Measurement of Creep Damage by the Natural Frequency Method

2002 ◽  
Vol 30 (3) ◽  
pp. 251 ◽  
Author(s):  
DR Petersen ◽  
RE Link ◽  
X Ling ◽  
S-t Tu
Keyword(s):  
Natural Frequency ◽  
Creep Damage ◽  
Frequency Method

The use of vibration measurements for the detection of diffuse creep damage

1981 ◽  
Vol 16 (1) ◽  
pp. 37-41 ◽  
Author(s):  
P Cawley ◽  
R D Adams ◽  
W J Plumbridge
Keyword(s):  
Oxide Layer ◽  
Natural Frequency ◽  
Speed Of Sound ◽  
Natural Frequencies ◽  
Creep Damage ◽  
Velocity Measurements ◽  
Brittle Transition ◽  
Apparent Modulus ◽  
Frequency Changes ◽  
Non Destructive

The feasibility of using measurements of structural natural frequencies for the non-destructive assessment of diffuse creep damage has been investigated for a 1 per cent chromium—½ per cent molybderum—¼ per cent vanadium steel crept at stresses above and below the ductile brittle transition stress. The frequency changes observed during creep were similar to those predicted for constant volume straining of the specimen. Uncertainties arose due to the formation of an oxide layer on the specimen surface but no evidence has been found to suggest that, in either range, significant independent changes of modulus or density occur during creep. It has also been shown that the speed of sound in a material is unaffected by the presence of small voids since the apparent modulus and density are changed in the same proportions. Ultrasonic velocity measurements cannot therefore, be used to detect voiding in its early stages. The results also suggest that natural frequency measurements are unlikely to detect this type of damage.

Application Research on Natural Frequency Method in Single Terminal Traveling Wave Fault Location

2013 ◽  
Vol 341-342 ◽  
pp. 1393-1396
Author(s):  
Li Gao ◽  
Hong Chun Shu
Keyword(s):  
Numerical Simulation ◽  
Natural Frequency ◽  
Traveling Wave ◽  
Fault Location ◽  
Travelling Wave ◽  
Application Research ◽  
Frequency Method ◽  
Location Method ◽  
Calculation Results

A method is provided to make natural frequency method be applied to single terminal traveling wave fault location in the paper. A group of fault distance suspected is calculated by single terminal method of traveling wave fault location method firstly, then deal with current travelling wave of fault by FFT to get the natural frequency reflecting fault location so that a fault distance can be calculated by it. Contrast the fault distance from natural frequency method and everyone of the group of fault distance suspected from single terminal method of traveling wave fault location method to determine the suspected fault distance closed to it is the calculation results we want. Numerical simulation shows the method can improve effectively the reliability of single terminal traveling wave fault location.

scholarly journals Natural Frequency Method: estimating the preferred walking speed of Tyrannosaurus rex based on tail natural frequency

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Pasha A. van Bijlert ◽  
A. J. ‘Knoek’ van Soest ◽  
Anne S. Schulp
Keyword(s):  
Energy Storage ◽  
Natural Frequency ◽  
Elastic Energy ◽  
Walking Speed ◽  
Natural Frequencies ◽  
Body Parts ◽  
Step Frequency ◽  
Frequency Method ◽  
Cost Of Transport ◽  
Moment Arms

Locomotor energetics are an important determinant of an animal's ecological niche. It is commonly assumed that animals minimize locomotor energy expenditure by selecting gait kinematics tuned to the natural frequencies of relevant body parts. We demonstrate that this allows estimation of the preferred step frequency and walking speed of Tyrannosaurus rex , using an approach we introduce as the Natural Frequency Method. Although the tail of bipedal dinosaurs was actively involved in walking, it was suspended passively by the caudal interspinous ligaments. These allowed for elastic energy storage, thereby reducing the metabolic cost of transport. In order for elastic energy storage to be high, step and natural frequencies would have to be matched. Using a 3D morphological reconstruction and a spring-suspended biomechanical model, we determined the tail natural frequency of T. rex (0.66 s −1 , range 0.41–0.84), and the corresponding walking speed (1.28 m s −1 , range 0.80–1.64), which we argue to be a good indicator of preferred walking speed (PWS). The walking speeds found here are lower than earlier estimations for large theropods, but agree quite closely with PWS of a diverse group of extant animals. The results are most sensitive to uncertainties regarding ligament moment arms, vertebral kinematics and ligament composition. However, our model formulation and method for estimation of walking speed are unaffected by assumptions regarding muscularity, and therefore offer an independent line of evidence within the field of dinosaur locomotion.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

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