This paper presents a fully coupled fluid-structure interaction (FSI) simulation model of a soft pneumatic actuator (SPA). Previous research on modelling and simulation of SPAs mostly involves finite element modelling (FEM), in which the fluid pressure is considered as pressure load uniformly acting on the internal walls of the actuator. However, FEM modelling does not capture the physics of the fluid flow inside an SPA. An accurate modelling of the physical behaviour of an SPA requires a two-way FSI analysis that captures and transfers information from fluid to solid and vice versa. Furthermore, the investigation of the fluid flow inside the flow channels and chambers of the actuator are vital for an understanding of the fluid energy distribution and the prediction of the actuator performance. The FSI modelling is implemented on a typical SPA and the flow behaviour inside the actuator is presented. Moreover, the bending behaviour of the SPA from the FSI simulation results is compared with a corresponding FEM simulation.

The high thermal stresses generated in the contacting surfaces of a multidisk clutch system (pressure plate, clutch disks, plate separators and piston), due to the frictional heating generation during the slipping, is considered to be one of the main reasons lead to premature failure in the contacting surfaces of clutches. A finite element technique has been used to study the transient thermo-elastic phenomena of multidisk dry clutch. The effect of the sliding speed on the contact pressure distribution, the temperature field and the frictional heat generated along the frictional surfaces are investigated. Analysis has been completed using axisymmetric model to simulate the multidisk clutch system. Ansys software has been used to perform the numerical calculation in this paper.

The heat generated during the sliding period at the initiation of engagement in friction clutches is considered to be one of the main reasons for the failure of the friction material. One way to reduce the risk of this problem is to increase the rate of heat transfer by convection or, in other words, reduce the heat content of the friction material (internal energy) and thereby increase the lifecycle of the friction clutch. In this paper, the finite element technique has been used to study the effect of radial circumferential grooves on the temperature distribution and the amount of energy transferred by convection for a dry friction clutch disk during a single engagement, assuming a uniform distribution for the thermal load between the contact surfaces (i.e., uniform wear on clutch surfaces). Three-dimensional transient simulations are conducted to study the thermoelastic coupling of the problem. The effect of the groove area ratio (GR, defined as the groove area divided by the nominal contact area) is investigated. Furthermore, this paper presents the equations for energy considerations and energy balance at any time for the friction clutch system. The numerical results show that the amount of energy transferred by convection from the friction material can be controlled (within a limitation) by adjusting the value of the groove area ratio. Commercial ANSYS13 software has been used to perform the numerical computations in this paper.

The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of the system. In this paper a detailed numerical study is presented for the cam and follower (flat-faced) lubrication including the effect of introducing an axial modification (parabolic shape) of the cam depth on the levels of film thickness and pressure distribution. This is achieved based on a point contact model for a cam and flat-faced follower system. The results reveal that the cam form of modification has considerable consequences on the level of predicted film thickness and pressure distribution as well as surface deformation.

Locomotion of walking insects is exceptionally efficient. The function of their leg joints in different movement scenarios depends on their kinematics and contacting conditions between moving parts. The kinematics was previously studied in some insects, but contact mechanics within the joints remains largely unknown. In order to understand the complex topology of the contacting surfaces of the leg joints in the Congo rose beetle Pachnoda marginata peregrina (Scarabaeidae, Cetoniinae), we have investigated the shape, the waviness, and the roughness of the joint base and its counter body by applying confocal laser scanning microscopy and white light interferometry. Additionally, we performed nanoindentation tests on the contacting joint surfaces, in order to analyze material properties (elasticity modulus and hardness) of the joint cuticle. We found two topological design principles of the contact surfaces that might be considered as adaptations for reducing frictional drag during leg movements. First, the contact pairs of all leg joints studied consist of convex and concave counterparts. Second, there is a smooth and a rough surface in contact in which microprotuberances are present on the rough surface. These principles might be potentially interesting for technical implications, to design bioinspired joints with both reduced friction and wear rate.