Thus, in the present contribution, an interplay between the martensite volume fraction and its hardness on the decrease of elastic modulus could be clearly manifested.

Abstract: This paper presents the results of the study of the effect of polymer materials compression and injection methods of molding on the physical and mechanical properties of the resulting samples. Widely used polymers such as poly-amide, thermoplastic elastomer and polyketone were taken as the objects of study. Granite composites based on polyamide were produced by PolyLab Rheomex RTW 16 twin-screw extruder, then modified with fine powders of schungite, graphite and silicon dioxide. Samples for testing in the form of double-sided blades were obtained by injection molding on a Babyplast 6/10V machine and compression molding on a Gibitre hydraulic press. Elastic-strength tests of the obtained samples were carried out on a tensile testing machine UAI-7000 M.

Abstract: Rheologic of a polymer pipe from cyclic temperature and internal pressure in one-dimensional and two-dimensional formulations is considered. The resulting equations of the finite element method allow one to calculate both single-layer and multilayer thick-walled pipes taking into account creep. In the calculation, the temperature dependences of the elastic and rheological parameters of polymer pipes were used. The effect of variable thermal conditions on the VAT of a PVC pipe is investigated. It has been established that under unsteady thermal conditions, stresses can occur significantly higher than in a stationary temperature field. This is explained by the fact that polymers have a component of deformation that is lagging in phase from stresses (highly elastic deformation).

Abstract: The thermoelastic stress, mechanical properties and defect content of bulk 4H n-type SiC crystals were investigated following adjustments to the PVT growth cell configuration that led to a 40% increase in growth rate. The resulting 150 mm wafers were compared with wafers produced from a control process in terms of wafer bow and warp, and dislocation density. Wafer shape was found to be comparable among the processes, indicating minimal impact on internal stress. Threading edge and threading screw dislocation densities increased and decreased, respectively, while basal plane dislocation densities were unaffected by the increase in growth rate. Loss of wafer planar stability was observed in certain cases. The elastic modulus was measured to be in the range of approximately 420-450 GPa for selected stable and unstable wafers, and was found to correspond to resistivity.

Abstract: From the compression test of steel fiber recycled mortar porous brick masonry, it was researched the effects of different amounts of steel fiber and recycled fine aggregate on compressive strength, failure morphology, elastic modulus, stress-strain law and Poisson's ratio performance. The test value is compared with the calculation formula of ordinary mortar porous brick given in GB 50003-2011.The test showed that the steel fiber recycled mortar porous brick masonry had better compressive strength and deformability.

Abstract: This study was conducted to assess the effect of CO₂ curing on the compressive strength of high strength pervious concrete. The factors studied to evaluate compressive strength of concrete on CO₂ curing pressure, curing time, and age of specimen at testing. Three Aggregate sizes, three CO₂ curing pressures, three CO₂ curing time, and three testing ages were used in this investigation. The research tried to produce a high strength pervious concrete and use carbon dioxide for curing to find out whether it could enhance the compressive strength. The results show that the compressive strength of the control group increases rapidly and its 90-day compressive strength closed to 60 MPa. The 1-day compressive strength has a major impact after CO₂ curing and their strength decreased by about 0% to 50% as compared to the control group. However, it is observed that there is only slight difference in relationship between modulus of elasticity and compressive strength obtained from 100 by 200mm cylinders with CO₂ curing.

Abstract: Cross laminated timber panels (CLT) are promising building structures that are actively used in the construction of buildings around the world. In Russia the construction is rarely used, despite the existing factories for their manufacturing. In regulatory documents there are no specific data on the elastic modulus for these structures. As a method for determining this calculated characteristic, a numerical experiment in the SCAD Office software package is proposed. During the experiment, panels of various thickness and different numbers of layers are considered. Based on the obtained displacements from the action of the applied load, the values of the elastic modules are determined and summarized in the table. According to the results of the calculation, graphs of dependences of the reduced elastic modules on the thicknesses and the number of layers are constructed and analyzed.

Abstract: In recent years, the growing interest in the development of 3D printing has focused more specifically on the utilization of eco-friendly, biodegradable and recycled materials. This paper presents the effect of the addition of cellulose filler on the tensile properties of filaments used in 3D printing. Cellulose-filled thermoplastic composite filaments were extruded from virgin polylactic acid (PLA), recycled acrylonitrile butadiene styrene (ABS), polystyrene (PS), and polyvinylchloride (PVC), and the effect of cellulose filler on the tensile properties of composite filaments was measured. The results revealed that the tensile properties of recycled thermoplastic filaments weakened remarkably whereas the tensile properties of the filament made of virgin PLA slightly improved. However, despite the differences in the results, it was found that cellulose-filled thermoplastic composite filaments can be produced as feedstock used in 3D printing.

Abstract: Ti-6Al-4V alloy have been used widely for biomedical application, but its elastic modulus is still higher compared with human bone. Moreover, it contains V and Al that have been reported as toxic element. In this study new beta type Ti-6Mo-6Nb-xSn (0, 4, 8 wt.%) have been developed. The aim of this study was to evaluate the Sn addition on microstructural transformation, mechanical behaviour, and corrosion resistance of Ti-6Mo-6Nb-xSn alloys. The Ti-6Mo-6Nb-xSn alloys produced by arc re-melting process and the obtain ingot were characterized using optical microscope, x-ray diffractometer, ultrasonic evaluation, Vicker’s hardness tester, and polarization test to evaluate the corrosion resistance. The result showed that Ti-6Mo-6Nb-8Sn has the lowest elastic modulus and Vicker’s hardness value. The Sn addition could suppress α phase formation. Ti-6Mo-6Nb-8Sn has lower corrosion rate compared to commercial Ti6Al4V.