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Lightweight, honeycomb core, sandwich panels form the major part of the body structure of Formula One racing cars. Key properties include high specific stiffness and specific strength, ease of fabrication, and the ability to tailor impact resistance. The engine and gearbox, which in current designs are placed at the rear of the car, are load-bearing components and must be attached to the sandwich body shell. Although techniques for introducing loads into the skins of sandwich panels, via inserts, are well established, for Grand Prix cars, where every gram of weight must be saved, efficiency is at a premium. Thus the shape of the insert is critical and the choice of the bonding adhesive and insert's material important. While it is possible to undertake preliminary design using simple methods, if a complex insert geometry is used, recourse to finite element (FE) analysis is inevitable. However, particular difficulties arise when using FE methods in these circumstances, notably the relatively small thickness of the panel skins and the discontinuity at the insert boundary. In the current paper these issues are addressed for a particular application. To assess the efficiency of load transfer, three different insert geometries are considered. The influence of element type, mesh size and boundary conditions are addressed and their influence on stress levels and discontinuities assessed. Ways of representing the honeycomb core are also considered, as is the need to involve non-linear effects, such as the shear stress-strain properties of the adhesive. The FE results are compared with experimental data obtained from testing a representative panel to which a photoelastic coating had been applied. Encouraging agreement between prediction and experiment was obtained, together with guidance as to the optimum insert shape.

Light-scattering techniques have been used for the direct, in situ observation of a crystallizing zeolite system. Information has been acquired on the kinetics of the early stages of the crystallization of silicalite and on the influence of various synthesis parameters on both nucleation and growth steps.

The high-temperature gas-cooled reactor (HTGR) core consists of several thousand prismatic graphite fuel elements arranged in columns within a prestressed concrete vessel. A major research and development effort was initiated in 1970 at General Atomic Company to study the dynamic response of the HTGR core arrangement to seismic excitation. This paper presents a discussion of the history and some of the results of this effort, with respect to advances made in the development of analytical methods. The computer programs developed to perform the analysis are described, along with certain techniques and the modeling required to utilize them. The purpose is to describe the nonlinear dynamic analysis techniques employed to analyze the HTGR core. Correlation of the codes is beyond the scope of the paper and will be discussed in subsequent publications. Each fuel column in the HTGR core is composed of stacked elements doweled together to ensure alignment of the coolant channels. Gaps exist between columns, allowing the elements to impact during a seismic disturbance. Analysis of this type of structure by standard structural dynamics techniques is not possible since both nonlinearities and discontinuities exist. One- and two-dimensional models of the three-dimensional core have been developed with explicit time integration methods. Various methods to treat the impact between elements are discussed. Three computer codes were developed. CRUNCH-1D models a one-dimensional horizontal strip through the core; CRUNCH-2D, a two-dimensional horizontal planar section; and MCOCO, a two-dimensional vertical planar section. The dynamic characteristics of these three representations of the full core structure are compared and the methods evaluated in the text. Plans for additional development and work to improve the techniques are also discussed.

A population balance approach is used to mathematically model continuous emulsion polymerization. The Smith-Ewart recursion relation is incorporated directly as the “rate of formation” relation for polymer, particles. As a result of this approach, the mechanism of free radical desorption from polymer particles is easily included, and finite termination rates in particles are allowed. Particle growth is incorporated in the model, and particle size distributions are easily obtained. A brief parameter study is conducted. Model predictions are compared to data from the literature. Practical consequences of changes in system parameters are discussed.

A mathematical model for continuous emulsion polymerization which accounts for the desorption of radicals from polymer particles is presented. The desorption factor has been incorporated into the Sato-Taniyama model and the resulting systems of equations solved iteratively. The effects of desorption on variables such as concentration of particles, polymerization rate, and average number of radicals per particle are illustrated. Fit of the model to experimental data is presented and discussed.

Specimens were strained in tension from room temperature to 550°C at strain rates in the range of 10 −3 –10 −4 /sec on iodide vanadium containing varying amounts of nitrogen in solid solution. Maxima in the tensile strength, yield strength, and strain-hardening coefficient, a minimum in the strain-rate sensitivity and the occurrence of serrated stress-strain curves were observed in the temperature range of 300° to 450°C. The activation energy for strain aging in vanadium was found to be 37.3 ± 3.7kcal/mole from the strain rate dependence of the strain-aging peak and 36.2 ± 4.5kcal/mole from a return-of-yield point method. These values agree well with those reported for the diffusion of nitrogen in vanadium as determined by other methods. Thus, the results of this investigation indicate that nitrogen is associated with many of the strain-aging effects observed in vanadium.