This talk intends to cover three different active materials in actuators, (1) piezoelectric laminate with FGM microstructure, (2) ferromagnetic shape memory alloy (FSMA) and (3) electroactive polymer (EAP). The advantage of using the FGM piezo laminate is to enhance its fatigue life while maintaining large bending displacement, while that of use in FSMA is its fast actuation while providing a large force and stroke capability and that of EAP is to provide largest displacement under modest applied voltage. Use of modeling of the above active materials is a key design step in optimizing its microstructure for enhancement of their performance.

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The overarching objective of this paper is to outline a vision for a plausible way for meeting the requirements of manufacturing high accuracy micro/meso-scale components and devices ((10)^2-(10)^4μm) in a broad range of materials. It is proposed that micro/meso-scale mechanical manufacturing methods, derived from their conventional macro-scale counterparts, performed on miniaturized equipment integrated in a massively parallel fashion into "micro-factories of the future" could meet the technological requirements (i.e., relative accuracy, geometric complexity, cost, etc.) and offer capabilities that are beyond those currently available. First, the rationale and justification for this concept is outlined followed by an account of the science and technology foundation needed and a synopsis of the scientific, technological and commercialization barriers that will have to be overcome in the course of the realization of the proposed concept.

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Bulk metallic glasses (BMG) are finding increasing structural and impact related applications due to their high elastic limit (&acd;2%), high strength (&acd;2GPa) and potential for large deformation through localized shear. However, BMGs pose considerable challenges to impact testing due to their inherent low strain to failure induced by strain localization. This paper describes recent advances in impact testing of BMGs using a modified split Hopkinson (Kolsky) pressure bar. Results are presented for the high-strain-rate behavior of a bulk metallic glass, Vitreloy 1 (Zr_<41.25>Ti_<13.75>Ni_<10>Cu_<12.5>Be_<22.5>). The material exhibits strong rate sensitivity at temperatures above its glass transition temperature under quasi-static loading but remains rate insensitive under dynamic loading conditions.

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High speed machining consists to use high speed feed rates and high frequencies of rotation in order to obtain a best finish surface integrity including geometric accuracy, surface roughness but also lower residual stresses. We are meanly interested by high speed milling. This technique is in constant development but the safety in the working environment seems to be not really studied. For example, if we assume a tool breakage by using an electro-spindle with the following characteristics : maximum rotation speed of 45000 rpm, maximum power of cut of 40 kW, and maximum tool diameter of 50 mm, the projectile is ejected with a velocity of 235 (m.s)^<-1>. Also it is necessary to determine the good choice for glazing in operator windows. An experimental investigation to assess the effect of projectile shape and velocity on the impact response of thin polycarbonate target plates was performed. Deformation and failure phenomena were observed and discussed.

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A specific experimental method, the split Hopkinson pressure bar (SHPB) technique has been used to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of (10)^3/s&acd;(10)^4/s. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from varying structures under dynamic loading are determined using the SHPB technique.

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Since titanium and aluminum alloys are the most promising structural materials for the high velocity vehicles, the impact tensile strength of the materials is presently investigated. Three kinds of aging treatments on the beta-titanium alloy and two on the 6061 aluminum alloy were performed, and the tensile deformation behaviors were identified in the wide range of the temperature and the strain rate. The stress-strain relations of the titanium alloy significantly depend on the temperature and the strain rate investigated. Thermally activated process concept was applied to explain the experimental results, and the stress-strain relations at high strain rates were well understood with taking account of adiabatic heating effect. In the case of the aluminum alloy, the temperature and the strain rate effects are significant only in the low temperature range. Both for the alloys investigated, the stress-strain curves depend on the microstructures, while the temperature and the strain rate effects are almost independent of the different aging treatments.

