scholarly journals Load-dependent Variable Gearing Mechanism of Muscle-like Soft Actuator

2021 ◽  
Author(s):  
Yingjie Wang ◽  
Chunbao Liu ◽  
Luquan Ren ◽  
Lei Ren
Keyword(s):  
Muscle Fibers ◽  
Gear Ratio ◽  
Pennation Angle ◽  
Complex Interaction ◽  
Loading Conditions ◽  
Essential Factor ◽  
Variable Loading ◽  
Shortening Velocity ◽  
Soft Actuator ◽  
Variable Loading Conditions

AbstractPennate muscle is characterized by muscle fibers that are oriented at a certain angle (pennation angle) relative to the muscle’s line of action and rotation during contraction. This fiber rotation amplifies the shortening velocity of muscle, to match loading conditions without any control system. This unique variable gearing mechanism, which characterized by Architecture Gear Ratio (AGR), is involves complex interaction among three key elements: muscle fibers, connective tissue, and the pennation angle. However, how three elements determine the AGR of muscle-like actuator is still unknown. This study introduces a Himisk actuator that arranges five contractile units at a certain pennation angle in a flexible matrix, the experiment and simulation results demonstrated that the proposed actuator could vary AGR automatically in response to variable loading conditions. Based on this actuator, we present a series of actuators by simulations with the varying pennation angle (P), elastic modulus of the flexible matrix (E), and number of contractile units (N) to analyze their effects on AGR, and their interaction by three-factor analysis of variance. The results demonstrated that P and N effect on the AGR significantly, while E effects on AGR slightly, which supported the idea that the P is the essential factor for the AGR, and N is also an important factor due to the capability of force generation. This provides a better understanding of mechanical behavior and an effective optimizing strategy to muscle-like soft actuator.

scholarly journals Estimating the Remaining Useful Life of Proton Exchange Membrane Fuel Cells under Variable Loading Conditions Online

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1459
Author(s):  
Penghao Wang ◽  
Hao Liu ◽  
Ming Hou ◽  
Limin Zheng ◽  
Yue Yang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Remaining Useful Life ◽  
Ohmic Loss ◽  
Loading Conditions ◽  
Variable Loading ◽  
Useful Life ◽  
Exchange Membrane ◽  
Variable Loading Conditions

The major challenges for the commercialization of proton exchange membrane fuel cells (PEMFCs) are durability and cost. Prognostics and health management technology enable appropriate decisions and maintenance measures by estimating the current state of health and predicting the degradation trend, which can help extend the life and reduce the maintenance costs of PEMFCs. This paper proposes an online model-based prognostics method to estimate the degradation trend and the remaining useful life of PEMFCs. A non-linear empirical degradation model is proposed based on an aging test, then three degradation state variables, including degradation degree, degradation speed and degradation acceleration, can be estimated online by the particle filter algorithm to predict the degradation trend and remaining useful life. Moreover, a new health indicator is proposed to replace the actual variable loading conditions with the simulated constant loading conditions. Test results using actual aging data show that the proposed method is suitable for online remaining useful life estimation under variable loading conditions. In addition, the proposed prognostics method, which considers the activation loss and the ohmic loss to be the main factors leading to the voltage degradation of PEMFCs, can predict the degradation trend and remaining useful life at variable degradation accelerations.

Structural Optimization Under Variable Loading Conditions

2000 ◽  
Author(s):  
Chin-Pun Teng ◽  
Jorge Angeles
Keyword(s):  
Structural Optimization ◽  
Stiffness Matrix ◽  
Elliptical Hole ◽  
Minimum Variance ◽  
Design Parameters ◽  
Variable Load ◽  
Loading Conditions ◽  
Optimum Structure ◽  
Variable Loading ◽  
Variable Loading Conditions

Abstract The problem of structural optimization under variable loading conditions is discussed here. We assume a linearly-elastic structure subject to one single load of constant magnitude but of arbitrary orientation. Moreover, we assume that the structure is discretized by finite elements. The result of this study is an optimality criterion: the eigenvalues of the stiffness matrix of the optimum structure observe a minimum variance. In other words, the optimum structure under variable load must have a stiffness matrix that is as close as possible to isotropy. Furthermore, in order to implement the foregoing criterion, we introduce a novel method of automatic mesh generation, that is based on the concept of penalty functions of nonlinear programming. Finally, we illustrate these concepts by means of the optimization of a triangular lamina of given side lengths, with an elliptical hole centered at its centroid, of a prescribed area, the design parameters being the semiaxes of the ellipse and the orientation of these axes with respect to the edges of the lamina.

Effect of Load Shape in Cyclic Load Variation on Dynamic Behavior of Spur Gear System

2012 ◽  
Vol 518 ◽  
pp. 119-126 ◽  
Author(s):  
Fakher Chaari ◽  
Walter Bartelmus ◽  
Radoslaw Zimroz ◽  
Taher Fakhfakh ◽  
Mohamed Haddar
Keyword(s):  
Cyclic Load ◽  
High Efficiency ◽  
Spur Gear ◽  
Industrial Applications ◽  
Time Varying ◽  
Spur Gears ◽  
Loading Conditions ◽  
Variable Loading ◽  
Load Shape ◽  
Variable Loading Conditions

Transmissions including spur gears are widely used in several industrial applications. They are characterized by high efficiency and capability to transmit high torques. A special attention should be made for transmissions running under varying loading conditions which have to be well monitored. The presence of this variability associated with defects that may occur in the transmission will complicate its condition monitoring. The first step to overcome this difficulty is to identify and characterize the dynamic response of the transmission in healthy conditions subjected to variable loading conditions. In this paper, a model based approach is presented in order investigate the influence of the loading shape on the vibration characteristics of the transmission. A dynamic model of a one stage spur gear transmission including a time varying loading conditions is developed. Two cases of loading conditions are considered. A parametric study is achieved and main conclusions are discussed.

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