- Email: [email protected]
Papers requested for material damping conference
It was shown that weldments present a twofold complication: the inhomogeneity of microstructure gives rise to strong variations of fracture properties, and the inhomogeneity of plastic properties leads to a variation of the driving force across the weld. The treatment of input data needs special attention. This includes the reliability of input quantities, like, for example, information on applied loads or residual stresses, the statistical treatment of fracture properties or a possible difference between nominal and actual data, such as tensile properties, structural dimensions, and SO o n .
Although a fair amount of time was reserved for the discussion of each paper, the discussions went on during
the breaks. Indeed, even if there had been no social events in the evenings, time would still have been short for talking to old friends, making new acquaintances, and enjoying the stimulating atmosphere of the meeting. It was these same social events--the reception by the City of Freiburg, a concert with chambermusic and the wine tasting excursion to the Kaiserstuhl--which made the conference so enjoyable. In summary the symp6sium was very successful. Important progress was made in understanding material behaviour and suggestions have been proposed for future work concerning, for example, transferability of specimen structure, ductile-brittle transition, the effect of microstructure
on the one hand, and reliability (and scatter) of material data on the other. It was suggested that the most important points made in each session should be summarized and published in the conference proceedings (available from MEP, Bury St. Edmunds, UK). Interested participants were able to visit the laboratories of the Fraunhofer-Institut fiir Werkstoffmechanik in Freiburg the day after the conference. At the end of the meeting everybody agreed that the local organizing committee did an excellent job. The participants as well as the accompanying persons felt very comfortable during their stay in Freiburg.
R. Kienzler
Recent studies on structural safety and reliability Current Japanese materlaim research, voltmae 5 Edited by: T. Nakagawa, H. Ishikawa and A. Tsurui Elsevier Applied Science, 1989, xiii+ 230 pp, £40.00
This volume of papers is the fifth in a series intended to bring the results of Japanese research in materials science and technology to the attention of a wider non-Japanese readership. Previous volumes have covered fatigue cracks, statistical research on fatigue and fracture, high temperature creep-fatigue, and localized corrosion. In addressing the subject of structural safety and reliability, this volume is concerned less with the behaviour of particular materials, and more with the development of tools and methodologies for determining the effect of uncertainty and variability in material behaviour on the safety and reliability of structures and systems. The book contains a total of 13 papers, divided into four groups entitled: reliability-based design; structural reliability analysis; inspection and maintenance; and software developments for reliability assessment. To some extent this division is rather arbitrary, as is the assignment of certain papers to one section rather than another. Two of the three papers in the
Int J Fatigue March 1990
final section are quite different from the rest of the book. One is a brief, but interesting, outline by S. Fukuda of the potential role of knowledge engineering. He argues that knowledge engineering should not be thought of as a replacement for conventional programming tools, but should be used with them as a way of examining the processes of analysis and design, thereby helping to avoid the large number of failures that occur as a result of existing knowledge not being correctly or fully applied. The other unusual paper is by F. Hara, who reports developments in the use of computer graphics to display safety conditions in an industrial system, using the Three Mile Island accident as an example. A coloured human face is used to express the state of the plant, and as the plant condition changes, the expression on the face and its colour also change. The colours are dramatic and deliberately non-realistic; however, by comparison with the images in children's cartoons for example, t h e final expressions seem to indicate a
remarkable degree of stoicism in the face of disaster. The system has so far only been tested for the accuracy of the response it produces using a set of ten students, presumably Japanese. One is inclined to believe that more demonstrative facial expressions might be required in other parts of the world. The remaining papers in the book are rather more conventional works developing aspects of reliability methodology and applying them to particular situations. The three papers in the structural reliability analysis section and the remaining paper in the software development section discuss applications to various types of structure. Between them they cover large framed structures, damaged redundant structures, bridges, and liquid storage tanks under earthquake loading. These papers are not greatly concerned with the details of material behaviour, but rather deal with the problems of complex loading and, in two papers, its redistribution through the structure as components fail. The paper on the reliability of damaged
137
redundant structures stands out from the others in the book by its use of fuzzy sets as part of its approach to quantifying and analysing uncertainty. The question of whether the concept of probability is, on its own, sufficient for all such problems, or whether some alternative concept, such as the fuzzy set, is also required remains one of great controversy; the authors, however, do not discuss this at all. Indeed, one of the characteristics of many, though not all, of the papers in this book is that they tend to take a problem and apply one method of solution to it without examining and discussing alternatives. The remaining seven papers are concerned with modelling various aspects of material behaviour, and are therefore probably those of greatest interest to materials scientists and engineers. They are largely concerned with failure by fatigue and fracture and include one specifically on fibrereinforced composites and one on alumina. The others are concerned with metals, though more often by default than by any clear statement to that effect. Again, most of these papers
show a reluctance to compare and contrast different approaches. For instance, four papers discuss the probabilistic description of flaw sizes and their detectability; all four use different models, and only one, by Ichikawa and Okabe, discusses alternatives and shows why the preferred model was adopted. Most of the papers are concerned with developing points of theory, with the necessary data being drawn from other sources. The main exception is the paper on alumina byYamada and Kitazumi which presents considerable test data for strength under static and impact loadings. Unfortunately the statistical analysis of these data does not include discussion of confidence limits. Apart from the discussion by Ichikawa and Okabe of appropriate forms for the probahilistic description of flaw sizes and their detectability, other points of theory discussed and developed include the definition of the scatter factor of the two-parameter Weibull distribution when used to model fatigue lives, the use of Markov chains to model fatigue crack growth and the use of Bayesian updating
techniques to determine inspection intervals. Taken all together the 13 papers give a good impression of the very wide range of research activities in Japan on the development and application of reliability approaches to problems of material and structural behaviour. In an area of rapidly developing research, there is perhaps something to be said for pursuing a wide range of different approaches and leaving it to time and a process of survival of the fittest to find the best. Certainly in the present case, the reader, having been presented with many different approaches to essentially similar problems, is left largely on his own to evaluate their relative merits. The papers are well written and presented. Most of the references quoted are also English language publications so that the non-Japanese reader should be able to follow at least some of the previous history of these researches.