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This study focuses on the constitutive modeling of a polymeric material-polyester elastomer (P-EM)-that exhibits temperature-dependent and visco-hyperelastic behavior. The material is experimentally characterized over a range of temperatures and loading rates-from-10℃ to 55℃ and at strain rates between (10)^<-2> and (10)^<-3>/s. The experimental results show that for compression to engineering strains of 40%, the behavior of P-EM is sensitive to both strain rate and temperature. The elastomer is assumed to be incompressible and a hyperelastic material model describes its finite deformation behavior. The WLF equation is used to model temperature dependence, while strain rate sensitivity is characterized by incorporating Maxwell relaxation elements. This approach involves eight material parameters, two of them to define temperature dependence and six to describe visco-hyperelasticity, these are determined from customized test methods. The fully defined material model is then incorporated into a commercial simulation software (ABAQUS) to predict the one-dimensional dynamic response of P-EM at different temperatures and strain rates. Comparison with experimental data shows that there is good agreement and that this model is able to describe the thermo-visco-hyperelastic behavior of the material examined.

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A modified split Hopkinson bar apparatus is employed to perform orthogonal machining of 6061-T6 aluminum alloy, and an array of HgCdTe high-speed infrared detectors is used to experimentally measure the temperature field distribution at the surface of the workpiece during this process. The effect of rake angle on the temperature field is examined. Three different rake angles are employed, 5,10 and 15 degrees, with two cutting velocities of 30 m/s and 45 m/s at a constant depth of cut of 0.5 mm. It is seen that the rake angle can vary both the maximum temperature as well as the distribution of the temperature field in the chip. For a cutting speed of 30 m/s, the maximum temperature decreased with an increase in rake angle from 251℃ for 5°rake angle to 237℃ for 10°rake angle and 196℃ for 15°rake angle. As the rake angle increases, the primary shear zone in the workpiece contributes less to the temperature distribution and the friction at the tool/chip interface dominates. It is also seen that as the cutting speed increases, maximum temperatures increase and a larger area of the workpiece is affected by the heat generation. For a 5°rake angle, the maximum temperatures increased from 251℃ at 30m/s to 290℃ for 45 m/s cutting speed.

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In order to estimate the strain rate dependence of the strain-induced martensite, the electric resistivity of austenitic stainless steel was measured using the constant current circuit before and after the tension test. The experiment was carried out at the room and nitrogen temperatures. Though the resistivity ratios at the high strain rate and low temperature were similar to the results at low strain rate and low strain rate and low temperature up to the strain of about 0.25,the resistivity at the strain above 0.25 was almost constant with the strain because of the internal heat generation by the conversion of the plastic work. Since the resistivity at room temperature test hardly depend on the strain and strain rate, the resisitivity ratios of the stainless steel were scarcely influenced by the deformation. Accordingly, it is clarified that the resistivity ratios were available as the parameters to parameters to estimate the quantity of the strain-induced martensite. Finally, the quantity was compared with the theoretical analysis presented by Olson etc.

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Novel experimental methods were proposed to easily and precisely evaluate the modes I, II and I+II fracture toughness of polymer matrix composite laminates under low-velocity impact loading. A ramped incident stress wave was applied to suppress the flexural vibration of the specimen caused by impact loading. A strain-based formula was employed to improve the accuracy of evaluation of the dynamic energy release rate. The validity of the proposed method was confirmed by the results of finite element analyses and dynamic experiments. The effects of loading rate and mode mixture on the interlaminar fracture behavior of carbon-fiber/epoxy composite laminates were investigated over a very wide range of loading rate from static to impact. The macroscopic fracture toughness clearly showed loading rate dependence regardless of mode ratio, and consequently the mixed mode fracture criterion varied with loading rate. The microscopic fracture morphology also showed loading rate dependence; cohesive fracture of matrix resin itself was dominant fracture mode at higher loading rate, whereas debonding of fiber/matrix interface was dominant fracture mode at lower loading rate.

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When a conventional split Hopkinson pressure bar (SHPB) is used to investigate the dynamic flow behavior of ductile metals, the results at small strains (ε<&acd;2%) are not considered valid due to fluctuations associated with the early portion of the reflected signal. When small-strain behavior is important, or when the large fluctuations in the loading pulses cannot be tolerated, the level of accuracy provided by a conventional SHPB is not acceptable. With the employment of a pulse-shaping technique, the dynamic elastic properties can be determined with a SHPB, as well as the dynamic plastic flow. This paper introduces the challenges associated with SHPB testing on ductile metals in the small strain range and presents remedies to obtain accurate dynamic properties. A description of the experimental technique, in particular, the implementation of the pulse-shaping method, and the experimental results on an aluminum metals with a variety of hardness will be presented.

