Search

This paper presented a finite element analysis of the effect of brazed residual stress on creep for stainless steel plate-fin structure using finite element code ABAQUS. The as-brazed residual stress distribution generated during the brazing process was obtained. Two cases, which are denoted Cases 1 and 2, were analyzed and compared to discuss the effect of as-brazed residual stress on creep. Case 1 was to carry out creep analysis just at the internal operating pressure. Case 2 was to perform the creep analysis considering the internal operating pressure in conjunction with as-brazed residual stress. The results show that due to the mechanical property mismatch between filler metal and base metal, large residual stress is generated in the brazed joint, which has a great influence on creep for stainless steel plate-fin structure. The creep strain and stress distribution of the overall plate-fin structure is obtained. The position that is most likely to fail is the fillet for the plate-fin structure at high temperature. Especially in the fillet interface, the creep strain and stress distribution are discontinuous and uncoordinated, which have great effect on creep failure. [DOI: 10.1115/1.2967807] Keywords: stainless steel plate-fin structure, brazed residual stress, creep, FEM

Multiple film cracking in the film/substrate systems is analyzed. The relationship is obtained between the fracture energy as well as the film strength and the film thickness.

The treatment of 300-mg/day isoflavones (aglycone equivalents) (172.5 mg genistein + 127.5 mg daidzein) for 2 years failed to prevent lumbar spine and total proximal femur bone mineral density (BMD) [...]

Abstract: The aim of this paper was to develop an in situ method to synthesize the TiN reinforced Ti3Al intermetallic matrix composite (IMC) coatings on Ti6Al4V alloy. The method was divided into two steps, namely depositing pure Al coating on Ti6Al4V substrate by using plasma spraying, and laser nitriding of Al coating in nitrogen atmosphere. The microstructure and mechanical properties of TiN/Ti3Al IMC coatings synthesized at different laser scanning speeds (LSSs) in laser nitriding were investigated. Results showed that the crack- and pore-free IMC coatings can be made through the proposed method. However, the morphologies of TiN dendrites and mechanical properties of coatings were strongly dependent on LSS used in nitriding. With decreasing the LSS, the amount and density of TiN phase in the coating increased, leading to the increment of microhardness and elastic modulus and the decrement of fracture toughness of coating. When the LSS was extremely high (i.e., 600mm/min), only a thin TiN/Ti3Al layer with thickness around of 100μm was formed near the coating surface. [Copyright &y& Elsevier]

Abstract: This paper uses finite element method to study the effect of Al2O3 film on thermal stresses in the bonded compliant seal (BCS) design of a planar solid oxide fuel cell. The effects of Al2O3 thickness, operating temperature, window frame thickness, foil thickness and cell length on thermal stresses have been discussed. The results show that compressive stresses are generated in Al2O3 film. A bowing deformation is generated due to the BCS design, which can trap and relax some thermal stresses. With Al2O3 thickness increase, compressive stresses in Al2O3 film and foil are decreased slightly, while tensile stresses in BNi2 and frame are increased. With operating temperature increase, compressive stress in Al2O3 is increased greatly, while the stresses in foil, BNi2 and frame are increased slightly. The bowing deformation is increased with operating temperature increase. The window frame thickness has little effect on thermal stresses and bowing deformation. With sealing foil thickness increase, thermal stresses and bowing deformation are increased. The cell length has little effect on thermal stresses, but reducing the cell length can decrease the bowing deformation. [Copyright &y& Elsevier]

Abstract: The aim of this paper was to develop an in situ method to synthesize the TiN reinforced Ti3Al intermetallic matrix composite (IMC) coatings on Ti6Al4V alloy substrate by using plasma spraying and laser nitriding. The microstructure and mechanical properties of TiN/Ti3Al IMC coatings synthesized at different nitrogen flow rates (NFRs) in laser nitriding were investigated. Results showed that the crack- and pore-free IMC coatings can be made through the proposed method. The morphology of TiN phase and mechanical properties of coatings were strongly dependent on nitrogen NFR in nitriding. The TiN phase exhibited dendrite-like and undeveloped morphology at low nitrogen NFR. At high NFR, the TiN phase showed granular-like morphology. With increasing NFR, the amount of TiN phase in the coating increased, leading to the increment of microhardness and elastic modulus and the decrement of fracture toughness of coating. [Copyright &y& Elsevier]