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Condition monitoring and damage assessment in structures
Pfastfc ene
prohhn
ydamaga
Jng w.
accumulation theory and its application in fatigue
Conf. Fatigue and Fracture In Steel and Concrete Structures, /SFF ‘91, Madras, India, Dec. 1991 Vol 1 (Oxford 81 IBH Publishing Co. Pvt. Ltd. New
Delhi,
India,
1991)
153-174,
A damage accumulation theory is proposed which leads to a simple fatigue crack propagation rate formula. The form&can be used to predict the drack growth rate in all the three regimes in the fatigue problem. Test data (Al 2219) reported were analysed with the formula, which gives a good result,
Mixed mode fatigue loading of surface flaws under moving loads. Ramakrishna, D.A. and Simha, K.R. Y. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
126-135
Experimental and theoretical investigations are conducted to determine mixed mode stress intensity factors for a surface flaw under a moving load. Theoretical work based on Flamants’ problem is compared with experimental results obtained via photoelasticity in conjunction with LEFM. Results show reversal in Ks as the load moves along the surface from one and to the other. This reversal is of significance for predicting fatigue life of components subjected to moving loads.
Modellhrg roblems in analysis of fatigue and fracture phenomena. Natarapn: E. and Rajaraman, A. Conf. atrgue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
117-124
Computers have significantly contributed to a better understanding of scientific and engineering problems, through numerical methods like finite elements. Availability of a number of finite element codes suitina a varietv of platforms is indicative of this development, and newer developemenis are taking piace in areas like fatigue, fracture and creep at a microlevel of response. Presented are modalling strategies for fatigue and fracture, using finite elements. Influence of modalling is highlighted with a typical application in reinforced concrete plates where the localities phenomenon due to impact is studied in detail, shown for propagation of fracture cone.
Role of fracture mechanics in the fatigue life evaluation of offshora tubular joints. Seetharaman, S. and Sreedhar, DS. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SSF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
107-116
Over the past few decades, fracture mechanics discipline has evolved as a reliable quantitative tool for the evaluation of fatigue life of welded components. Recently, the application of this technique has been extended to the case of welded tubular joints used in steel offshore structuras. The problem of tubular joints is complex owing to the geometry and nature of stress distribution. Examined are the complexities involved, and fracture mechanics as a rational method for the fatigue life evaluation of tubular joints is presented.
s
Fati ue evaluation of MAPS calandrir tube sheet after installation of erator sparger tube. Bhasin, V., Chattopadhyay, J. and Kushwaha, Conf. Fatigue and Fracture in Steel and Concrete Structures, ISFF ‘91, Madras, India, Dee 1997 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd,
New
Delhi,
India,
1991)
91-105
Presented is simplified methodology adopted for fatigue evaluation of Madras Atomic Power Station fMAPS) calandria tube sheet following proposed replacement of calandria tubes by moderator spargar tubes. Linear elastic fracture mechanics (LEFMI was used for fatigue crack growth evalution. Crack propagation vs. fatigue cycles behaviour was evaluated for a postulated part through thickness crack at lattice location where calandria tube will be replaced by moderator sparger tube. To ensure safety against unstable crack propagation, crack stability assassmant was made for two situations-while rolling moderator sparger tube l304LSSl at tube sheet lattice hole and after its installation when reactor goes into operation. A finite elemant computer program was developed to evaluate stress intensity factors for two-dimensionsal (2-D) problems. J-integral approach was used rather than quarter point crack-tip elements.
