Papers by Keyword: Plastic Work

Abstract: In order to solve the problem that the mechanical properties of containers and pipelines are difficult to evaluate during service, this paper focuses on the quantitative expression of hardness and mechanical properties. Taking the X70 pipeline steel as the research object, with 12 welds of the tensile test and 192 times the hardness of indentation test, the establishment of a mathematical application suitable for engineering applications. The results shows: The hardness, indentation parameters and mechanical properties of the weld, base metal and heat affected zone did not change significantly with the pipe wall thickness, it is reasonable to test the hardness of the outer wall of the pipeline at the scene; Vickers hardness distribution can effectively explain the fracture of the specimen, hardness and plastic work was inversely proportional.

Abstract: This paper discusses the plastic deformation and fracture development of Ti-alloy under uniaxial tension. The energy dissipation and transfer characteristics in the plastic deformation and fracture processes were analyzed using acoustic emission (AE), thermal infrared (TIR) imaging, and thermocouples. Uniaxial tension tests were carried out, during which TIR images were obtained and the AE energy was observed. The mechanical characteristics of Ti-alloy with I-type cracks were analyzed based on the TIR images, AE energy, and temperature. The plastic work of the Ti-alloy specimen was found to dissipate as thermal energy rather than AE energy. Moreover, the TIR images were correlated well with the AE energy observed during the plastic deformation and fracture processes of the material.

Abstract: The present study details the results of finite element analysis (FEA) based predictions for microstructure evolution in ATI 718Plus^® alloy during the hot deformation process. A detailed description of models for static grain growth and recrystallisation is provided. The simulated average grain size is compared with those experimentally measured in aerofoil parts after forging trials. The proposed modified JMAK model has proved to be valid in the main body of the forging. The results predicted for the surface are less accurate. The recrystallised grain size on the surface is smaller than in the centre of the part which corresponds to the experimental results and reflects the main trend.

Abstract: This work is devoted to theoretical and experimental study of energy dissipation and storage processes in titanium alloys under quasistatic loading. The specimen surface temperature was measured by infrared camera FLIR SC 5000 (a spectral range of 3-5 micron). Extending previous results of the research group in Perm, we coupled the experimental investigation of temperature evolution with a statistical description of the mesodefect ensemble. It allowed us to propose a thermodynamic internal variable model of heat dissipation in metals.

Abstract: Complex hierarchical assembly and presence of large amount of organics and water content are responsible for enough amount of plasticity in bone material. Plastic properties are not only important to assess the various changes and fracture risk in bone but also for the development of better bone implants and joint replacements. The present study is focused on the post-yield behavior of cortical bone. The plastic properties of goat femoral and tibiae cortical bone were assessed and compared in terms of plastic modulus (H), tangent modulus (Et), plastic work (Wp) and plastic strain (εp) using uniaxial tensile test. Both femoral and tibiae cortical bone were found to be having similar post-yield behavior and significant stiffness loss was observed in both the bones during plastic deformation. The value of plastic modulus for femoral cortical bone was found to be 1.2 times higher as compared to the corresponding value for tibiae cortical bone. This shows higher hardening rate for femoral cortical bone. It was also observed that femoral bone requires higher energy during plastic deformation until fracture as compared to tibiae cortical bone.

Abstract: Deformation behavior of high strength steel with a tensile strength of 590 MPa under biaxial tension was investigated for a work equivalent plastic strain range of 0.002 0.16. The test material was bent and laser welded to fabricate a tubular specimen with an inner diameter of 44.6mm and wall thickness of 1.2 mm. Using a servo-controlled tension-internal pressure testing machine, many linear stress paths in the first quadrant of stress space were applied to the tubular specimens. Moreover, biaxial tensile tests using a cruciform specimen were performed to precisely measure the deformation behavior of the test material for a small strain range following initial yielding. True stress-true plastic strain curves, contours of plastic work in stress space and the directions of plastic strain rates were measured and compared with those calculated using selected yield functions. The plastic deformation behavior up to an equivalent plastic strain of 0.16 was successfully measured. The Yld2000-2d yield function most closely predicts the general work contour trends and the directions of plastic strain rates of the test material.

Abstract: A 3D thermal-mechanical coupled was established for simulation model with technique of engineering thermodynamics and theory of nonlinear finite element during H-Beam rolling. The whole process of H-Beam rolling was repeated overall, and base on the known rolling regulations. The rules of temperature distribution were obtained for intersection deformation of web and flange during H-Beam hot rolling, and 45 steel as rolling stock. The studied achievements indicated that temperature of the stock presented tendency fall down, but tendency heighten in some domain, because of the thermal conductivity, heat radiation and convection and heat generation of plastic work done. The simulation results will have guiding meaning for defining rolling regulations and precise boundary condition of temperature for H-Beam.