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A simple scheme to avoid the formation of 1-node connected hinges and checkerboard patterns in topology optimization is presented. It is formulated in terms of a single constraint that is inexpensive to compute. It is easy to incorporate in existing topology optimization implementations, and there is no difficulty in choosing the constraint value, as it should ideally be zero.

Abstract The power transmission efficiency of continuously variable transmissions (CVTs) based on the pushing metal belt is acknowledged to be lower than that of discrete ratio alternatives. This tends to negate the potential fuel economy benefits that are obtained by improved engine/load matching with a CVT. This series of three papers details an investigation into the loss mechanisms that occur within the belt drive as a first step to obtaining improvements in efficiency. Experimental work has been undertaken to investigate the no-load and low-load torque losses associated with a pushing metal V-belt CVT. This first paper describes a new analysis of the principal torque losses occurring in the metal belt CVT due to relative motion occurring between the belt segments and bands. The work takes into account new findings in other research and changes in the design of the metal V-belt. The torque loss model proposed in this paper is supported by experimental data from several different test procedures. A number of additional torque loss mechanisms, due to pulley deflections, are described in Part 2 of the series. The findings from this current paper support an analysis of belt-slip losses, which is described in detail in Part 3.

A tendon-driven manipulator having redundant tendons may possess more flexibility in operation, such as optimizing the performance of tendons, reducing the burden of each tendon, and providing fail-safe features. The purpose of this paper is to investigate the design of tendon-driven manipulators with a fail-safe feature, that is, to synthesize a system that may still remain controllable as any of the tendons have broken down or malfunctioned. Characteristics of tendon-driven manipulators are briefly discussed. Criteria for tendon-driven manipulators with redundant tendons and fail-safe feature are then established. Subsequently, constraints for such system are derived from the structure of tendon-driven manipulator. Associated with the criteria, manipulators can remain controllable when any of the tendons fails to function. Finally, a geometric method for determining the structure is developed. Examples of two-DOF and three-DOF tendondriven manipulators are demonstrated.

We present a dynamic simulation of a wire rope involving both contacts with a winch drum and hydraulic systems using the finite element method. Rapid winch operation often causes disorderly winding of the wire rope, which is an important quality problem. Dynamic simulation is, therefore, required for design of the hydraulic winch system on construction machinery. The wire rope is modeled using by truss elements considering large displacement motion. The contact between the wire rope and the winch drum is modeled using by variable-length truss elements and bilinear spring elements. An improved Newton method is proposed for nonlinear dynamic analysis. Simulation results show that some lever operations result in rope looseness and intense pressure fluctuation.

Abstract The power transmission efficiency of continuously variable transmissions (CVTs) based on the pushing metal belt is acknowledged to be lower than that of discrete ratio alternatives. This tends to negate the potential fuel economy benefits that are obtained by improved engine/load matching with a CVT. This series of three papers details an investigation into the loss mechanisms that occur within the belt drive as a first step to obtaining improvements in efficiency. This second part follows on from an initial paper in which an analysis was performed of the losses that occur due to relative motion between the bands and segments of the belt. Additional experimental work has been performed indicating that a significant deflection occurs in the pulleys of the variator. Further torque-loss models are proposed in addition to that discussed in Part 1, representing a smaller but still significant torque loss associated with the belt. The work takes into account new findings in other research and changes in the design of the metal V-belt. The third paper in this series develops a number of models to predict belt-slip losses in the variator system, based on force distribution models developed in Part 1.

Abstract The power transmission efficiency of continuously variable transmissions (CVTs) based on the pushing metal belt is acknowledged to be lower than that of discrete ratio alternatives. This tends to negate the potential fuel economy benefits that are obtained by improved engine/load matching with a CVT. This series of three papers details an investigation into the loss mechanisms that occur within the belt drive as a first step to obtaining improvements in efficiency. This third paper follows on from two previous papers in which an analysis was performed modelling the torque losses that occur due to relative motion between the bands and segments of the belt, and between the pulleys and the belt due to pulley deflection effects. It describes additional experimental work, measuring the belt-slip speed tangentially about both of the pulleys in the variator. Additional loss models are proposed beyond those discussed in Parts 1 and 2 to describe the belt-slip phenomena, based on existing theory proposed by others. The analysis produced in this paper is validated against a range of experimental data and additionally through its close interaction with the torque-loss and torque-force distribution models proposed in Parts 1 and 2. The work takes into account new findings in other research and changes in the design of the current metal V-belt.

Abstract In this study, factors influencing the accuracy of the durability estimation for an automotive V-belt pulley were investigated using finite element analysis (FEA). The bolt load, centrifugal load, and stress history were considered for fatigue life calculations, and their effects on the accuracy of the durability estimation were analysed. The stress history of a pulley that experienced a compressive load induced by belt tension, bolt load, and centrifugal load was determined by performing a consecutive static FEA on the rotating pulley. An estimation of the V-belt pulley fatigue life was based on a damage analysis of 36 load steps. Durability tests for the pulleys were then performed to verify the analysis results. The analysis and experimental results were closely correlated. Additional analyses were performed using the same procedure by isolating each factor and studying its effect on the durability estimation. The results revealed that the bolt load in the pulley analysis was not negligible in improving the accuracy of the analysis, and showed that more stress history must be used for the fatigue life calculations.

Abstract This paper discusses a new approach to detecting the detachment of one belt tooth in mechanical transmission systems with synchronous belts, which involves monitoring vibrations in the bodies linked to the pulley. A preliminary numerical analysis was carried out in order to estimate and compare the forces acting on the pulley in a healthy synchronous belt and in a belt lacking one tooth. Simulation results show that the lack of a tooth causes moderate but not negligible variations in the tangential force on the pulley. These variations involve different vibration behaviours that can be studied by analysing vibration signals in the frequency domain. Tests applied using a suitable experimental apparatus confirmed the numerical results. In the power spectrum, the lack of a tooth caused variations in peak amplitudes at multiples of the belt running frequency. In this study, where low frequencies were investigated, the displacement sensor performed better than the accelerometer for vibration measurements.

Abstract In this paper, the belt-pulley mechanical loss for a metal belt continuously variable transmission is investigated. A bond-graph model for the belt-pulley mechanical loss is developed from the viewpoint of the power flow by assuming that all power losses are attributed to the torque loss. The coefficients of the power loss model are obtained from the experiments. It is found from the simulations and experiments that the steady state belt-pulley loss depends on the line pressure, the input torque, and the rotational speed while the transient loss depends on the rotational speed, the shift speed, and the inertial torque.

Abstract This paper proposes a novel concept for reducing driving torque fluctuations of planar linkages by the application of non-circular gears. The circular gears normally used in gear linkage mechanisms are replaced by a pair of non-circular gears. The design method includes two individual stages: linkage synthesis and gear ratio synthesis. An optimization model is developed for determining the appropriate transmission ratio function of the non-circular gear pair to meet user-specified requirements and constraints. Two examples are given to demonstrate this method and to verify its feasibility.