Download or read book Determination of Fatigue Crack Growth Rate by the Potential Drop Method Set up and Calibration written by O. Vosikovsky and published by . This book was released on 1975 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determining the Potential Drop Calibration of a Fatigue Crack Growth Specimen Subject to Limited Experimental Observations written by PC. McKeighan and published by . This book was released on 1994 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Six separate calibration techniques are applied to potential drop (PD) and crack length data from 23 experimental datasets. Five of the techniques use limited experimental input gained during precracking and after test completion to derive the coefficients associated with the calibrations. The datasets include SE(B) and M(T) specimens, fatigue crack growth (FCG) tests and foil analog simulations as well as various aluminum alloys and steel. A comparison of the calibration techniques is undertaken in terms of crack length and the subsequent effect on stress intensity factor errors. The best calibration techniques using two PD and crack length data pairs are the two-point modified and post-test corrected Johnson's equation. Using these methods, 21 of the 23 tests satisfy a criterion based on an acceptable ±2% mean variation in stress intensity factor. If a statistical assessment of the data is made, only 30 to 35% of the tests satisfy this criterion. Finally, the crack length prediction errors that result from the different calibrations can typically cause a 15 to 30% variation in FCG rate da/dN at a given ?K level. This difference is found to be primarily due to errors in the ?K calculation.
Download or read book Fatigue Crack Growth Measurement and Data Analysis written by S. J Hudak and published by ASTM International. This book was released on 1981 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture Mechanics Fourteenth Symposium STP 791 written by Lewis and published by ASTM International. This book was released on 1983-08 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Fatigue Crack Growth Rate Specimen Suitable for a Multiple Specimen Test Configeration written by FR. Deshayes and published by . This book was released on 1993 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new experimental approach developed by fatigue crack growth rates can be determined for multiple specimens tested in series. This involves a geometry such that the response to cyclic loading in each specimen is mutually independent. Relationships between the stress intensity factor, compliance, and crack length and between direct-current potential drop and crack length have been analytically evaluated for the proposed specimen geometry. An appropriate side-groove depth that avoided crack deviation from the intended plane of extension was determined experimentally, and an analytical expression that accounted for reduced thickness in the crack plane was verified. Calibration curves between crack length and compliance and between crack length and potential drop were experimentally verified as well, and the stress intensity-crack length characteristics for the specimen were confirmed by comparing da/dN-?KI curves with those for conventional C(T) specimens. A customized, five specimen frame was designed and fabricated in conjunction with a 98-kN MTS actuator and interfaced with a commercially available control system, the hardware and software of which were modified to accommodate multiple-specimen control and data acquisition. The utility of the proposed specimen and test procedure is discussed within the context of threshold and near-threshold crack growth rate determinations where long test times are normally required for data development, particularly for low cyclic frequency applications such as nuclear and offshore.
Download or read book Investigation of Constraint Effect on Fatigue Crack Growth Rate Measurements written by Veronika Hochfellner and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For the purpose of reliable life prediction the fatigue crack growth behaviour of a material has to be well-known. Therefore standardized fatigue crack growth tests are made with test specimens of the material. The obtained fatigue crack growth data is taken as material specific data and is given without any information of the test conditions and used specimen geometry. However, in several studies a geometry dependency of the test specimen on the fatigue crack growth data is found. Hence in this investigation experiments on fatigue crack growth behaviour are made with two different specimen geometries, the middle tension specimen M(T) and the compact (tension) specimen C(T). The direct current potential drop (DCPD) method is used to determine the crack lengths which is calibrated with the aid of beach marks and crack detection gauges. Two different configurations of the DCPD method are implemented to gain acceptable results. With the obtained data fatigue crack growth curves are established which are analysed regarding the geometry influence of the used test specimens. Discrepancies in the fatigue crack growth curves between the tested specimens are found. With these findings an approach is tested to create a material curve which is independent of the specimen geometry. However, this approach is not leading to satisfactory results. The implementation of the DCPD method in its main configuration on the used experimental setup proves to be applicable for fatigue crack growth tests on different geometries and will be used in further studies at low temperatures.
