Bridgestone (Japan)

In this study, we conducted dynamic performance verification tests on High Damping Rubber Bearing (HDR). A test specimen was a full-scale HDR with a rubber outer diameter of 1,500mm. Large displacements of 875 mm and high velocities of 1,660 mm/s were applied to the specimen. We confirmed that the HDR showed stable dynamic characteristics under sinusoidal waves with various loading conditions. Furthermore, the HDR exhibited stable behavior even when a seismic response wave exceeding 1,500mm/s under low compressive stress was applied.

We investigate the coupled evolution of heterogeneous strain, crystallinity, and stress fields in natural rubber (NR) sheets containing a circular hole during uniaxial stretching, with a focus on how strain-induced crystallization (SIC) influences local stress concentration at structural discontinuities. By high-resolution digital image correlation, an empirical strain-crystallinity relationship and a hyperelasticity analysis firmly grounded in stress–strain data obtained under diverse deformation modes, we quantitatvely map the spatial distributions of strain, SIC, and stress in the extreme vicinity (≈0.2 mm) of the defect. Local strain concentration at the lateral hole edges triggers pronounced SIC, resulting in strong stiffening and a stress concentration factor (Kt*) as high as 4.5─significantly exceeding classical elastic predictions. Upon further stretching, Kt* plateaus, eventually as SIC develops in the far-field region, promoting a more homogeneous stress distribution. The SIC-induced stiffening also generates a highly anisotropic stress field near the hole edges due to preferential reinforcement along the crystalline orientation. The localized SIC causes characteristic hole-shape evolution, where the hole becomes increasingly elongated along the stretching axis compared with the fully amorphous state. These findings elucidate the fundamental interplay between SIC and local stress concentration in elastomers with structural discontinuities and provide mechanistic insights for designing defect-tolerant, high-toughness rubber materials.

Tail fluke loss in cetaceans compromises locomotion and impairs social functioning, posing serious welfare challenges. Rehabilitation strategies that address both physical performance and behavioral reintegration are essential for improving quality of life in affected individuals. This study evaluated the outcomes of a structured, two-phase rehabilitation program applied to Sami, an adult Indo-Pacific bottlenose dolphin (Tursiops aduncus) that underwent tail-fluke amputation, with an emphasis on locomotor function, behavioral adaptation, and long-term welfare. The rehabilitation protocol comprised two phases. Phase 1 focused on restoring vertical tail-beat locomotion through a combination of range-of-motion exercises and the use of a custom-designed prosthetic tail fluke. Swimming performance was quantitatively assessed using biologging devices under three conditions: without tail flukes, with the prosthetic tail, and in healthy conspecifics. Phase 2 introduced structured cohabitation with familiar individuals to promote social reintegration. Behavioral data were collected before and after rehabilitation to evaluate affiliative engagement and activity patterns. While maximum swim speed remained lower than in healthy individuals, propulsion per stroke significantly improved with prosthetic use. Notably, the subject dolphin retained species-typical vertical tail-beat motion even after prosthesis discontinuation, indicating motor pattern adaptation. Post-rehabilitation, affiliative behavior increased to 17% of total observed activity-more than twice that of a healthy control-while resting behavior markedly declined. No aggression or abnormal behaviors were observed. This study demonstrates that a welfare-centered, multi-phase rehabilitation framework can effectively promote both functional recovery and social reengagement in dolphins with severe caudal injuries. The long-term retention of adaptive locomotor and social behaviors highlights the potential of integrative approaches to enhance the quality of life in physically compromised cetaceans.

This paper proposes a multi-input high linearity single-slope ADC for temperature to digital converter to achieve dynamic thermal management in advanced systems on chips. An auto-zero analog comparator is employed to compare the selected input voltage and the ramp signal generated by counting logic and a segmented DAC. Three techniques are proposed for the analog comparator to enhance the linearity of the single-slope ADC. Fabricated in 65nm CMOS process, the core circuits occupy 0.125 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, Measured temperature error is within ±1.8°C from −15°C to 125°C. Measurement results show that the single-slope ADC-based temperature to digital converter has excellent linearity.

Abstract This study has developed the sliding contact resonance (SCR) method, which measures three timescales, in no contact, stationary contact, and sliding contact, to investigate the mechanism of abrasion pattern (AP) formation engraved on rubber surfaces. The SCR method employs a unique homemade apparatus of a single-degree-of-freedom forced oscillation system utilizing a macroscale sliding contact between a rubber roller and a rigid surface. This paper focuses on the timescales, based on the hypothesis that the product of the drive speed and an intrinsic time determines the AP spacing. As a result, we find that it is not the mechanical or material timescale, but rather the timescale of sliding contact, that determines the limiting AP spacing. Their strong correlation suggests that the intrinsic time of the rubber surface, required for deformation and recovery in sliding contact, determines the periodic spacing engraved on the surface.

