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A SKELETAL structure is defined as one which can be ideally represented by linear (one‐dimensional) members appropriately connected at point nodes. The members are not necessarily straight or in one plane. The term structure will be used to denote a skeletal structure.

This paper aims to develop a new 3-level implicit numerical method of order 2 in time and 4 in space based on half-step cubic polynomial approximations for the solution of 1D quasi-linear hyperbolic partial differential equations. The method is derived directly from the consistency condition of spline function which is fourth-order accurate. The method is directly applied to hyperbolic equations, irrespective of coordinate system, and fourth-order nonlinear hyperbolic equation, which is main advantage of the work.

In this method, three grid points for the unknown function w(x,t) and two half-step points for the known variable x in spatial direction are used. The methodology followed in this paper is construction of a cubic spline polynomial and using its continuity properties to obtain fourth-order consistency condition. The proposed method, when applied to a linear equation is shown to be unconditionally stable. The technique is extended to solve system of quasi-linear hyperbolic equations. To assess the validity and accuracy, the method is applied to solve several benchmark problems, and numerical results are provided to demonstrate the usefulness of the method.

The paper provides a fourth-order numerical scheme obtained directly from fourth-order consistency condition. In earlier methods, consistency conditions were only second-order accurate. This brings an edge over other past methods. In addition, the method is directly applicable to physical problems involving singular coefficients. Therefore, no modification in the method is required at singular points. This saves CPU time, as well as computational costs.

There are no limitations. Obtaining a fourth-order method directly from consistency condition is a new work. In addition, being an implicit method, this method is unconditionally stable for a linear test equation.

Physical problems with singular and nonsingular coefficients are directly solved by this method.

The paper develops a new fourth-order implicit method which is original and has substantial value because many benchmark problems of physical significance are solved in this method.

The selection of a system of cut releases which would render a continuous skeletal structure statically determinate is governed principally by the topological and geometric characteristics of the structure, and to a lesser extent by its material properties. Only the topological aspects will be considered here, the other factors being purposely excluded. It is shown how the knowledge of the topology of the structure can be exploited to improve the conditioning of the associated equations of compatability. Owing to difficulties inherent in the design of any automatic procedure for the reduction to a canonical form, a method of condensation has been evolved for complex multi‐member structures. In this way the large scale features of the structure are taken into account without neglecting the effect of local characteristics.

The advent of jet and rocket propulsion in our present age has brought the problems of combustion right into the foreground. While much is known, still more theoretical and experimental research is necessary to extend our knowledge of combustion phenomena in combustion chambers and rockets. This impelled the Advisory Group for Aeronautical Research and Development (AGARD) of N.A.T.O. to collect all the latest information and results of research in the field of combustion science by forming a Combustion Panel and by inviting competent experts from Europe and the United States to discuss some of the most acute problems, and thus inspire interest and suggest directions for further research. The first Colloquium was held in December 1952 in Rome, and a further and more systematic one in December 1953 in Cambridge.

Many failures of aircraft structural components in the past were attributed to cracks emanating from joints, which are identified as the most critical locations. In cases using the recently emerging structural health monitoring (SHM) systems, continuous monitoring needs be carried out at many major joint locations. The purpose of this paper is to develop computational techniques for fastener joints, including the possible change in contact conditions and change in boundary values at the pin-hole interface. These techniques are used for the prognostic analysis of pin-loaded lug joints with rigid/elastic pin subjected to fatigue loading by estimating the residual life of the component at any given instance to assist the SHM systems.

Straight attachment lug joints with rigid/elastic push-fit pin and smooth pin-hole interface are modelled in commercial software MSC PATRAN. In each case, the joint is subjected to various types of fatigue load cycles, and for each type of cycles, the critical locations and the stress concentrations are identified from the stress analysis. Later, for each type of fatigue cycle, the number of cycles required for crack initiation is estimated. A small crack is located at these points, and the number of cycles required to reach the critical length when unstable crack growth occurs is also computed. The novelty in the analysis of life estimations is that it takes into account possible changes in contact conditions at the pin-hole interface during load reversals in fatigue loading.

