Field Application of Externally Stress-Relieved Drill Collars

1977 ◽  
Vol 99 (1) ◽  
pp. 149-151
Author(s):  
L. A. Primm
Keyword(s):  
Fatigue Life ◽  
Stress Relief ◽  
Field Application ◽  
External Stress

This paper discusses the 1975 field results of the application of external stress relief grooves on drill collars. It contains a formula for the calculation of the groove diameter and makes recommendations for how and where to cut these features. Increased connector fatigue life was gained.

Micromechanics Method to Evaluate Fatigue Life of Ni-Based Superalloys during Morphological Evolution

2008 ◽  
Vol 385-387 ◽  
pp. 221-224
Author(s):  
Wen Ping Wu ◽  
Ya Fang Guo ◽  
Yue Sheng Wang
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Life Prediction ◽  
Morphological Evolution ◽  
Mean Field ◽  
Prediction Method ◽  
Field Method ◽  
External Stress ◽  
Equivalent Inclusion ◽  
Evolution Of Precipitates

A quantitative life prediction method has been proposed to evaluate fatigue life during morphological evolution of precipitates in Ni-based superalloys. The method is essentially based on Eshelby’s equivalent inclusion theory and Mori-Tanaka’s mean field method. The shape stability and life prediction are discussed when the external stress and matrix plastic strain are applied. The calculated results show that the fatigue life is closely related with microstructures evolution of precipitates. The magnitude and sign of the external stress and matrix plastic strain have an important effect on fatigue life of Ni-based superalloys during the morphological evolution of precipitates.

scholarly journals Fracture patterns in thin films and multilayers

2003 ◽  
Vol 795 ◽  
Author(s):  
Alex A. Volinsky ◽  
Dirk C. Meyer ◽  
Tilmann Leisegang ◽  
Peter Paufler
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Residual Stress ◽  
Stress Relief ◽  
Fracture Pattern ◽  
External Stress ◽  
Final Fracture ◽  
Fracture Patterns ◽  
Buckling Delamination ◽  
Applied Stresses

ABSTRACTWhile there are many stress relief mechanisms observed in thin films, excessive residual and externally applied stresses cause film fracture. In the case of tensile stress a network of through-thickness cracks forms in the film. In the case of compressive stress thin film buckling is observed in the form of blisters. Thin film delamination is an inseparable phenomenon of buckling. The buckling delamination blisters can be either circular, straight, or form periodic buckling patterns commonly known as telephone cord delamination morphology.While excessive biaxial residual stress is the key for causing thin film fracture, either in tension, or compression, it is the influence of the external stress that can control the final fracture pattern. In this paper we consider phone cord buckling delamination observed in compressed W/Si and TiWN/GaAs thin film systems, as well as spiral and sinusoidal though-thickness cracks observed in Mo/Si multilayers under 3-point high-temperature bending in tension.

Stress Relief in Solder Joints Due to the Application of a Flex Circuit

1991 ◽  
Vol 113 (3) ◽  
pp. 240-243 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Solder Joints ◽  
Stress Relief ◽  
Physical Design ◽  
Thermal Contraction ◽  
Analysis Model ◽  
Rigid Substrate

A stress analysis model is developed to assess the stresses in solder joints caused by thermal contraction mismatch between a low expansion flex-circuit (FC) and a high expansion rigid substrate. It is shown that application of low expansion FCs can result in significant stress relief for solder joints. This is due to the fact that the force acting on a joint cannot exceed the buckling force for the adjacent portion of the FC. It is shown that the strains in solder joints interconnecting FCs to rigid substrates can be made very small, thereby resulting in a substantially longer fatigue life of the interconnection. In the executed example these strains are about two orders of magnitude smaller, than in the case of a rigid board. The obtained results can be utilized as guidance in physical design of assemblies with FCs.

Is Titanium Drillpipe Applicable to Offshore Drilling? A Question from a Corrosion Fatigue Perspective

SPE Journal ◽  
2021 ◽  
pp. 1-17
Author(s):  
Hao Yu ◽  
Yisheng Mou ◽  
Zhanghua Lian ◽  
Qiang Zhang
Keyword(s):  
Corrosion Resistance ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Service Life ◽  
Corrosion Fatigue ◽  
Field Application ◽  
Drilling Mud ◽  
Offshore Drilling ◽  
Rotary Drilling ◽  
Short Period

