Volume 15, Issue 1
February 1992, pages 1-89
pp 1-1 February 1992
pp 3-25 February 1992
Engineering structures experience impulsive loads during the time of natural disasters like earthquakes, cyclones and collisions. The design of structures resistant to such natural disasters requires an understanding of the deformation and fracture behaviour of the materials constituting the structure under impulsive loading conditions. In this paper the various aspects of dynamic plastic deformation and fracture of common engineering materials are reviewed and contrasted with their behaviour under static loading conditions.
pp 27-34 February 1992
The major area of research in dynamic fracture has been the extension of the concept of static fracture toughness to predict crack arrest for a propagating crack. In this work crack propagation due to a ductile (microvoid) mechanism and cleavage (brittle) mechanism, as well as transition from one mode to another, has been analysed theoretically. Dynamic fracture toughness as a function of crack velocity has been determined. Temperature distribution near a propagating crack tip has been predicted for plane stress condition. The effect of reflected stress wave in a single edge notch specimen under transient crack growth conditions has also been analysed.
pp 35-46 February 1992
Shock wave research is a multidisciplinary field. In materials science, it is used to study equation-of-state, phase transitions and mechanical properties. In material processing, synthesis, powder compaction, shock sintering, shock welding etc. have been the prominent applications. We have been doing shock wave research at Trombay during the last two decades. Recently, we have built a single-stage gas gun to generate shock pressures in samples. In this paper, we describe this facility and some work done on the interpretation of shock-induced phase transitions.
pp 47-54 February 1992
A review of the current state-of-knowledge in risk-based earthquake-resistant design of pipeline systems is presented. Damage to pipelines during past earthquakes is studied, and the necessity of evaluating the risk to such systems from earthquakes for their economic design is illustrated. The various aspects of seismic risk analysis of pipeline systems are briefly studied and a conclusion reached that given a tectonic and seismic data for the region in which pipelines lie, in addition to proper definition of various levels of pipeline unserviceability, it is possible to estimate the earthquake hazards to such pipelines with a reasonable degree of accuracy. Since this subject is of topical interest to this country, with increasing number of pipeline systems laid in earthquake-prone areas, specific areas are identified where more information is required before meaningful seismic risk analysis of pipelines can be done in India.
pp 55-65 February 1992
Failures of thousands of dwellings and that of a large number of engineered and non-engineered buildings and other industrial structures, caused by cyclones every year are of serious concern to professional engineers, scientists and researchers. The quality of common building materials used in the coastal regions of India such as stone and brick masonry, timber, steel and reinforced cement concerte, tiles, AC and other roofing sheets and also the effective methods of construction adopted, significantly affect the strength of structures in resisting severe cyclones. This paper discusses the common deficiencies on the properties of the materials used for walls and roofing of housing and other industrial structures, in resisting cyclonic wind forces and the ineffective construction practices leading to poor strength of overall structure. The paper also suggests some of the simple techniques to improve the cyclonic resistance of the structures.
pp 67-76 February 1992
Conventional materials (natural and man-made fibres, plastics, wood, paper etc.) used in everyday life are, in different degrees, liable to ignition. This fact has impelled the development of new materials which are inherently resistant to flame and heat or to modify these materials by using flame-retardant additives/treatments to meet the stringent regulations set for fire protection.
This paper gives an overview of the newly developed inherently flame-retardant fibres and engineering plastics specifically aramids, polyimides, polybenzimidazole, novoloid, polyphenylene sulphide and carbon fibres. The use of various additives and FR finishes has also been highlighted.
pp 77-89 February 1992
Materials technology has been identified by most industrialized nations as a key enabling technology which will provide major economic and competitive advantages to industry. Numerous market forecasts show a strong growth potential in advanced materials applications in diverse industrial sectors. This paper discusses the need for standards and standardized methods for material specification and how this can stimulate the market by providing increased confidence in the design and performance of products.
Only a limited number of standards exist for advanced materials, but recently there has been an upsurge of interest worldwide and some countries are very active in developing standards. This is illustrated for some key materials sectors such as advanced ceramics and polymer-matrix composites. Standardization of test and evaluation methods for advanced materials is seen by many countries as a priority area. Methods used for conventional materials can be modified but in some cases new methods have to be developed, both of which approaches require underpinning research.
Trade in materials is international in nature and therefore it is very important to harmonize national standards and develop truly international standards which will help remove technical barriers to trade. This requires effort at a national level in order to collaborate in the international fora and negotiate from a position of strength. Both producers and users of materials need to become involved in standards-related activities. In underpinning prestandards research VAMAS, the Versailles Project on Advanced Materials, plays an important role and is developing an internationally recognized technical infrastructure from which standards can be developed. This paper discusses the need and scope for international collaboration in standards-related activities.
Volume 42 | Issue 5
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