Applied Mechanics and Materials Vol. 575

Abstract: Acceptable variations in the length of the valve stem, in a conventionally manufactured valve, give room to the possibility of the stem to buckle and get jammed in the guide. Salvaging such a situation is expensive and time consuming. The present paper addresses this problem by increasing the compliance of the valve stem by introducing holes in it. The desired elastic deformation along the length, however, causes transverse deformation, which needs to be minimized. The use of multiple holes helps achieve this. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 5 parameters. The optimal settings eliminate the buckling and thus make the operation of the valve stem robust against manufacturing variabilities.

Abstract: Effect of annealing temperature on microstructures and properties of warmly deformed SCRAM (Super-clean Reduced Activation Martensitic) steel on Gleeble-3500 thermo-simulation machine was investigated. The results showed that an increase in the annealing temperature can result in increasing the martensitic lath width from 0.48 um to 0.65 um and decreasing the dislocation density from 6.4×10¹⁵ m^-2 to 2.8×10¹⁵ m^-2 in SCRAM steel. The specimen exhibited high reduction of area and total elongations when the annealing temperature is up to 600 oC. The tensile fracture surface observation indicated that dimples became more uniform and deeper and cleavage fracture traces disappeared with the annealing temperature increasing. The irradiation-induced helium bubbles and hardening were observed in all the specimens after helium implantation to 1e + 17/cm² at 450 oC. The helium bubbles became larger but less when the annealing temperature increased. The optimal annealing temperature is 450 oC in this experiment.

Abstract: The two-phase closed thermosyphon (TPCT), which is essentially a gravity-assisted wickless heat pipe, utilizes the evaporation and condensation of the working fluid inside the TPCT to transport heat. This experimental study was carried out to understand the thermal performance of circular finned thermosyphon using nanofluid with alcohol and was analyzed, compared with alcohol and base fluid DI water. The concentration of nanoparticle used in this setup was 110mg/lit of TiO₂ combined with 0.2 ml of ethylene glycol. The heat input (Q) were 10W, 12W, 14 W and 16 W and the orientation 30°, 45°, 60° and 90°.The results demonstrate that TiO₂ nanofluid with 0.2 ml of ethylene glycol improves the performance through reduction in thermal resistance by 85.86%.

Abstract: The problem of variable cross-section beam carrying a moving heavy load is investigated. UG software is used to build a three-dimensional model of the beam. The finite difference method and finite element method are used static analysis for the variable cross-section beam carrying a moving heavy load. The static deformation of the beam guide surface is obtained. Comparing the data of the two method, the feasibility of the method is verified. This paper give a guide surface load curve research method of variable cross-section beam carrying a moving heavy load.

Abstract: The millimeter-wave terminal guidance ammunition monitoring scanning field is small. The modified design is in order to improve the search section trajectory guidance. This study established seeker search area to capture the target model, which leads to the missile engine unpowered glide distance formula after flameout. At the millimeter-wave terminal on the missiles contraction section ballistic. Each missile is designed for the flat road, the swash decline ballistic programs. Flat missile road program scans and does not shrink. Its flight speed falls and declines rapidly, has different gliding distance and terminal velocity. After the missile engine is flameout, its start-gliding speed is great. Ramp fell ballistic program enhances the air-air (or air-ground) guided missile’s gliding ability, helping to improve range. But shortcomings are that target tracking scanning domain contracts. Using the seeker optical axis in the pitch direction can achieve accurate positioning with the height precession. Two ballistic designs can both meet the target seeker’s scanning, thus effectively improve the striking precision.

Abstract: Application of the evolutionary structural optimization (ESO) approach for structural acoustic optimization is investigated. Combining the sizing optimization, a more appropriate rejection criterion for ESO was put forward. There is a trial of applying modified evolutionary structural optimization (MESO) method in dynamic response problem. Finally, the topology optimization of plate structure under harmonic loading as example, the MESO approach is conducted. The numerical results show that the MESO is feasible in topology optimization analysis; and it expands the application of traditional ESO theory.

Abstract: According to broken edges and cracks emerging in traditionally machining cemented carbides (CP1) materials, this paper carried out some experimental researches on high and ultra-high grinding process for these materials, and considered the effect of process parameters on grinding forces, surface roughness, surface quality; discusses the calculation of the single grinding average normals force and relationship with maximum undeformed chip thickness and theoretical critical normal loads; probes the removal mechanisms of cemented carbide in high/ultra-high grinding process.

Abstract: Labyrinth seals are widely used in rotating fluid machinery, due to its simplicity, low-cost and reliability. In this paper, the effect of cavities on leakage loss in straight-through labyrinth seals are studied by changing gas condensability. The fluid flow characteristics through straight-through labyrinth seals are obtained by using viscous flow analysis along with a RNG k-ε turbulence model. The numerical calculation and various gas pressure is that leakage of compressible gas is greater than that of incompressible gas. The result is investigated by the heating effect of labyrinth seal and density characteristics of compressible gas.

Abstract: Focus on the problem that traditional aircraft design thought can’t meet the security and economy requirement of modern aircraft, studying the optimum design method based on damage tolerance for overall beam. For example with aircraft overall beam, constructed the optimization model based on support vector machine agent model with the lightest weight of the structure as the optimization objective, the minimum residual strength value as the constraint, section parameters as the design variables, through mathematical programming, get the optimization results under different residual strength requirement value, and calculate the crack growth life.

Abstract: Turbine cascade aerodynamic losses are heavily related to incidence. Conventional researches have been focused on a single blade row upon the convention that the whole turbine cascade has a universal incidence for all blades on the cascade and accordingly the overall aerodynamic loss of the cascade is the same as a single blade row. However, there are exceptional situations in engineering practice that each blade of a turbine cascade has a different incidence. When a turbine disk is inclined to its design position due to manufacturing errors and/or operating malfunctions, the incidence for a blade on the cascade varies along the circumference of the turbine disk. For such case, the conventional research conclusions are no longer adequate. The present paper is motivated to extend the conventional researches to account for such case. Based on the-state-of-the-art works in this field, new sophisticated correlations for turbine cascade aerodynamic losses were developed to cope with the problems with turbine disk inclination. Numerical simulations were performed to examine the effects of turbine disk inclination on the aerodynamic losses. Beneficial conclusions and remarks are given in the end.