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Self-supporting run-flat tires (SSRFTs) achieve good zero-pressure driving ability by reinforcing the sidewalls, and the structural shape of sidewall insert rubber (SIR) is critical in influencing the mechanical characteristics of SSRFTs. In this paper, an SSRFT contour model is established by combining the radial tire contour theory and the design elements of SIR. The influence of two design parameters (maximum width L and maximum thickness H) of SIR on the tire stiffness characteristics and the contact characteristics is analyzed in depth, and the accuracy of the model is verified by the tire mechanics bench test. The results show that the radial stiffness of SSRFTs is positively correlated with two design parameters; an increase in L affects the stress concentration at the end of SIR, while a change in H has a more drastic effect on the stress distribution of SIR, leading to a large change in both the location of the deformation of SIR and the maximum equivalent stress; under rated pressure conditions, when L is less than 100 mm, the overlap between SIR and the tread decreases, which in turn makes the contact characteristics of SSRFTs closer to that of a normal tire, and obtains better comfort and abrasion resistance; under zero-pressure conditions, the maximum contact stress of the tread is the smallest when the H is 8 mm, but when H is less than 6 mm, the contact characteristics appear to deteriorate uniformly, and the maximum contact stress continues to rise. The results of the research provide a reference value for the selection of the design parameters for SIR and the optimization of the dynamic performance of SSRFTs. [ABSTRACT FROM AUTHOR]

We have particularly investigated the correlation law of the effect of different carbon black fillings on the hyper-elastic mechanical behavior of natural rubber by conducting uniaxial tensile tests over a wide range of deformations with different volume fractions of carbon black fillings (0%, 4.7%, 8.9%, 12.8%, 16.4%, 19.7%, 22.7% and 25.2%). The results show that the stress-strain curve for carbon black filled rubber increases with the amount of filling, meaning that the rubber gradually becomes "harder". We explore the correlation between the carbon black filling volume and the parameters of the Yeoh constitutive model by examining the Yeoh constitutive model to characterize the hyper-elastic mechanical behavior of rubber with different carbon black fillings. A quantitative relationship between the material parameters and the carbon black filling volume in the Yeoh constitutive model is presented. A method for calculating the material parameters of the Yeoh constitutive model is developed, and it predicts the correlation between the hyper-elastic properties of rubber and the volume fraction of the carbon black filling. [ABSTRACT FROM AUTHOR]

Self-supporting run-flat tires (SSRFTs) achieve good zero-pressure driving ability by reinforcing the sidewalls, and the structural shape of sidewall insert rubber (SIR) is critical in influencing the mechanical characteristics of SSRFTs. In this paper, an SSRFT contour model is established by combining the radial tire contour theory and the design elements of SIR. The influence of two design parameters (maximum width L and maximum thickness H) of SIR on the tire stiffness characteristics and the contact characteristics is analyzed in depth, and the accuracy of the model is verified by the tire mechanics bench test. The results show that the radial stiffness of SSRFTs is positively correlated with two design parameters; an increase in L affects the stress concentration at the end of SIR, while a change in H has a more drastic effect on the stress distribution of SIR, leading to a large change in both the location of the deformation of SIR and the maximum equivalent stress; under rated pressure conditions, when L is less than 100 mm, the overlap between SIR and the tread decreases, which in turn makes the contact characteristics of SSRFTs closer to that of a normal tire, and obtains better comfort and abrasion resistance; under zero-pressure conditions, the maximum contact stress of the tread is the smallest when the H is 8 mm, but when H is less than 6 mm, the contact characteristics appear to deteriorate uniformly, and the maximum contact stress continues to rise. The results of the research provide a reference value for the selection of the design parameters for SIR and the optimization of the dynamic performance of SSRFTs.

Fast pneumatic network (fast Pneu-Net, fPN) actuators made of silicone materials have aroused increasing attention these years for their promising applications in soft robotics. To enrich current research, we present a novel fPN actuator that consists of parallelogram-shaped chambers and aluminum endoskeleton that takes the shape of human finger. The proposed actuator can bend at multi-positions when inflated, bringing about more degrees of freedom controllability. Additionally, the performed finite element analysis indicates that the parallelogram-shaped chamber that tilts 30° towards the distal end exhibits an increase in deformation for about 11 % compared to the rectangle-shaped counterpart, offering an improved bending performance. An analytical model that based on the pressurized hyperelastic membrane theory is developed to estimate the actuator's bending angles/profiles at varied pressures. Geometric relation of the chamber interactions upon deformation is discussed depending on whether the lateral walls are contact or not. The stress-strain relation of the elastomer is described using 3-term Yeoh constitutive model. Experimental validations on the theoretical calculations are carried out, from which the coefficient of proportionality that takes into account the effect on deformation caused by the embedded endoskeleton is determined. Furthermore, the Modified Denavit-Hartenberg (MDH) notation is employed to establish the forward kinematics of the actuator, and the numerical calculations are compared with the physical actuator. [Display omitted] • An enhanced fPN actuator that contains metallic segments, the controllability of bending positions is made possible. • A novel parallelogram-shaped chamber that offers better bending performance compared to the rectangle-shaped counterpart. • A computationally less expensive model is developed where the chamber interactions are discussed under a 2D scenario. [ABSTRACT FROM AUTHOR]