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In order to design thin-walled impact-resistant structure, for example, an automotive body, dynamic behavior of thin plate is essential. So far, except for laminated composite materials, high velocity tensile test of thin plate specimen did not attract impact researchers' and engineers' attention very much. In this paper, the previous thin plate specimen assembly for the one bar method was improved. The one bar method has been utilized for cylindrical specimens of various solid materials and is known as an effective high velocity tensile testing technique. Unfortunately, the previous assembly introduced a tremendous initial peak on stress-strain curves, even for aluminum alloys. With a new specimen assembly, stress-strain curves for IF (Interstitial-atom Free) steel and 7075-T6 aluminum alloy obtained by the one bar method were almost equivalent to those obtained by the tensile version of the split Hopkinson pressure bar method.

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The tensile strength and energy absorption of dissimilar metal friction welds between 6061 Al alloy and Type 304 stainless steel at high rates of loading are determined using the split Hopkinson bar. Round tensile specimens machined from as-welded butt joints of 12 mm diameter are used in both static and impact tension tests. Friction welding is conducted using a brake type friction welding machine under two different welding conditions. The effects of welding parameters and loading rate on the tensile properties of friction welded butt joints are investigated. It is demonstrated that the tensile properties are greatly affected by the welding conditions, and are slightly enhanced with increasing loading rate. Macroscopic observations reveal that the tensile fracture mode of friction welded butt joints varies with loading rate, depending on the welding conditions. Microhardness measurements are performed to examine the extent of the heat-affected zone (HAZ) across the weld interface. The slight enhancement in the tensile properties of friction welded butt joints with increasing loading rate is due to the strain rate dependence of the thermally-softened 6061 Al alloy base material.

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The technologies of the numerical analysis made remarkable progress to understand the geoscience phenomena. However, in these approaches the subsurface has been modeled by a continuum medium and the finite difference method, finite element method, or boundary element method are adopted to solve the governing equations. Therefore it has been hard to treat the discontinuous phenomena. In this paper, The authors adopt the discrete element method to simulate the elastic wave propagation and also the Hopkinson bar effect. The simulation results showed this approach is quite useful for the analyzing the blasting and/or discontinuous phenomena in the subsurface.

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Two-material combinations to form a component are possible by welding or brazing, but a more cost-effective means for small components is to perform the assembly using powder injection molding and a new concept termed bi-metallic molding. This requires two materials (feedstocks) be formed sequentially into a molding cavity, and then the two materials must co-sinter to full density. Several automotive applications justify the expense of bimetal powder injection molding, assuming the sintering process can be optimized. Candidate applications are associated with sensors, actuators, and wear components. The scale-up is demonstrated with several geometries and property combinations.

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The internal stress of graded powder compacts during sintering is analyzed by using plate theory with shrinkage and warpage taken into consideration. Diagrams giving the in-plane stress on the surface of the compacts, produced by mismatch and bending, are presented as a function of sintering stress and viscosity. The diagrams show the contours of tension and compression as well as the direction of warpage for given multilayered substrate. When the viscosity of the top layer is smaller than that of the substrate, the shrinkage constrained by the substrate significantly influences the internal stress. In the opposite case, the bending stress dominates the stress condition. The tension/compression boundaries in the diagrams change according to the number and the thickness of the graded layers as well as the sintering stress and the viscosity.

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Hybrid Atomization is a new developed powder making process that hybridizes free fall gas atomization with centrifugal atomization well. This technique can produce very fine, spherical powders with mean diameters around ten micrometers and high yields economically. Its concept and basic principles were discussed. Process experiments were carried out and the optimal processing conditions obtained. Results show that the influences of processing parameters and optimum conditions are very different from those in conventional atomization processes. A new correlation of atomization equation applicable to hybrid atomization is proposed and discussed.