W. Manners
PRELIMINARY PROGRAMME 9TH INTERNATIONAL CONFERENCE ON EXPERIMENTAL MECHANICS COPENHAGEN, DENMARK 20 TO 24 AUGUST 1990 Organized on behalf of the Permanent Committee for Stress Analysis. Co-sponsored by the Society for Experimental Mechanics, the IMEKO Technical Committee for Experimental Mechanics and the Japan Society of Mechanical Engineers. The preliminary programme with titles and authors of about 300 accepted or provisionally accepted abstracts from 29 countries has now appeared. Among the subjects are: Stress Analysis by thermoelastic techniques. Experimental contact mechanics. Experimental techniques used on composite systems. New developments in residual stress measuring techniques. Experimental techniques used on cementitious materials and concrete structures. Materials- and Structural testing. Photoelasticity, interference holography, speckle and grid methods. Instrumentation and data processing. The conference includes an instrument exhibition. Exhibitors having announced their presence are mentioned in the preliminary programme. The preliminary programme together with registration- and hotel reservation forms are available from: Conference Secretariat Department of Structural Engineering, Technical University of Denmark, Building 118 DK.2800 Lyngby, Denmark
138
Phone: Telex: Fax:
+45 42 37529 +45 42 +45 42
88 35 11 dthdia dk 88 3282 or 88 2239
Int J Fatigue March 1990
Although a fair amount of time was reserved for the discussion of each paper, the discussions went on during
the breaks. Indeed, even if there had been no social events in the evenings, time would still have been short for talking to old friends, making new acquaintances, and enjoying the stimulating atmosphere of the meeting. It was these same social events--the reception by the City of Freiburg, a concert with chambermusic and the wine tasting excursion to the Kaiserstuhl--which made the conference so enjoyable. In summary the symp6sium was very successful. Important progress was made in understanding material behaviour and suggestions have been proposed for future work concerning, for example, transferability of specimen structure, ductile-brittle transition, the effect of microstructure
on the one hand, and reliability (and scatter) of material data on the other. It was suggested that the most important points made in each session should be summarized and published in the conference proceedings (available from MEP, Bury St. Edmunds, UK). Interested participants were able to visit the laboratories of the Fraunhofer-Institut fiir Werkstoffmechanik in Freiburg the day after the conference. At the end of the meeting everybody agreed that the local organizing committee did an excellent job. The participants as well as the accompanying persons felt very comfortable during their stay in Freiburg.
