DEVELOPMENT OF A METHOD FOR MECHANICAL PROCESSING OF RUBBER SHAFT FROM SOFT RUBBER FOR POLYGRAPHY EQUIPMENT

The article discusses the current problem of machining a rubberized shaft from soft rubber, in particular turning, for printing equipment. During the processing of rubberized shafts with soft rubber, galling, burning, tearing of pieces of rubber and cutting ability of the cutter occur, sharpened cutters are not enough for a full passage along the entire length of the shaft.

Thermal Conductivities of Crosslinked Polyisoprene and Polybutadiene from Molecular Dynamics Simulations

For the first time, the thermal conductivities of vulcanized polybutadiene and polyisoprene have been investigated according to their degree of crosslinking. The C-C and C-S-S-C crosslink bridges, which can be obtained via vulcanization processes using peroxides and sulfur, respectively, are considered. The temperature dependence of the thermal conductivity of soft rubber derived from molecular dynamics (MD) simulations is in very good agreement with the experimental results. The contributions of bonded and non-bonded interactions in the MD simulations and their influence on the thermal conductivities of polyisoprene and polybutadiene are presented. The details are discussed in this paper.

Влияние продолжительности контакта и глубины индентирования на адгезионную прочность: эксперимент и численное моделирование

The adhesive contact between a steel spherical indenter and a layer of transparent soft rubber fixed on a glass substrate is experimentally investigated. Obtained experimental results are compared with theory and numerical simulation, which demonstrates satisfactory agreement between these three approaches. The influence of the indenter time in the contact and the indentation depth on the value of the adhesive strength of the contact is studied. The features of experiments conducted under conditions of controlled displacement (fixed grips) and controlled force (fixed load) are discussed.

An Alternative Approach to Substructuring in Vibratory Systems Containing Soft Rubber Isolators

Built-up structures, such as airplanes, ships, and even refrigeration systems, which have many components, can be substructured to speed up and facilitate the process of calculating the vibratory response of the complete system. In many structures, there are rubber isolators that connect component parts, and these connections can each occur over a finite distributed area. It is often convenient and intuitive to substructure the system at the isolators. However, in previous work, it has been shown that the frequency response of the complete system does not always agree with the frequency response of the system calculated from the mobilities of the subsystems. It was thought that this was due to the distributed area connection of the isolators, and this motivated the study reported in this article. An investigation into some issues that occur when substructuring a system that contains soft distributed isolators is described. Using finite element models, it is shown that if a system is substructured, such that the interface between the substructures occurs at a soft rubber isolator, then there is a limited frequency range over which the frequency response function of the assembled system is accurate. It is further shown that it is far better to substructure the system, at stiff, discrete connections, if possible. The frequency range over which the frequency response of the assembled system should then be more accurate over a much wider frequency range.

Euphorbia rimireptans (Euphorbiaceae, Articulofruticosae), a new species from the Skeleton Coast, Namibia

Euphorbia rimireptans, here described as a new species, is known only from the northern part of the Skeleton Coast (part of the Namib Desert) in the Kaokoveld Centre of Endemism, northwestern Namibia. These perennial shrublets grow on rocky outcrops of latite under harsh desert conditions. Diagnostic characters for E. rimireptans include the procumbent, sometimes pendant habit, the soft, rubber-like terete or slightly tapering branches that are curved or ± straight, frequently orientated in the same direction from the base, and the glabrous or sparsely hairy capsule, which releases verrucose ovoid seeds. A comparison of some of the more prominent morphological features to differentiate between E. rimireptans and its possible nearest relative, E. giessii, is provided.