scholarly journals Model-Based Experimental Development of Passive Compliant Robot Legs from Fiberglass Composites

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Shang-Chang Lin ◽  
Chia-Jui Hu ◽  
Wen-Pin Shih ◽  
Pei-Chun Lin
Keyword(s):  
Elastic Moduli ◽  
Curved Beam ◽  
Spring Model ◽  
Hexapod Robot ◽  
Experimental Development ◽  
Circular Shape ◽  
Displacement Experiments ◽  
Compliant Robot ◽  
Force Displacement ◽  
Beam Mechanics

We report on the methodology of developing compliant, half-circular, and composite robot legs with designable stiffness. First, force-displacement experiments on flat cantilever composites made by one or multifiberglass cloths are executed. By mapping the cantilever mechanics to the virtual spring model, the equivalent elastic moduli of the composites can be derived. Next, by using the model that links the curved beam mechanics back to the virtual spring, the resultant stiffness of the composite in a half-circular shape can be estimated without going through intensive experimental tryouts. The overall methodology has been experimentally validated, and the fabricated composites were used on a hexapod robot to perform walking and leaping behaviors.

Modeling the Compliance of a Variable Stiffness C-Shaped Leg Using Castigliano’s Theorem

2010 ◽  
Author(s):  
Yasemin O¨. Aydın ◽  
Kevin C. Galloway ◽  
Yigit Yazicioglu ◽  
Daniel E. Koditschek
Keyword(s):  
Rigid Body ◽  
Closed Form ◽  
Variable Stiffness ◽  
Dynamic Equations ◽  
Hexapod Robot ◽  
Static Loads ◽  
Compliant Robot ◽  
Circular Beam ◽  
Robot Leg ◽  
Castigliano’S Theorem

This paper discusses the application of Castigliano’s Theorem to a half circular beam intended for use as a shaped, tunable, passively compliant robot leg. We present closed-form equations characterizing the deflection behavior of the beam (whose compliance properties vary along the leg) under appropriate loads. We compare the accuracy of this analytical representation to that of a Pseudo Rigid Body (PRB) approximation in predicting the data obtained by measuring the deflection of a physical half-circular beam under the application of known static loads. We briefly discuss the further application of the new model for solving the dynamic equations of a hexapod robot with a C-shaped leg.

Predicting the elastic moduli of three-dimensional (four-step) braided tubes using a spatial spring model

2012 ◽  
Vol 47 (8) ◽  
pp. 991-1000 ◽  
Author(s):  
Chung-Li Hwan ◽  
K-H Tsai ◽  
Wen-Liang Chen ◽  
SJ Sun
Keyword(s):  
Elastic Moduli ◽  
Three Dimensional ◽  
Spring Model

Classical micromechanics modeling of nanocomposites with carbon nanofibers and interphase

2011 ◽  
Vol 45 (23) ◽  
pp. 2401-2413 ◽  
Author(s):  
Jaesang Yu ◽  
Thomas E. Lacy ◽  
Hossein Toghiani ◽  
Charles U. Pittman ◽  
Youngkeun Hwang
Keyword(s):  
Cross Section ◽  
Elastic Moduli ◽  
Carbon Nanofiber ◽  
Hollow Nanofibers ◽  
Multilayered Coatings ◽  
Notable Effect ◽  
Self Consistent ◽  
Micromechanics Modeling ◽  
Force Displacement ◽  
Composite Properties

A micromechanics parametric study was performed to investigate the effect of carbon nanofiber morphology (i.e. hollow vs. solid cross-section), nanofiber waviness, and both nanofiber–resin interphase properties and dimensions on bulk nanocomposite elastic moduli. Mori–Tanaka and self-consistent models were developed for composites containing heterogeneities with multilayered coatings. For a given nanofiber axial force–displacement relationship, the elastic modulus for hollow nanofibers can significantly exceed that for solid nanofibers resulting in notable differences in bulk nanocomposite properties. In addition, the development of a nanofiber–resin interphase had a notable effect on the bulk elastic moduli. Consistent with results from the literature, small degrees of nanofiber waviness resulted in a significant decrease in effective composite properties.

Instrumentation for Measurement of Lingual Strength

1968 ◽  
Vol 11 (1) ◽  
pp. 189-193 ◽  
Author(s):  
Lois Joan Sanders
Keyword(s):  
Single Channel ◽  
Displacement Transducer ◽  
Tongue Pressure ◽  
Maximum Pressure ◽  
Research Use ◽  
Direct Writing ◽  
Significant Difference ◽  
Pressure Unit ◽  
Force Displacement ◽  
Consistent Response

A tongue pressure unit for measurement of lingual strength and patterns of tongue pressure is described. It consists of a force displacement transducer, a single channel, direct writing recording system, and a specially designed tongue pressure disk, head stabilizer, and pressure unit holder. Calibration with known weights indicated an essentially linear and consistent response. An evaluation of subject reliability in which 17 young adults were tested on two occasions revealed no significant difference in maximum pressure exerted during the two test trials. Suggestions for clinical and research use of the instrumentation are noted.

Epitaxial Growth in Dislocation-Free Strained Alloy Films

2002 ◽  
Vol 715 ◽  
Author(s):  
Zhi-Feng Huang ◽  
Rashmi C. Desai
Keyword(s):  
Deposition Rate ◽  
Elastic Moduli ◽  
Composition Dependence ◽  
Critical Thickness ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Joint Stability ◽  
Alloy Films ◽  
The Stability ◽  
Stability Results

AbstractThe morphological and compositional instabilities in the heteroepitaxial strained alloy films have attracted intense interest from both experimentalists and theorists. To understand the mechanisms and properties for the generation of instabilities, we have developed a nonequilibrium, continuum model for the dislocation-free and coherent film systems. The early evolution processes of surface pro.les for both growing and postdeposition (non-growing) thin alloy films are studied through a linear stability analysis. We consider the coupling between top surface of the film and the underlying bulk, as well as the combination and interplay of different elastic effects. These e.ects are caused by filmsubstrate lattice misfit, composition dependence of film lattice constant (compositional stress), and composition dependence of both Young's and shear elastic moduli. The interplay of these factors as well as the growth temperature and deposition rate leads to rich and complicated stability results. For both the growing.lm and non-growing alloy free surface, we determine the stability conditions and diagrams for the system. These show the joint stability or instability for film morphology and compositional pro.les, as well as the asymmetry between tensile and compressive layers. The kinetic critical thickness for the onset of instability during.lm growth is also calculated, and its scaling behavior with respect to misfit strain and deposition rate determined. Our results have implications for real alloy growth systems such as SiGe and InGaAs, which agree with qualitative trends seen in recent experimental observations.

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