Search

Lower limb exoskeletons with actuators aid physically challenged individuals in walking. We had developed a novel, lighter than conventional, magnetic strain wave gear for exoskeletons. However, output shaft was not rotated when overloaded even through input shaft was rotated (step out phenomenon). Then, the transmission torque was limited by a step-out phenomenon. In the paper, we aimed to elucidate a step-out phenomenon for future design. We observed deformation shape of two types of magnetic strain wave gears, through multi flexible dynamics analysis with magnetic force database and measurement using displacement sensors. Basically, the deformation shape was ellipse. The phase difference between rotational angle of input shaft and tilt angle of ellipse deformation shape was enlarged when the load was increased. The phase different became excessive and the deformation shape was changed to true circle when overloaded showed. Compared a gear with small 4-pole magnets, a gear with large 16-pole magnets could keep deforming shape and it had higher limitation torque.

In the treatment of dentofacial deformities in oral and maxillofacial surgery, a maxilla-mandibular bone is cut using a rotary cutting tool. Generally, an oral and maxillofacial surgeon determines the end of cutting with a cutting bar by sensory change transmitted from the cortical bone(hard layer) to the cancellous bone (soft layer) in the hand of the surgeon. It is required the extensive experience and advanced surgical skills to avoid a risk of sequelae due to excessive damage to blood vessels and nerves caused by excessive cut. Therefore, it is important to establish an objective and quantitative index for the cancellous bone reaching in order to perform the procedure safely. The purpose of this study is to construct an evaluation index for judging the accession of the cutting bar at the cancellous bone. This study focuses on the density of the frequency spectral component of the vibration acceleration of the handpiece and defines the change in the density of the spectral component as a new evaluation index. The accuracy of the proposed evaluation index was evaluated by the artificial bone cutting tests simulating the oral and maxillofacial surgery. In addition, the effects of proficiency in the surgery on the judgment results were examined.

Low temperature difference Stirling engine is an excellent teaching material for mechanical design because (1) students can experience all of four dynamics (material mechanics, fluid dynamics, thermodynamics, and dynamics of machinery) by designing and constructing it, (2) it is safe even if the design is not appropriate, so it allows students to freely try their own ideas, (3) there are many variations of engine configurations, including types and mechanisms, so there is much room for creativity and ingenuity, and (4) as the structure is simple, it is easy for students to understand if their ideas make sense. On the other hand, it is not easy to construct a working engine because of its low power. In order to make low temperature difference Stirling engines more effective teaching materials, this paper describes the design and fabrication of a low temperature difference Stirling engine with high power per swept volume that can run at higher speed. The results of analyzing the working fluid temperatures in the expansion and compression spaces indicate that the temperature ratio increases with increasing speed even in a low temperature difference Stirling engine. We found that an arrayed resin regenerator can provide high performance, and realized that a Stirling engine with a power piston swept volume of 4.5 cc and using hot water and ice as heat sources can run at a maximum power of 171 mW and a maximum speed of 31.3 Hz. Compared with other low temperature difference Stirling engines, the power per swept volume of test engine is more than 10 times higher and the rotational speed is nearly three times higher than those of the low temperature difference Stirling engines already reported. The results show that low temperature difference Stirling engines with high power per swept volume can be designed and fabricated by using 3D printers, and the value of the low temperature difference Stirling engine as a teaching material has been enhanced.

In this paper, we propose a vibration suppression method that takes fuel cutoff into account for an automobile powertrain during rapid acceleration and investigate its effectiveness. An automobile powertrain transmits engine torque to the tires, which causes vibration of the vehicle body during rapid acceleration. The engine is used as an actuator to control this vibration. However, the engine output has a constraint by fuel cut. This degrades the vibration suppression effect of vibration control. In addition, all vehicles will be controlled via controller area networks. The discretization width of control signals and the communications traffic are in the relationship of trade-off. The communications traffic in vehicles will increase in the future. Therefore, we need a control system that can suppress vibration even with coarse discretization widths. In this study, we propose a powertrain vibration control method using an optimal dynamic quantizer as the countermeasure. Optimal dynamic quantizer minimizes the effects on the tracking error (in the control system) due to the quantization. Then, we quantitatively examine the robustness at various quantization widths for the proposed control system. As a result, the optimal dynamic quantizer allows for smoother acceleration while suppressing vibration compared to the case with static quantizers. In conclusion, the performance of the proposed control system is investigated quantitatively.

This paper deals with the reproducibility of the running safety limit diagram of multi-connected vehicle using the reduced-order-model. The vehicle model consists of 10 cars and has 210 degrees of freedom. It needs much time to simulate the car’s behavior and make the running safety limit diagram by numerical calculation because the model has enormous degrees of freedom, so we consider about model reduction to decrease the calculation time. So far, when the types of car’s characteristics or input waves have been changed, we reconstructed reduced-order-model for each case, so it is difficult to make the running safety limit diagram which needs various types of input waves (many cases of frequency or acceleration amplitude) when using the reduced-order-model. Therefore, in this study, we use an index called as ‘multiplicity’ of mode for all of 210 modes, and make ‘common’ reduced-order-model by using modes whose multiplicities are high. As a result, if the common model included 20 – 60 modes, the model could reproduce the running safety limit diagram of original model, and the calculation cost decreased by 75 % when 20 – 50 modes, and by 35 % when 60 modes. Considering both accuracy and calculation cost, 50 modes was better to make the diagram. Moreover, the reduced-order-model which included 50 modes was also applicable to the running safety limit diagram using real seismic waves.

Since many bolted connections are used in rolling stock, it is necessary to improve the prediction accuracy of stress distribution of the connections in order to reduce the weight and improve the reliability of the structure. In addition, it is important to balance accuracy and reduction computation time by using low-dimensional elements such as shell and beam in the analysis of large structures such as rolling stock. The purpose of this study is to verify the practicality of the simplified finite element modeling method for bolted joints of attachment rails in rolling stock composed of aluminium alloy hollow extrusions, which was proposed in the previous study. In order to understand the behavior of the joints, static load tests were conducted on a full-scale specimen with four attachment rail bolt joints, in which combined tensile, shear, and bending loads were applied, and the strains in the vicinity of the joints were obtained. Simplified modeling using shells, beams, and RBE3 elements was also performed on the specimen. The results showed that the deformation mode of the attachment rail could be reproduced by the simplified model. In addition, the results of the simplified model agreed with the test results in terms of the strain distribution at the nominal section of surface plate and the observed maximum error was 5.0%. It was also confirmed that the simplified model could reproduce the local strain distribution in the extrusion direction and the transverse direction of the extrusion of the attachment rail near the bolted joint. Therefore, we concluded that this simplified modeling method could be practically applied to modeling of bolted joints of attachment rails in actual underfloor equipment of vehicles.