Download or read book Fatigue Crack Measurement written by Kenneth James Marsh and published by . This book was released on 1991 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determination of Calibration Function for Fatigue Crack Propagation by Measurement Surface Deformation written by J. Predan and published by . This book was released on 2015 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Components and structures exposed to elastic dynamic loading respond with elastic strains on the surface of the material. Mechanical response could be monitored by deformations on the surface. The measurements and monitoring of these parameters could be performed with electronic devices for on-line measurements, controlled by computerized systems. Fatigue-induced flaw growth was monitored on a four-point specimen, loaded by cyclic dynamic bend forces. The flaw growth was monitored by strain gauges with a standard resistance of 120 ?. After performance of fractal-graphical measurements, a flaw-growth analysis was performed to determine the shape, propagation, and cross sections of the crack. To determine the stress-intensity factor, a numerical model was developed based on measured crack shapes, material properties, and cyclic loading data of the actual tested specimen. The investigation results showed that the derived calibration curve could be used to predict surface deformations as a result of crack propagation and growth, but not crack initiation. With the determination of surface deformation, one could follow the crack transition from the semi-elliptical surface crack to the through-thickness crack. The stress-intensity factor has been determined numerically by using the finite-element method for five different fatigue-crack fronts. Results show that fatigue crack on the surface of specimens propagated under an almost constant stress-intensity factor value. Consequently, in our case, the fatigue-crack growth rate was constant during transition from a surface semi-elliptical crack to a through-thickness crack front. The aim of this paper is to describe methodology and results based on experimental and numerical modeling during crack propagation and potential use of this technique for online monitoring purposes.
Download or read book Potential Drop Method for Measuring Fatigue Crack Growth written by A. E. CARDEN and published by . This book was released on 1973 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: IN FATIGUE CRACK GROWTH (FCG) EXPERIMENTS TWO OF THE ESSENTIAL MEASUREMENTS ARE CRACK LENGTH AND CYCLE NUMBER. CRACK LENGTH MEASUREMENT GENERALLY HAS THE LEAST PRECISION AND IS THE MOST EXPENSIVE TO OBTAIN SINCE IT IS USUALLY VISUALLY OBSERVED AND MANUALLY RECORDED. SEVERAL ATTEMPTS HAVE BEEN MADE TO AUTOMATE THE MEASUREMENT AND RECORDING OF THE CRACK LENGTH BUT THE PRECISION WAS LOW WHEN THE CRACK LENGTHS ARE SMALL. A POTENTIAL DROP METHOD DEVELOPED BY MARKOCHEV HAS BEEN APPLIED TO FCG AT ELEVATED TEMPERATURE ON CN SHEET AND CT 2T SPECIMENS WITH GOOD RESULTS. A DIVIDER CIRCUIT GIVES THE RATIO OF THE POTENTIAL DROP NEAR THE CRACK TIP TO THAT IN A SHUNT. OUTPUT IS THEREFORE INSENSITIVE TO CURRENT LEVEL. THE DERIVATIVE OF THE OUTPUT VERSUS CRACK LENGTH IS CONSTANT FROM THE INITIAL CRACK LENGTH TO ABOUT 1/2 A/W. WITH OPERATIONAL AMPLIFIERS AND A MILLIVOLT RECORDER, CRACK LENGTH VERSUS CYCLE NUMBER CAN BE CONTINUOUSLY RECORDED. THE THRESHOLD LEVEL FOR FCG CAN BE MUCH MORE PRECISELY DETERMINED. INCUBATION PERIODS FOR FCG ARE CLEARLY OBSERVED AFTER OVERLOADS. FCG OF 10 TO THE 8TH POWER IN/CYCLE ARE EASILY DEFINED. THE THRESHOLD DELTA K FOR INCOLOY WAS DETERMINED TO BE ABOUT 4 KSI(IN) 1/2 IN LESS THAN 60 HOURS OF TESTING. WITH VISUAL OBSERVATION THE THRESHOLD LEVEL WAS JUDGED TO BE ABOUT 8 KSI(IN) 1/2 IN ABOUT 300 HR OF TEST TIME. THE LOWEST CRACK GROWTH RATE IN THE VISUAL METHOD WAS ABOUT 10 TO THE MINUS 7 IN/CYCLE.
