Granular materials hold significant promise for the development of high-performance, lightweight vibrationdamping elements, offering increased levels of safety and comfort. This study focuses on exploring the vibration damping properties of pre-stressed granular material. A comprehensive investigation is conducted, to show by how much the damping properties can be improved in a simple solution if the solid material is replaced by granulate from the same material, while maintaining the macro geometry. Experimental results demonstrate that the granular material exhibits a remarkable improvement of up to 560 % in vibration damping performance compared to the same bulk material.

This enhancement is attributed to the synergistic effects of two governing factors. Firstly, the pressure-frequency superposition principle operates at the molecular scale, particularly prominent under high pre-stress conditions. Secondly, physical interactions between granules, commonly referred to as the strong force-network phenomenon, play a vital role at the macro scale, particularly influential under low pre-stress conditions. The combination of these effects that complement each other, results in overall superior energy absorption performance.

The drag force acting on cars in tandem arrangement has been studied in the previous study by using a wind tunnel or a passing water tank in the range of Reynolds number of 8.0×10³ to 10⁶. Generally, it is supposed that the drag force on the following car is reduced by the presence of the leading car in a tandem arrangement, which is called as the slipstream effect.However, in the previous study, it was found that the drag force on the following car increased comparing with that of the single car in the specific conditions both of the inter-vehicle distance and the Reynolds number. To clarify factors increasing the drag force on the following car, we investigated the flow field around car models by numerical simulation and experiment with both PIV and pressure measurement.

This study aims to clarify the robustness of a value of a decay exponent. This parameter characterizes the decay characteristics of grid-generated turbulence obtained using a wind tunnel experiment and a numerical simulation. Here, largeeddy simulation is used as the numerical analysis in this study. Decay characteristics of the isotopically decaying turbulence are compared with those of the grid turbulence reproduced in the wind tunnel experiment. Main results of this study are that the values of the decay exponent for grid turbulence are obtained after compensating for the negligible wind tunnel blockage effect, that homogeneous isotropic turbulence is reproduced using large-eddy simulation with a value of the decay exponent that is close to the experimentally measured value of the decay exponent, and that the effects of anisotropy and Reynolds stress obtained in this study using LES are not significant.

In order to achieve carbon offsets and the SDGs by 2050, there is a need to reduce CO₂ emissions and advance clean energy creation technologies. In addition to reducing CO₂ emissions, it is crucial that we also reduce the energy we consume in industry, society, and our daily lives in order to lessen our impact on the environmental. In light of this, our study focuses on energy harvesting, which is one of the energy-saving technologies. As part of our research on energy harvesting, we investigated electrical power generation when flow-induced self-excited vibration is generated in a PVDF film in a uniform flow. The generated voltage and current were investigated by installing a rectangular PVDF in a uniform flow and varying the flow velocity. When the PVDF motion in the flow was visualized, it vibrated significantly while maintaining twodimensionality in the spanwise direction. Further, when the self-excited vibration generated a strong upward or downward flow near the downstream edge of the PVDF film was formed.

Micro-droplet collision-coalescence processes can be observed more efficiently by detecting the approaching droplets in advance of the holographic reconstruction. In this study, we experimentally verify the mathematical formulation of the relationship between the stripe pattern on the spectral distribution of the hologram of two micro-droplets and their relative displacement. This relationship enables us to directly estimate the droplet displacements from the spectral distributions of holograms. We record holograms with two dot-printed glass plates while varying the inter-dot distance and confirm that the stripe pattern appears and varies with the distance between the dots. We also confirm that the detected stripe spacings of recorded holograms fit well with the theoretical spacing values calculated with our formula when the two dots are close but not colliding. Our method contributes to a better understanding of cloud microphysical processes, which can lead to more accurate precipitation prediction.

Space debris removal missions in Earth orbit have gained momentum worldwide in recent years. A significant key to debris removal missions is the technology for simulating the motion of the target debris. This study developed a hardwarein-the-loop simulator to imitate the out-of-operation small spacecraft in space. In addition, this study combined the hardware simulator with the motion estimation system. The performance and motion accuracy of the hardware simulator was evaluated, and validity was confirmed with practical precision.