Ball bearings are used for many mechanisms. For the precious linear motion mechanism, it is very important to know the ball bearing deformation because the driving load is supported by the bearing. Especially, for the focus control mechanism of the optical telescope, even a very small deformation is not negligible because a sub-micron precision is required for the driving stroke. The Hertz’s formula is very familiar to the relation between the load and the displacement in a small contact area. Hertz derived the formula by using a potential of the electricity distribution in the ellipsoid body. However, it is reported that an error becomes large when the contact area is large. It is a reason that the elliptic paraboloid is used for the ellipsoid body in the Hertzian contact theory. Some modified equations are reported by Nishihara et.al, Tatara and Villaggio. However, the modified equations by Nishihara et al. and Villaggio are a little different from the FEM result. Therefore, in this paper, a contact deformation for the 2 equivalent spheres is analyzed by the indirect-fictitious boundary integral method. For the relation between the load and the displacement, a new modified equation with the fractional expression is derived in this paper. And, for the relation between the load and the contact radius, it is confirmed that the Hertz’s formula is correct.

Vibration reduction strategies based on wave propagation phenomena, such as generating band gaps in periodic structures, are attracting attention in the field of mechanical engineering. This paper investigates how the structural and material compositions influence band gap characteristics (band gap frequencies and width) of composite beams of metallic materials with flat surfaces. The composite beams in this study are composed of the periodic structure of the "unit cell," and a unit cell consists of two different parts (called cells a and b). Numerical analysis to obtain a dispersion curve by applying the wave finite element method (WFEM) was first carried out to check band gap generation in the metallic composite beams. The relationship between structural characteristics (bending rigidity ratio, mass ratio, or length of the two parts of the unit cell) and the band gap characteristics was investigated numerically using the WFEM. Some composite beams with a band gap lower than 1 kHz with a broad frequency band were designed. Then, their frequency response characteristics were calculated using a commercial FEM software Ansys to confirm the vibration reduction (or suppression) effect in the specified frequency band. Actual metallic composite beams were created using a metal 3D printer, and excitation tests were conducted to verify the numerical results. As a result, band gap generation was demonstrated experimentally. Numerical investigations were also carried out to design composite beams of two different metals to have a wider band gap.

This study investigated the compression molding of hybrid composite materials using waste concrete powder (WCP) and bagasse fiber (BF) as a novel reuse procedure for waste concrete. The matrix of the composite material was applied to powder-type polyethylene (PE) to facilitate the compression molding of the gas vent. The WCP was obtained by milling siliceous waste concrete using a pot mill procedure. The main constituent of the WCP was quartz. The flexural strength and modulus of the hybrid composite material, in which BF was added to mix the powder with PE and WCP, increased with increasing BF content and exhibited a maximum value at a BF content of 30 wt. %. Next, to improve the mechanical properties of the hybrid composite material, we attempted to improve the adhesiveness between PE and BF by increasing the molding temperature. The mechanical properties of the hybrid composite material with a BF content of 40 wt. % exhibited the highest values at a molding temperature of 413 K. Furthermore, by increasing the WCP content in the hybrid composite material with a BF content of 40 wt. %, the flexural strength exhibited the maximum value at a WCP content of 20 wt. %. Therefore, it was revealed that the composite material using PE powder and WCP could be strengthened by adding BF.

For isotropic dissimilar materials, it is well known that the stress state can be expressed by two independent material composite parameters named Dundurs parameters αiso, βiso. Similar composite parameters were also derived for orthotropic dissimilar materials as α , β , ΓA , ΓB , ρA , ρB . Compared to two parameters in isotropic dissimilar materials, anisotropic dissimilar materials have such six independent material parameters, making it much more difficult to use previous analysis results and requiring the new analysis each time. In this study, first, the interface crack in orthotropic dissimilar materials is analyzed by applying the proportional method. Second, the singular stress field in orthotropic materials is compared with that in the isotropic dissimilar material under the condition α = αiso，β = βiso. The results show that the singular stress field in orthotropic dissimilar material can be evaluated within a few percent error in most cases from that in isotropic dissimilar material when α = αiso，β = βiso. In this isotropic replacement by applying α = αiso，β = βiso, the singular interface stress distributions in orthotropic dissimilar plates can be estimated within the 10% error even when the material anisotropy is widely changed.

In modern vehicle development, concurrent modular design, which is a productive manufacturing approach that uses pre-made and interchangeable modules to build vehicles and subsystems, has become mainstream to improve design efficiency and strengthen market responsiveness along with the increasing trend towards electrification and electronic systematization. The achievement of the modular design method is also desired in the design of vibration related to several performances such as durability and noise performance. However, developing the modular design method is a challenging task as the performance is influenced by all the subsystems constituting the whole structure. In this paper, a method for reshaping the eigenmode of only focused subsystem to the desired one is proposed as one of the modular design methods. The formulations to calculate a desired eigenmode shape of the focused subsystem are derived based on the dynamic stiffness matrix-based sub-structuring approach and the perspective of maintaining the relationship of vibration coupling between subsystems, which is constituted of internal forces and the eigenmode vector on coupling region where the forces act. Furthermore, the one-on-one correspondence between the reshaping amount of eigenmode and the dynamic stiffness matrix deviation for the reshaping is built involving the finite element model of the focused subsystem and the boundary conditions by expanding the formulation above. Therefore, reshaping to the desired eigenmode with realizable structural modification is achieved. Finally, this proposed method is applied to a numerical case study to reduce vibration responses by allocating modal strain energy to a focused subsystem from the perspective of increasing damping effect.

In the natural sciences, a common methodology is to observe phenomena, formulate a hypothesis, and verify it. However, human errors such as pedal mis-operation occur very infrequently, making it difficult to apply this methodology. Therefore, we established a method to artificially generate a pedal mis-operation situation on a driving simulator. Specifically, the method is remotely changing the pedal position so that the driver would not notice it. In this experiment, we acquired video and driving data. In this paper, we extracted driver features from the accumulated data and investigated them. The results showed that aging slows down the transition from accelerator pedal mis-operation to correct brake operation. In addition, it was found that elderly drivers tended to press the accelerator pedal again after mishandling the accelerator pedal. It is inferred that the higher incidence of mis-step accidents among younger drivers in the statistics is due to the higher frequency of pedal misapplication errors. On the other hand, it was found that the influence of driving frequency and gender was small. We confirmed that driver characteristics can be divided into "ability axis" and "personality and driving habit axis" by principal component analysis. Furthermore, decision tree analysis was used to analyze the driver features that allow the driver to operate the brakes correctly even if there is a accelerator pedal mis-operation.

