scholarly journals Natural Frequency Method (Impact Acoustic Method) For Crack Defect Evaluation In Steel Parts

2020 ◽  
Author(s):  
Yulian Kin ◽  
Krasimir Zahariev
Keyword(s):  
Natural Frequency ◽  
Acoustic Method ◽  
Frequency Method ◽  
Crack Defect

Effect of Multiple Location Defects on the Dynamics of Draft Gear used in Freight Railway Wagon

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Sachin S. Harak ◽  
Satish C. Sharma ◽  
Sanjay Shukla ◽  
Parinay Gupta ◽  
Sanjay Kumar ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Base Plate ◽  
Longitudinal Direction ◽  
Mode Shapes ◽  
Damage Scenarios ◽  
Railway Wagon ◽  
Crack Location ◽  
Draft Gear ◽  
Element Approach ◽  
Crack Defect

The present work investigates the effect of crack location on the modal frequency of draft gear used in autocouplers of freight railway wagon for various orientations. First seven mode shapes of a healthy draft gear have been determined using finite element approach. Defect of semi-elliptical shape is modelled in the lateral as well as longitudinal direction of the draft pad which is a component of draft gear. Various damage scenarios have been simulated by considering multiple locations of the crack in the draft gear for different orientations. Effect of crack orientation and defective pads location on the natural frequency of draft gear is analysed. It is seen that for single defective pad as well as multiple defective pads, the natural frequency of draft gear is dependent on the dynamics of draft pad. It is also observed that defect in consecutive pads causes more change in frequency as compared to single defective pad. As far as the location of defective pad is concerned, it is seen that the draft gear frequency is more sensitive to defective pads located either near the housing base plate or top follower. This study provides a tool to diagnose crack defect in draft gear based on vibration characteristics.

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

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.

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