Many researchers have conducted mechanical experiments on beetle exoskeletons (cuticulae) because there is much to learn about their structure and strength. Although the time elapsed between the moments the beetles are sacrificed and the moments in which mechanical experiments could be conducted influences the mechanical properties of the cuticula, it has not been given enough importance in previous studies. This study experimentally clarified the relationship between the elapsed time and stiffness. Cantilever specimens were fabricated from the head horns of male beetles (Trypoxylus dichotomus), and bending tests were conducted 3, 16, and 65 days after the sacrifice. The humidity at the experiments were also recorded because the stiffness of the cuticula depends on the moisture content. Even though humidity during the experiment varied over a wide range of -31 to +23 % for 16 and 65 days compared to 3 days after sacrifice, the change in stiffness for 16 and 65 days compared to 3 days after sacrifice was only -12 to +6 %. The results provide clear numerical guidance when referring to stiffness data from previous studies in which the time since sacrifice was not clear, and when starting future studies discussing stiffness of cuticula.

This paper deals with a method for generating simulation images from a random pattern image and finite element analysis results for the development and performance evaluation of digital image correlation techniques (DIC). The input random pattern image can be either an actual captured image or an artificially generated image. An image before deformation is generated directly from the input random pattern image and the finite element model. The gray value at an integer pixel position in the image after deformation is determined by finding the position of that point in the image before deformation and estimating the gray value using gray level interpolation. This method can be used to generate 3D images for digital volume correlation (DVC) as well as images for digital image correlation. The effectiveness of the proposed method is demonstrated by showing examples of global DIC and global DVC results. The simulation images generated by the proposed method can be used to develop and improve DIC techniques and to study various parameters in DIC, such as subset dimensions, shape functions, element types, and random patterns. Therefore, it is expected to efficiently advance research on DIC/DVC methods.

Extreme corrosion on steel sheet piles, which includes thickness loss and pitting corrosion, has been observed in service canal walls. This extreme corrosion decreases the durability of steel sheet piles and causes buckling phenomena. This study aims to detect strain concentration around pitting corrosion on a steel sheet pile sample in bending stress fields with acoustic emission (AE) and digital image correlation (DIC) methods. In experimental procedures, three types of test samples were used, which had different types of thickness loss and pitting corrosion, even thickness loss, and no thickness loss. A fourpoint bending test with AE and DIC methods was conducted for these samples. In analytical procedures, AE hits, AE energy, and AE source locations in each loading process are analyzed. The DIC method are used to detect strain distribution on surfaces of the test samples. As results, AE sources and maximum principal strain concentrate around the pitting corrosion. The timeseries of the strain concentration detected using the DIC method correspond to those of the AE hits. Thus, the AE and DIC methods can be used to detect the relationship between AE hits, AE sources, and strain concentration in the bending process.

Magnetite nanoparticles are often used as heating carriers for hyperthermia applications and have recently gained attention as a cancer treatment method. The physical properties and functions of magnetic nanoparticles depend on their size and shape. Therefore, it is important to maintain a narrow size distribution and a constant shape. This study aimed to investigate the effect of varying the heating conditions in the pyrolysis method on the shape of magnetite nanoparticles. The results indicated that the size of magnetite nanoparticles increased in proportion to the increase in heating temperature due to Ostwald ripening. The particles were generally circular in shape, but some were polygonal, indicating the crystalline structure of the iron atoms. The results show the occurrence of crystal growth and Ostwald ripening. Magnetite nanoparticles should be formed under lowtemperature heating conditions to obtain a particle size of approximately 12 nm, a requirement for inducing hyperthermia. On the other hand, the particle shape was generally spherical with an aspect ratio accepted in the 1.5, which was found in a cube, indicating that shape evaluation was not highly important.

In the present study, experimental study was conducted on delamination caused in the compression bending test of organic semiconductor devices, and the effect of layer structure, bending strain, and bending frequency on delaminating occurrence and progression was investigated and discussed. In order to improve the flexibility of the flexible OLED, the authors have conducted a tensile test and investigated the delamination behavior due to crack susceptibility and compressive strain of constituent materials of organic semiconductor elements so far. In this study, specimens such as PEN substrate / PEDOT Alq / MgAg, PEN substrate / PEDOT / CBP / MgAg were prepared using wet process and vacuum process and subjected to compression bending test. As a result, the number of stripes due to delamination showed a constant value or a decreasing tendency when the compressive strain was 1% or more, and it was found that the maximum width of the stripes tended to increase although the minimum width of the stripes was not greatly changed. This is considered to be due to the fact that the width of the fringes initially generated increases with the increase in compressive strain and merges with the adjacent stripes.