In this paper, we present a void topology identification analysis in structures based on the level-set-based topology optimization using a weighted sensitivity method. The void topologies are identified by using the observed hammering response data and the gradient of the Lagrange function with respect to the level-set function. The numerical simulation of structural oscillation is performed by the finite element method, and the void topology identification analysis is formulated by the adjoint variable method. An improvement of how to give numerical parameters in the weighted sensitivity method is conducted, and numerical tests are carried out for minimization problem of the Rosenbrock function. The improved procedure is applied for the void topology identification analysis, and applicability of the proposed method is shown in this paper.

Impact vibration due to the train passage at the joint of tongue rail has been known to induce the fatigue fracture of the hinged lug of turnouts. The impact vibration is considered to be enhanced by the mismatch of rails, the gap between the tongue rail and the base plate, and the loss of the tightening force of the bolt at the joint plate. However, the detailed mechanism has been unrevealed since the direct observation of the joint during train passage is inaccessible. In this study, we first measure the displacements of the tongue rail at the joint during train passage using small-size cameras. We evaluate the turnout whose hinged lug was broken. Displacement measurements show that the heel of the tongue rail (close to the joint) moves vertically downward by 3.9 mm and the toe of the tongue rail moves vertically upward by 2.3 mm when the train passes through the joint. Finite element analysis reveals that the downward displacement of the heel is caused by the gap between the tongue rail and the base plate and the upward displacement of the toe is caused by the rotation of the tongue rail around the supporting base plate. Acceleration measurements show that two peaks of impact acceleration enlarge the acceleration amplitudes (4400–7500 m/s2). Finite element analysis reveals that the first and second peaks are caused by the collision between the tongue rail and the wheel and that between the tongue rail and the base plate, respectively. Our results indicate that the gap between the tongue rail and the base plate should be minimized in addition to the mismatch of rails to reduce the amplitude of the impact vibration.

The objectives to extend the available range of pipe supports up to plastic region are below; one is to enlarge the loading capacity, and the other is to add damping to piping systems using the absorption effect of seismic energy due to the elastic-plastic hysteresis property. However, the pipe support design that balances these two functions is difficult. In this study, a design concept to achieve both of these functions is proposed and its feasibility is shown. First, the effectiveness of the elastic-plastic design with the allowable load for the existing elastic-plastic pipe supports was compared. The results showed that although an increase in loading capacity can be expected due to elastic-plastic pipe supports, the damping effect depends on the shape of the supports, so that damping due to plasticity cannot be expected much. To obtain sufficient damping effect, an additional design process is required to adjust the yield load for each support. Next, to overcome this drawback, an elastic-plastic pipe support with a hybrid structure of frame type structure and cantilever structure was proposed. The frame-type structure ensures pipe support and prevents excessive deformation of the piping, and the cantilever structure increases the damping effect. This proposed design makes it easy to optimize both functions.

This paper describes a consideration of the difference in wheel/rail tangential contact force characteristics between in running tests and in laboratory experiments. To improve the accuracy of vehicle dynamics analysis, it is important to obtain the relationship between the tangential contact force coefficient and the slip ratio under realistic conditions. Since these characteristics cannot be obtained by numerical analysis, running tests on commercial lines and laboratory experiments using a twin-disk rolling machine are carried out. On the other hand, under conditions of high slip ratios, these characteristics differ between cases where the tangential contact force coefficient between wheel/rail remains contact and cases where the tangential contact force coefficient decreases. In this study, focusing on the state of the coefficient of friction between wheel/rail, a 3D-MBD model which can simulate vehicle behavior during braking was constructed on the SIMPACK commercial software, and these different reasons and their relationships were discussed. The result clarified that the difference in these characteristics is due to whether the friction coefficient on the contact surface is constant or fluctuating during the measurement by numerical analysis. That is, the characteristics measured in laboratory experiments can be modeled by Kalker’s rolling contact theory with a constant friction coefficient, and the characteristics measured in running tests can be modeled by combining the characteristics obtained by the Kalker’s theory under the conditions of different friction coefficients at each running distance.

This study investigates a new method for the effective application of active secondary suspension for reducing vertical vibration of the carbody to improve ride comfort of railway vehicles. So far, most previous control methods have contributed to reducing the vibration of the rigid body modes of the carbody at approximately 1 Hz or the first bending mode at approximately 10 Hz. However , in modern high-speed vehicles, higher frequency vibrations generally have a relatively greater influence on vertical ride comfort than vibrations of around 1–2 Hz. Focusing on this fact, the authors propose active secondary suspension with feedback control of the vertical vibration velocity of the bogie frame as a method for reducing carbody vibrations in a wide frequency band above 2 Hz to improve ride comfort. Numerical simulations were carried out to simulate the actual running of a Shinkansen using a vehicle model corresponding to a Shinkansen vehicle with 14 degrees of freedom, considering the vertical and longitudinal dynamics of the vehicle. The results show that this method is mainly effective in reducing vertical carbody vibration above 3 Hz and that the frequency band for vibration reduction can be extended to 1 Hz or lower by combining this method with feedback control of the vertical displacement of the bogie.

The simultaneously iterative procedure proposed by the authors is applied to elastoplastic problems with damage. From the definition of a coupled problem of the weak form of the equilibrium equation and the constraint conditions for plastic yielding and damage evolution at every material point, the authors develop a numerical procedure based on the block Newton method to solve them with simultaneous linearization. In the proposed block Newton method, the consistent tangent can be derived algebraically, and the internal variables, which consist of the plastic parameter and the damage parameter, can also be updated algebraically without any local iterative calculations. Furthermore, the pseudo-stress for the residuals of both the yield condition and the damage evolution law is incorporated into the linearized weak form of the equilibrium equation. Thus, the proposed approach allows us to simultaneously reduce the residuals in the coupled boundary value problems. Some numerical examples illustrate the validity and effectiveness of the presented procedure for elastoplastic problems with Lemaitre damage model.