Summary In offshore horizontal well drilling, one of the major challenges is the large dogleg severity in the buildup section due to the shallow depth of reservoirs. In such a case, the drillstring has to bend itself to fit the borehole trajectory and suffers greatly from the high alternating stress while rotary drilling. This could lead to fatigue fracture of the drillpipe within a short period. The corrosion from drilling mud may exacerbate the failure risk. Titanium alloy, as a new drillpipe material, has the characteristics of excellent corrosion resistance and low elastic modulus, which can theoretically extend the fatigue life. To study the performance of titanium alloy drillpipe quantitatively, titanium alloy material, and G105 steel of the same grade are compared to obtain the microscopic characteristics and macroscopic properties through experimental tests. Moreover, the mechanism of passive film formation of the two materials is analyzed in the corrosion fatigue (CF) environment. Then, the experimental results are extended to modeling the actual drillstring assembly and simulating its service life in the field practice of offshore drilling. Our numerical results indicated that the titanium alloy drillpipe has much better corrosion resistance but only half the stress level of G105 steel under the same dogleg severity and axial force, which makes its fatigue life over 23 times longer. Eventually an economic appraisal is given by considering the full-service life of the drillpipe. The research results of this paper can provide a detailed theoretical basis and reference for field application and can popularize the use of titanium alloy drillpipe.

Stress relief by annealing under external stress in Fe-based metallic glasses

2018 ◽  
Vol 124 (16) ◽  
pp. 165108 ◽  
Author(s):  
M. C. Ri ◽  
D. W. Ding ◽  
S. Sohrabi ◽  
B. A. Sun ◽  
W. H. Wang
Keyword(s):  
Metallic Glasses ◽  
Stress Relief ◽  
External Stress

scholarly journals Experimental Investigation on the Fatigue Life of Ti-6Al-4V Treated by Vibratory Stress Relief

Metals ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 158 ◽  
Author(s):  
Han-Jun Gao ◽  
Yi-Du Zhang ◽  
Qiong Wu ◽  
Jing Song
Keyword(s):  
Experimental Investigation ◽  
Fatigue Life ◽  
Stress Relief

Effect of CO2 Saturation and Desorption on the Fatigue Life of Polycarbonate

1994 ◽  
Vol 116 (4) ◽  
pp. 451-456 ◽  
Author(s):  
K. A. Seeler ◽  
Vipin Kumar
Keyword(s):  
Shear Strength ◽  
Fatigue Life ◽  
Yield Strength ◽  
Fatigue Cracks ◽  
Saturation Pressure ◽  
Stress Relief ◽  
Shear Fatigue ◽  
Static Yield ◽  
Swelling Strain ◽  
Slow Growing

The effect of a cycle of CO2 saturation and desorption on the yield strength, Young’s modulus, and fatigue life of polycarbonate was investigated. The fatigue life of the saturation-cycled polycarbonate exceeded that of unprocessed polycarbonate by up to a factor of thirty. The fatigue life of these rough-surfaced saturation-cycled specimens was approximately equal to or greater than that of polished smooth bar specimens. The increase in fatigue life is a function of the CO2 saturation pressure, reaching a maximum at the same saturation pressure at which there is no further reduction in static yield strength. The increased fatigue life is hypothesized to result from one or more of following mechanisms: (1) reduction of shear strength promoting slow-growing shear fatigue cracks: (2) “healing” or blunting of pre-existing flaws or microcracks by swelling strain or by stress relief strain resulting from plasticization by CO2 during saturation.

Plastic Bag Waste on Hotmixture Asphalt as Modifier

2018 ◽  
Vol 789 ◽  
pp. 20-25
Author(s):  
Nyoman Suaryana ◽  
Edwin Nirwan ◽  
Yohanes Ronny
Keyword(s):  
Fatigue Life ◽  
Resilient Modulus ◽  
Asphalt Mixture ◽  
Field Application ◽  
Plastic Waste ◽  
Marine Debris ◽  
Production Plant ◽  
Additional Time ◽  
Moisture Sensitivity ◽  
Plastic Bag

Indonesia is the second largest country to contribute plastic marine debris in the world. Onthe other hand, Indonesia is facing pavement problem due to various reasons, so it needs to improvethe pavement quality and performance. The addition of plastic waste to the hot mix asphalt (HMA)actually have beneficial effect to improve the pavement quality. Utilization of plastic waste in roadconstruction is conducted by incorporating the plastic waste into the asphalt mixture as an additivewith dry or wet mix process. The objective of this research is to investigate the laboratoryperformance of asphalt mixture using plastic waste addition and its effect on the moisture sensitivity,resistance to deformation and the fatigue life of the asphalt mixture. The addition of plastic waste inHMA will increase the Marshall stability and the resilient modulus of the mixture, improve strippingresistance, moisture sensitivity and also the rutting resistance. Up to a certain plastic content, theaddition of plastic waste will improve the fatigue life and the ravelling resistance of the HMA, on thecontrary excesive addition of the plstic waste will decrease the fatigue life and ravelling resistancecompare to the conventional HMA. The field application is very simillar to conventional HMA,except it requires additional time during dry mix process in the production plant.

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