Download or read book Fatigue Testing and Analysis written by Yung-Li Lee and published by Elsevier. This book was released on 2011-04-18 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue Testing and Analysis: Theory and Practice presents the latest, proven techniques for fatigue data acquisition, data analysis, and test planning and practice. More specifically, it covers the most comprehensive methods to capture the component load, to characterize the scatter of product fatigue resistance and loading, to perform the fatigue damage assessment of a product, and to develop an accelerated life test plan for reliability target demonstration. This book is most useful for test and design engineers in the ground vehicle industry. Fatigue Testing and Analysis introduces the methods to account for variability of loads and statistical fatigue properties that are useful for further probabilistic fatigue analysis. The text incorporates and demonstrates approaches that account for randomness of loading and materials, and covers the applications and demonstrations of both linear and double-linear damage rules. The reader will benefit from summaries of load transducer designs and data acquisition techniques, applications of both linear and non-linear damage rules and methods, and techniques to determine the statistical fatigue properties for the nominal stress-life and the local strain-life methods. - Covers the useful techniques for component load measurement and data acquisition, fatigue properties determination, fatigue analysis, and accelerated life test criteria development, and, most importantly, test plans for reliability demonstrations - Written from a practical point of view, based on the authors' industrial and academic experience in automotive engineering design - Extensive practical examples are used to illustrate the main concepts in all chapters
Download or read book Characterization of Fatigue Crack Initiation and Propagation in Ti 6Al 4V with Electrical Potential Drop Technique written by and published by . This book was released on 1988 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Methods and Models for Predicting Fatigue Crack Growth Under Random Loading written by and published by ASTM International. This book was released on with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Risk Management of Safety and Dependability written by W Wong and published by Elsevier. This book was released on 2010-04-16 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The issue of risk should be embedded into the mindset of every engineer and manager to improve safety and dependability. Companies can be held accountable through law when a gross failing in health and safety management has fatal consequences. Here risk management, the organisational structure required and the main factors needed for its successful execution are explored. What risks must be managed as a legal requirement? How is risk quantified? What methods can be used to reduce risk? Such questions are addressed, alongside case histories of disasters to illustrate failures in risk management.In an easy-to-read and accessible way, The risk management of safety and dependability presents the key factors involved in successful risk management, so that even non-experts in small and medium-sized organisations, as well as engineers and managers, can apply sound safety and dependability principles. - Complies with the recommendations of the Engineering Technology Board - Assesses ways of recognising hazards and procedures for reducing risk in the design of processes, plant and machinery - Provides detailed accounts of three major disasters and describes the lessons to be learnt in relation to risk management
Download or read book Journal of Testing and Evaluation written by and published by . This book was released on 1980 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A High Sensitivity Potential Drop Technique for Fatigue Crack Growth Measurements written by Graham Clark and published by . This book was released on 1979 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the design features of a highly sensitive and accurate system for monitoring the growth of fatigue cracks in laboratory specimens of various geometries. The system is based on the potential-drop method which utilizes the electrical resistance changes associated with fatigue crack growth through the specimen cross-section to detect crack length increments of a few micrometers. The technique is suitable for automation, and tests may be completed with a minimum amount of operator interference. A computer-based data-processing method is described, and the performance of the system in measuring both absolute crack length and crack growth rate is evaluated.
Download or read book Experimental Mechanics of Solids written by Cesar A. Sciammarella and published by John Wiley & Sons. This book was released on 2012-03-26 with total page 769 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental solid mechanics is the study of materials to determine their physical properties. This study might include performing a stress analysis or measuring the extent of displacement, shape, strain and stress which a material suffers under controlled conditions. In the last few years there have been remarkable developments in experimental techniques that measure shape, displacement and strains and these sorts of experiments are increasingly conducted using computational techniques. Experimental Mechanics of Solids is a comprehensive introduction to the topics, technologies and methods of experimental mechanics of solids. It begins by establishing the fundamentals of continuum mechanics, explaining key areas such as the equations used, stresses and strains, and two and three dimensional problems. Having laid down the foundations of the topic, the book then moves on to look at specific techniques and technologies with emphasis on the most recent developments such as optics and image processing. Most of the current computational methods, as well as practical ones, are included to ensure that the book provides information essential to the reader in practical or research applications. Key features: Presents widely used and accepted methodologies that are based on research and development work of the lead author Systematically works through the topics and theories of experimental mechanics including detailed treatments of the Moire, Speckle and holographic optical methods Includes illustrations and diagrams to illuminate the topic clearly for the reader Provides a comprehensive introduction to the topic, and also acts as a quick reference guide This comprehensive book forms an invaluable resource for graduate students and is also a point of reference for researchers and practitioners in structural and materials engineering.
Download or read book Calibration of AC Potential Drop Technique for Sizing of Fatigue Cracks in Welded Joints written by Chaar, M and published by . This book was released on 1987 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