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The mechanochemical reaction of TiO_2 and Mg via mechanical alloying of Mg, TiO_2 and Al has been investigated. Reduction of TiO_2 is evident from substantial formation of MgO. Weakening of Mg and TiO_2 diffraction peaks along with broadening suggests refinement in grain size. Mechanically milled powder shows completion of reaction upon subsequent heat treatment while the reaction of the unmilled powder is still incomplete. Analysis suggests that the milled powder undergoes self-propagation while unmilled powder does not.

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The solid-state synthesis of Mg_2Si intermetallic by Powder Metallurgy (P/M) processing has been discussed in this study. Fist of all, the influences of the particle characteristics of input raw materials, such as Mg and Si powder, and the compacting conditions on the behavior in forming Mg_2Si were investigated. The surface oxide films of raw powder, in particular MgO, causes to prevent the reaction between Mg and Si because of its thermal stability. After destroying such oxide films, the increase of the contacting area of both powders is effective on the progress of the reaction of Mg with Si to synthesize Mg_2Si. Considering these results, bulk mechanical alloying (BMA) process, which assists to refine the elemental mixture powder and to break the surface oxide films by cyclic plastic works such as extrusion and compaction processes, was employed. For example, when using Mg/Si composite powder via BMA process with the cycle number over 100 cycles, the temperature in synthesizing Mg_2Si is about 473K, and is shifted to the extremely low temperature range. Via route of BMA over 300cyles on Mg-33.33mol%Si mixture powder, Mg_2Si fine particles of 30-100nm in diameter were in-situ formed during BMA process.

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The mechanical properties of the solid-state synthesized Mg_2Si/Mg composites from the mixed Mg-Si powders have been investigated. Results indicate the macro-hardness (HRE) and the tensile strength of the composites increase with increasing the Si content and decreasing the Si size. The particle size of the synthesized Mg_2Si depends on the initial Si size; the mechanical properties of the Mg_2Si/Mg composite are therefore remarkably improved by using fine Si particles or by decreasing the grain size of Mg matrix grains via bulk mechanical alloying process.

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To produce magnesium alloy with ultra fine-grain, size, an aluminum powder was mixed to turning chips of AZ31 alloy with various contents, and then they were mechanically alloyed for various milling times. Microstructural changes of the mechanically alloyed powder with milling were investigated. Super-saturated solid solutions of the magnesium phase are formed in the Mg-12mol%Al, its crystalline size has a nanometer scale. The solid solutions are formed the eutectic structure together with Mg_<17>Al_<12> in the 30mol%Al powder mixtures mechanically alloyed for long milling time. In the case of the Mg-40mol%Al and 61.5mol%Al powders, the formation of the intermetallic compounds yields by the mechanical alloying for shorter milling time, and these crystals become to amorphous phase after the prolonged milling time. The harness of particles in the mechanically alloyed powder increases with forming of the super saturated solid solution or the intermetallic compound and their refining.

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Al-Ni-Zr amorphous compacts were produced via Vacuum Hot Press (VHP) technique for various conditions from amorphous powders through double mechanical alloying (DMA), and their mechanical properties were examined. As a result, a relative density of the compact increases as compacting pressure increases, then it becomes constant until 700&acd;800MPa, and begins to rise over that pressure range, again. When the compacting pressure is the range of the density is stable, the both of the rupture strength and the maximum deflection show the maximum value. Below that pressure, conspact is not packed enough, and above that pressure, the crack inside compact occurs due to over pressure. Therefore, that range of pressure can be thought optimum compacting pressure to form Al-Ni-Zr amorphous consolidation. Further, the effect of consolidation process is also studied from the structural standpoint. As a result, it is understood the most suitable condition of VHP is at the compacting temperature when amorphous phases begin to crystallize.

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For the Thixomolding of magnesium alloys, process technology has not been developed so far. In this study, investigation of the relationship between the molding conditions and the defects was performed using "Design of experiment". The variable factors in those molding conditions are die temperature, magnesium slurry injection temperature, and injection speed. Die temperature has some influence on the fluidity of magnesium slurry, even up to the limit of die temperature. Magnesium slurry temperature is preferred to be at a high temperature for the fluidity of magnesium slurry. For the injection speed, the fluidity was optimized at a higher injection speed. When the die cavity thickness became smaller, a gap between designed thickness and stock thickness of molded part increased.