three
Fatigue performance of normal weight and Ii htweight aggregate concrate baams ralnforced with high tensile steef . Dave, N.J., Attlsha, H.P. and Al Sanjari, K.A.A. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘97, Madras, India, Dee 1997 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
627-636
With the introduction of limit state philosophy into various codes of practice during the last three decades, more attention is being paid to the control of deflection and cracking. Consequently, codes of practice now specify the limits of deflection and crack widths. The increasing availability and use of higher strength steel as reinforcement can often result in designs which can satisfy the ultimate limit state of collapse, but in which the limit state of serviceability fiacontrol of deflection and cracking) may become critical, particularly under long-term sustained and/or fatigue loading. This problem would be even more severe if use is made of lightweight aggregate concrete. As part of an extensive programme of investigation, 18 fullsized rectangular concrete beams have been tasted-nine under short-term static loading and-nine under fatigue loading employing two different types of concrete (normal weight and lightweiahtl and four different tvoes of steel with nominal vield strength or 0.2% proof stress ranging from 275 to ‘590 N/mm*. Four lightweight aggregate concrete beams also contained fibre-reinforced cement (frc) channel as surface reinforcement. Described are the details of the test programma. The behaviour is compared of the beams subjected to static and fatigue loading with respect to ultimate load, deflection and cracking, ie the limit states of safety and serviceability. Steels ware Unisteels 410 and 550, Kam 60 and a mild steel.
418
Method for reducing the fatigue crack growth rate of cracks in the aluminium alloy fusalage skin of an aircraft structure. Parker, E.R. and Parker, W. J. US Patent 5071492 (10 Dee 1991) A method and apparatus for reducing the fatigue crack growth rate of cracks in the Al alloy fuselage skin of aircraft structures are disclosed. A fatigue crack is identified, the crack having a tip defining the direction of crack propagation. Temperature differentials are produced between a “arrow strip of the skin and portions of the skin adjacent to this narrow strip extending from the crack tip to a predetermined distance forward of the crack tip. The temperature differentials produced between the narrow strip and adjacent unheated portions of the aircraft skin ara sufficientlv high so that the expansion due to heating causes plastic flow to occur in the heated strip. The plastic flow results in a residual tensile stress which acts in the direction of crack propagation when the system is returned to a normal service temperature. This residual tensile stress is of a sufficient magnitude to retard the crack growth rate effectivelv.
Magnetic garkhausen noise anal sis for stud ing fatigue damage. Bhattacharya, O.K., Vaidyanathan, 8, Rao, K.B., KY alyanasundram, P. and !%f!Fatigue and Fracture in Steel and Concrete Strucrures /SFF ‘91 Madras, India, Dee 1997 Vol 2 (Oxford & IBH Publishing Cd. Pvt. Ltd: New
Delhi,
India,
1991)
1137-1151
The importance of a suitable non-destructive test technique such as Barkhausen noise (BN) analysis for the characterization of fatigue damage is highlighted. A brief overview of the information on BN analysis for fatigue damage available in the literature is given. The results of the analysis of the magnetic Barkhausan noise fBN) signals carried out on signals obtained from two unloaded control specimens and four fatigue-loaded polycrystalline commercial Fe specimens are discussed. The BN signals have bean acquired under both a closed field and an open field with a magnetic cyclic frequency (33 MHz) using experimental setups that ware developed. Among the parameters derived from the acquired BN signals, promise is shown by the cumulative event counts obtained under an open magnetic field before the magnetic reversal. Under a closed field of magnetization, the same parameter, although not as good as the one under an open field, is still batter than the other parameters under closed field. Graphs.
pdlition
monitoring
and damage
assassment
in structuras.
Dover,
Co&. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 7991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd. New
Delhi,
India,
1991)
1087-1109
Recent developments in the alternating current field measurement (ACFM) technique have made it possible to detect and size cracks in components and structures in one operation. The results from such operations can be assessed from inspection reliability data to provide an input to remaining life calculations. A new software package FACTS is now available for the determination of remaining life. FACTS includes service load history simulation, SCF and SIF determination, and materials data, and gives fatigue crack growth rata prediction and remaining life estimates. The software package has been validated by design companies. The combination of these developments gives the possibility of a full non-destructive evaluation for tubular welded joints. This work is now being extended to give a probabilistic approach (RISC) and improved inspection reliability data on performance trends (ICON). These will eventually provide a knowledge-based system approach to inspection scheduling.
