There is a vibration speaker device called an audio exciter. The potential of the exciter as a vibration device was investigated by conducting experiments on a single steel plate and comparing the results with the impact test method using an impulse hammer. The power spectrum results showed that the exciter was able to vibrate up to approximately 20 kHz, and it was shown that it was possible to predict the magnitude of the exciter's FRF from the impulse hammer FRF results. Furthermore, a comparison with the impulse hammer results showed that the ILF identification was qualitatively better.

This article describes a developed education material designed to enhance welding skills in a short period. By comparing the current and voltage during waveform welding based on the welding posture of both experts and beginners, the differences in their data characteristics were clarified. This method allows users to estimate the presence and location of welding defects without relying on traditional non-destructive inspections, such as X-rays. Specifically, the education material used a welding plate size of L150 * W250 * t9mm for multi-layered butt welding, employing various postures: flat, horizontal, vertical, and overhead. To enhance the learning experience, a video featuring appropriate captions showcasing special welding techniques and insights from experts was created. This video was uploaded to AR glasses, which students wore while practicing welding. Afterward, this welding support education material was able to clarify the useful education material for students, then they provided candid feedback to the authors. Based on these results, the validity of the developed education material was confirmed.

Pollination work for fruit trees involves an extremely large amount of work. To solve this problem, we have been developing a rotary-wing UAV system that sprays pollen into the center of target flowers or flower clusters based on image processing. This paper describes the design and prototyping of a pollen atomizer and the results of experiments. A pressurized container was used to reduce weight and gain the flying distance of pollen. The mass flow rate to be discharged using the pressurized air depends on the nozzle diameter. Thus, the relationship between the nozzle diameter and the spray duration was determined by calculations and experiments. Based on these results, the sprayer was designed, and the spray form and number of injections were investigated by experiments.

The issues with pressurized metered-dose inhaler (pMDI) used for inhalation therapy in respiratory diseases include the misalignment of spray timing and inhalation, which can lead to medication adhering in the oral cavity and potential side effects. Spacers allow the aerosolized medication to linger in the chamber, enabling the patient to inhale at their own timing, thus eliminating the need for synchronization of spraying and inhalation. However, the adherence of medication to the spacer’s interior can reduce the amount of medication that can be inhaled. In this study, we used a system combining an inhalation simulator and an aerodynamic particle sizer (APS) to replicate patients inhalation patterns and measure the amount of aerosolized medication and particle size distribution, investigating the impact of spacers on aerosolized particles. By using a spacer, the inhalation speed and volume do not affect the process, allowing approximately 80% of the aerosolized medication to be inhaled under appropriate conditions. However, at slower inhalation speeds, the influence of the one-way valve was observed, indicating that it is necessary to select a spacer that matches the inhalation speed. Additionally, the amount of medication available for inhalation decreased with prolonged retention time after spraying, suggesting that patients should be instructed to begin inhalation promptly after spraying.

Prime structures are link chains with 0 DoF (degrees of freedom), not including subchains with 0 or fewer DoF, which are expected to be used in systematic kinematic analyses and design of link mechanisms. This paper describes the motion analysis of link chains induced from spatial prime structures. For all 3-link spatial prime structures, namely, RCS, PCS, RSS, PSS and CCC prime structures, and a 4-link spatial prime structure with a single kinematic loop, kinematic analysis methods are established. Displacements, velocities and accelerations of link chains, which are induced from prime structures by removing one link, are derived. More than one link chain is induced from a prime structure, but if an analysis method is developed for one link chain, others can be easily analyzed using coordinate transformation. In the displacement analysis, we derive algebraic solutions as possible, and for the rest, we develop a method to find all solutions, including complex solutions as solutions for a higher-order algebraic equation. Displacement of a multi-loop prime structures is also analyzed with combination of analyses of several single-loop prime structures. For an example of the application of prime structures, the motion of a spatial RCS-R-PSS 6-link mechanism with 1 DoF is analyzed. It was confirmed that the proposed analyses were correct and effective because the results with the proposed analyses completely agreed with those obtained from CAD software.

Electrical discharge machining (EDM) is capable of achieving high-precision dimensions and surface roughness on high-hardness metallic materials, making it a critical process in mold manufacturing. EDM is well-suited for deep hole machining in high-hardness materials due to its low machining force. However, when using a commercial die-sinking EDM machine for deep hole machining, the process significantly slows down when the aspect ratio (L/D) exceeds 5. If the machining debris and gas bubbles present between the electrodes can be effectively removed, it is anticipated that deeper holes could be machined more efficiently. In this study, we investigate the use of specially designed electrode shapes for deep hole machining. It is expected that different electrode shapes will result in different behaviors of the bubbles and machining debris between the electrodes. To enhance the removal of bubbles and debris, it is crucial to understand the fluid flow between the electrodes. In this research, we conducted CFD (Computational Fluid Dynamics) analysis to consider the impact of electrode shape on the flow between the electrodes. We report the findings on how electrode shape affects the flow of the machining fluid and the removal of bubbles between the electrodes.

