Experimental Evaluation of an Equation Applicable for Surface Cracks Under Tensile or Bending Loads

2009 ◽  
pp. 597-597-23 ◽  
Author(s):  
WG Reuter ◽  
JS Epstein
Keyword(s):  
Experimental Evaluation ◽  
Surface Cracks ◽  
Bending Loads

scholarly journals Failure Assessment for the High-Strength Pipelines with Constant-Depth Circumferential Surface Cracks

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
X. Liu ◽  
Z. X. Lu ◽  
Y. Chen ◽  
Y. L. Sui ◽  
L. H. Dai
Keyword(s):  
Finite Element ◽  
Practical Interest ◽  
High Strength ◽  
Influence Functions ◽  
Surface Cracks ◽  
Constant Depth ◽  
Long Distance ◽  
Integrity Assessment ◽  
Failure Assessment ◽  
Bending Loads

In the oil and gas transportation system over long distance, application of high-strength pipeline steels can efficiently reduce construction and operation cost by increasing operational pressure and reducing the pipe wall thickness. Failure assessment is an important issue in the design, construction, and maintenance of the pipelines. The small circumferential surface cracks with constant depth in the welded pipelines are of practical interest. This work provides an engineering estimation procedure based upon the GE/EPRI method to determine the J-integral for the thin-walled pipelines with small constant-depth circumferential surface cracks subject to tension and bending loads. The values of elastic influence functions for stress intensity factor and plastic influence functions for fully plastic J-integral estimation are derived in tabulated forms through a series of three-dimensional finite element calculations for different crack geometries and material properties. To check confidence of the J-estimation solution in practical application, J-integral values obtained from detailed finite element (FE) analyses are compared with those estimated from the new influence functions. Excellent agreement of FE results with the proposed J-estimation solutions for both tension and bending loads indicates that the new solutions can be applied for accurate structural integrity assessment of high-strength pipelines with constant-depth circumferential surface cracks.

scholarly journals A Damage Tolerance Model for Plates with Surface Cracks Under Combined End Force and Bending

2014 ◽  
Vol 8 (1) ◽  
pp. 562-566
Author(s):  
Yuan Haiyang ◽  
Wu Yunxin ◽  
Liao Zhiqi
Keyword(s):  
Mathematical Model ◽  
Aluminum Alloy ◽  
Damage Tolerance ◽  
Surface Cracks ◽  
Critical Crack ◽  
Reference Stress ◽  
Bending Load ◽  
Bending Loads ◽  
Tolerance Model ◽  
Shallow Crack

Reference stress statuses and the critical crack sizes are analyzed systematically and in detail for rectangle surface cracks in plates under combined endforce and cross-thickness bending loads via the ‘global’ reference stress method. The relationships of critical crack width and depth are obtained from the critical crack sizes analysis. Based on the net-section plastic collapse of the flawed component, a damage tolerance mathematical model for plates with single crack was built, which did not consider the contact of crack faces and it can be used for plates with a shallow crack or a deep crack under combined endforce and cross-thickness bending load. Using this mathematical model, the damage limits of aluminum alloy plates under different bending loads are obtained and a simplified damage tolerance model for aluminum alloy plates is established via regression analysis. The results obtained from the model and the regression model agree well with the experimental results especially when a/t<0.8. The test results show that the model can be fast and conveniently predict the damage limits for plates with surface cracks under bending.

scholarly journals CONTROL OF ELEMENTS OF CONSTRUCTION MACHINES AND METAL STRUCTURES USING LOW-APERTURE MAGNETOSTRICTIVE SENSORS

2019 ◽  
Vol 41 (4) ◽  
pp. 78-83
Author(s):  
I.V. Bohachev
Keyword(s):  
Delay Time ◽  
Ultrasonic Testing ◽  
Signal Amplitude ◽  
Surface Cracks ◽  
Testing Methods ◽  
Metal Structures ◽  
Depth Study ◽  
Bending Loads ◽  
Pass Through

The aim of the work is to develop a method and technique for ultrasonic testing of elements of building machines and metal structures using low-aperture magnetostrictive transducers.A study was conducted to detect cracks in the prototype. The crack was grown artificially by repeated variable bending loads on the part.It was shown that the delay time for the signal to pass through the cracked section of the sample increased by 0,5∙10-6 s compared to the delay time when the signal passed through the defect-free portion of the sample, and the signal amplitude decreased by more than 10 times.Currently, ultrasonic testing methods for detecting surface cracks are the most promising. It seems advisable to direct further actions to an in-depth study of the transformation and interference of various types of waves in ultrasound paths and the development of methods for monitoring various objects.

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