scholarly journals Modeling and characterization of cyclic relaxation and ratcheting using the distributed-element model

2008 ◽  
Vol 32 (4) ◽  
pp. 501-513 ◽  
Author(s):  
Dar-Yun Chiang
Keyword(s):  
Element Model ◽  
Cyclic Relaxation

Experimental Characterization of a Flexible Two-Link Manipulator Arm

1993 ◽  
Author(s):  
Randall L. Mayes ◽  
G. Richard Eisler
Keyword(s):  
Element Model ◽  
Input Voltage ◽  
Analytical Models ◽  
Experimental Characterization ◽  
Frequency Range ◽  
Flexible Links ◽  
Beam Elements ◽  
Output Torque ◽  
Manipulator Arm

Abstract Experiments were performed to verify the analytical models for a robotic manipulator with two flexible links. A finite element model (FEM) employing two-dimensional beam elements was used to model the structure. A proportional model relating input voltage to output torque was used for both hub and elbow joint motors. With some minor adjustments to the link stiffness, the FEM modal frequencies matched the experimentally extracted frequencies within 1.5%. However the voltage-torque relationship for the hub motor was found to exhibit dynamics in the frequency range of interest.

Design and characterization of a hybrid soft gripper with active palm pose control

2020 ◽  
Vol 39 (14) ◽  
pp. 1668-1685 ◽  
Author(s):  
Vignesh Subramaniam ◽  
Snehal Jain ◽  
Jai Agarwal ◽  
Pablo Valdivia y Alvarado
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structure ◽  
Element Model ◽  
Open Loop ◽  
Aspect Ratios ◽  
Maximum Payload ◽  
Wide Range ◽  
Pose Control

The design and characterization of a soft gripper with an active palm to control grasp postures is presented herein. The gripper structure is a hybrid of soft and stiff components to facilitate integration with traditional arm manipulators. Three fingers and a palm constitute the gripper, all of which are vacuum actuated. Internal wedges are used to tailor the deformation of a soft outer reinforced skin as vacuum collapses the composite structure. A computational finite-element model is proposed to predict finger kinematics. Thanks to its active palm, the gripper is capable of grasping a wide range of part geometries and compliances while achieving a maximum payload of 30 N. The gripper natural softness enables robust open-loop grasping even when components are not properly aligned. Furthermore, the grasp pose of objects with various aspect ratios and compliances can be robustly maintained during manipulation at linear accelerations of up to 15 m/s2 and angular accelerations of up to 5.23 rad/s2.

Finite element model for the characterization of deleterious phases by eddy current technique

2012 ◽  
Vol 39 (1-4) ◽  
pp. 305-310 ◽  
Author(s):  
Maria C.L. Areiza ◽  
Rodrigo Sacramento ◽  
Joao M.A Rebello ◽  
Rubem L. Sommer ◽  
Diego Gonzalez
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Eddy Current ◽  
Element Model ◽  
Current Technique

Sensitivity analysis of the wheel–rail normal contact on the basis of continuous factors

2016 ◽  
Vol 231 (9) ◽  
pp. 1022-1034
Author(s):  
Florian Dörner ◽  
Tobias Bettinger ◽  
Christian Schindler
Keyword(s):  
Sensitivity Analysis ◽  
Rail Steel ◽  
Lateral Displacement ◽  
Element Model ◽  
Normal Contact ◽  
Wagon Wheel ◽  
Input Parameters ◽  
Important Input ◽  
Wheel Radius

The exact characterization of the wheel–rail normal contact situations is essential for its wear, fatigue, and guidance analysis. To simulate this contact, numerous input parameters are required. Many of them have to be estimated. The aim of this sensitivity analysis was to investigate the direct effects and interactions of the input parameters on the contact pressure distribution of a freight wagon wheel on a straight track. For this purpose, a finite element model was parametrized in such a way that all the parameters were continuous. This research demonstrates that the output parameters of the wheel–rail contact simulations have a broad deviation and the input variable with the most influence on the contact form and position is the lateral displacement of the wheelset. Nevertheless, the profile shape of the wheel and rail, the wheel radius, and the relative wheel–rail inclination are important input parameters as well, and also need to be considered for exact simulations of the wheel–rail contact. On the other hand, the deviation of material parameters of wheel and rail steel can be neglected.

scholarly journals Viscoelastic and poroelastic mechanical characterization of hydrated gels

