Papers by Keyword: Strain

Abstract: Virtual NC lathe machining simulation system is carried out with Visual C++ and Open Inventor software. The system possesses visible UI, interactive inputting workpiece and machining parameters, the integration of geometric simulation and physical simulation, all the simulation functions including real-time display machining process, tool moving, workpiece geometry shape change, the generation and movement of iron simulation, workpiece pressure shape change could be realized. Tool temperature analysis and stress & strain analysis are simulated in the cutting process by FEM. The simulation results show the high efficiency of the simulation algorithm, reasonable simulation results, lifelike. The practice and training could be replaced by the virtual one. The system is applied to verification of NC code, quality evaluation of machine operators, operators, CNC programming staff training and other functions.

Abstract: As the action mechanisms of various factors affecting concrete durability are different, it is difficult to understand the durability of concrete exposed to multiple factors using only mechanism analysis. Converting each action mechanism to an appropriate macroscopic mechanical effect can simplify complicated durability problems. Here we study concrete beams exposed to common environmental factors: cyclic freezing and thawing, bending stress and chloride attack. By converting each mechanism into a mechanical process and analyzing its effect on concrete, a damage model based on strain was established. Freezing-induced tensile stress is essentially a low-cycle fatigue tensile stress, as represented by a saw-tooth model. The maximum strains when the maximum freezing-induced tensile stress coupled with the four-point bending stress in every freeze-thaw cycle were measured, and found to increase with freeze-thaw cycling. Our damage model provides a new approach to predict the service life of concrete, and guidance for durability design of concrete.

Abstract: The high temperature strength of aluminum can be improved by forming thermal stable precipitates of microalloying elements such as Er, Sc and Zr. Our previous research indicates that composite addition of Er and Zr can improve the amount of precipitations, but the aging time to approach the peak hardness is relatively long. In this paper, we will focus on the deformation behavior of the Al-Er-Zr alloy during hot deformation process and the corresponding microstructure evolution. The results show that the strain can induce rapid precipitation in Al-Er-Zr alloy during hot working conditions. The mechanism of the rapid precipitation and its effect on thermomechanical processing are discussed.

Abstract: A pipe segment system has been used to estimate its inherent resilience properties for the variation of mass flow rate, inlet temperature and inlet pressure. Superheated steam is taken as the process fluid. The magnitude of the resilience decreases from 927.8 kJ/m³s to 43 kJ/m³s and 31.5 kJ/m³s for variation of mass flow rate, inlet pressure and inlet temperature respectively. In this work, a novel methodology has been described for quantification of inherent system resilience and resilience magnitude has been found to be highest (927.8 kJ/m³s) in case of variation of mass flow rate through the pipe segment system. A useful correlation T = T_a(1-e^-nL)+T_se^-nL has been formulated for estimation of process fluid temperature, T at any pipe length, L.

Abstract: The spiral shaft parts have been widely applied in machinery and equipment manufacturing industry, the paper based on DEFORM-3D, the rigid-plastic finite element model of cross wedge rolled spiral shaft parts was established. The rolling process was simulated, the strain laws were analyzed, and the characteristics of metal flow were explored. From which we can find Plate cross wedge rolled spiral shaft parts is completely feasible. The results provide the theoretic basis for precision deformation of cross wedge rolled spiral shaft parts.

Abstract: The SCRAM steel was processed by warm deformation on Gleeble-3500 thermo-simulation machine. The effect of strain on the microstructures and mechanical properties of SCRAM steel was investigated. The results show that an increase in the strain can result in refining the martensitic laths, increasing the volume fraction of precipitates and the dislocation density in SCRAM steel. The martensitic lath width decreases from 0.83 μm to 0.48 μm and the dislocation density increases from 1.3 × 10¹⁵ m^-2 to 6.4 × 10¹⁵ m^-2 in SCRAM steel. The specimen exhibits high ultimate tensile strength and yield strength but low reduction of area and total elongations when the strain (ε) is up to 0.5. The tensile fracture surface observation indicates that dimples become smaller and shallower while tear ridges drastically grow up with the strain increasing.

Abstract: In recent years, polyurea has been successfully applied as a coating material for increasing the survivability of structures and components subjected to critical impact loading conditions. It was also shown that if a polyurea coating is reinforced with ceramic particles or short glass fibers, an enhanced benefit on the overall impact resistance due to the increased dissipation properties of the material can be observed. Notwithstanding the use of polyureas as coating materials for structures protection, other applications where control and damping of vibrations is of concern would benefit from the high dissipation characteristics of the reinforced elastomer. Nevertheless, there are well known drawbacks in the use of the reinforced elastomers which can be identified in their pronounced nonlinear behavior under cyclic loads and the softening of their mechanical properties. In order to investigate such a phenomenon, in this manuscript we present an experimental investigation conducted on the effects of different volume fractions of the same filler on the response of a polyurea elastomer at varying amplitudes of the applied strain. The characterization of the materials was conducted by using a dynamic mechanical analyzer (DMA). From our preliminary results we observed that in the case of polyurea reinforced with short glass fibers, the nonlinear response of the polymer at varying strain amplitudes becomes evident for fillers volume contents of 10%. Furthermore, the nonlinearity of the response of the material due to the Payne effect seems to be associated with the complex fibers-matrix interaction rather than the disruption of the agglomeration of the fillers under load.

Abstract: In this study, an experimental investigation was conducted in order to determine the effect of different adhesive thickness (i.e., 0.1, 0.5, 0.7 and 1 mm) on strength of ductile adhesive joint. The study scope covers both experiment and analysis. In particular, two different types of material, aluminum and stainless steel as adherents were used and joined by using a specific adhesive jig. By using universal tensile machine (UTM), three-point-bending (3PB) test was conducted. To obtain the result from the experiment, continuous load is applied to the adhesive until the adhesive become fracture. The result obtained has enabled the clarification of failure behavior mechanisms and characteristics of adhesive bonding.

Abstract: Pulley strain aggravated whole-Part abrasion, affected friction and lubricates state of metal belt continuously variable transmission. Pulley strain was analyzed by analytical method and finite element analysis. The results indicate that with the increase of transmission ratio, the driver pulley compressive strain is increases after reduces for a while, and the driven pulley increase. Compressive strain dense when radius is lesser and vice versa. Two methods results are basically the same, whereby demonstrating that the model is rational and that the analysis results are reliable.

Abstract: Constrained groove pressing (CGP) is a newly developed severe plastic deformation technique for producing ultra-fine grained sheet metals. In this study, the effects of friction on tensile properties, microstructure and strain distribution of commercially pure Al sheets were investigated using experimental and numerical methods. Results show that the improvement of contact condition between the dies and sheet suspends the occurrence of micro-cracks and induces more CGP passes. A finer and more homogeneous microstructure is obtained after 6 passes with Teflon layers as lubricant. The ductility of CGP sheets experiences apparent enhancement while the strength gradually decreases. In addition, the uniformity of strain distribution falls with the increase of friction coefficient.