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A new MIM in-process joining technique has been developed for more complicated and functional MIM components by application of exuded wax from green compacts during solvent debinding step. Same and different materials using various stainless steels and iron were combined, and the joining behaviors and properties were investigated by tensile test and microscopic observation. Perfect joining thin and hollow compacts were obtained for the combination of same and different stainless steels, whereas it was difficult to join the iron and stainless steel compacts in hydrogen atmosphere because of the different starting temperature of shrinkage. However, pretty good joined iron and stainless steel compacts were obtained by consideration of particle size and vacuum atmosphere. Finally, for she combination of ferro-silicon and austenitic stainless steel compacts, high functionality (magnetic (1.60Tesla) & non-magnetic) and perfect joint were obtained.

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The strengthening mechanism of Fe-Cu alloy from rapidly solidified powder was investigated. The powder microstructure was changed by annealing. The as-atomized and annealed powders were consolidated by groove rolling at a warm temperature in order to avoid recystallization and to maintain the powder microstructure. Copper was precipitated in ferrite matrix and at primary powder boundaries in any of the consolidated samples; the precipitation was coarser in the samples from the annealed powders. The results of the tensile testing showed strengthening occurred by copper addition in both samples; the magnitude of the strengthening was larger in the samples from the as-atomized powder. The minute and uniform copper distribution in the samples from the as-atomized powder results in larger strengthening effect.

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The effect of mechanical alloying condition on the characteristics of mechanically alloyed powder (MA powder) was investigated. The difference in sintering behavior between the MA powder and the elementally mixed powders by a V-blender (V-blended powder) and the microstructure and shape memory characteristics of the sintered alloys were also examined. The MA powder was fabricated by milling using a planetary ball mill and was sintered by a spark-plasma sintering method at various temperatures. The powder agglomerated and cold welded and its particle size became larger with an increase in milling time. The mixture of Ti and Ni powders changed into an amorphous state by processing for 3.6ks more than 300rpm. The alloy of the MA powder showed more homogeneous phase of TiNi than that of the V-blended powder produced in a same manner, however the former showed a lower density than the later due to a larger particle size of its MA powder of before-sintering.

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The Ti-Ni-Cu shape memory alloys by elemental powders were fabricated using a spark-plasma sintering method. The influence of Cu content in Ti-Ni-Cu alloys on the microstructure, tensile properties and thermo-mechanical properties was examined. The microstructure, tensile properties and thermo-mechanical properties of the sintered-compacts were improved greatly by performing the solution treatment and the shape memory treatment. The yielding behavior due to the stress-induced martensite in stress-strain curves of the alloy, that is similar to that of the cold-worked alloy, took place after elastic deformation at any Cu content. The tensile strength and elongation of the alloy with Cu content around 9at% were more than 400 MPa and 6%, respectively. The alloys of higher Cu contents showed a superelastic-like behavior, and the shape memory characteristics of the alloys were confirmed to be superior. The cyclic deformation characteristics of the alloys were more stable than that of the cold-worked alloy.

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In this paper, it is shown that the hybrid forming techniques are used perfectly for metal forming in China by several examples. This technique accords with Chinese requirements. It reduces the metal forming force greatly, increase the life of die very much and reduces the investment of equipments and the cost of production are down greatly under guarantee quality of forging part.

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A fuzzy logic model was developed to predict and control forming pressure in the Maslennikov deep drawing process. A total of eleven variables including blank material, blank thickness, blank diameter, drawing ratio, friction coefficient, rubber hardness, compression ratio of rubber ring, strain, strain-rate, temperature and of blank and assistant punch force are taken into consideration. The model consists of two layers to correlate these variables to the forming pressure by generating a set fuzzy rules from the experimental and theoretical data. Membership functions and fuzzy rule bases for application to annealed aluminum (Al-O) are presented in details to demonstrate the modeling steps of such a complex forming process by fuzzy logic. High performance has been demonstrated when predicting the forming pressure limits and flow stress of aluminum blank (Al-O). Basede on such fuzzy model, a control system is proposed to monitor and control forming pressure in the Maslennikov deep drawing process.

