Advanced Materials Research Vol. 681

Abstract: The blade, made of TC11 titanium alloy, is prone to result in fatigue failure in the formidable environment in aero-engine. So a higher performance request of the material is brought forward. In this paper, laser shock peening(LSP) as a solution is applied to TC11 titanium alloy and microstructure, residual stress and microhardness with and without LSP were examined and compared via transmission electron microscope(TEM), X ray diffraction(XRD)and microhardness tester. The TEM results indicate that a great high density of dislocations are generated and evolve into the dislocation wall, sub-boundary and grain boundary. The nanocrystallites are formed and become smaller and more uniform with greater impacts. A high compressive residual stress above -540MPa is introduced with an increasing plastically affected layer with different impacts. The microhardness test result shows that LSP can obviously increase the hardness by 20 percent or so, and the affected depth increases with the impact from 600μm to 1200μm.

Abstract: Based on the vibration information, a mixed sensitivity method is presented to identify structural damage by combining the eigenvalue sensitivity with the generalized flexibility sensitivity. The sensitivity of structural generalized flexibility matrix is firstly derived by using the first frequency and the corresponding mode shape only and then the eigenvalue sensitivity together with the generalized flexibility sensitivity are combined to calculate the elemental damage parameters. The presented mixed perturbation approach is demonstrated by a numerical example concerning a simple supported beam structure. It has been shown that the proposed procedure is simple to implement and may be useful for structural damage identification.

Abstract: Finite element modeling of stabilized soils requires various data obtained from comprehensive laboratory experiments. High shear strengths and expensive test procedure of lime and cement stabilized soils almost make it impossible to attain a well describing data of stabilized materials to apply in FE models in some cases; Thus, this study has considered unconfined compressive strength as a not expensive laboratory strength test and utilized estimating functions presented recently for stabilized materials to evaluate the shear strength parameters of treated materials to be used in computer simulations. The estimated properties were applied in FE modeling to verify which estimating function is more appropriate for lime and cement treated granular soils. The study results show that at the mid-range strength of stabilized soils most of applied functions have a good compatibility with laboratory conditions but at lower or higher strengths some of functions would excel.

Abstract: The damage characteristics of the steel-Kevlar-steel structure are studied by nonlinear dynamics software. The whole destruction process of the sandwich structure is simulated. Moreover, the transmission and reflection of the shock wave in the structure are analyzed. It shows that the damage zone of the structure is just under the explosive. It is significantly different from the damage under non-contact explosion. The composite material has an effect on the spread of the shock wave, and effectively reduces the peak pressure. The sandwich structure has a good anti-impact performance. The results help to design and assess blast-resistant structures under contact explosion.

Abstract: Thermal stresses in 304 stainless steel plate-fin structure at steady condition were calculated by finite element method. A squential coupling calculation procedure was developed to obtain the temperature and thermal stress distribution. The effects of plate thickness, fin thickness and filler metal thickness on thermal stresses were discussed. The results show that the thermal stresses in plate-fin structure are complex and nonuniform. The peak thermal stresses are shown in the fillet. With the plate thickness and fin thickness increasing, the thermal stresses are increased. The peak stresses are decreased as the filler metal thickness increasing.

Abstract: This paper describes the strong, weak ion exchange resin in combined application of the principle, calculation method, and combined with the actual introduction of the combined application of the equipment and operation mode.

Abstract: The adhesive strength between the metallic sheets and the way to remove the waste are the key problems of the laminated object manufacturing (LOM) for metallic functional parts. To solve these problems, a novel resistance welding double-station LOM was presented in this paper with its basic principles and implementation approach introduced. With 302 stainless steel sheets of 0.1mm in thickness as the model material, the rapid laminated manufacturing for metallic parts was conducted. As a result the plastic rapid injection mold shows its diffusion welding effect between sheets up to complete combination and its strength is more than 600MPa. The surface of plastic product injected according to the mold reaches the standard in dimensional accuracy and surface finish. The experiment has proved that the resistance welding double-station LOM is an effective method of the direct rapid manufacturing for metal parts of high strength.

Abstract: Drawing is an important process during carbon fiber production. How to obtain the fittest drawing ratios distribute scheme is a typical multi-objective optimization problem. We propose a novel cooperative immune clonal selection algorithm (CICSA) to obtain the optimal linear density and breaking elongation ratio. The CICSA features in synergetic evolution, clonal operation and mutation operation. Compared with the immune algorithm and the genetic algorithm, it has the best performance in precision and convergence time.

Abstract: BaBi2Nb2O9/PVDF (polyvinylidene fluoride) composite ultrafiltration (UF)membranes were prepared by alloying BaBi2Nb2O9 (BBN) particles uniformly in the PVDF solution (15% polymer weight) and used a phase-inversion method. This paper studied the effect of the concentration of BBN from 0% to 5% in 0.2Mpa on pure water flux and rejection rate to Bovine serum albumin (BSA). The cross-sectional structures of composite membranes were observed by scanning electron microscopy (SEM). Moreover, XRD results revealed the crystal structure of PVDF. The experimental results showed that the BBN/PVDF composite ultrafiltration membranes were superior in separation performances than the pure PVDF membranes due to the addition of BBN.

Abstract: A heat transfer model for vaporizing in vacuum electron beam welding on magnesium alloy is developed based on the laws of heat conduction and energy conservation. The vaporizing time of the main metal elements in AZ series magnesium alloy is calculated using the model. The results show that the vaporization of Mg element will precede the Zn element under the affecting of high energy density electron beam. The vaporizing times of alloying elements are not entirely dependent on the level of the boiling point, to a certain extent, also dependent on the thermal diffusivity and are closely related to the latent heat of vaporizing and melting of the materials. The change of beam spot diameter of electron beam also greatly alters the heat transfer characteristics of electron beam heat source beam. As the strong vaporizing effect of Mg element will occur within several milliseconds, the keyhole induced by the metal elements vaporizing is formed only within several milliseconds, but also the deep penetration welding effect of vacuum electron beam welding of magnesium alloys will be obtained in a very short period of time.