A fati ue testing facility for structures and structural components. Rae, A.G. I%!., Raghava, G. and Gandhi, P. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
957-968
Fatigue is one of the principal modes of failure to be considered in the design of any structure which is subjected to repeated cycles of loading during its life. Offshore structures, aircraft structures, automotive components, and systems including rails and sleepers, bridges, and industrial structures supporting machine-induced dynamic loads fall under this category. Structural Engineering Research Centre, Madras, has established a computer-controlled fatigue testing laboratory fully equipped to conduct arperimental and analytical studies on fatigue behaviour of structures and structural components. The facilities available in the laboratory and the experimental and analytical expertise available in the area of fatigue in structures and structural components are highlighted.
An expert system for fatigue testing of airframes. Gubarev, V.V., Grif, M.G., Metyolkin, N.G., Seryoznov, A.N. and Sklyarov, A.A. Conf Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91 Madras, India, Dee 1991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
923-927
Discussed is the application of an expert system for fatigue testing of airframes, Functional connections between the expert systems and the systems of the test rig are determined. The knowledge base for the system is based on three types of knowledge. such as knowledge of the equipment failures, of the airframe, and of the test techniques. The data are presented in terms of productions and frames.
Design end ap lication of a vibro-tasting system for Iarga-scale l-beams. Budau, P.U., S!chmreg, H. and Vie/sack, P. Conf. Fafigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 2 (Oxford 81 IBH Publishing Co. Pvt. Ltd. New Delhi, India, 1991) 859-865 The vibrotesting system described is used successfully for various kinds of l-beams, Even beams with a mass of 534 kg/m, length 13.5 m, height 1046 mm and moment of inertia 1 132 150 cm4 are under investigation. Their tasting frequency is approx 40 Hz, which implies 2000000 stress cvclas in ~24 h. The reached stress level, 180 Nimm2, corresponds to a mid-amplitude of approx 10 mm. In comparison, a single static load of 2820 kN would be needed to aat the same disolacemant. The syst& is kept moving by a power input of onlvhkW. During the fasts, power consumption, stress amplitude and frequency of oscillation are continuouslv monitored. Changes in the oscillation frequency ara often proposed in literature as
I=
Int J Fatigue November
1992
prohhn
ydamaga
Jng w.
accumulation theory and its application in fatigue
Conf. Fatigue and Fracture In Steel and Concrete Structures, /SFF ‘91, Madras, India, Dec. 1991 Vol 1 (Oxford 81 IBH Publishing Co. Pvt. Ltd. New
Delhi,
India,
1991)
153-174,
A damage accumulation theory is proposed which leads to a simple fatigue crack propagation rate formula. The form&can be used to predict the drack growth rate in all the three regimes in the fatigue problem. Test data (Al 2219) reported were analysed with the formula, which gives a good result,
Mixed mode fatigue loading of surface flaws under moving loads. Ramakrishna, D.A. and Simha, K.R. Y. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
126-135
Experimental and theoretical investigations are conducted to determine mixed mode stress intensity factors for a surface flaw under a moving load. Theoretical work based on Flamants’ problem is compared with experimental results obtained via photoelasticity in conjunction with LEFM. Results show reversal in Ks as the load moves along the surface from one and to the other. This reversal is of significance for predicting fatigue life of components subjected to moving loads.
Modellhrg roblems in analysis of fatigue and fracture phenomena. Natarapn: E. and Rajaraman, A. Conf. atrgue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
117-124
Computers have significantly contributed to a better understanding of scientific and engineering problems, through numerical methods like finite elements. Availability of a number of finite element codes suitina a varietv of platforms is indicative of this development, and newer developemenis are taking piace in areas like fatigue, fracture and creep at a microlevel of response. Presented are modalling strategies for fatigue and fracture, using finite elements. Influence of modalling is highlighted with a typical application in reinforced concrete plates where the localities phenomenon due to impact is studied in detail, shown for propagation of fracture cone.