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In deep drawing of metal containers, consistent flange width is desirable since the trimmed flange can be curled to accept lid in the final seaming operation. There are many material and process parameters that would influence the final flange geometry. In this paper, the feasibility of using blank holder force control to obtain consistent flange width in high speed production environment is studied. With the developed image processing techniques, flange width and earing characteristics can be identified. In the event that the flange deviates from the specification, blank holder force can be controlled to correct the discrepancy in the subsequent stroke. The proposed control system prevents deep drawn parts drift away from the ideal quality settings and thus will reduce production down time.

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Our approach to control of forging process centers around having a measurable process attribute follow a reference input. In other words, the control task is that of command following which also rejects process disturbances. Using artificial neural networks an effective control scheme is developed for a forging process. Numerical simulations indicate that such controller provides high performance in terms of command following and disturbance rejection. Moreover, it is fairly robust to model uncertainties.

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In this paper, the rolling of thin strip is simulated by a 3-D rigid plastic finite element method (FEM), which considers friction variation models. The calculated rolling pressure, spread and forward slip, taking into account a suitable friction variation model in the roll bite are in good agreement with the experimental values. Based on the FE simulation, the calculated strip velocity at the exit of roll bite is obtained, and the effect of the friction variation on the shape and flatness of strip is presented, the characteristic of the snaking of strip is also described in this paper.

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A major objective in the design of rolling mills is the achievement of required final temperature and grain size in the rolled bar. Therefore, the problem is posed as an inverse problem : Determine the input conditions and the pass sequence for the desired finish temperature and grain size. This paper presents a hybrid inverse method that uses FEM, DOE and ANN techniques for developing an inverse agent. The FEM and DOE techniques are used to calculate the phenomenological and microstructural process data which is needed for training the forward and inverse neural networks. These networks are then used for process parameter design. The results of this agent are verified using FEM simulation. It is seen that the inverse agent predicts the thermomechanical conditions well for grain sizes and finishing temperatures within the training envelope. For other values, a few predictor-corrector iterations are needed to converge to a good final solution.

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The Author develops die life analyzer working on the internet with using the cooperation with independent databases of cold forging die-life instances. The instance databases are established with HTML and XML on the internet, that the forging engineers access them with www browser usually as references for their forging process design. Furthermore, the analyzer deals these databases as a knowledge base to predict and analyze forging die-life and the cause of short life. The author considers die-life analysis as the risk analysis that the life of target tool is to be worse than a life of instances. The author has developed die-life analyzer using risk tree networks and fuzzy linguistic risk calculation. The author investigates the causes of short life to perform risk analysis tree network. A cause, we call a parent node, is divided to more detail causes, we call daughter nodes. Daughter nodes are connected to its parent nodes with weights, and risk value of parent node is calculated as average of daughter nodes' value with the extension principle. The risk values of causing shorter life than instances, that is to be the risk value of the top of all nodes, are calculated through the above process finally. After then, the system predicts die life with interpolation using die life instances and the corresponding risk values making die life shorter.

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In the deep drawing of thin steel sheets, a complex die with blank hold structure is generally used to prevent wrinkle and crack and the deep drawing process should be repeated several times to get the final product shape. However, in the case of forming a hot rolled steel plate that the thickness is in the range of 3-5mm, it is possible that the final product shape can be formed by simple structure die using few deep drawing process. Furthermore, it is also possible that the high quality product shape with differential thickness on the same section can be formed by combining cold forging processes. In this present paper, the hollow Spline shaft has been manufactured from a thick plate by the deep drawing and extrusion processes. The product quality has been evaluated from various viewpoints.