Heat transport characteristics of three-dimensional pulsating heat pipe (3D-PHP) have been investigated experimentally. The 3D-PHP consists of 20 tubes and heating block made of copper. The 3D-PHP has 2 layers of 5 turn flow paths (10 tubes) and the layers are interconnected. The operational orientation of 3D-PHP was bottom heat. The bottom of heating block was heated by a ceramic heater. Copper tubes that played a role of heat dissipation fin were cooled by air flow. Fluorinert FC-72 was used as the working fluid and filling ratio was 50 % of the channel volume. The 3D-PHP was tested for various air velocity and heat load. Heat load increased by 10 W to 100 W and decreased by 100 W to 10 W. It was found that the thermal resistance at decreased heat load was lower than that at increased heat load for the same heat load when the heat load was lower than the start-up heat load. On the other hand, when heat input was higher than the start-up heat load, the thermal resistance at decreased heat load were approximately as same as that at increased heat load for the same heat load. Those were confirmed for all cooling air velocities within the scope of this study.

This paper considered a new implementation method for the stable manifold method, which is one of the nonlinear optimal control methods, using the state-dependent Riccati equation (SDRE) method. In the conventional stable manifold method, the optimal trajectory of the control object was generated by integrating the Euler-Lagrange equations corresponding to the Hamiltonian in the inverse time direction, and the state feedback control law was obtained by a polynomial approximation of the obtained solution. However, implementing this method using polynomial approximation is difficult due to problems such as determining the degree of the approximation formula, the computational cost of the approximation calculation itself, and the inability to perform polynomial approximation for complex trajectories. In contrast, the proposed method in this study aimed to achieve pseudo-nonlinear optimal control by using the SDRE method to track the optimal trajectory obtained by the stable manifold method. This method is easier to implement than the conventional stable manifold method because it does not use polynomial approximation, which is a barrier to applying it to actual systems, and instead uses a linear optimal control framework to track the optimal trajectory. The effectiveness of this method was demonstrated by swing-up and stabilization control experiments of a rotary inverted pendulum.

Particle dampers (PD) can be embedded in structures fabricated via selective laser melting (SLM) because the raw powder (particle diameter : several tens of micrometers) remains in closed spaces during SLM. However, most PD studies have focused on coarse particle sizes larger than 1 mm and low frequencies below 100 Hz; there is insufficient evaluation of PD attenuation characteristics and particle behavior for particle sizes from tens of micrometers to sub-millimeters and in the 100 to 1000 Hz band. In this study, the equivalent viscous damping coefficients of spherical zirconia balls with nominal sizes of 0.05, 0.10, 0.20, and 0.40 mm are measured under different vibration accelerations (from 9 to 148 m/s2(rms)) and frequencies (from 100 to 800 Hz) to experimentally investigate the effect of fine particle diameters on the damping properties. It is deduced that in the frequency range above 200 Hz, the equivalent viscous damping coefficients of the coarse particle diameter are greater than those of fine particles at accelerations below the range of 15.7–22.4 m/s2(rms). In contrast, the equivalent viscous damping coefficients of the fine particles are greater than those of the coarse particles at accelerations above the 15.7–22.4 m/s2(rms) range. In addition, to determine the reason for these tendencies, the behavior of particles with a nominal size of 0.05 mm, which is close to the raw powder, is observed through a window using a high-speed microscope camera. The results reveal that in the low acceleration range, the inertial force does not overcome the static friction force owing to poor flowability caused by adhesion force, and the particles are always stationary with respect to the sealed container.

The focused acoustic field formed under the water surface raised by ultrasound exposure was numerically investigated to elucidate the relationship with the surface rising prior to ultrasonic atomization. The effect of surface tension was newly added to the computational scheme constructed in the previous paper (Orisaki and Kajishima, 2022) and the direct numerical simulation based on compressible fluid dynamics was conducted. The water surface above the sound source rises. When the risen surface shape changes into a dome due to the effect of surface tension, the acoustic antinode with strong focusing appears inside the dome and the water surface begins to rise rapidly. In case of the insufficient sound source pressure, the gentle risen surface is kept, and acoustic peak spots remain deep due to the small curvature of the surface. These results suggest that the dome formation increases the acoustic pressure amplitude at the dome center and promotes acoustic cavitation there. On the dome surface, the kinetic energy density with the phase opposite to acoustic pressure increases, which causes the increase in the acoustic radiation pressure.

Zinc-air batteries are widely considered as the next-generation rechargeable batteries due to their high energy density, low cost, and high safety. However, internal short circuits caused by zinc dendrite growth and bubble generation by side reaction during high-speed charging can deteriorate battery performance. To address this issue, a zinc-air flow battery with an electrolyte flow has been proposed for high-speed charging, and previous studies have shown improved cycle performance. Optimization of operating conditions for practical use requires elucidation of the behavior of the zinc electrode and bubble with electrolyte flow during battery operation, but this remains unclear. This study utilized operando X-ray imaging to investigate the zinc electrode and bubble behavior of a zinc-air flow battery during charging. The results revealed that when charging without electrolyte flow, zinc was deposited in a dendrite structure, and the dendrite growth rate increased with the charging speed. In contrast, it was observed that dendrite growth was suppressed, and dense zinc deposition was achieved even under high current density conditions when charged with a flowing electrolyte. Furthermore, the voltage fluctuation due to a decrease in the reaction area caused by the bubbles generated by water reduction was successfully suppressed when the flow was present. This was achieved by removing the bubbles through convection, which prevented the increase in overvoltage. Overall, it can be said that the flow of electrolytes has a positive effect on battery performance, as it helps to achieve a more uniform deposition of zinc and to prevent voltage fluctuation.

Since boiling is a phenomenon with high heat transfer performance, it is expected to be used in various industrial fields such as emergency cooling in nuclear power plants, power device cooling for EVs and next-generation CPU cooling in data centers. So far, various research on boiling have been carried out in the background of these trends. In particular, many studies have been conducted to improve the critical heat flux (qCHF) which is the limit of boiling heat transfer. However, since the mechanism of qCHF is a complex phenomenon, the methods of qCHF improvement are still unconstructed. Here we demonstrate the high-performance heat transfer surface using electrodeposition which fabricates copper porous plate. We found that this copper porous plate has higher qCHF (3.7 MW/m2) than the plain surface (1.3 MW/m2) in saturated pool boiling of water at atmospheric pressure. The structure of copper porous plates is investigated by X-ray CT and SEM. The copper porous plates have a honeycomb porous structure consisting of porous area and vapor escape channels extending vertically from the substrate. In addition, the diameter of the vapor escape channels increases from the substrate to the top surface. This surface structure can supply the coolant to the heat transfer surface with the reduction of pressure drop. Our results show that the mechanism of qCHF improvement using porous plate depends on the wicking phenomenon and structure. We expect that these results will help in the development of high-performance heat transfer surfaces for various industrial applications.

