Physical correlates of human-like softness elicit high tactile pleasantness

Touching an object can elicit affective sensations. Because these sensations are critical for social interaction, tactile preferences may be adapted to the characteristics of the human body. We have previously shown that compliance, a physical correlate of softness, increased the tactile pleasantness of a deformable surface. However, the extent to which object compliance similar to the human body elicits tactile pleasantness remains unknown. We addressed this question by using a wide range of compliances and by measuring the distribution of compliance of human body parts. The participants numerically estimated the perceived pleasantness or softness while pushing tactile stimuli with their right index fingers. The perceived softness monotonically increased with increasing compliance and then leveled off around the end of the stimulus range. By contrast, pleasantness showed an inverse U pattern as a function of compliance, reaching the maximum between 5 and 7 mm/N. This range of compliance was within that for both hand and arm. These results indicate that objects with similar compliance levels as those of human body parts yield the highest pleasantness when pushing them.

The Influence of Non-Pneumatic Tyre Structure on its Operational Properties

A non-pneumatic tyre (NPT) is a novel type of safety tyre that is designed to provide similar elastic properties to those offered by conventional pneumatic tyres. The main advantage of NPT is the lack of compressed air (like in a pneumatic tire) to ensure adequate traction forces and directional control. Suitable materials and the appropriate geometry of the supporting structure allows to achieve properties provides by pneumatic tires. Flexible spokes and closed structure like honeycomb are the most common solutions of supporting structure. Appropriate geometry, thickness and materials of this part affect the NPT properties; radial stiffness, unit pressure in the contact patch and the parameters of an area in contact with a non-deformable surface. The paper presents the FEM NPT model (NPT_0), which was validated with the results of experimental research of NPT. The NPT_0 model is subject to further modifications (layout and shape of the radial spokes) was used in the study. Seven new geometries of NPT supporting structure were selected for simulation tests. During the numerical tests the radial stiffness, unit pressure in the contact patch and the parameters of an area in contact with a non-deformable surface were determined. It has been observed that an increase in the curvature of the spokes reduced radial stiffness and increased the length of the contact path.

Theoretical determination of the distribution of forces and the size of the boundaries of the contact in the interaction of the deformable drive wheel with the soil

The article presents the results of an analytical determination of the forces distribution along the length of the contact curve of the driving deformable wheel on the deformable supporting surface, and also are defined the boundaries of the contact zone. The case in a flat statement of the problem is considered. The supporting surface and the surface of the deformable wheel are represented as a continuous deformable medium. The shape of the wheel in the contact zone is represented by the circle equation, which in the contact zone is expanded in a Macloran-series. By using conditions at the boundaries of the contact zone, a system of equations is obtained from which the sizes of the contact zone are determined. The solution of these equations allows one to find expressions of the sizes of the contact zone of the deformable wheel with the deformable surface, depending on the mechanical properties of the wheel materials and the supporting surface, from the geometric dimensions of the wheel and from the loads applied to it. In addition, the results of the studies allow us to determine the analytical expression of the coefficient of rolling resistance of a deformable wheel over a deformable surface, depending on their mechanical properties, geometric parameters, and the loads applied to it.

Mechanical response of a surface of increasing hardness covered with a nonuniform polymer brush: a numerical simulation model

The contributions to the force on a deformable surface covered with polymer brushes can be accounted for separately.