Software for High Frequency Control of Variable Amplitude Fatigue Tests

1986 ◽  
Vol 25 (2) ◽  
pp. 181-194 ◽  
Author(s):  
M. A. Pompetzki ◽  
R. H. Saper ◽  
T. H. Topper
Keyword(s):  
High Frequency ◽  
Frequency Control ◽  
Fatigue Tests ◽  
Variable Amplitude ◽  
Variable Amplitude Fatigue

Fatigue of Stabilized SS and 316 NG Alloy in PWR Environment

2006 ◽  
Author(s):  
Jussi P. Solin
Keyword(s):  
Stainless Steels ◽  
Fatigue Tests ◽  
Test Results ◽  
Constant Amplitude ◽  
Low Oxygen ◽  
Variable Amplitude ◽  
Variable Amplitude Fatigue ◽  
Reduction Factors

Strain controlled constant and variable amplitude fatigue tests for 316NG and Titanium stabilized stainless steels in low oxygen PWR waters were performed. The stabilized steel has been plant aged for 100 000 hours. Constant amplitude test results at 0,01 Hz sinusoidal straining comply with predicted lives according to the Fen approach for both materials. Spectrum straining both in air and in environment caused predicted life reduction factors (about 3) for the stabilized steel, but for the 316NG steel spectrum straining in environment resulted to a larger reduction in life.

Corrosion Fatigue of AZ91E-T6 Cast Magnesium Alloy in a 3.5 Percent NaCl Aqueous Environment

1995 ◽  
Vol 117 (3) ◽  
pp. 293-298 ◽  
Author(s):  
R. I. Stephens ◽  
C. D. Schrader ◽  
K. B. Lease
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloy ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Constant Amplitude ◽  
Variable Amplitude ◽  
Cast Magnesium Alloy ◽  
Cast Magnesium ◽  
Variable Amplitude Fatigue

The objective of this research was to obtain and compare constant and variable amplitude fatigue behavior of AZ91E-T6 cast magnesium alloy in both an air and 3.5 percent NaCl aqueous corrosive environment. An additional objective was to determine if commonly used models that describe fatigue behavior and fatigue life are applicable to this material and test environment. Fatigue tests included constant amplitude strain-controlled low cycle fatigue with strain ratio, R, equal to 0, −1 and −2, Region II constant amplitude fatigue crack growth with load ratio, R, equal to 0.05 and 0.5 and variable amplitude fatigue tests using keyhole notched specimens. In all fatigue tests, the corrosion environment was significantly detrimental relative to the air environment. Mean strains influenced fatigue life only if accompanied by significant mean stress. The Morrow and Smith, Watson, and Topper mean stress models provided both accurate and inaccurate fatigue life calculations. Likewise, variable amplitude fatigue life calculations using the local strain approach and based upon the formation ofal mm crack at the keyhole notch were both accurate and fairly inaccurate depending on the specific model used.

scholarly journals Effects of variable amplitude loading on fatigue life

2015 ◽  
Vol 6 (3) ◽  
pp. 10 ◽  
Author(s):  
Niels Laseure ◽  
Ingmar Schepens ◽  
Nahuel Micone ◽  
Wim De Waele
Keyword(s):  
Offshore Structures ◽  
Fatigue Tests ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Industrial Sectors ◽  
Closure Mechanism ◽  
Physical Phenomena ◽  
Published Research ◽  
Variable Amplitude Fatigue ◽  
Plasticity Induced Crack Closure

This paper is a review of published research on variable amplitude loading of steels. The use of service spectra for different industrial sectors and specifically for offshore applications is first considered. Constant amplitude fatigue failure models are not representative for these applications. The JONSWAP spectrum shows potential to be used as service spectrum for offshore structures. Further investigation of variable amplitude fatigue is needed to get insight in the various phenomena linked to the variable amplitude. Observed trends in fatigue crack growth rate in variable amplitude fatigue tests on steels, such as the effects of overloads and underloads (occurring as single events, sequential events or block loadings), are discussed. Furthermore, suggestions of the underlying physical phenomena behind the load interaction effects due to variable amplitude loading are presented. It can be concluded that the plasticity induced crack closure mechanism is the most profound explanation for the acceleration effect in overloads and the retardation effect observed in underloads.