The authors developed a vibration suppression device (VSD) that has variable moment of inertia using magneto-rheological (MR) fluid in order to get series inertia mass effect for vibration reduction. In previous paper, the proto-type VSD was manufactured and the variable series inertia mass effect was confirmed. From the experimental results, the series inertia mass effect can be switched by the current of electromagnets. And theoretical model of solidified form of the fluid was proposed by formula and the trend were closed the experimental results. Then the vibration tests of 1DOF system with the VSD were conducted by a shaking table. Vibration reduction of the VSD was confirmed. The current of the electromagnet was controlled by using the reinforcement learning. But the fluid behavior inside the flywheel has not investigated before. In this paper, to investigate the fluid behavior inside the flywheel, it is analyzed by computational fluid dynamics (CFD). Three types of the flywheels are manufactured, and 2 types of electromagnets are used here. Equivalent inertia mass in totally 20 cases of the flywheel and the electromagnets are numerically calculated by using the OpenFOAM, and also measured in experiments. From the analytical results, convection is initially occurred in the direction of the magnetic poles when the magnetic field applies, and then the particles are eventually solidified at locations other than near the magnetic poles. Finally, the analytical results are compared with the theoretical and the experimental results.

In general, the life of a rolling bearing is calculated as the total number of rotations until rolling fatigue occurs on the raceway. However, when rolling bearings are used under light loads and high rotational speeds, they are damaged not by rolling fatigue on the raceways but by cage wear due to lubrication life. In such cases, the conventional method for calculating the rolling bearing life is not applicable. Rolling bearings for traction motors of railway vehicles (hereafter referred to as traction motor bearings) are one example of this and are replaced primarily due to lubrication life. However, there is no practical way to calculate lubrication life and these rolling bearings are replaced empirically. The purpose of this paper is to obtain basic data to create a method for calculating lubrication life. Therefore, traction motor bearings were rotated under conditions like actual operating conditions to reproduce damage due to lubrication life. As a result, damage due to lubrication life could be reproduced, so the next step was to investigate the effect on lubrication life when the operating conditions of traction motor bearings were varied as parameters. The parameters considered were “bearing temperature”, “vibration acceleration”, and “grease mass”. As a result of these verifications, lubrication life decreased exponentially when the bearing temperature was increased. In addition, lubrication life decreased exponentially when vibration acceleration was increased. Furthermore, lubrication life increased logarithmically when the grease mass was increased. The effects of these verified parameters on lubrication life could all be formulated within this paper.

This paper describes the construction of the numerical model of a passive damping device called eMDVA (embedded Mass Dynamic Vibration Absorber) and experimental investigation of the eMDVA's multi-modal damping effect for elastic vibrations of a plate-like structure. The eMDVA consists of a ball-like mass embedded in a viscoelastic medium; and the mass can vibrate in every direction. When the thickness of the viscoelastic medium differs in the X, Y, and Z directions, the ball-like mass has different natural frequencies for every vibration direction. An appropriate numerical model that can predict these natural frequencies correctly is needed to design the eMDVA; in particular, defining the viscoelastic properties is an important and challenging subject. In this work, the Prony series is used to express the viscoelastic material, and the setting process of the coefficients in the Prony series is studied. It has been shown that using a sufficient number of terms in the Prony series and using sufficient measurement data to define their coefficient leads to good results in expressing the viscoelastic material. Using the constructed viscoelastic model, vibration characteristics of the eMDVA, such as the change of the natural frequencies versus the viscoelastic material's shape change and frequency response characteristics, are investigated numerically using a commercial finite element software Ansys. After that, an eMDVA is produced and applied to a plate-like elastic structure. A series of excitation tests are conducted, and the multi-mode vibration reduction effect by the eMDVA has been demonstrated.

Chatter vibration generated in cutting thin-walled cylindrical workpiece is self-excited vibration caused by the coupling of two natural vibration modes which have the same number but different position of the node diameters in thin-walled cylindrical workpiece (sine mode and cosine mode). The stability of the coupled vibration system can be determined by whether the gain of the open-loop transfer function is greater than 1 at the phase crossover frequency of the open-loop transfer function. Since the natural frequency of the sine mode and the natural frequency of the cosine mode of a thin-walled cylindrical workpiece match, the natural frequency becomes the phase crossover frequency with a phase lag of 180°. The open-loop transfer function of this coupled vibration system is represented by the product of three quantities，cutting depth - principal force characteristics (block 1), principal force - thrust force characteristics (block 2), thrust force - translational displacement characteristics (block 3). Of these three characteristics, only the thrust force - translational displacement characteristics reflect differences in workpiece dimensions. In this paper, it is shown that the generation of chatter vibration can be predicted from the value of thrust force - translational displacement characteristic at natural frequency (resonance peak value).

In order to experimentally determine the controlled variable values realizing a quasi-zero stiffness of a cable driven continuum robot, this paper presents an experimental method for quantitatively and accurately assessing the stability of a robot in a static equilibrium state with the controlled variables being kept at their target values. Experimental stability assessment requires consideration of the difficulty for an actual robot to achieve the unstable static equilibrium states and the fact that measurement errors can greatly affect stability assessment. Thus, the proposed experimental method assesses the stability of a robot by determining the smallest eigenvalue of the Hessian matrix of the total potential energy through measuring the relationship betweensmalldisplacementandworkdonebyexternalforcesfromastaticequilibriumstatetobeassessed. This measurement sets the controlled variables on an experimental robot that stably achieve the static equilibrium state instead of the controlled variables to be assessed. Moreover, an additional small displacement is given in the same direction as the eigenvector of the smallest eigenvalue of the Hessian once obtained. Then the stability of a planar 3-DOF continuum robot consisting of a variable-length elastic rod and two cables with the controlled variables set as the rod length and the cable tensions was assessed by the derived stability analysis and the proposed experimental method. The experimental results showed that the stability of both stable and unstable static equilibrium states was quantified, with a high repeatability of the results. Additionally, the stability assessment value decreased from positive to negative with the increasing cable tensions, consistent with the theoretical results. Furthermore, giving the additional small displacement enables a more accurate assessment of the stability. Finally, an approximation of the experimental results successfully determined the controlled variable values that allow the experimental robot to realize the neutral static equilibrium state.

