Advanced Materials Research Vols. 295-297

Abstract: The tension-torsion thin walled tube specimens were used as the researching object in this paper. The method of determination to the critical plane which has the maximum normal strain and maximum shear strain was expounded. The strain state on the critical plane under non-proportional loading was analyzed, and the unified prediction model was used to calculate the fatigue life. In order to research the influence of phase difference on fatigue life under the non-proportional loading, the relation of the equivalent strain and the phase difference in different positive strain amplitude and different strain amplitude ratio were analyzed. It’s found that the dangerous phase difference which has the shortest fatigue life is in direct relation with the strain amplitude ratio. The general formula of dangerous phase difference is presented. Through the material mechanics performance and fatigue parameters of uniaxial stress state, the coefficients in the formula can be obtained and the coefficients of 15 kinds of common materials are given for practical application.

Abstract: An electrical – thermal coupled finite element model (FEM) is developed to investigate the temperature distribution during spark plasma sintering (SPS) with a pre-designed graded graphite die. The sample used in this investigation consists of five layers with different contents of Ti and TiB (45 wt % Ti, 55 wt %Ti, 65 wt % Ti, 75 wt % Ti and 85 wt % Ti). The temperature distribution in gradient Ti-TiB composites was obtained. Owing to the use of the die with changing cross section, a temperature difference of 142K in the axial direction inside the sample is achieved, while the maximum radial temperature difference is 6.2 times less than the axial one.

Abstract: A self-built broadband tunable infrared source is introduced here, and its notable merits are all-optical and high-conversion-efficiency. This infrared source contains an internal signal seed and two noncollinear optical parametric amplifiers. Based on this infrared source, we demonstrate the high harmonic generation from the different atomic and molecular gases using the different driving wavelengths. These results indicate that such system is ideally suited to be used as a tunable source for the laser processing and the physical science.

Abstract: Fiber metal laminates provide superior mechanical properties over conventional metal alloys. However, they show a very poor recyclability due to its composite nature. Unique recycling technique is developed to recycle both the glass fiber and the aluminum alloy. The process consists of a thermal delamination and an alloy refining step. In this paper, two fiber metal laminates were presented for their thermal delamination behavior and metal recyclability: Lacomet and GLARE. The results indicate that the thermal delamination is robust and energy-efficient, and the aluminum alloy has very high recovery rate and can be used in its original applications. The recovered glass fiber can be re-used in similar or non-critical applications.

Abstract: The splitting-operator method has been widely used in the numerical simulation of complex combustion system with its high computation efficiency. The main difficult encountered in the method is how to integrate the stiff chemical kinetics ordinary differential equation (ODE) efficiently and accurately in each grid node of flow field. Although several ODE software packages such as LSODE and VODE have very predominant performance in integrating stiff and non-stiff case, it couldn’t ensure the positivity of mass fraction in integrating stiff chemical kinetic ODE. A detail liquid rocket hypergolic bipropellant combination of Monomethylhydrazine (MMH)/Red Fuming Nitric Acid (RFNA) chemical mechanism consisting of 550 elementary reactions among 83 species was constituted basing on several relevant literatures firstly. And then a modified implicit iterative difference algorithm with variable time steps was developed to tackle the problem of mass fraction non-positive. The results from the integration of MMH /nitrogen tetroxide (NTO) chemical kinetic ODE indicate that the algorithm is always retain stability and positive value of mass fraction. The time step length would also be automatically adjusted at different chemical reaction time in the algorithm to keep its computational efficiency.

Abstract: Focused on the question of laser welding break of hot rolling strip steel JZZ, The causings of defect of laser welding were studied experimentally with the Trumph TLF12000 fast-flow CO₂ laser,. and the methods of avoiding the defect were porposed. The results showed that owing to the steel plate was thicker and big welding velocity, resulted in large depth/breadth ratio and high cooling velocity , the solidification crack occurred during welding process. When the method of laser welding with filling metal was used,the welding defect was avoided , the better performance index of weld as good as that of base metal is available.

Abstract: Inclusive of the consideration for Solid-Liquid double phase character of dike construction, fuzzy comprehensive judgement system model was set up on the basis of Analytic Hierarchy Process as well as Fuzzy Consistency Theorem. With normal membership of fuzzy function, dike construction safety comprehensive judgement was realized by the help of weighted theorem that had been fabricated in the foregoing contents. With indirect theorem of model discrimination, generalized multi-dimension weighted fuzzy discriminating model was set up on the basis of fuzzy comprehensive evaluation. Furthermore, dike section system safety model discrimination for representative dike section was realized and sensitivity analysis for model system was carried out.

Abstract: Notched tensile strength (NTS) of the Ti-6Al-4V (Ti-6-4) to Ti-6A16V-2Sn (Ti-6-6-2) dissimilar laser welds were determined, which had been subjected to post-weld heat treatment (PWHT) over the temperature range of 482-704°C. The results indicated for the weld with the PWHT at 482°C the fusion zone (FZ) and heat-affected zone (HAZ) showed a peak hardness, as compared with other welds at the counterpart regions, whereas, the weld with the PWHT at 704°C had the lowest hardness among the welds. In all the welds, the FZ of the weld subjected to PWHT at 482°C possessed the lowest NTS, while the as-welded and the weld with PWHT at 704°C had superior NTS to others. The presence of grain boundary α, which promoted grain boundary shear, accounted for the typical features of mainly transgranular fracture with intergranular dimples of the welds.

Abstract: Bio-remediation of urban rivers is an important issue that has aroused extensive attention both at home and abroad. The ecological anti-seepage technology of Na-bentonite is becoming the most environment-friendly technologies. The ecological anti-seepage technology is stated and its the ecological effects is analyzed based on the principles of the eco-hydraulic engineering. The ecological effects is in a word, it is that river shapes naturalized, river channel sections diversificated, reiver bed anti-seepage naturalized, surface water and underground water connected, and interfering ecosystem minimized. It is showed that the ecological anti-seepage technology of the Na-bentonite is accord with the ecological hydraulic engineering principles perfectly and is worth making more spread rapidly.

Abstract: Dry-film and zinc-phosphate (Zn-P) lubricants were compared for potential applications of dry-film lubricant in tube cold forming processes through the twist compression test. Test results showed that the coefficient of friction (m) had no significant difference between Zn-P soap lube and dry-film lube. The lube coating breakdown time is different between Zn-P soap and dry-film lube. A preliminary industrial trial with dry-film coated tube through the cold drawn over a mandrel showed that the tube surface quality is good and comparable with the Zn-P coated tubes.