scholarly journals Experimental Study on Variable-Amplitude Fatigue of Welded Cross Plate-Hollow Sphere Joints in Grid Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Jin-Feng Jiao ◽  
Hong-Gang Lei ◽  
Y. Frank Chen
Keyword(s):  
Fatigue Life ◽  
Hollow Sphere ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Metallographic Analysis ◽  
Variable Load ◽  
Random Loading ◽  
Variable Amplitude ◽  
Different Types ◽  
Variable Amplitude Fatigue

The fatigue stress amplitude of the welded cross plate-hollow sphere joint (WCPHSJ) in a grid structure varies due to the random loading produced by suspending cranes. A total of 14 specimens considering three different types of WCPHSJs were prepared and tested using a specially designed test rig. Four typical loading conditions, “low-high,” “high-low,” “low-high-low,” and “high-low-high,” were first considered in the tests to investigate the fatigue behavior under variable load amplitudes, followed by metallographic analyses. The experimental and metallographic analysis results provide a fundamental understanding on the fatigue fracture form and fatigue mechanism of WCPHSJs. Based on the available data from constant-amplitude fatigue tests, the variable-amplitude fatigue life of the three types of WCPHSJs was estimated using the Miner rule and Corten-Dolan theory. Since both accumulative damage theories yield virtually same damaging results, the Miner rule is hence suggested to estimate the fatigue life of WCPHSJs.

Effects of Laryngeal Topical Anesthesia on Voice Fundamental Frequency Perturbation

1980 ◽  
Vol 23 (2) ◽  
pp. 274-283 ◽  
Author(s):  
David Sorensen ◽  
Yoshiyuki Horii ◽  
Rebecca Leonard
Keyword(s):  
Fundamental Frequency ◽  
High Frequency ◽  
Frequency Control ◽  
Topical Anesthesia ◽  
Proprioceptive Feedback ◽  
Adult Males ◽  
Voice Fundamental Frequency

Fundamental frequency perturbation (jitter) during sustained vowel phonations of speakers under topical anesthesia of the larynx was investigated for five adult males. The results showed that the average jitter was significantly greater under the anesthesia than normal conditions, and that the jitter difference between the two conditions was more prominent at high frequency phonations. Implications of these data for tactile and proprioceptive feedback in phonatory frequency control are discussed.

Open-Source Real-Time Robot Operation and Control System for Highly Dynamic, Modular Machines

2013 ◽  
Author(s):  
Andrew Peekema ◽  
Daniel Renjewski ◽  
Jonathan Hurst
Keyword(s):  
Control System ◽  
Open Source ◽  
Real Time ◽  
High Frequency ◽  
Performance Test ◽  
Frequency Control ◽  
Human Robot Interaction ◽  
Sensors And Actuators ◽  
Key Innovation ◽  
Hard Real Time

The control system of a highly dynamic robot requires the ability to respond quickly to changes in the robot’s state. This type of system is needed in varying fields such as dynamic locomotion, multicopter control, and human-robot interaction. Robots in these fields require software and hardware capable of hard real-time, high frequency control. In addition, the application outlined in this paper requires modular components, remote guidance, and mobile control. The described system integrates a computer on the robot for running a control algorithm, a bus for communicating with microcontrollers connected to sensors and actuators, and a remote user interface for interacting with the robot. Current commercial solutions can be expensive, and open source solutions are often time consuming. The key innovation described in this paper is the building of a control system from existing — mostly open source — components that can provide realtime, high frequency control of the robot. This paper covers the development of such a control system based on ROS, OROCOS, and EtherCAT, its implementation on a dynamic bipedal robot, and system performance test results.

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