Enhanced Stop-Drill Repair Procedure for Cracked Structures

2008 ◽  
pp. 190-190-31 ◽  
Author(s):  
MA Landy ◽  
H Armen ◽  
HL Eidinoff
Keyword(s):  
Repair Procedure ◽  
Cracked Structures

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

Qualification of M256 Breechblock Repair Procedure

1994 ◽  
Author(s):  
David A. Porter ◽  
William E. Marcoux ◽  
Alice E. Fish
Keyword(s):  
Repair Procedure

scholarly journals Fatigue Life Improvement of Cracked Aluminum 6061-T6 Plates Repaired by Composite Patches

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1421
Author(s):  
Armin Yousefi ◽  
Saman Jolaiy ◽  
Reza Hedayati ◽  
Ahmad Serjouei ◽  
Mahdi Bodaghi
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Plastic Strain Amplitude ◽  
Composite Patch ◽  
Life Improvement ◽  
Cracked Structures ◽  
Aluminum Plates ◽  
High Flexibility

Bonded patches are widely used in several industry sectors for repairing damaged plates, cracks in metallic structures, and reinforcement of damaged structures. Composite patches have optimal properties such as high strength-to-weight ratio, easiness in being applied, and high flexibility. Due to recent rapid growth in the aerospace industry, analyses of adhesively bonded patches applicable to repairing cracked structures have become of great significance. In the present study, the fatigue behavior of the aluminum alloy, repaired by a double-sided glass/epoxy composite patch, is studied numerically. More specifically, the effect of applying a double-sided composite patch on the fatigue life improvement of a damaged aluminum 6061-T6 is analyzed. 3D finite element numerical modeling is performed to analyze the fatigue performance of both repaired and unrepaired aluminum plates using the Abaqus package. To determine the fatigue life of the aluminum 6061-T6 plate, first, the hysteresis loop is determined, and afterward, the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted and validated against the available experimental data from the literature. Results reveal that composite patches increase the fatigue life of cracked structures significantly, ranging from 55% to 100% for different applied stresses.

scholarly journals An Extended Finite Element Method (XFEM) Study on the Elastic T-Stress Evaluations for a Notch in a Pipe Steel Exposed to Internal Pressure

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 507
Author(s):  
K. Yakoubi ◽  
S. Montassir ◽  
Hassane Moustabchir ◽  
A. Elkhalfi ◽  
Catalin Iulian Pruncu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Extended Finite Element Method ◽  
Research Study ◽  
Extended Finite Element ◽  
T Stress ◽  
Cracked Structures ◽  
Element Method

The work investigates the importance of the K-T approach in the modelling of pressure cracked structures. T-stress is the constant in the second term of the Williams expression; it is often negligible, but recent literature has shown that there are cases where T-stress plays the role of opening the crack, also T-stress improves elastic modeling at the point of crack. In this research study, the most important effects of the T-stress are collected and analyzed. A numerical analysis was carried out by the extended finite element method (X-FEM) to analyze T-stress in an arc with external notch under internal pressure. The different stress method (SDM) is employed to calculate T-stress. Moreover, the influence of the geometry of the notch on the biaxiality is also examined. The biaxiality gave us a view on the initiation of the crack. The results are extended with a comparison to previous literature to validate the promising investigations.

The Application of Fluoresced Gel for the First Alkali Silica Reaction Evidence in Thailand

2011 ◽  
Vol 368-373 ◽  
pp. 613-616 ◽  
Author(s):  
Suvimol Sujjavanich ◽  
Krit Won-In ◽  
Wacharakorn Wongkhamchan ◽  
Pisutti Dararutana
Keyword(s):  
Uv Light ◽  
Effective Means ◽  
Accelerated Expansion ◽  
Alkali Silica Reaction ◽  
Interface Zone ◽  
Expansion Test ◽  
Existing Structures ◽  
Coarse Aggregates ◽  
The Matrix ◽  
Cracked Structures

The study of the first alkali silica reaction (ASR) case in Thailand was conducted on fluoresced gel under UV light technique. It was done on ten random cored samples from different cracked structures of ten year-aged project and the other three cored samples from no-crack structure of one building and two bridges, ages older than 40 years. It was study on areas of suspected ASR gel in the interface zone (ITZ), aggregates and paste in the vicinity. The results of reflected area indicated the evidence of ASR gel at aggregate’s rim and the nearly areas as well as in some cracks in the matrix of 9 in 11 samples of the first set. The amount of reactive coarse aggregates was found in the range of 5-90% of total coarse aggregate content, which was supported by the expansion results of same cored samples from previous study. The results of this study indicated that the fluoresced gel technique provided the satisfied results which confirmed the accelerated expansion test from previous study. They can be used as an effective means for ASR screening test of existing structures both in the field and in laboratory.

Methodology for in situ stress intensity factor determination on cracked structures by digital image correlation

2010 ◽  
Vol 1 (4) ◽  
pp. 344-357 ◽  
Author(s):  
V. Richter‐Trummer ◽  
P.M.G.P. Moreira ◽  
S.D. Pastrama ◽  
M.A.P. Vaz ◽  
P.M.S.T. de Castro
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Digital Image Correlation ◽  
Intensity Factor ◽  
Digital Image ◽  
Strain Field ◽  
Image Correlation ◽  
Content Type ◽  
Cracked Structures

PurposeThe purpose of this paper is to develop a methodology for in situ stress intensity factor (SIF) determination that can be used for the analysis of cracked structures. The technique is based on digital image correlation (DIC) combined with an overdetermined algorithm.Design/methodology/approachThe linear overdeterministic algorithm for calculating the SIF based on stress values around the crack tip is applied to a strain field obtained by DIC.FindingsAs long as the image quality is sufficiently high, a good accuracy can be obtained for the measured SIF. The crack tip can be automatically detected based on the same strain field. The use of the strain field instead of the displacement field, eliminates problems related to the rigid body motion of the analysed structure.Practical implicationsIn future works, based on the applied techniques, the SIF of complex cracked plane stress structures can be accurately determined in real engineering applications.Originality/valueThe paper demonstrates application of known techniques, refined for other applications, also the use of stress field for SIF overdeterministic calculations.

Optimization of a Weld Overlay on a Plate Structure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
John Goldak ◽  
Mahyar Asadi ◽  
Jianguo Zhou ◽  
Stanislav Tchernov ◽  
Dan Downey
Keyword(s):  
Welding Process ◽  
Francis Turbine ◽  
Transient Temperature ◽  
Weld Repair ◽  
Weld Overlay ◽  
Hydroelectric Project ◽  
Repair Procedure ◽  
Strain Stress ◽  
Welding Direction ◽  
Interpass Temperature

An overlay weld repair procedure on a 1066.8×1066.8 mm2 square plate 25.4 mm thick was simulated to compute the 3D transient temperature, microstructure, strain, stress, and displacement of the overlay weld repair procedure. The application for the overlay was the repair of cavitation erosion damage on a large Francis turbine used in a hydroelectric project. The overlay weld consisted of a 4×6 pattern of 100×100 mm2 squares. Each square was covered by 15 weld passes. Each weld pass was 100 mm long. The total length of weld in the six squares was 36 m. The welds in each square were oriented either front-to-back or left-to-right. The welding process was shielded metal arc. The analysis shows that alternating the welding direction in each square produces the least distortion. A delay time of 950 s between the end of one weld pass and the start of the next weld pass was imposed to meet the requirement of a maximum interpass temperature to 50°C.

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