The current work on fastener joints brings out the way the load reversals leading to change in contact conditions (consequently changing boundary conditions) are handled during fatigue loading on a push-fit joint. The novel findings are the effect of the size of the hole/lug width, elasticity of the material and the type of load cycles on the fatigue crack initiation and crack growth life. Given other parameters constant, bigger size hole and stiffer pin lead to lesser life. Under load controlled fatigue cycles, pull load contributes to significant part of fatigue life.

The analysis considers the changing contact conditions at the pin-hole interface during fatigue cycles with positive and negative stress ratios. The results presented in this paper are of value to the life prediction of structural joints for various load cycles (for both pull-pull cases, in which the load ratios are positive, and pull-push cycles, where the load ratios are negative). The prognostic data can be used to effectively monitor the critical locations with joints for SHM applications.

In the first five months of 1963, 33,700 boys entered apprenticeships directly from school — 29 per cent of the total. This represents a decline in relation to the corresponding months of 1962, for which the proportion was 34·1 per cent. Over the full 12 months of 1962 the proportion was 36·2 per cent. The figures for 1961 and 1960 were 37·9 per cent and 36 per cent. Although there was a decline in the proportion from 1961 to 1962, in actual fact, the total of apprentice placements in 1962, at 121,500, was a record.

The contributions which Prandtl has made to the science of fluid dynamics are so numerous and so important that any work from his pen on this subject must be keenly anticipated. Moreover, Prandtl has a gift for clear exposition and for simplicity of illustrations which stems from his deep understanding of the subject. It is a pleasure to record that, in the main, this book has fulfilled all that the reviewer anticipated from it. It is true that it bears a number of similarities to his earlier works, and inevitably there are certain repetitions. At the same time, the subject in all aspects is brought very fully up to date, particularly in the matter of references.

Lug joints with fasteners play a crucial role in connecting many major components of the aircraft. Most of the failures in the past were credited to the damages initiating and progressing from these types of joints. Ensuring the structural integrity of these fastener joints is a major issue in many engineering structures, especially in aerospace components, which would otherwise lead to fatal failure. The purpose of this paper is to adopting the prognostic approach for analysing these lug joints with fasteners subjected to off-axis loading by estimating the crack initiation and crack growth life of these joints. This data will be useful to estimate the remaining life of these joints at any given stage of operations, which is mandatory in structural health monitoring (SHM).

Straight and tapered lug joints are modelled using the finite element method in MSC PATRAN and analysed in MSC NASTRAN. These lug joints are analysed with a push fit fastener. The contact/separation regions at the pin–lug interface are carefully monitored throughout the analysis for various loading conditions. Critical locations in these lug joints are identified through stress analysis. Fatigue crack initiation and fatigue crack growth analysed is carried out at these locations for different load ratios. A computational method is proposed to estimate the cycles to reach crack initiation and cycles at which the crack in the lug joint become critical by integrating several known techniques.

Analysis carried out in this paper describes the importance of tapered lug joints, particularly when subjected to non-conventional way of loading, i.e. off-axis loading. There is a partial loss of contact between pin and lug upon pin loading, and this does not change further with monotonically increasing pin load. But during load reversals, there is a change in contact/separation regions which is effectively handled by inequality constraints in the boundary conditions. Crack growth in these lug joints pertains to mixed-mode cracking and is computed through the MVCCI technique.

Most of the earlier works were carried out on in-plane pin loading along the axis of symmetry of the lug. The current work considers the off-axis pin loading by loading the lug joints with transverse and oblique pin load. The significance of taper angle under such loading condition is brought in this paper. The results obtained in this paper through prognostic approach are of direct relevance to the SHM and damage tolerance design approach where the safety of the structural components is of foremost priority.

A quotation in one of the papers of this collection observes that ‘… The progress of science is not linear, but rises exponentially at a very high rate …’ Publishers would do well to consider this situation as it affects them since, with astronautics only regarded as a reputable field of endeavour for perhaps fifteen years, the gestation period for this collection of papers has encompassed more than two. The title therefore has a somewhat hollow ring and some of the prophecy has become accomplished fact.

Under this heading arc published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.