This paper presents a data augmentation method for generating a surrogate model of numerical analysis results. The proposed method focuses on the relative frequency of learning data for generating a learning model using deep learning techniques. Generally, data augmentation techniques are known to be useful for improving prediction accuracy. Adding noise and data duplication are commonly used for predicting numerical simulation results, but it is essential to carefully consider the amount of noise or choose a duplication target. However, these techniques are not appropriate for generating surrogate models. The reason is that the numerical analysis results mostly have high data imbalance, and no specific solution has been presented. The method proposed in this paper solves this problem and aims to be a simple and highly versatile data augmentation method. This paper describes the application of the proposed method to predict two-dimensional stress fields. It was confirmed that by increasing the number of data augmentations using the proposed method, the prediction errors were reduced for three different stress components stably. Additionally, it was confirmed that the prediction accuracy improved 5.81 to 27.0% compared to that of the data augmentation by simple duplication.

In recent years, condition monitoring technologies have been widely developed aiming at safer railway operation and maintenance cost reduction. Condition monitoring systems of railway for both from onboard and on track have been widely studied thanks to the recent development of sensors. Using equipped sensors on track, as an example of the bogie abnormality detection, the diagonal imbalance of wheel-load for four wheels in a bogie is closely related to the running safety on curve. If serious problem happens in the bogie frame, the diagonal imbalance may change, and wheel load reduction occurs. For these reasons, the monitoring of the diagonal imbalance from track has a potential usefulness. However, in our previous research, the measured imbalance can be varied even though the focused bogies run on the track under almost the same condition such as boarding rate, vehicle velocity and so on. If the cause of variation is clarified, the limit of abnormality detection accuracy can be clarified. Therefore, in this study, variation of the measurement of bogie’s diagonal wheel-load imbalance are investigated. Furthermore, factors that affect the variation of the measurement is investigated using MBD simulation.

In the development of mechanical structures, it has been required for a long time to establish a modular design method of resonance by controlling the vibration coupling among subsystems. From the analytical perspective of coupled vibration among modules, the kernel compliance analysis (kCA) method exists. The kCA method has the advantage of being able to analyze vibration coupling when modules, which will be called subsystems below, are connected with multiple degrees of freedom. However, the kCA method is not directly applicable to damped systems. This is because the kernel compliance matrix, which is the core of the kCA method, of the damped system is a complex symmetric matrix. To avoid the difficulty, in this paper, the Autonne-Takagi factorization is employed instead of the general eigenvalue decomposition to decompose the complex symmetric matrix. Furthermore, the old-type frequency-based substructuring was introduced so that vibration coupling analysis can be performed among multi-subsystems. With these extensions of the kCA, a method to analyze the energy distribution ratio between subsystems was derived. By using the analysis results, it is possible to shift the resonance frequency and determine the appropriate placement of damping materials.

This paper describes a method for continuously measuring the contact position between the wheel and rail using strain gauges. The authors investigated the relationship between the bridge output sensitivity rate and the change in the placement of strain gauges using the result of finite element analysis for the instrumented wheelset. It is noted that the bridge output sensitivity rate is defined as the bridge output change per unit distance of the contact position (load position). Based on the result, strain gauges position suitable for measuring contact position was identified. On the other hand, static load tests were conducted on the instrumented wheelset with strain gauges attached to measure contact forces (wheel load, lateral force, and tangential force) and positions, respectively. The test results were found to be generally consistent with the finite element analysis results, and it was also observed that the load position of each contact force influenced each bridge output. Finally, this paper proposes a method for calculating the contact position by solving a nonlinear equation. The calculation uses the results of the load tests and also wheel rotation angle, bridge outputs, wheel load, lateral force and tangential force which measured in running railway vehicle. Simulations were performed for various cases, and the contact positions were obtained stably and continuously. This suggests that the proposed method is reasonable and applicable to various situations.

This paper discusses an approximate multiscale stochastic stress analysis of a randomly arranged unidirectional fiber reinforced composite plate under the transverse tensile loading. The multiscale stochastic stress analysis is desired for quantitative apparent strength evaluation of composites with random microstructure, and an efficient method has been attractive in terms of computational efficiency. In particular, since huge numbers of fibers are included in an actual composite structure, accurate and efficient estimation of microscopic maximum stresses for random fiber location variation and their probabilistic properties is required. For this analysis, the successive local approximation method is employed. The effectiveness of the approximate multiscale stochastic stress analysis has been discussed, while the square array is assumed in previous literature. For applicability confirmation of the method to evaluation of an actual problem, the usage of a hexagonal array model should be discussed. From these backgrounds, the above analysis with the hexagonal array model is performed, and validity and effectiveness of this approach are discussed with the numerical results.

In this study, we have developed a non-destructive inspection system for detecting external wall tile delamination by incorporating a pulse water jet impingement force into a suspended apparatus. The delamination inspection using a pulse water jet offers flexibility in adapting to variations in the distance between the inspection device and the inspection surface, a challenge inherent to the suspended apparatus. Furthermore, the delamination inspection using a pulse water jet exhibits exceptional safety and cost-effectiveness. Using this inspection system, we conducted a delamination detection test on tiles with delaminated mortar and were able to detect it. The inspection speed of this apparatus is approximately 10 centimeters per second in horizontal movement, allowing for an inspection rate of roughly 18 square meters per hour for tiles with a 50-millimeter spacing. This inspection speed is comparable to that achievable by human operators. Moreover, the system can perform inspections at heights of up to 30 meters above ground level. This inspection system has the potential to address the issue of labor shortage by facilitating automation.

Oxymethylene dimethyl ether (OME) is a promising carbon neutral fuel for reducing well-to-wheel CO2 emission and expected to suppress soot formation due to the lack of C-C bond. The present study aims to develop a chemical reaction model to predict soot formation processes of OME3. Initial reaction processes of OME3 within 10 ns after the onset of reaction were traced using molecular dynamics simulation under various Φ-T conditions (Φ: equivalence ratio, T: temperature), and reasonably converted to a chemical reaction model. The model was coupled with a conventional soot formation model for paraffinic fuels, which enables to simulate soot formation processes of OME3. The Φ-T map of soot yield for OME3 was calculated and it appeared that OME3 can largely suppress soot formation compared with n-hexane as a paraffin fuel. Reaction path analysis revealed that the formation of unsaturated C2 species for OME3 is delayed and reduced compared with n-hexane, which leads to the soot suppression effect of OME3.

