Flexible Member Pump

Keyword(s):  
Author(s):  
Larry L. Howell ◽  
Ashok Midha

Abstract The analysis of systems containing highly flexible members is made difficult by the nonlineararities caused by large deflections of the flexible members. The analysis and design of many such systems may be simplified by using pseudo-rigid-body approximations in modeling the flexible members. The pseudo-rigid-body model represents flexible members as rigid links, joined at pin joints with torsional springs. Appropriate values for link lengths and torsional spring stiffnesses are determined such that the deflection path and force-deflection relationships are modeled accurately. Pseudo-rigid-body approximations have been developed for initially straight beams with externally applied forces at the beam end. This work develops approximations for another fundamental type of flexible member, the initially curved beam with applied force at the beam end. This type of flexible member is commonly used in compliant mechanisms. An example of the use of the resulting pseudo-rigid-body approximations in compliant mechanisms is included.


2016 ◽  
Vol 10 (31) ◽  
pp. 119-123
Author(s):  
Alžbeta Sapietová ◽  
Michal Sekerka ◽  
Milan Vaško ◽  
Milan Sapieta
Keyword(s):  

Author(s):  
Jennifer Ferriss-Hill

This introductory chapter provides a background of Horace's Ars Poetica, a 476-line poem revered for over fifteen hundred years as the indispensable guide for practicing poets. Ars Poetica provided a blueprint for efforts at “updated” rules of literary composition and it inspired numerous famous translators and imitators. Yet this poem has proven hard to love for recent readers. As its ostensible value as “a kind of literary 'Magna Carta'” receded and it ceased to be widely regarded as a document that could ever sincerely aid in literary composition, the Ars Poetica came to develop an entrenched reputation of being tedious and devoid of artistry. This duality is inevitably tied up with the understanding of it as modeled upon earlier Greek works, a relation that both granted the Ars Poetica a greater standing and yet doomed it to be seen as “an anthology of previous ideas, not a system of thought in which each idea has its place as a living and flexible member of an organically unified discourse.” This book then considers the Ars Poetica as a complete and exceptional literary achievement in its own right. It also elucidates the key place of the Ars Poetica in the Horatian corpus.


2021 ◽  
Author(s):  
Shanzeng Liu ◽  
Zhaopeng Sun ◽  
Gang Shen ◽  
Yunwang Li

Abstract The characteristics and optimization analysis of a four-bar compliant mechanism with one flexible member (or flexible joint) are carried out. Firstly, based on the pseudo-rigid body model theory of the compliant mechanism, the kinematics relationship, system kinetic energy and potential energy of the general four-bar compliant mechanism are analyzed, and the dynamic model of the four-bar compliant mechanism is established by using Lagrange's equation. Secondly, through the creation of the energy equation of the four-bar compliant mechanism and the analysis of the first and second derivatives of the input variables, the parametric conditions for the existence of the bistable characteristics of the four-bar compliant mechanism with one flexible member are proposed. Then, taking the compliant bistable switch as an example, the internal relations between the driving characteristics of the four-bar compliant mechanism, the initial motion position of the mechanism and the parameters of the flexible member are explored. Finally, based on the improvement of the performance of the compliant bistable switch, the optimization analysis of the maximization of the motion range of the driving link and the maximization of the deformation energy of the flexible member are carried out. The research provides a theoretical basis for the product development and control of a bistable four-bar compliant mechanism.


Transport ◽  
2005 ◽  
Vol 20 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Brosnislovas Spruogis ◽  
Arūnas Jakštas

Couplings abruptly changing their torsional rigidity and carrying capacity when the transmitted torque reaches a particular value are considered. This state is achieved either changing the conditions of the deformation of a flexible member or by excluding it from torque transmission. In the presented paper the conditions of mode variation are determined and some relationships for determining major parameters of couplings are given.


2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Shichao Cui ◽  
Ryan L. Harne

Abstract The acoustic energy attenuation capabilities of traditional Helmholtz resonators are enhanced by various methods, including by coupled resonators, absorbing materials, or replacement of rigid walls with flexible structures. Drawing from these concepts to envision a new platform of adaptive Helmholtz resonator, this research studies an adaptive acoustic resonator with an internal compliant structural member. The interaction between the structure and acoustic domain is controlled by compression constraint. By applying uniaxial compression to the resonator, the flexible member may be buckled, which drastically tailors the acoustic-structure interaction mechanisms in the overall system. A phenomenological analytical model is formulated and experimentally validated to scrutinize these characteristics. It is found that the compression constraint may enhance damping capabilities of the resonator by adapting the acoustic-structure interaction between the resonator and the enclosure. The area ratio of the flexible member to the resonator opening and the ratio of the fundamental natural frequency of the flexible member to that of the enclosure are discovered to have a significant influence on the system behavior. These results reveal new avenues for acoustic resonator concepts exploiting compliant internal structures to tailor acoustic energy attenuation properties.


Author(s):  
Caifang Meng ◽  
Zuo Dai ◽  
Jianzhong Cha

Abstract An optimum synthesis of a compound mechanism with flexible member (CMFM) is reported in this paper. First, the concepts of the first order optimum synthesis (FOOS) and the second order optimum synthesis (SOOS) are given. Then, the SOOS for the CMFM in a complete period and a half of period are carried out based on the mathematical model established for the SOOS of the CMFM. The results of the SOOS are obtained through the IIO software, an integrated intelligent optimization software environment, and the differences between specified and generated angular velocities are analyzed.


Author(s):  
Lael Odhner ◽  
Aaron Dollar

Robot manipulators having elastic links or flexure joints have a number of advantages, especially in simplifying the control of contact with other objects. However, current simplified parametric models of flexure motion do not accurately predict the behavior of these mechanisms under large deflections. This paper presents a “smooth curvature model” of flexure behavior that describes the curvature of a highly flexible member such as a flexure joint using a basis of three orthogonal polynomials. Using this model, we show that it is possible to predict the planar stiffness these mechanisms, even in cases where the deformation of the hinge is too large for the linear Euler-Bernoulli beam bending model. Using both finite element methods and the much less computationally expensive proposed model, numerical results will demonstrate that it is possible to accurately predict the in-plane compliance of a highly flexible mechanism in the presence of an external load. The results of this work are significant because they demonstrate that the behavior of flexure-based robotic mechanisms can be modeled quickly and with few parameters, enabling their use in closed-loop control for situations where collision safety is a concern, and rigorous model-based path planning for obstacle avoidance, among other applications.


1993 ◽  
Vol 8 (3) ◽  
pp. 189-197 ◽  
Author(s):  
A.L. El-Sheikh

The conventional procedure for the analysis of space trusses, lattice domes and similar structures, assumes that member-end joints behave as pure pins or, in some cases, as rigid joints. However, experimental studies have shown that these joints typically exhibit some level of flexural stiffness and are therefore flexible (semi-rigid). It was reported that the characteristics of the space truss jointing system play a major role in truss response (see Refs. 1,2,3). The results of experiments conducted on space trusses with rigid or flexible joints produced less brittle behaviour than that found for assemblies with nominally-pinned joints. A nonlinear beam-column element with end springs has been developed to model the actual rotational stiffness of truss member-node connections, and its stiffness expressions are presented in this paper. Incorporation of this element in the numerical analysis of space trusses has led to better predictions of behaviour and strength when compared to the commonly-used two-noded frictionless truss element. This new element was used successfully in the numerical analysis of two non-composite and one composite double-layer space truss, and the results are presented in this paper.


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