Role of fracture mechanics in the fatigue life evaluation of offshora tubular joints. Seetharaman, S. and Sreedhar, DS. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SSF ‘91, Madras, India, Dee 1991 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
107-116
Over the past few decades, fracture mechanics discipline has evolved as a reliable quantitative tool for the evaluation of fatigue life of welded components. Recently, the application of this technique has been extended to the case of welded tubular joints used in steel offshore structuras. The problem of tubular joints is complex owing to the geometry and nature of stress distribution. Examined are the complexities involved, and fracture mechanics as a rational method for the fatigue life evaluation of tubular joints is presented.
s
Fati ue evaluation of MAPS calandrir tube sheet after installation of erator sparger tube. Bhasin, V., Chattopadhyay, J. and Kushwaha, Conf. Fatigue and Fracture in Steel and Concrete Structures, ISFF ‘91, Madras, India, Dee 1997 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd,
New
Delhi,
India,
1991)
91-105
Presented is simplified methodology adopted for fatigue evaluation of Madras Atomic Power Station fMAPS) calandria tube sheet following proposed replacement of calandria tubes by moderator spargar tubes. Linear elastic fracture mechanics (LEFMI was used for fatigue crack growth evalution. Crack propagation vs. fatigue cycles behaviour was evaluated for a postulated part through thickness crack at lattice location where calandria tube will be replaced by moderator sparger tube. To ensure safety against unstable crack propagation, crack stability assassmant was made for two situations-while rolling moderator sparger tube l304LSSl at tube sheet lattice hole and after its installation when reactor goes into operation. A finite elemant computer program was developed to evaluate stress intensity factors for two-dimensionsal (2-D) problems. J-integral approach was used rather than quarter point crack-tip elements.
three
Fatigue performance of normal weight and Ii htweight aggregate concrate baams ralnforced with high tensile steef . Dave, N.J., Attlsha, H.P. and Al Sanjari, K.A.A. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘97, Madras, India, Dee 1997 Vol 1 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
627-636
With the introduction of limit state philosophy into various codes of practice during the last three decades, more attention is being paid to the control of deflection and cracking. Consequently, codes of practice now specify the limits of deflection and crack widths. The increasing availability and use of higher strength steel as reinforcement can often result in designs which can satisfy the ultimate limit state of collapse, but in which the limit state of serviceability fiacontrol of deflection and cracking) may become critical, particularly under long-term sustained and/or fatigue loading. This problem would be even more severe if use is made of lightweight aggregate concrete. As part of an extensive programme of investigation, 18 fullsized rectangular concrete beams have been tasted-nine under short-term static loading and-nine under fatigue loading employing two different types of concrete (normal weight and lightweiahtl and four different tvoes of steel with nominal vield strength or 0.2% proof stress ranging from 275 to ‘590 N/mm*. Four lightweight aggregate concrete beams also contained fibre-reinforced cement (frc) channel as surface reinforcement. Described are the details of the test programma. The behaviour is compared of the beams subjected to static and fatigue loading with respect to ultimate load, deflection and cracking, ie the limit states of safety and serviceability. Steels ware Unisteels 410 and 550, Kam 60 and a mild steel.
418
Method for reducing the fatigue crack growth rate of cracks in the aluminium alloy fusalage skin of an aircraft structure. Parker, E.R. and Parker, W. J. US Patent 5071492 (10 Dee 1991) A method and apparatus for reducing the fatigue crack growth rate of cracks in the Al alloy fuselage skin of aircraft structures are disclosed. A fatigue crack is identified, the crack having a tip defining the direction of crack propagation. Temperature differentials are produced between a “arrow strip of the skin and portions of the skin adjacent to this narrow strip extending from the crack tip to a predetermined distance forward of the crack tip. The temperature differentials produced between the narrow strip and adjacent unheated portions of the aircraft skin ara sufficientlv high so that the expansion due to heating causes plastic flow to occur in the heated strip. The plastic flow results in a residual tensile stress which acts in the direction of crack propagation when the system is returned to a normal service temperature. This residual tensile stress is of a sufficient magnitude to retard the crack growth rate effectivelv.
