Design of NRL66.4: An Electro-Hydraulic 6-DoF Parallel Robotic Multiaxial Material Testing System

2019 ◽  
Author(s):  
John G. Michopoulos ◽  
Athanasios P. Iliopoulos ◽  
John C. Steuben ◽  
Benjamin D. Graber
Keyword(s):  
Degrees Of Freedom ◽  
Material Testing ◽  
Multiaxial Fatigue ◽  
Current Status ◽  
Testing System ◽  
Damage Propagation ◽  
Propagation Modeling ◽  
Multiaxial Testing ◽  
Reaction Forces ◽  
6 Degrees Of Freedom

Abstract Contemporary material testing applications such as high throughput material testing under realistic conditions, emulation of in-service loading conditions for the qualification of additively manufactured parts, material failure and damage propagation modeling validation and material constitutive characterization, are all underscoring the demand for an automated multiaxial testing capability. In order to address these needs, the present work introduces the initial progress of the design and prototyping of a 6 degrees of freedom (6-DoF) robotic system to be used as such a testing infrastructure. This system is designed to be capable of enforcing 6-DoF kinematic or force controlled boundary conditions on deformable material specimens, while at the same time measuring both the imposed kinematics and the corresponding reaction forces in a fully automated manner. Furthermore, as an extension to our previously prototyped systems, the system proposed here is designed to apply both quasi-static loading but also cyclic loading for enabling multiaxial fatigue studies. In addition to the architecture, the design and current status of its implementation for the most critical sub-systems is presented.

Towards a Recursive Hexapod for the Multidimensional Mechanical Testing of Composites

2010 ◽  
Author(s):  
John G. Michopoulos ◽  
John C. Hermanson ◽  
Athanasios Iliopoulos
Keyword(s):  
Composite Material ◽  
Boundary Conditions ◽  
Mechanical Testing ◽  
Material Testing ◽  
Inverse Methods ◽  
Current Status ◽  
Historical Evolution ◽  
Mechatronic System ◽  
Custom Design ◽  
Reaction Forces

Automated inverse methods for material constitutive characterization under multidimensional loading conditions has motivated the custom design, manufacturing and utilization of mechatronic loading machines. This present paper reports on the architecture of a mechatronic system capable of enforcing 6-DoF kinematic boundary conditions on deformable material specimens under testing, while at the same time measuring both the imposed kinematics and the corresponding reaction forces in a fully automated manner. This system has a recursive nature as it consists of a hexapod configuration that repeats itself six times. In addition to the architecture, we also present the historical evolution, and current status of its manufacturing implementation and the initial fielding of our system for composite material testing and characterization.

Prognosis of Blade Material Fatigue Using Elman Neural Networks

2007 ◽  
Vol 10-12 ◽  
pp. 558-562
Author(s):  
Ji Hong Yan ◽  
P.X. Wang
Keyword(s):  
Neural Networks ◽  
Material Testing ◽  
Testing System ◽  
Material Degradation ◽  
Trend Prediction ◽  
Damage Propagation ◽  
Material Fatigue ◽  
Fatigue Data ◽  
Fatigue Severity ◽  
Propagation Prediction

Prognosis of major components such as blades, rotors, valves of steam turbine is crucial to reducing operating and maintenance costs. Prognostic strategies can assist to detect, classify and predict developing faults, guarantee reliable, efficient and continuous operation of electric plants, and may even result in saving lives. In this paper, a recurrent neural network based strategy was developed for blade material degradation assessment and fatigue damage propagation prediction. Two Elman Neural Networks were developed for fatigue severity assessment and trend prediction correspondingly. The performance of the proposed prognostic methodology was evaluated by using blade material fatigue data collected from a material testing system. The prognostic method is found to be a reliable and robust material fatigue predictor.

4D in in vivo 2-photon laser scanning fluorescence microscopy with sample motion in 6 degrees of freedom

2011 ◽  
Vol 200 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Sabine Scheibe ◽  
Mario M. Dorostkar ◽  
Christian Seebacher ◽  
Rainer Uhl ◽  
Frank Lison ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Laser Scanning ◽  
Degrees Of Freedom ◽  
Sample Motion ◽  
6 Degrees Of Freedom

Workspace, dexterity and dimensional optimization of microhexapod

2015 ◽  
Vol 35 (4) ◽  
pp. 341-347 ◽  
Author(s):  
E. Rouhani ◽  
M. J. Nategh
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Screw Theory ◽  
Design Parameters ◽  
Dimensional Synthesis ◽  
Content Type ◽  
Workspace Analysis ◽  
The Difference ◽  
Flexure Joints ◽  
6 Degrees Of Freedom

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

An improved calibration curve between soil pH measured in waterand CaCl2

Soil Research ◽  
2002 ◽  
Vol 40 (8) ◽  
pp. 1399 ◽  
Author(s):  
B. L. Henderson ◽  
E. N. Bui
Keyword(s):  
Statistical Analysis ◽  
Water Resources ◽  
Soil Ph ◽  
Calibration Curve ◽  
Smooth Function ◽  
Degrees Of Freedom ◽  
Additive Model ◽  
Smoothing Spline ◽  
Look Up Table ◽  
6 Degrees Of Freedom

A new pH water to pH CaCl2 calibration curve was derived from data pooled from 2 National Land and Water Resources Audit projects. A total of 70465 observations with both pH in water and pH in CaCl2 were available for statistical analysis. An additive model for pH in CaCl2 was fitted from a smooth function of pH in water created by a smoothing spline with 6 degrees of freedom. This model appeared stable outside the range of the data and performed well (R2 = 96.2, s = 0.24). The additive model for conversion of pHw to pHCa is sigmoidal over the range of pH 2.5 to 10.5 and is similar in shape to earlier models. Using this new model, a look-up table for converting pHw to pHCa was created.

Radiation-tolerant robotic complex URS-2

2021 ◽  
Vol 9 (2) ◽  
pp. 142-150
Author(s):  
Ivan Guschin ◽  
Anton Leschinskiy ◽  
Andrey Zhukov ◽  
Alexander Zarukin ◽  
Vyacheslav Kiryukhin ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Control Device ◽  
Control Panel ◽  
Original Design ◽  
Innovative Methods ◽  
Control Computer ◽  
Robotic Arm Control ◽  
6 Degrees Of Freedom ◽  
Radiation Tolerant

The results of the development of a radiation-tolerant robotic complex URS-2 for operation in hot cells at nuclear enterprises are presented. The robotic complex consists of several original components: robotic arm, control device with force feedback, control panel with hardware buttons and touch screen, control computer with system and application software, control-and-power cabinet. The robotic manipulator has 6 degrees of freedom, replaceable pneumatic grippers and is characterized by high radiation tolerance, similar to that of mechanical master-slave manipulators. The original design of the control device based on the delta-robot model that implements a copying mode of manual control of the robotic complex with force feedback is presented. The hardware and software solutions developed has made it possible to create a virtual simulator of the RTC for testing innovative methods of remote control of the robot, as well as teaching operators to perform technological tasks in hot cells. The experimental model of the robotic complex has demonstrated the ability to perform basic technological tasks in a demo hot cell, both in manual and automatic modes.

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