Accuracy and Precision of Crack Length Measurements Using a Compliance Technique

1983 ◽  
Vol 11 (2) ◽  
pp. 150 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
MB Vieth ◽  
RL Hewitt
Keyword(s):  
Crack Length ◽  
Accuracy And Precision ◽  
Length Measurements

Method for validating CT length measurement of cracks inside solder joints

2016 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Tamás Garami ◽  
Oliver Krammer ◽  
Gábor Harsányi ◽  
Péter Martinek
Keyword(s):  
High Resolution ◽  
Crack Length ◽  
Solder Joints ◽  
Life Time ◽  
Percentage Error ◽  
Content Type ◽  
Lack Of Information ◽  
Length Measurements ◽  
Set Up ◽  
Ct Measurement

Purpose – This paper aims to develop a method to measure the length of cracks inside solder joints, which enables the validation of computed tomography (CT) crack length measurements. Design/methodology/approach – Cracks were formed inside solder joints intentionally by aging solder joints of 0603 size resistors with thermal shock (TS) test (−40 to +140°C, 2,000 cycles), and CT images were captured about them with different rotational increment (1/4, 1/2 and 1°) of sample projection. The length of cracks was also measured with our method, which is based on capturing high-resolution radiography X-ray images about the cracks in two perpendicular projection planes. The radiography results were compared to the CT measurements. The percentage error for the different CT rotational increment settings was calculated, and the optimal CT settings have been determined. Findings – The results have proven that reducing the rotational increment increases the sharpness of the captured images and the accuracy of crack length measurements. Nevertheless, the accuracy compared to high-resolution radiography measurements is only slightly better at 1/4° rotational increment than in the case of 1/2° rotational increment. It should be also noted that the 1/4° increment requires twice as much time for capturing the images as the 1/2° increment. So, the 1/2° rotational increment of sample projection is the optimal setting in our investigated case for measuring crack lengths. Practical implications – The developed method is applicable to find the optimal settings for CT crack length measurements, which provides faster analysation of large quantity samples used, e.g. at life-time tests. Originality/value – There is a lack of information in the literature regarding the optimisation of CT measurement set-up, e.g. a slightly larger value of the sample rotational increment can provide acceptable resolution with much faster processing time. Thus, the authors developed a method and performed research about optimising CT measurement parameters.

scholarly journals Machine Learning Based Prognostics of Fatigue Crack Growth in Notch Pre-cracked Aluminum 7075-T6 Rivet Hole

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Robert Haynes ◽  
Ghanashyam Joshi ◽  
Natasha Bradley
Keyword(s):  
Machine Learning ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Initiation ◽  
Crack Length ◽  
Crack Growth ◽  
Particle Filtering ◽  
Fatigue Crack Initiation ◽  
Length Measurements ◽  
Aluminum 7075

Constant stress amplitude fatigue tests were conducted on the notch pre-cracked Aluminum 7075-T6 rivet hole dog-bone coupons. Monitoring of visible surface crack length by special surface engraving using digital microscope images and by ultrasonic sensors signals was carried out to yield fatigue crack length measurements in relation to number of fatigue cycles applied. The experimental results provide ultrasonic sensor validation for fatigue crack length measurements. Fracto-graphic examination of failed fatigue surfaces has provided further confirmation of notch pre-crack length, crack initiation process, and crack growth marker bands. These experimental inputs were used in NASGRO and AFGROW software fatigue crack growth simulations. The simulation results did not match the crack initiation fatigue life measured by experiments. However, there was good agreement with crack growth simulations of larger cracks. Hence, we plan to develop a machine learning application that will learn the fatigue crack initiation and crack growth processes from data obtained from our own experiments and other fatigue data available from AFGROW databases. Nonlinear AutoRegressive models with eXogenous input (NARX) artificial neural network were used to predict crack growth longer than 5.0-mm. Particle filtering modeling with Bayesian updating was applied to these experimental data for prognostics of fatigue crack growth. A concept design and preliminary implementation results will be presented.

Back Face Strain Calibration for Crack Length Measurements

1994 ◽  
Vol 22 (6) ◽  
pp. 512 ◽  
Author(s):  
DR Petersen ◽  
WJD Shaw ◽  
W Zhao
Keyword(s):  
Crack Length ◽  
Length Measurements ◽  
Back Face

Application of the Electrical Potential Method to Crack Length Measurements Using Johnson's Formula

1981 ◽  
Vol 9 (3) ◽  
pp. 218 ◽  
Author(s):  
KC Lieb ◽  
R Horstman ◽  
KA Peters ◽  
CF Enright ◽  
RL Meltzer ◽  
...  
Keyword(s):  
Crack Length ◽  
Electrical Potential ◽  
Potential Method ◽  
Length Measurements

R Curves from Compliance and Optical Crack-Length Measurements

2010 ◽  
Vol 93 (9) ◽  
pp. 2814-2821 ◽  
Author(s):  
Stefan Fünfschilling ◽  
Theo Fett ◽  
Rainer Oberacker ◽  
Michael J. Hoffmann ◽  
Hüseyin Özcoban ◽  
...  
Keyword(s):  
Crack Length ◽  
Length Measurements

scholarly journals A Variance Model in NRTK-Based Geodetic Positioning as a Function of Baseline Length

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 262
Author(s):  
Ömer Gökdaş ◽  
M. Tevfik Özlüdemir
Keyword(s):  
Reference Station ◽  
Baseline Length ◽  
Mean Square ◽  
International Gnss Service ◽  
Virtual Reference ◽  
Variance Model ◽  
Accuracy And Precision ◽  
Length Measurements ◽  
The Mean ◽  
Mean Differences

This study examines the effect of baseline length on accuracy and precision in Network Real-Time Kinematic (NRTK) positioning and develops an experimental mathematical model to express this effect. The study also measures the performances of the Flaechen Korrektur Parameter (FKP) and Virtual Reference Stations (VRS) methods at different baseline lengths. The study makes use of the stations that form two Continuously Operating Reference Station (CORS) networks, one of which is local and the other national. Calculations were made to perform various geodetic operations, such as datum transformations between the two networks, identifications of positional velocities, and epoch shifting. BERNESE (v5.2) software was used to identify coordinate values assumed to be true based on International GNSS Service (IGS) products. No significant changes were observed in the RMSE values in baseline lengths of up to 40 km. In contrast, an average linear correlation of 69.2% was determined between precision and baseline length. Measurements were evaluated and tested using the variance model created as a function of the baseline length, in line with the aims of the study, and the results were found to be consistent. Moreover, in an examination of the Root Mean Square Error (RMSE) and precision values of the FKP and VRS measurements, no significant differences were observed. The mean differences were at the millimetre level.

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