Recently, there has been a growing interest in utilizing surface texture to enhance the tribological properties of sliding components. Particularly noteworthy is the application of tool vibration at ultrasonic frequencies for efficiently generating surface textures. This study focuses on generating surface texture on the end surface of a stainless steel disk through ultrasonic assisted turning. The mathematical expression of the theoretical texture configuration, derived from the tool trajectory, is closely aligned with the actual machined surface. A novel geometric analysis was conducted to address the challenge of interference between the finished surface and the flank surface, resulting in a reduction in texture height. This analysis revealed that the texture height error from the theoretical value was limited to within 10%. Ball-on-disk tribological experiments were also performed on the textured surface to assess starting friction phenomena. The findings indicated that surfaces with texture exhibited a more minor fluctuation in the starting friction coefficient compared to those without texture. In summary, this paper explores the efficient generation of surface texture on stainless steel disks using ultrasonic assisted turning. Theoretical configurations were mathematically expressed and aligned well with actual machined surfaces. The study also introduced a novel geometric analysis to address interference-related texture height reduction. Moreover, tribological experiments demonstrated that textured surfaces experienced a more stable starting friction coefficient, highlighting the potential of surface texturing for improving tribological properties in sliding components.

Currently, measurement of long and thin objects is done by the contact method. However, some problems such as long measurement time including fixing the gauge and the object to be measured and the effects of buckling and other problems caused by contact loading. Therefore, there is a need for length measurement of long and slender objects in a short time with high accuracy. In this study, we deem that the non-contact spatial frequency filtering method, which has been studied and developed in our laboratory, can satisfy the requirements given in this study. This method adopts the optical configuration of the traditional projection optical system, but removes the transmitted ray and only allows the high-order diffracted rays generated by the edge of the object to be measured to enter the camera under the condition of parallel ray irradiation. At this time, the diffracted ray generated by the edge of the object to be measured will appear as a bright-dark-bright line segment on the camera. And the position with the lowest brightness value in the dark part will be the specific position of the edge of the object to be measured that is illuminated by parallel light. The standard deviation of the results in 30 repeated placement experiments was around 1 micrometer.

A rotary tungsten inert gas (TIG) torch has been developed to enhance the quality and complexity of fabrications in wire and arc additive manufacturing (WAAM). This study explores the influence of arc length on deposition characteristics within a rotary TIG torch by adjusting the wire feed speed, travel speed, and shielding gas type. The findings reveal that the unique vertical wire feeding mechanism of the rotary TIG torch prevents the wire-feeding position shift typically observed in conventional TIG processes. However, extended arc lengths in the rotary TIG setup tend to induce arc deflection and molten metal scattering due to the employment of a tilted electrode. Specifically, at high wire feed and travel speeds, bead continuity is compromised by molten metal scattering. Conversely, at low travel speeds relative to wire feed speeds, defect-free deposition is achievable across a broad arc length spectrum from 4 to 20 mm using rotary TIG. Furthermore, decreasing the wire feed speed in proportion to the current and increasing the heat input per material input minimizes the contact time between the wire and the molten pool, thus mitigating arc deflection. Employing helium-mixed gas as a shielding gas facilitates defect-free deposition over an extensive range of arc lengths, even under conditions that typically induce humping with pure argon.

Low-frequency vibration cutting technology can actively generate an intermittent cutting process in which chips are broken up by vibrating the tool in the feed direction synchronized with the spindle rotation. The sinusoidal oscillation superimposed to feed drive motion triggers cutting thickness fluctuations so that air cutting occurs. To attain efficient and practical machining, selection of appropriate conditions for low-frequency vibration cutting is important. From a practical point of view, it is necessary to analyze the cutting process for its effects on tool wear as well as chip breakup. Low-frequency vibration cutting has been reported to reduce average cutting force and average cutting temperature. On the other hand, few studies have analyzed the effect of tool trajectory on the tool life, and thus the mechanism has not been fully clarified. In this study, the effects of low-frequency vibration on the tool life in turning operations were experimentally investigated for carbon steel, stainless steel, and titanium alloys. In low-frequency vibration cutting of ductile materials such as carbon steel and stainless steel, tool damage was significantly improved by designing an intermittent cutting process with large amplitude. On the other hand, the tool life for titanium alloys was deteriorated in low-frequency-vibration cutting. The experimental results indicated that the higher the vibration speed, the faster the tool wear progression in titanium alloy machining. Model-based analysis of the cutting force revealed a characteristic mechanism of the flank wear development that depends on the tool trajectory with low frequency vibration.

Some nanoscale technologies are being employed without a full understanding of the underlying phenomena. Both static and dynamic observations of nanoparticles are essential for investigating these phenomena. While there are several methods for static observation such as scanning electron microscopy typically in a vacuum environment, however, there are few methods for dynamic observation. One of the dynamic observation methods is to observe nanoparticles using an evanescent field, a unique field that emerges only near the surface being observed. The dynamic observation method has been proposed for measuring the three-dimensional positions of moving nano-particles in liquid using a multi-wavelength evanescent field. However, the absolute height of the nano-particles remains unexplored in this study. Hence, to establish this method, it is necessary to confirm the absolute distance or the height from the surface being observed at the same position by other reference measurement methods. In this paper, an optical resin with a refractive index close to the water was formed as an invisible reference tilt surface that was thinner than 200 nm in height. We also constructed a compact interferometric optical system to utilize optical interferometry that can measure the height of the tilt resin without contact and with nanoscale accuracy. Polystyrene standard nano-particles suspended in water were deposited onto the water-invisible tilt resin and was measured the height at each position on the tilt resin by a multi-wavelength evanescent field. As a result, it was confirmed that the 3D position measurement of particles using multi-wavelength evanescent fields tends to follow the resin surface height well. At the heights under approximately 100 nm, the differences in height were less than 5 nm between multi-wavelength evanescent fields and interferometry measurement, and the precision (2σ) also was approximately 5 nm.

An investigation is carried out through experiments and numerical calculations for the improvement of the resolution of measuring the pitch deviation of a diffraction scale grating with the diffracted beams. Since the changes in angles of diffraction of the diffracted beams detected by an optical head are utilized to evaluate the pitch deviation in the method, the sensitivity of the optical head directly affects the resolution for measurement of the pitch deviation. Meanwhile, in the previous studies, the resolution of a laser-autocollimation unit in the optical head for the detection of the change in the angle of diffraction of a diffracted beam has been limited to approximately 0.1 arc-second; this has been a bottleneck in increasing the resolution for measurement of the pitch deviation. In this paper, an investigation using a prototype optical head is first conducted in preliminary experiments to clarify the cause of the degradation of the resolution for measurement of the pitch deviation. Numerical calculations are also carried out to confirm the influence of the multiple longitudinal modes (MLM) of a laser beam, which is suggested as the main cause of the degradation of resolution in the results of preliminary experiments. Based on the results of experiments and numerical calculations, an attempt is made to employ a laser beam having a single longitudinal mode (SLM) in the optical head. The pitch deviation of a scale grating with a nominal pitch of 4 μm is measured by a prototype optical head with an SLM laser to verify the improvement of the resolution for measurement of the pitch deviation.