In the chemical industry, there is a strong demand for achieving carbon neutrality and promoting the circular use of resources. Utilizing basic chemicals like olefins effectively is a highly efficient approach to meet these goals. We are advancing the development of new materials focused on sustainability and the circular economy. As part of this effort, we are developing a new thermoplastic elastomer (TPE) primarily composed of ethylene, specifically an ethylene/styrene/butadiene terpolymer (ESB). TPEs are plastic materials that exhibit rubber-like softness without requiring special treatments to maintain these properties. This characteristic makes TPEs excellent materials for saving resources and energy. The structure of ESB can be freely controlled by adjusting the proportions of the materials used, the reaction conditions, and the catalysts (substances that facilitate chemical reactions). This control over the structure significantly influences the properties of ESB, such as strength, self-healing capability, and degradability. Consequently, this provides new guidelines for developing innovative materials. This paper aims to provide a clear and comprehensive explanation of how ESB is designed and how its molecular design influences its material properties.

Long slip-critical bolted joints are extensively used in steel-bridge construction to accommodate increasing traffic loads and optimise steel components. However, as the joint length increases, challenges arise owing to interference with secondary members, uneven bolt force distribution leading to premature failure, and reduced serviceability limit strength. Existing design codes incorporate reduction factors based on joint length to address these issues. This study proposes a hybrid bolt joint that combines friction and bearing-type bolted connections to reduce the joint length while maintaining or improving strength. Finite element analysis was used to investigate the interactive effects of bearing and friction connections, load sharing of hybrid connections, component deformation, and reductions in friction and bearing forces. The results show that the hybrid joint exhibits a uniform load distribution among the friction bolts but an uneven bearing force distribution among the bearing bolts, with the foremost bolt experiencing severe friction force loss. An effective correction factor was proposed to account for the reduction in friction and bearing forces. This study defines the serviceability limit state based on bolt shank shear yielding and provides recommendations for the strength assessment and design of hybrid bolted joints ( α s F s + α b F b ). The results contribute to the development of rational compact joints for steel-bridge construction and address the challenges associated with long multi-row bolted joints. • Reveals interactive effects between friction and bearing load transfer by using FEM. • Uneven bearing force causes friction loss in the front bolt from shear bending. • Correction factors are applied to assess both friction and bearing forces effectively. • Hybrid connection SLSs are defined by bolt shear yield and net cross-section yield. • Hybrid joint can provide more strength with fewer bolts compared to friction type.

The aim of this report is to investigate the potential of using surplus electricity generated by wind turbines in a power-to-heat (P2H) setup serving the Danish district heating market. The research establishes a theoretical position on variable renewable energy, district heating, heat pumps, boilers, and thermal energy storage through academic literature and industry professional reporting research. The empirical section touches upon the same topics, focusing on total energy production, curtailment, and district heating (DH) in Denmark. An analysis of the amount of curtailed power production in combination with electricity spot prices was used to calculate the corresponding heating demand that could be achieved if the power was used for large-scale heat pumps and electric boilers. It was found that the potential power-to-heat supply ranges from 18,100 to 63,380 households across the scenarios analyzed. The conclusion is that there seems to be a clear potential for redirecting the surplus electricity into DH to meet part of the Danish heat demand, and that the ongoing technological development of DH, thermal energy systems (TES), and variable renewable energy (VREs) in combination with market conditions favors a focus on sector coupling and P2H in the future.

The study focuses on the prediction technology of rubber block friction properties on ice. The 2-D simplified block model with sipes (narrow grooves) and the mechanical analysis methodology are applied to understand the complex tribological phenomena and improve winter tire grip on icy roads. The friction forces on ice are assumed to consist of adhesion force, viscous drag of water film, and ploughing effects of sipe edges. Based on this assumption, the ice temperature distribution and friction coefficient in the contact patch are predicted. The effects of sipe density and block stiffness on tire tread pattern are evaluated. Experimental results partially validated the predicted friction coefficients. The study also proposed new sipe structures with high-density short sipes to improve ice performance. Tentative test results indicate the effectiveness of these new structures.

Repair of damaged paint-coating is an important issue in extending the service life of steel bridges. When repainting the paint-coating, the substrate steel is subject to surface preparation for removing the deteriorated original paint-coating and rust and appropriately making the steel surfaces rough. Although blasting and power tools are used for surface preparation, dust and noise are generated during the work. Therefore, the removal of paint-coating is performed prior to the surface preparation. A new paint-coating removal method by using induction heating (IH) is noted recently. The steel is rapidly heated by IH for removing the paint-coating easily. However, there are many unknowns regarding the influence of IH paint-coating removal on the durability of repaint-coating. In this study, the influence of removing paint-coating by IH on the durability of repaint-coating was evaluated through a series of accelerated corrosion experiments. The results of the 168-day accelerated corrosion experiments showed that the removal of paint-coating by IH did not cause a loss of the durability of repaint-coating compared to the case without using IH for the paint-coating removal.