Hip fracture following a fall is common in elderly people who have poor bone strength. The pattern of trochanteric hip fractures differs among patients and some cases of fracture are difficult to reduce. The loading condition at the proximal femur is one of the factors that affect the fracture pattern. Understanding the relationship between the loading condition and the fracture pattern would improve the accuracy of reduction and promote early healing. A previous study suggested that a bone fracture analysis based on finite element (FE) analysis could be useful for clarifying this relationship. However, such bone fracture analysis has not been verified. This study verifies the validity of a bone fracture analysis by a comparison with the results obtained in a mechanical test for porcine femurs. For both the mechanical test and the FE analysis, a fall to the side was assumed. The tendencies of the load-displacement curves obtained in the mechanical test and the analysis were consistent. There was significant correlation between the mechanical test and the analysis results for all evaluation indices. Furthermore, the fracture states were mostly consistent. These results confirm the validity of a bone fracture analysis.

Softness perception of human is used to perceive material characteristics of touched surface and is applied to devices for haptic feedback and robots with tactile perception. However, there is a lack of study that investigates the mechanism of softness perception. In this study, we developed a fingertip finite element (FE) model to simulate contact between fingertip and plate and then validated the model and the simulation. Additionally, parametric study was conducted to investigate the effect of material properties of touched plate on mechanical responses of fingertip, which was expected to reveal the mechanism of softness perception. The simulation was validated in terms of length and width of contact area when touching surface. As a result, the simulation results were in good agreement with the experimental results reported in previous study. Furthermore, in the parametric study, material properties of touched plate FE model were adopted as parameters. Consequently, differences in minimum principal strain inside the fingertip FE model were found between simulation results using plate FE models with different material properties. Hence, the differences seem to be cues for softness perception.

Metastasis is initiated by an invasion of cancer cells from a primary lesion through the interstitial extracellular matrix (ECM) due to metastatic potential in a process termed the epithelial–mesenchymal transition (EMT). The EMT consists of biomechanical interactions between the ECM and migrating cancer cells as they push and pull their way through ECM collagen fibers. The traction force between a cancer cell and the ECM is a vital parameter in these biomechanical interactions. Therefore, several studies have examined the traction force of various cancer cells before and after EMT using two-dimensional (2D) or 2.5D culture; however, these traction forces have not yet been explored using 3D culture. In this study, we investigated traction force changes in cancer, human cervical cancer (HeLa), and human breast adenocarcinoma (MCF-7) cells before and after EMT in a 3D collagen gel. EMT was induced in HeLa cells using transforming growth factor-β (TGF-β); the addition of TGF-β increased traction forces. Increased cell traction forces by EMT could contribute to enhanced invasiveness and metastasis among cancer cells. This study provides valuable insight into traction forces in identical cancer cell lines surrounded by a collagen-rich ECM network before and after EMT.

Abstract: A quantitative evaluation of the mechanical properties of the human body is significant in the medical and nursing care fields in Japan, owing to the super-aging population. Here, the material properties of the soft tissues of the skin were investigated to prevent pressure ulcers caused by positional immobilization owing to surgery and bedridden conditions. A rheometer and cutometer were used to measure the viscoelasticity of the skin on the arms of three males in their twenties and three soft tissue substitute materials (urethane resin, gelatin, and silicone rubber). The results obtained were analyzed and compared to develop a simple and quantitative whole-body mechanical property measurement technique. The ratios of the viscous to elastic parameters obtained using the instruments were compared. The trends for all materials were consistent. Higher correlations were observed for the rheometer loss tangent tan δ ( loss modulus G" / storage modulus G' ) with the viscoelastic index R parameter of the cutometer having a correlation coefficient r ≥ 0.9. The tan δ of the rheometer can be estimated from the R6 ( = ratio of viscoelastic to elastic extension ) of the cutometer if the time at which the displacement of both measurements occurs is the same.

To achieve a uniform flow in a honeycomb filler, a new type of perforated plate was developed for installation inside the header located upstream of the honeycomb. The homogenisation effect was evaluated based on the pressure loss and standard deviation of the velocity. Compared to the unmodified perforated plate parameters, the maximum flow velocity near the centre of the improved perforated plate reduced to values ranging between approximately 1/17 and 1/10, and the standard deviation decreased to values ranging between approximately 1/38 and 1/9 in each honeycomb.