R. Kienzler
Recent studies on structural safety and reliability Current Japanese materlaim research, voltmae 5 Edited by: T. Nakagawa, H. Ishikawa and A. Tsurui Elsevier Applied Science, 1989, xiii+ 230 pp, £40.00
This volume of papers is the fifth in a series intended to bring the results of Japanese research in materials science and technology to the attention of a wider non-Japanese readership. Previous volumes have covered fatigue cracks, statistical research on fatigue and fracture, high temperature creep-fatigue, and localized corrosion. In addressing the subject of structural safety and reliability, this volume is concerned less with the behaviour of particular materials, and more with the development of tools and methodologies for determining the effect of uncertainty and variability in material behaviour on the safety and reliability of structures and systems. The book contains a total of 13 papers, divided into four groups entitled: reliability-based design; structural reliability analysis; inspection and maintenance; and software developments for reliability assessment. To some extent this division is rather arbitrary, as is the assignment of certain papers to one section rather than another. Two of the three papers in the
Int J Fatigue March 1990
final section are quite different from the rest of the book. One is a brief, but interesting, outline by S. Fukuda of the potential role of knowledge engineering. He argues that knowledge engineering should not be thought of as a replacement for conventional programming tools, but should be used with them as a way of examining the processes of analysis and design, thereby helping to avoid the large number of failures that occur as a result of existing knowledge not being correctly or fully applied. The other unusual paper is by F. Hara, who reports developments in the use of computer graphics to display safety conditions in an industrial system, using the Three Mile Island accident as an example. A coloured human face is used to express the state of the plant, and as the plant condition changes, the expression on the face and its colour also change. The colours are dramatic and deliberately non-realistic; however, by comparison with the images in children's cartoons for example, t h e final expressions seem to indicate a
remarkable degree of stoicism in the face of disaster. The system has so far only been tested for the accuracy of the response it produces using a set of ten students, presumably Japanese. One is inclined to believe that more demonstrative facial expressions might be required in other parts of the world. The remaining papers in the book are rather more conventional works developing aspects of reliability methodology and applying them to particular situations. The three papers in the structural reliability analysis section and the remaining paper in the software development section discuss applications to various types of structure. Between them they cover large framed structures, damaged redundant structures, bridges, and liquid storage tanks under earthquake loading. These papers are not greatly concerned with the details of material behaviour, but rather deal with the problems of complex loading and, in two papers, its redistribution through the structure as components fail. The paper on the reliability of damaged
137
redundant structures stands out from the others in the book by its use of fuzzy sets as part of its approach to quantifying and analysing uncertainty. The question of whether the concept of probability is, on its own, sufficient for all such problems, or whether some alternative concept, such as the fuzzy set, is also required remains one of great controversy; the authors, however, do not discuss this at all. Indeed, one of the characteristics of many, though not all, of the papers in this book is that they tend to take a problem and apply one method of solution to it without examining and discussing alternatives. The remaining seven papers are concerned with modelling various aspects of material behaviour, and are therefore probably those of greatest interest to materials scientists and engineers. They are largely concerned with failure by fatigue and fracture and include one specifically on fibrereinforced composites and one on alumina. The others are concerned with metals, though more often by default than by any clear statement to that effect. Again, most of these papers
show a reluctance to compare and contrast different approaches. For instance, four papers discuss the probabilistic description of flaw sizes and their detectability; all four use different models, and only one, by Ichikawa and Okabe, discusses alternatives and shows why the preferred model was adopted. Most of the papers are concerned with developing points of theory, with the necessary data being drawn from other sources. The main exception is the paper on alumina byYamada and Kitazumi which presents considerable test data for strength under static and impact loadings. Unfortunately the statistical analysis of these data does not include discussion of confidence limits. Apart from the discussion by Ichikawa and Okabe of appropriate forms for the probahilistic description of flaw sizes and their detectability, other points of theory discussed and developed include the definition of the scatter factor of the two-parameter Weibull distribution when used to model fatigue lives, the use of Markov chains to model fatigue crack growth and the use of Bayesian updating
techniques to determine inspection intervals. Taken all together the 13 papers give a good impression of the very wide range of research activities in Japan on the development and application of reliability approaches to problems of material and structural behaviour. In an area of rapidly developing research, there is perhaps something to be said for pursuing a wide range of different approaches and leaving it to time and a process of survival of the fittest to find the best. Certainly in the present case, the reader, having been presented with many different approaches to essentially similar problems, is left largely on his own to evaluate their relative merits. The papers are well written and presented. Most of the references quoted are also English language publications so that the non-Japanese reader should be able to follow at least some of the previous history of these researches.
W. Manners
PRELIMINARY PROGRAMME 9TH INTERNATIONAL CONFERENCE ON EXPERIMENTAL MECHANICS COPENHAGEN, DENMARK 20 TO 24 AUGUST 1990 Organized on behalf of the Permanent Committee for Stress Analysis. Co-sponsored by the Society for Experimental Mechanics, the IMEKO Technical Committee for Experimental Mechanics and the Japan Society of Mechanical Engineers. The preliminary programme with titles and authors of about 300 accepted or provisionally accepted abstracts from 29 countries has now appeared. Among the subjects are: Stress Analysis by thermoelastic techniques. Experimental contact mechanics. Experimental techniques used on composite systems. New developments in residual stress measuring techniques. Experimental techniques used on cementitious materials and concrete structures. Materials- and Structural testing. Photoelasticity, interference holography, speckle and grid methods. Instrumentation and data processing. The conference includes an instrument exhibition. Exhibitors having announced their presence are mentioned in the preliminary programme. The preliminary programme together with registration- and hotel reservation forms are available from: Conference Secretariat Department of Structural Engineering, Technical University of Denmark, Building 118 DK.2800 Lyngby, Denmark
138
Phone: Telex: Fax:
+45 42 37529 +45 42 +45 42
88 35 11 dthdia dk 88 3282 or 88 2239
Int J Fatigue March 1990