Key Engineering Materials Vols. 297-300

Abstract: The double-vertical-column frame component, 8780mm high, is the key structure of Electrical Slag Founding Furnace (ESFF). Due to its structural complexity and crucial functional role in the entire equipment, the frame structure is actually the most sensitive part of cost-effective manufacturing. Properties design, in which both static and dynamic properties are analyzed in order to meet the functionality requirement, is widely believed as important as other production processes, such as requirement identification, conceptualization, DFM and so on. And its deterministic role in cost effective manufacturing has been discussed in many historical literatures. Finite Element Analysis (FEA), one of most powerful engineering tool, has long been employed in designing of the frame component aiming to reduce computational time and improve computational precision, either in presence of separated tool or as an integrated utility in CAD systems, for a long time. However seamless integration FEM into Computer-Aided-Design is still a challenging topic and one of the bottlenecks of cost-effective design recognized by scientists in the past. Based on a 3D solid model created with the CAD-system-compatible software SolidWorks, Finite Element Analysis (FEA) of the Furnace frame structure was carried out, which provided easily utilized data for the successive manufacturing processes as well as near-instantaneous feedbacks to designing process.

Abstract: Degradation of the gas turbine hot-gas-path components, the 1st stage blades and vanes, serviced for a period was evaluated by measuring the mechanical properties. For this, tensile and impact tests on these gas turbine parts were performed. Microstructure of the substrate and coating layers were also observed. The mechanical properties of the serviced blades were degraded by about 30% comparing with those of unused ones. In terms of the microstructure, the dissolution of the secondary g’ phase and subsequent coarsening of precipitates were observed in the substrate. And the interdiffusion zone near the coating layer was disappeared.

Abstract: To predict the creep-rupture life of type 316LN stainless steels which are major structural components of liquid metal reactors, a number of creep-rupture data were collected through literature survey and experimental data of KAERI. Using the data, the creep-rupture life was analyzed by means of the Larson-Miller, the Orr-Sherby-Dorn and the Manson-Haferd parametric methods. Polynomial equations for predicting the creep life were obtained. In order to analyze the acceptance and use of the parametric methods, standard error values were accurately investigated by statistical process of the creep data. As for the results, the three parametric methods are found to be favorable in predicting the creep life of type 316LN stainless steel. Each method did not generate a large error in the standard error of the estimate with variations of the temperatures, but the Orr-Sherby-Dorn and the Manson-Haferd methods showed a better agreement than the Larson-Miller one. Especially, at higher the 700oC, the Manson-Haferd method conformed well to the experimental data. The reason is because the Manson-Haferd method includes two constants of ta and Ta.

Abstract: Assessment of the integrity of structures such as reactor pressure vessels is a critical issue in relevant industries. In a full integrity assessment, the presence of initial residual stresses (RS) needs to be taken into account. An initial RS field is introduced into a type 316 stainless steel cylindrical vessel with no defects and to one with a partial circumferential crack on its outer surface. Relaxation of RS following several proof load cycles, in form of internal pressure, applied to the vessel is explored using finite element simulations. It is found that the proof loading process generally relaxes the RS and is proved to be beneficial to both cracked and un-cracked vessels with or without the presence of initial RS. Interaction of residual stresses with warm pre-stressing is further investigated using A533B steel at room and low temperature subjected to axial loading. The results are compared with similar analyses but with no introduction of an initial RS field to explore the interaction effects on fracture resistance, as well as the role of partial crack on the RS distribution / redistribution. The differences are discussed and illustrated.

Abstract: This aim of this study is to investigate the effect of UV (Ultra Violet ray) irradiation on the interfacial adhesion strength between thin ceramic films and polymer substrate. Electric conductive films based on polymer substrates have attracted attention for use in flexible optoelectronic devices. It is well known that the mechanical properties of polymeric materials are degraded by UV irradiation. Therefore, it is considered that the UV irradiation also affects the interfacial adhesion strength between ceramic coating and polymer substrate. The interfacial adhesion strength was measured by Multi-stages peel test. The results show that the interfacial strength decreases with UV irradiation. However, if a filter layer is installed between ceramic and polymer substrate, the degradation ratio becomes small.

Abstract: Bending performances of aluminum square tube beams reinforced by aluminum plates under three point bending loads have been evaluated using experimental tests combined with theoretical and finite element analyses. Basic properties of aluminum materials used for initial input data of the finite element simulation were obtained from the true stress-true strain curves of specimens which had bean extracted from the Al tube beams. True stresses were determined from applied loads and cross-sectional area records of a tensile specimen with a rectangular cross-section by real-time photographing. True strains were obtained from in-situ local elongation measurements of the specimen gage portion by the multi-point scanning laser extensometer. Four kinds of aluminum tube beam specimens adhered by aluminum plates were employed. The bending deformation behaviors up to the maximum load described by the numerical simulation were in good agreement with experimental ones. An aluminum tube beam strengthened by aluminum plate on the upper web showed an excellent bending capability.

Abstract: With the recent progress in flexible manufacturing systems (FMS) in industry, increasing attention has been given to Automatic Guided Vehicle (AGV) systems. An AGV is a self-powered unit for transporting materials between stations without needing to be controlled by an operator. Such a system has several sensors to recognize the external state, and it is designed to travel between stations without external assistance. To manage each device quickly and independently it requires a distributed controller with a main computer as the host, as well as a number of micro-controllers. In this study, an AGV system with dual motor drive was constructed. A Pentium 4 personal computer was set up as the main host for the distributed control, and this communicated with other micro-controllers in the management of the motor. The speed of each motor was also controlled by a micro-controller.

Abstract: High-heeled women have been identified with balance control problems. The purposes of this study were to objectively quantify the displacements and velocities of center-of-pressure (COP) of body during waist pulling and to compare the differences between barefooted and high-heeled situations. We used a waist pulling system which has three different magnitudes to sway the subjects. We found that the kinematic information of barefooted and high-heeled women’s COP is very important in understanding the mechanism of postural balance control of women in every-day life. In the high-heeled’s case, the displacement of COP increases by 9% (1kg), 33% (2kg), 44% (3kg) as against bare footed. Also the velocity of COP grows two times than that of the bare footed. COP analysis in postural balance study of high-heeled women is considered useful in development of the safety systems that prevent high-heeled women from falling.

Abstract: The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces (JRF) of the ankle joint during the waist pulling, and to assess the ankle JRF according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 camera motion analysis system, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and JRF during the recovery of postural balance control. From the experiment using mass-falling perturbation, joint moments were larger than those from the experiment with milder perturbation using air cylinder pulling system. However, joint reaction forces were similar nevertheless the difference in joint moment. From the results, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movements or compensating JRF by distributing the forces on surrounding soft tissues. The results of this study provide us important insights for understanding the relationship between balance control and ankle injury mechanism.

Abstract: The rifle impact on human body is affected by the posture of human for rifling. The interaction human-rifle system influences on a firing accuracy. In this paper, impact analysis of human model for standing posture is carried out. ADAMS code and LifeMOD are used in impact analysis of human model and modeling of the human body, respectively. At the shooting, human model is affected by rifle impact during 0.001 second. Performed simulation time for shooting is 0.3second. Applied constraint condition to human-rifle system is rotating and spherical condition. As the results, displacement of the rifle and transfer path analysis of impact on human model is presented.