2009 ◽  
Vol 24 (3) ◽  
pp. 973-979 ◽  
Author(s):  
Matteo Galli ◽  
Kerstyn S.C. Comley ◽  
Tamaryn A.V. Shean ◽  
Michelle L. Oyen
Keyword(s):  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Mechanical Characterization ◽  
Element Model ◽  
Mechanical Analysis ◽  
Intrinsic Permeability ◽  
Unconfined Compression ◽  
Future Studies ◽  
Dependent Behavior

Measurement of the mechanical behavior of hydrated gels is challenging due to a relatively small elastic modulus and dominant time-dependence compared with traditional engineering materials. Here polyacrylamide gel materials are examined using different techniques (indentation, unconfined compression, dynamic mechanical analysis) at different length-scales and considering both viscoelastic and poroelastic mechanical frameworks. Elastic modulus values were similar for nanoindentation and microindentation, but both indentation techniques overestimated elastic modulus values compared to homogeneous loading techniques. Hydraulic and intrinsic permeability values from microindentation tests, deconvoluted using a poroelastic finite element model, were consistent with literature values for gels of the same composition. Although elastic modulus values were comparable for viscoelastic and poroelastic analyses, time-dependent behavior was length-scale dependent, supporting the use of a poroelastic, instead of a viscoelastic, framework for future studies of gel mechanical behavior under indentation.

scholarly journals Experimental and Analytical Characterization of Drop Impact Behavior for a Mobile Haptic Actuator

2017 ◽  
Author(s):  
Byungjoo Choi ◽  
Jiwoon Kwon ◽  
Yongho Jeon ◽  
Moon Gu Lee
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Free Fall ◽  
Element Model ◽  
Impact Behavior ◽  
Air Resistance ◽  
Impact Reliability ◽  
The Impact ◽  
The Finite Element Model

Impact characterization of linear resonant actuator (LRA) is studied experimentally by newly developed drop tester, which can control various experimental uncertainty such as rotational moment, air resistance, secondary impact and so on. The feasibility of this test apparatus was verified by comparison with free fall test. By utilizing a high-speed camera and measuring the vibrational displacement of spring material, the impact behavior was captured and the damping ratio of the system was defined. Based on the above processes, the finite element model was established and the experimental and analytical results were successfully correlated. Finally, the damage of the system from impact loading can be expected by developed model and as a result, this research can improve the impact reliability of LRA.

scholarly journals Seismic Strengthening of the Bagh Durbar Heritage Building in Kathmandu Following the Gorkha Earthquake Sequence

Buildings ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 128 ◽  
Author(s):  
Rabindra Adhikari ◽  
Pratyush Jha ◽  
Dipendra Gautam ◽  
Giovanni Fabbrocino
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Gorkha Earthquake ◽  
Seismic Safety ◽  
Early 19Th Century ◽  
Heritage Sites ◽  
Greco Roman ◽  
Heritage Building ◽  
Definition Of

The so-called Greco-Roman monuments, also known as neoclassical monuments, in Nepal represent unique construction systems. Although they are not native to Nepal, they are icons of the early 19th century in the Kathmandu valley. As such structures are located within the heritage sites and historical centers, preservation of Greco-Roman monuments is necessary. Since many buildings are in operation and accommodate public and critical functions, their seismic safety has gained attention in recent times, especially after the Gorkha earthquake. This paper first presents the background of the Bagh Durbar monument, reports the damage observations, and depicts some repair and retrofitting solutions. Attention is paid to the implementation of the different phases of the structural characterization of the building, the definition of reference material parameters, and finally, the structural analysis made by using finite element models. The aim of the contribution consists of comparison of the adequacy of the finite element model with the field observations and design of retrofitting solutions to assure adequate seismic safety for typical Greco-Roman buildings in Nepal. Thus, this paper sets out to provide rational strengthening solutions compatible with the existing guidelines rather than complex numerical analyses.

Characterization of Delamination in Laser Microtransfer Printing

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Ala'a M. Al-okaily ◽  
John A. Rogers ◽  
Placid M. Ferreira
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Laser Heating ◽  
Thermal Gradient ◽  
Heterogeneous Materials ◽  
Element Model ◽  
Extensive Study ◽  
Materials Integration ◽  
Gradient Fields

Microtransfer printing is rapidly emerging as an effective method for heterogeneous materials integration. Laser microtransfer printing (LMTP) is a noncontact variant of the process that uses laser heating to drive the release of the microstructure from the stamp. This makes the process independent of the properties or preparation of the receiving substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Furthermore, a thermomechanical finite element model (FEM) is developed, using the experimentally observed delamination times and absorbed powers, to estimate the delamination temperatures at the interface, as well as the strain, displacement, and thermal gradient fields.

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