According to W. Edwards Deming, American companies require nothing less than a transformation of management style and of governmental relations with industry. In Out of the Crisis, originally published in 1982, Deming offers a theory of management based on his famous 14 Points for Management. Management's failure to plan for the future, he claims, brings about loss of market, which brings about loss of jobs. Management must be judged not only by the quarterly dividend, but by innovative plans to stay in business, protect investment, ensure future dividends, and provide more jobs through improved product and service. In simple, direct language, he explains the principles of management transformation and how to apply them.

Out of the Crisis

Self-healing polymeric materials: A review of recent developments

Nonlinear Programming: A Unified Approach

This paper is a review of low-velocity impact responses of composite materials. First the term ‘low-velocity impact’ is defined and major impact-induced damage modes are described from onset of damage through to final failure. Then, the effects of the composite's constituents on impact properties are discussed and post-impact performance is assessed in terms of residual strength.

Review of low-velocity impact properties of composite materials

Topology optimization is the process of determining the optimal layout of material and connectivity inside a design domain. This paper surveys topology optimization of continuum structures from the year 2000 to 2012. It focuses on new developments, improvements, and applications of finite element-based topology optimization, which include a maturation of classical methods, a broadening in the scope of the field, and the introduction of new methods for multiphysics problems. Four different types of topology optimization are reviewed: (1) density-based methods, which include the popular Solid Isotropic Material with Penalization (SIMP) technique, (2) hard-kill methods, including Evolutionary Structural Optimization (ESO), (3) boundary variation methods (level set and phase field), and (4) a new biologically inspired method based on cellular division rules. We hope that this survey will provide an update of the recent advances and novel applications of popular methods, provide exposure to lesser known, yet promising, techniques, and serve as a resource for those new to the field. The presentation of each method's focuses on new developments and novel applications.

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A survey of structural and multidisciplinary continuum topology optimization: post 2000

The ability to understand and predict fatigue life remains a key technical factor in maintaining aircraft fleets which are required to safely operate up to their design lives, and sometimes beyond. In particular military aircraft are often required to achieve long lives under demanding operational conditions. The load spectra applied to these aircraft are complex and highly variable, and experience has shown that traditional fatigue prediction tools do not always perform well in calculating the lives of modern, highly optimised airframes. This paper summarises a semi-empirical model that appears to be capable of producing more accurate fatigue life predictions using flight load spectra based on realistic in-service usage. The model relies on experimentally derived variable amplitude crack growth (CG) data. The model itself is founded on the observation that, as a first approximation, for lead cracks in many materials the log of the crack depth is proportional to the number of spectrum loading blocks. This relationship can also be used to define the effective crack-like size of the initiating discontinuity. The implications of this exponential growth, including the crack depth dependency of the crack growth rate are discussed, leading to a reconciliation of a Paris-type growth model with that of the earlier Frost and Dugdale stress-cubed growth relationship. The exponential CG model provides an alternative and more accurate means of assessing variable amplitude fatigue life, particularly of highly stressed structures.

Spectrum Fatigue Crack Growth Evaluation Using Variable Amplitude Data

The present invention provides a method for (i) repairing a structural weakness, or (ii) preventing or inhibiting the initiation of a structural weakness, or (iii) preventing or inhibiting the progression of a structural weakness in an aircraft frame element, the method comprising the step of bonding a plurality of particles to the element, the bonding being effected under conditions allowing the plurality of metallic particles to form a substantially continuous layer over the area of weakness, or the predicted area of weakness. The metallic particles may be deposited on the frame element by a cold spray process such as supersonic particle deposition. The structural weakness may be a stress corrosion crack in the aircraft frame element.

Methods for restoring an aircraft frame element

A finite element analysis of delamination behaviour in a circular laminate

In the context of aircraft sustainment, multiplicative manufacturing is defined as the simultaneous application of subtractive and additive manufacturing processes to extend the fatigue life of an operational structure. In this chapter, we illustrate the potential of multiplicative manufacturing via the LAU7 missile launcher housing. It is shown that applying SPD to the external surface of the LAU7 missile launcher housing, further reduces the peak stress at the critical location, in comparison to only adopting a shape optimization solution, by approximately 29%. This reduction in the stress field would enable the allowable crack size to be increased from 0.5 mm to approximately 2.14 mm and would effectively triple the time to the allowable crack size.

Multiplicative Manufacturing and Aircraft Sustainment

This paper presents recent developments in the optimal design of structural components with fracture constraints. To minimise the computational effort it is suggested that an initial “near optimum” shape be used. Indeed, one approach could be to begin with the optimal shape for the non cracked geometry. This initial near optimum shape could then be used in conjunction with the alternating finite element method for multiple cracks, which builds on existing CAD based finite element models, and the resultant formulation then linked to available optimisation codes. This approach is illustrated by considering the problem of an optimum cut-out geometry for a rectangular plate subjected to a 4:1 and a 2:1 biaxial stress field. When considering the problem of shape optimisation with static fracture constraints, it was found that the optimal shape for the uncracked geometry was not the same as the optimal solution for the cracked problem. It was also found that for the optimal case, the stress intensity factors for same length cracks emanating at any arbitrary point around the hole were approximately constant along most of its circumference. This behaviour is intuitively expected for an optimised geometry where it all locations around the hole should be equally critical. The analysis also reveals that, as the geometry of the cut out or hole changes, the location of the crack that causes the maximum stress intensity factor can also change. This makes it necessary to consider flaws at a range of locations around the hole.

Rhys Jones

Papers

Spectrum Fatigue Crack Growth Evaluation Using Variable Amplitude Data

Methods for restoring an aircraft frame element

A finite element analysis of delamination behaviour in a circular laminate

Multiplicative Manufacturing and Aircraft Sustainment

Structural optimisation with damage tolerance constraints