A method for optimizing the shape, posture and arrangement of sipes based on parametric design factors was developed to improve the grip performance of winter tyres. This is a method that involves repeatedly conducting friction coefficient measurement experiments on a group of 3D-printed models made of materials with physical properties equivalent to tyre rubber, and Bayesian optimization of multiple parameter combinations that are expected to enhance performance. First, the effectiveness of this method was verified by evaluating the step-by-step improvement in grip performance with each iteration of the Bayesian optimization loop. Furthermore, we attempted to improve grip performance on the newly emerged ‘Twist sipe’ design created by expanding the design space while confirming the effectiveness of this method. Finally, the discussion revolved around the type and selection of acquisition functions necessary for acquiring a Gaussian process regression model that will be used in selecting the combination of design factors for the next loop in Bayesian optimization.

In this study, the strength improvement of adhesive joint is discussed for the steel/epoxy butt joints due to the duplicated interaction of additional notches. The experiment is conducted by varying the adhesive layer thickness h and the notch depth t in the range h =0.1~2.0mm and t =0.4~1.7mm when the specimen diameter D =12.7mm and the interval between the notch and the interface c =1.0mm. The intensity of the singular stress field (ISSF) at the interface end is analyzed by the proportional method, as well as the interface stress distribution. The results show that the adhesive strength can be expressed as a constant ISSF independent of h and t except for too deep notch. The adhesive strength σ_c^JIS (h) of the butt joint measured by following JIS (Japan Industrial Standard) without notch increases with decreasing h due to the interaction of upper and lower adhesive bondlines. The adhesive strength for the case of additional notches increases with increasing t due to the duplicated interaction. The analytical and experimental results showed that the adhesive strength can be improved due to the duplicated interaction of suitable additional notch.

It is generally known that springback occurs in the bending process of rebars. Prediction of springback is important to improve the quality of bent rebars. Studies have been conducted on the prediction of springback using CAE. It has been reported that variations in the material properties required for analysis can lead to variations in the predicted results and that material modeling and calculations can be very time-consuming. There is a generally known equation for angle change with springback. This equation is for bending with a uniform radius of curvature. Bent rebars do not have a uniform radius of curvature due to the processing method. The purpose of this research is to establish a springback prediction method by in- process measurement of bending machines. In this report, as a first step, the angle change with springback when round steel bar is bent by in the targeted processing method was considered based on the equation about springback. By examining the shapes for each region of bent steel bar, it is possible to calculate the angle change with springback based on the equation about springback. The angle change with springback at the target rotation angle for rebar can be predicted by bending with unloading before reaching the maximum bending angle using a bending machine.

This article describes experimental studies using in-situ observation and electric contact resistance method (ECR) on lubrication properties of polyisobutylene (PIB) used as screw tightening lubricant under various surface roughness conditions. The results showed that in the case of surface roughness Ra of 0.011 μm, the separation degree showed 0.87-1 in the test duration, while in the case of Ra of 0.095 μm, the degree decreased over time and reached to zero in the full starvation regime. In addition, wear occurred on the contact area at the condition under low separation degree. It was also found that under the full starvation condition, shear stress was relatively high which corresponded to that in the solid state, and that the stress did not relate with the surface roughness. In the spinning friction test, wear was observed on the contact surface in high surface roughness condition, meanwhile the shear stress was almost similar to that in low roughness conditions. These results reveal that even in high roughness condition, the direct contact occurred on the surfaces was local, and that the solid-like film formed on the surface inhibited significant wear. The lubrication condition in the actual tightening process was also discussed from the results based on this study.

In recent years, the improvement of productivity by increasing working speed has been demanded in the production of liquid packaging bags such as retort pouches for food and infusion bags for medicine. Conventional vacuum suction grippers cannot sufficiently handle these packaging bags because they are soft in various shapes and sizes, and deform a lot due to inertial forces when transported at high speeds. Therefore, we developed a vacuum suction gripper equipped with a link mechanism to follow the deformation of packaging bags during transfer and to suppress the deformation. This adsorption gripper is designed to effectively convey flexible materials, and its effect on the conveying characteristics of flexible materials was investigated through experiments. The experimental results showed that the link mechanism was able to prevent flexible objects from falling. In particular, the results indicated that appropriate spring conditions can suppress the deformation of flexible objects during acceleration. These results are expected to contribute to improvements in the design and manufacturing process of vacuum suction grippers.

When torque characteristics of a grease-lubricated small ball bearing, 608, were experimentally checked, the results showed that even bearings from the same manufacturer had large variations in torque, and that the torque did not converge even after 24 hours at low rotational speed. However, after the experiment, the internal grease was washed away, and the torque was measured using the same bearing with a small amount of oil for lubrication, the torque was low and no variations or fluctuations were not observed. The reason why there were torque variations, even though the amount of grease sealed was almost the same, was thought to be due to the state of grease filling. Therefore, in this study, torque in a small ball bearing 6204, was measured with different state of grease filling using a device that can fill a fixed amount of grease into a targeted position. Then, the effect of the initial state of grease filling to the torque was clarified.