The federal financing of large-scale engineering projects
Abstract The financial condition of the federal government can not be a source of comfort to the managers of large-scale projects. On the one hand, a gradual absorption of the large deficits into a growing economy increases the financial risks of large projects. On the other hand, the significant cuts in federal spending are likely to fall disproportionately on these same projects. As a result strategic thinking about such ventures will need to include: a) financial mechanisms that place greater reliance on private resources, states and localities and, with that reliance, allow greater non-federal participation in project design and management; b) the way that the financial structure of a large-scale project can build and nurture the coalition of interests essential for its survival; c) the concept that a large scale project is a provider of services, rather than an object of intrinsic value; and d) meshing the financial and technological characteristics of a macro-engineering project with these new realities.
The Space Shuttle Program: A Policy Failure?
The 5 January 1972 announcement by President Richard Nixon that the United States would develop during the 1970's a new space transportation system—the space shuttle—has had fundamental impacts on the character of U.S. space activities. In retrospect, it can be argued that the shuttle design chosen was destined to fail to meet many of the policy objectives established for the system; the shuttle's problems in serving as the primary launch vehicle for the United States and in providing routine and cost-effective space transportation are in large part a result of the ways in which compromises were made in the 1971-72 period in order to gain White House and congressional approval to proceed with the program. The decision to develop a space shuttle is an example of a poor quality national commitment to a major technological undertaking.
Damage initiation and propagation in composite shells subjected to impact
Abstract The paper investigates the impact-induced damage initiation and propagation for laminated composite shells under low-velocity impact. A three-dimensional eight-node non-conforming element is described to analyze interlaminar stress distribution, and progressive failure. The damage analysis is performed by using Tsai–Wu quadratic failure criterion, Tsai’s damage modes and an additional delamination formula at all Gaussian points. The damage modes considered are matrix cracking, fiber breakage and delamination. The progressive failure is expressed by reducing stiffness of the material at all failed Gaussian points. Special attention is centered on curved laminates. Impact energy threshold for the onset of damage and transient damage size are predicted for composite shells. The analyses of the flat and curved laminates are compared for discussing their different damage mechanism. In addition, the influence of the stacking sequence, the thickness and the radius of curvature on damage behavior of composite shells are studied.