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The paper details the factors affecting on mechanical properties of soft martensitic stainless steel castings which have lower carbon contents and increased nickel contents of up to 6% compared with normal martensitic stainless steel castings. The effect of alloying elements and impurities on the microstructural features and tempering characteristics has been considered in detail, with special reference to reverted austenite and temper embrittlement. The mechanical properties have also been investigated and it has been shown that the best combination of strength and toughness is obtained when tempered at around 900K. Addition of Mo have been shown to improve toughness degradation due to slow cooling from the tempering temperature. Lowering P and S contents lead to superior toughness and fatigue properties. The threshold stress intensity range has been shown to decrease with increasing stress ratio depending on P content.

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Influence of the abnormal structure, such as scattered chill structure or cold shut, in JIS AC4CH (Al-7.3%Si-03.%Mg) aluminum alloy squeeze castings on the reliability of mechanical properties was investigated. The shot time lag (STL) and the heat transfer coefficient between molten alloy and shot sleeve were changed as the process parameters to control the formation of the abnormal structure. Both the tensile strength and its reliability were remarkably improved by using the powder lubricant or by decreasing the STL Regarding the fracture elongation, the average elongation was improved due to the reduction of abnormal structure on the fracture surface. However, the reliability of the fracture elongation was sufficiently improved by neither STL nor the type of lubricants. It is found that the reduction of abnormal structure is effective to improve the strength and fracture elongation of squeeze castings.

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To compute the thermal mechanical stresses and susceptibility of the material to crack during strip casting process, a coupled finite element simulation on temperature, solidification and inelastic deformation was carried out based on a unified viscous fluid model including elastic, visco-plastic deformation, thermal expansion and dilatation due to solidification. The distribution of temperature and stresses on strip surface and in nip zone was analyzed under various casting speeds. Susceptibility of the solidifying material to fracture was evaluated with a stress-crack criterion. The weakest position and effect of casting speed were clarified.

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Melt Drag process is one of Rapid Cooling Solidified Methods with single roll. This method can cause two effects : the improvement of the quality by rapid cooling solidification and the simplification of process. The experimental device that is suitable for magnesium was made, and the manufacturing of magnesium strip was conducted in present study. For the experiments we used pure magnesium and magnesium alloy AZ31. This study aims at showing the possibility of this process as a new magnesium processing technology. From experiments, it was possible that magnesium strip was produced in Melt Drag process. And the temperature of molten magnesium decreased suddenly in the gutter and the tundish. When it exceeded 750℃, the viscosity increased due to the oxidization and the molten metal temperature decreased drastically. When roll speed increased, the cooling time on the roll became short. But, the amount of dragging solidified phase decreased and a cooling effect by decreasing strip thickness was dominative.

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Since saving of resources and energy and global environment came to be taken up, aluminum has been paid attention because it is easy to recycle and its specific tensile strength is high. The quantity of aluminum forged parts increases to the variety products. however, for the characteristic is good, aluminum products have been used without considering for the cost. With these points as background, we developed new process of the continuous casting method to which applied the Melt Drag Process. It is successful in producing the various forms of forging raw materials with attaining near net-shape for the present. In present study, we analyzed the solidification and forming mechanisms. Solidification in slug was presumed from variations of temperature and the solid fraction in a slug each part that had calculated.

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This paper presents a numerical method in order to forecast thermo-mechanical behavior and the residual stress in the thermal spray coating process by using of high velocity oxygen fuel(HVOF). A set of coupled equations of the heat conduction and stress/strain and solidification based on the metallo-thermo-mechanical theory is introduced into the simulation of thermal spraying. Here, A inelastic constitutive equation with capacity to represent relation of stress/strain during rapid solidification is employed. The numerical modeling based on the finite element method is proposed to solve the heat conduction associated with solidification in the sprayed layer and residual stresses on the interface between multi-layer materials, especially. In this paper, the simulated results of the temperature filed, solidified domain and residual stresses in the sprayed layer including interfacial combinations between substrate and spray layer are presented, and the validity of the calculated results is discussed in comparison with the measured results by using of X-ray diffraction.

