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The design of the Jaguar is remarkable in that optimisation was applied during design. In this paper read before the Royal Aeronautical Society, the authors revealed that the techniques which have for long been dismissed as impractical in aviation have now been proved valid even in the design of military aircraft.

WHEN aluminium alloys are subjected to elevated temperatures their mechanical properties arc affected not only by the temperatures but also by the time of exposure. In order to illustrate the effect of such exposure the most widely adopted practice is to describe the change in properties by means of heat factors representing the ratio of property level after exposure to that obtained in the unhcated condition. Typical carpet plots of such heat factors against temperature and time are shown in fig. 1, and represent strength reductions after exposure to constant temperatures for the indicated times. Stiffness data at elevated temperatures arc usually confined to plots of elastic modulus against temperature and time and occasionally a few stress‐strain curves or tangent modulus curves for specific thermal conditions.

Expert systems technology as an area of artificial intelligence is coming to the field of structural mechanics. A number of expert systems have been developed or are under development. This paper consists of two parts. A brief discussion of the basics of expert systems and their concepts is given in the first part. The second part reviews the prototype of expert systems developed as an aid for finite element analysis and design optimization. Twelve different expert systems are described. A partial list of books on expert systems in general is given in the Appendix.

THE idea of a dual analysis in finite elements of a given structure was put forward in Ref. 4. The first analysis should be of the displacement type, using conforming displacement models of the finite elements. This results in a continuous, piecewise differcntiable displacement field in the whole structure, for which linear elasticity theory predicts lower bounds to the local static influence coefficients. The second analysis should be based on equilibrium models of the finite elements. The stress field within the structure is then continuously transmitted across the interfaces and satisfies detailed equilibrium conditions in the interior of each element. This property furnishes upper bounds to the influence coefficients.

This aircraft, or more exactly this integrated weapons system, is undoubtedly of major importance to both the British aircraft industry and the Royal Air Force. It is beyond question the most exacting project which the British industry has undertaken and as such has demanded adoption of the latest techniques, materials, equipment and management procedures as well as pursuit of research and development programmes on an unprecedented scale. In terms of air power, this system represents a substantial advance on any comparable aircraft or system currently in service and will give the Royal Air Force a strike and reconnaissance capability at high and low level which is possibly unmatched by any other air force in the world. The design philosophy of the TSR‐2 as it applies to an aircraft designed primarily for the high‐speed, low‐level strike/reconnaissance role was described in detail in the December 1963 issue of Aircraft Engineering (Ref. 1) but since that initial appraisal of the TSR‐2 was written some eleven months ago, there has been a gradual release of further information concerning the aircraft, its systems, power plant and equipment. It is the purpose of this article to bring the story up to date in that particular context, although it should be emphasized that the TSR‐2 is still subject to the strictest security embargo and it will be many years before a detailed study of the complete weapons system can be published. It is not intended to cover the same ground as the earlier article (Ref. 1) attempted but, before proceeding to detailed consideration of the systems, a brief overall description of the aircraft is given for the sake of completeness.

THE power plant for the Concord supersonic transport has evolved from an optimization study which showed that a medium‐pressure ratio turbojet would be the best compromise for a transatlantic M=2•2 civil aircraft. The detail design of the engine intake and nozzle systems is currently proceeding in the Design Offices of British Aircraft Corporation and Bristol Siddeley Engines in England and S.N.E.C.M.A. in France.

This paper aims to describe the development of an advisory system that helps building sound finite element (FE) models from computer-aided design data, with actual uncertainty levels expressed by error values in per cent, as today there is no widely accepted tool for FE idealisation error control.

The goal is to provide a computer-aided engineering (CAE) environment which assists the FE modelling phase. A demonstration program has been developed that leads the user through a step-by-step process and helps to detect idealisation errors. Uncertainties are identified and analysed following the procedure. An example illustrates the methodology on the collapse analysis of aerospace stiffened panels.

The design shows how a knowledge-based system can be used to aid a safe virtual product development.

The extension of current CAE environments is difficult, as the programs do not provide sufficient flexibility, changeability and FE solver independence. New developments can take the presented concept as a starting point.

The application of error control strategies increases the FE modelling fidelity and can prevent incorrect design decisions. The practical conversion of FE idealisation support depends on the ambitions of CAE software providers.

This research shows how a previously paper-and-pencil-based error control procedure can be transformed to an easy-to-use tool in modern software.

Materials with anisotropic conductivity are frequently used as sensors in electrical industries. In this paper, an anisotropic conductivity tensor to express Hall effect in n‐type semiconductors is derived and its steady‐current field is solved using the finite element method. Some numerical examples are given and comparison with measured data is discussed.

Prof Dr lng. Heinrich Hertel celebrated his 75th birthday on 13th November 1976. He was born in Düsseldorf, went to school in Magdeburg, passed his preliminary examination for civil engineering in 1923 at the Technical University in Munich and graduated in 1926. He was awarded his doctorate for engineering at the Technical University, Berlin, in 1931. Heinrich Hertel had already begun his scientific work at the German Institute of Research for Aviation in Berlin Adlershof five years earlier. In 1933 he left Aldershof and joined Prof Dr Ernst Heinkel as chief technical assistant. One year later he was appointed technical director of the Heinkel‐Werke. In 1938 he was made honorary professor. In 1939 he was nominated into the board of management of Junkers Flugzeug‐ und Motorenwerke AG, Dessau, as head of aircraft development.

This paper presents a set of Mathematica modules that organizes numerical integration rules considered useful for finite element work. Seven regions are considered: line segments, triangles, quadrilaterals, tetrahedral, wedges, pyramids and hexahedra. Information can be returned in floating‐point (numerical) form, or in exact symbolic form. The latter is useful for computer‐algebra aided FEM work that carries along symbolic variables. A few quadrature rules were extracted from sources in the FEM and computational mathematics literature, and placed in symbolic form using Mathematica to generate own code. A larger class of formulas, previously known only numerically, were directly obtained through symbolic computations. Some unpublished non‐product rules for pyramid regions were found and included in the collection. For certain regions: quadrilaterals, wedges and hexahedra, only product rules were included to economize programming. The collection embodies most FEM‐useful formulas of low and moderate order for the seven regions noted above. Some gaps as regard region geometries and omission of non‐product rules are noted in the conclusions. The collection may be used “as is” in support of symbolic FEM work thus avoiding contamination with floating arithmetic that precludes simplification. It can also be used as generator for low‐level floating‐point code modules in Fortran or C. Floating point accuracy can be selected arbitrarily. No similar modular collection applicable to a range of FEM work, whether symbolic or numeric, has been published before.