Magnetic garkhausen noise anal sis for stud ing fatigue damage. Bhattacharya, O.K., Vaidyanathan, 8, Rao, K.B., KY alyanasundram, P. and !%f!Fatigue and Fracture in Steel and Concrete Strucrures /SFF ‘91 Madras, India, Dee 1997 Vol 2 (Oxford & IBH Publishing Cd. Pvt. Ltd: New
Delhi,
India,
1991)
1137-1151
The importance of a suitable non-destructive test technique such as Barkhausen noise (BN) analysis for the characterization of fatigue damage is highlighted. A brief overview of the information on BN analysis for fatigue damage available in the literature is given. The results of the analysis of the magnetic Barkhausan noise fBN) signals carried out on signals obtained from two unloaded control specimens and four fatigue-loaded polycrystalline commercial Fe specimens are discussed. The BN signals have bean acquired under both a closed field and an open field with a magnetic cyclic frequency (33 MHz) using experimental setups that ware developed. Among the parameters derived from the acquired BN signals, promise is shown by the cumulative event counts obtained under an open magnetic field before the magnetic reversal. Under a closed field of magnetization, the same parameter, although not as good as the one under an open field, is still batter than the other parameters under closed field. Graphs.
pdlition
monitoring
and damage
assassment
in structuras.
Dover,
Co&. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 7991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd. New
Delhi,
India,
1991)
1087-1109
Recent developments in the alternating current field measurement (ACFM) technique have made it possible to detect and size cracks in components and structures in one operation. The results from such operations can be assessed from inspection reliability data to provide an input to remaining life calculations. A new software package FACTS is now available for the determination of remaining life. FACTS includes service load history simulation, SCF and SIF determination, and materials data, and gives fatigue crack growth rata prediction and remaining life estimates. The software package has been validated by design companies. The combination of these developments gives the possibility of a full non-destructive evaluation for tubular welded joints. This work is now being extended to give a probabilistic approach (RISC) and improved inspection reliability data on performance trends (ICON). These will eventually provide a knowledge-based system approach to inspection scheduling.
A fati ue testing facility for structures and structural components. Rae, A.G. I%!., Raghava, G. and Gandhi, P. Conf. Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
957-968
Fatigue is one of the principal modes of failure to be considered in the design of any structure which is subjected to repeated cycles of loading during its life. Offshore structures, aircraft structures, automotive components, and systems including rails and sleepers, bridges, and industrial structures supporting machine-induced dynamic loads fall under this category. Structural Engineering Research Centre, Madras, has established a computer-controlled fatigue testing laboratory fully equipped to conduct arperimental and analytical studies on fatigue behaviour of structures and structural components. The facilities available in the laboratory and the experimental and analytical expertise available in the area of fatigue in structures and structural components are highlighted.
An expert system for fatigue testing of airframes. Gubarev, V.V., Grif, M.G., Metyolkin, N.G., Seryoznov, A.N. and Sklyarov, A.A. Conf Fatigue and Fracture in Steel and Concrete Structures, /SFF ‘91 Madras, India, Dee 1991 Vol 2 (Oxford & IBH Publishing Co. Pvt. Ltd, New
Delhi,
India,
1991)
923-927
Discussed is the application of an expert system for fatigue testing of airframes, Functional connections between the expert systems and the systems of the test rig are determined. The knowledge base for the system is based on three types of knowledge. such as knowledge of the equipment failures, of the airframe, and of the test techniques. The data are presented in terms of productions and frames.
Design end ap lication of a vibro-tasting system for Iarga-scale l-beams. Budau, P.U., S!chmreg, H. and Vie/sack, P. Conf. Fafigue and Fracture in Steel and Concrete Structures, /SFF ‘91, Madras, India, Dee 1991 Vol 2 (Oxford 81 IBH Publishing Co. Pvt. Ltd. New Delhi, India, 1991) 859-865 The vibrotesting system described is used successfully for various kinds of l-beams, Even beams with a mass of 534 kg/m, length 13.5 m, height 1046 mm and moment of inertia 1 132 150 cm4 are under investigation. Their tasting frequency is approx 40 Hz, which implies 2000000 stress cvclas in ~24 h. The reached stress level, 180 Nimm2, corresponds to a mid-amplitude of approx 10 mm. In comparison, a single static load of 2820 kN would be needed to aat the same disolacemant. The syst& is kept moving by a power input of onlvhkW. During the fasts, power consumption, stress amplitude and frequency of oscillation are continuouslv monitored. Changes in the oscillation frequency ara often proposed in literature as
I=
Int J Fatigue November
1992