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Cavitation Shotless Peening (CSP) is a new method of surface modification. Cavitation impacts induced by collapses of cavitation bubbles produce compressive residual stress and work hardening on the material surface. In the case of CSP, shots were not required and that is why we call it Cavitation Shotless Peening. At CSP, cavitation was induced by high-speed submerged water jet with cavitation, i.e., a cavitating jet, whose intensity and occurring region of cavitation impacts could be controlled by parameters such as upstream pressure and nozzle size. The authors have already revealed that lifetime of forging die treated by CSP was extended by about 50% compared with the non-peened forging die. In this paper, in order to make clear the mechanism of increase of lifetime of forging die, alloy tool steel (JIS SKD61) was tested both in non-peened and peened conditions. Compressive residual stress was measured by an X-ray diffraction method. Comparison between the non-peened specimen and cavitation shotless peened specimen revealed that improved mechanical properties leading to longer life-time of the forging die were favourable in CSP.

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In this study, surface modification was tried on the aluminum alloy A5083 by irradiating YAG laser beam after sticking stainless steel powder to the surface. The focus position, the stainless steel powder thickness and Ar gas flow rate are changed under at fixed laser power and laser moving speed. As a result, thick surface modified layer could be obtained with high hardness and flat surface in which a crack did not occur.

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There is an increasing need to extend the application of aluminum alloys in mechanical elements. However, the tribological properties of aluminum alloys are generally inferior compared with conventional tribo-materials. Plasma spraying method is one of surface modification technology, which is possible to synthesize the thick coatings enough to bear sliding wear of engineering applications. A series of hyper-eutectic aluminum-silicon alloys has been synthesized with different percentage of silicon ranging from 16wt% to 50wt% by a low pressure plasma spraying method. The friction and wear of Al-Si based films have been studied using a reciprocating sliding under the lubricated condition. The hyper-eutectic Al-Si alloys (Al-40wt%Si-5wt%Cu-1wt%Mg) showed the lowest wear in the Al-Si films, however, the wear rate was not enough for the industrial applications. In order to improve the tribological properties, two tentative approach : heat treatment and whisker reinforcement, have been examined independently. The hardness and wear resistance have been improved significantly by both methods.

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In order to improve the wear resistance of stainless steel extrusion dies, the mechanical properties of diamond-like carbon (DLC) films deposited on SUS630 (17-4PH) substrates have been investigated. It was clearly shown that wear resistance of the dies was significantly improved when high-voltage pulse pretreatment was applied before DLC deposition by DC plasma CVD. The DLC film showed good wear resistance against cordierite clay in an extrusion experiment. Furthermore, in order to strengthen the adhesion between the DLC film and the substrate which were deposited, TiCN films was fabricated as a buffer layer between DLC and SUS630 substrates. It was found that DLC film with high adhesion strength was prepared at relatively low CH_4 gas pressure of 6 Pa.

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This paper presents a tribology model for hot forging operations. The friction model considers contact patches where an initial film thickness is entrained at the contact patch edges and evolves within the patch during the forging operation. The initial entrained film thickness is obtained from simplified solutions of the Reynolds equation. Film thickness evolution is dictated by a Reynolds equation formulation that includes the stretch term and roughness effects on lubricant transport. Surface roughness of the workpiece is allowed to evolve in the process, and the real fractional contact area is then calculated based on the roughness and film thickness assuming a Gaussian surface. Friction is calculated based on the real area of contact. The program is implemented as a user routine in a popular commercially available finite element code, DEFORM 2D.

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For space mechanical components, the characteristics of silver thin film dispersed nano-cluster diamond powder as a solid lubricant film had been investigated. The silver films dispersed the cluster diamond powder were made on the 440C stainless steel disks under vacuum of 3×(10)^<-2>Pa at 1080K without graphitization of the nano-cluster diamond powder. Frictional characteristics of the films were investigated by a pin-on-disk friction test in injected nitrogen gas atmosphere (30%RH, 15% oxygen gas) and under ultra high vacuum of 2×(10)^<-6>Pa. Initial Hertzian contact pressure was set almost 0.7GPa. The sliding speed between the pin and the disk was about 30mm/s. Compared with ion-plated silver film, the lifetime of the film dispersed the nano-cluster diamond powder was 100 times longer in nitrogen gas atmosphere. The initial friction coefficient showed 0.2,and then it showed stable 0.4 for a while. The cluster diamond powder is considered to prevent the wear of the silver film.

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