This study developed a voxel-based method to simulate machining error caused by elastic deformation of the tool and workpiece in end milling. The tool and workpiece shapes are represented by a set of cutting edge points and a voxel model, respectively. The cutting force is calculated based on the collision state between the cutting edge points and workpiece voxels. The elastic deformation is analyzed based on tool and workpiece elastic deformation models and the predicted cutting force. The tool deflection is predicted by a composite model of a cantilever beam and spring. In addition, each voxel representing the workpiece is connected to adjacent voxels using beam elements to build a stiffness matrix for the workpiece. The stiffness matrix and the predicted cutting force are used to predict the workpiece deflection. The predicted workpiece deflection is converted to tool distortion, which keeps the geometric relation between the tool and workpiece equivalent. By considering the tool deflection and distortion corresponding to the workpiece deflection, the cutting edge trajectory is simulated. Machining error can be obtained from the predicted cutting edge trajectory. The change in the workpiece shape is represented by removing voxels. The advantages of this method are that re-meshing is not required to update the workpiece shape change and that re-building the stiffness matrix is not time consuming. Additionally, both models to predict the cutting force and the deflection are linked closely to each other based on the voxel model. It is very important to consider the effect of the elastic deformation on the uncut chip thickness calculation in the cutting force prediction. Especially in the cutting of a thin wall, the effect of the elastic deformation on the uncut chip thickness in the cutting force prediction is quite large. The predicted machining error in the cutting operation of a thin wall had good agreement with the measured one in the experimental verification.

This paper examines the machining accuracy when simultaneously machining pilot holes and threads, and the machining accuracy when machining threads after pilot hole drilling. To verify them, cutting forces were measured in the tool rotation coordinate system using a wireless holder. To examine the influence of the machining area of the tool bottom edge machining the pilot hole, three patterns of pilot hole diameters (φ0 mm, 7.0 mm, and 8.5 mm) were used. The results showed that when the pilot hole diameter is φ0 mm, the cutting force in the plane direction does not increase significantly compared to the case with a pilot hole due to the offset effect of the cutting forces generated by the facing cutting edges when machining the bottom edge. Therefore, if chip entrapment can be prevented, it is highly possible to omit the pilot hole, improve machining efficiency, and maintain machining accuracy. It was also found that tool vibration could be reduced. However, when the pilot hole diameter is Φ0, the load in the tool axis direction increases. Therefore, it was also found that machine rigidity and tool life must be considered due to the increased load during machining. These results are summarized in this paper.

This study proposes a method for extracting the machining region machined by swarf machining and hole drilling from a Standard Triangulated Language (STL) data exported from 3D CAD and automatically generating a tool path. First, a method is proposed for extracting the machining region and obtaining geometric features, such as slope, curved surfaces, holes, and pockets, from the STL data exported from 3D CAD. The STL data uses only triangular mesh data and drops all information, which is necessary for extracting the removal volume for the machining and geometrical characteristics. Then, a half-edge algorithm is proposed that clarifies the connection relationship between planes by integrating triangular meshes of the same plane in a model in STL data and realizes automatic extraction of machining regions through the analysis of shape data. Subsequently, a method is proposed to determine the 5-axis indexing posture and generate a tool path according to the geometrical features of the machining region. A machining experiment was conducted to validate the effectiveness of the proposed method. As a result of the machining experiment, it was confirmed that the tool path automatically generated from the STL data exported from 3D CAD can be machined without any problems and with a practical level of accuracy.

The main study objective was to evaluate the influence of the perspective "Internal" (coolant is supplied to the channel inside the indexable insert body) and "Combined" (coolant is supplied to the rake and flank faces through the channel inside the indexable insert body) Cooling Schemes on the temperature of the contact point between the tool and the workpiece, on the heat distribution inside the indexable insert body, and (additionally) on the cutting forces. The contact point temperature and cutting forces were investigated during the non-orthogonal turning of SUS304 Stainless Steel at speeds of 180, 140, and 100 m/min with constant feed and depth of cut. The heat distribution was examined through 2D simulations using DEFORM 2D3D software. The evaluation of the perspective cooling schemes' influence on the selected parameters was performed by comparing the obtained data with the test results of the "traditional" external cooling and dry cutting under similar cutting modes. According to the comparison results, the perspective cooling schemes demonstrated a slight decrease (~3-7%) in the temperature of the contact point between the tool and the workpiece, a significant decrease in the heat distribution (~38-55%) inside the indexable insert body and, in some cases, a decrease of the cutting forces. Based on the study results, the authors confirmed the influence of perspective cooling schemes on the selected parameters and suggested a further positive effect of these schemes' utilization on the cutting tool life.

Automated process planning is one of the means to shorten production lead time, and there have been many previous studies because it is particularly effective for high-mix, low-volume production factories. However, to build a practical automated process planning for organic shapes, it is necessary to consider the computational cost and keep the machining time as short as possible. Therefore, this study proposes an automated process planning system that effectively combines turning, which has good workpiece removal efficiency, and milling, which allows more flexible machining. The system extracts the contour line model and its solid of revolution as point cloud data from the 3D CAD model in STL format, and performs process planning based on these extracted point cloud data, the specified workpiece geometry, and the machining conditions. Furthermore, it automatically generates tool paths and NC programs that consider tool interference. Machining experiments were conducted on a multitasking machine to verify the validity of the automated process planning system proposed in this study. As a result, it was confirmed that the proposed system can perform automated process planning for organic shapes, and is effective in reducing machining time when roughing by turning is applied.

Non-step drillings of deep holes with twist drill are required to achieve high production rates in machine shops. However, tool breakage sometimes occurs due to chip clogging in the holes. The surface finish is also deteriorated by chip scratching. These machining troubles are induced by the change in the chip flow accompanied by tool wear progress. This paper discusses the cutting process in drillings of deep holes in terms of the geometrical change in the cutting edge with the tool wear. The chip flows towards the radial direction with the change in the edge shape when the tool wear increases. Then, the chip clogging in the hole induces a large oscillation in the cutting force. The chip flow is also analyzed with the change in the edge shape due to the tool wear by the energy-based force simulation.