Penny-shaped crack in a sphere embedded in an infinite medium

We consider the problem of determining the stress intensity factor and the crack energy in an Isotropie, homogeneous elastic sphere embedded in an infinite Isotropie, homogeneous elastic medium when there is a diametrical crack in the sphere. We assume that the crack is opened by an internal pressure and the sphere is bonded to the surrounding material. The problem is reduced to the solution of a Fredholm integral equation of the second kind in the auxiliary function φ($\text{t}$). Expressions for the stress intensity factor and the crack energy are obtained in terms of φ($\text{t}$). The integral equation is solved numerically and the numerical values of the stress intensity factor and the crack energy are graphed.     

Influence of Superheat on Microstructure and Mechanical Properties of Ductile Cu47.5Zr47.5Al5 Bulk Metallic Glass-Matrix Composite

Generally bulk metallic glasses (BMGs) posses very less ductility and toughness at room temperature. Over the recent past years to improve up on these properties in many alloy system BMG composites have been developed. It was also reported that Cu_47.5Zr_47.5Al₅ BMG composite shows a very high strength together with an extensive work hardening-like behavior of large ductility around 18%. In this study, the influence of superheat on microstructure and the resulting mechanical properties in Cu_47.5Zr_47.5Al₅ bulk metallic glass-matrix composite alloy has been studied. The Cu_47.5Zr_47.5Al₅ melt solidifies into a composite microstructure consisting of crystalline precipitates embedded in an amorphous matrix. The crystalline phase consists of B2 CuZr (cubic primitive with CsCl structure) with a small amount of monoclinic CuZr martensitic structure embedded in an amorphous matrix. The volume fraction of crystalline phases varies with melting current as well as position along the length of the as-cast rod, depending on the local cooling condition. The volume fraction and the distribution of the crystalline precipitates are heterogeneous in the amorphous matrix. Room temperature uniaxial compression tests revealed high yield strength ranging from 796 to 1900 MPa depending upon the volume fraction of the crystalline phases present. The presence of the dendritic B2 CuZr significantly improved the ductility. The BMG composites show a pronounced plastic strain up to 14% for the higher volume fraction of crystalline phase.     

A study of seeds of musk melon (Cucumis melo L.): A lesser known source of edible oil

The oil content and oil characteristics of seeds of 91 accessions of musk melon (Cucumis melo), including two allied species collected from different parts of the world, have been studied to assess their variability. Oil content (on a whole seed basis) ranged from 12.5 to 39.1% and iodine values from 106.0 to 124.1. Gas liquid chromatographic analysis showed that only linoleic, oleic, palmitic and stearic acids were present. Unsaturated fatty acids constituted 64.6–88.2% of the total fatty acids present. The proportion of kernel in the seeds of different accessions, varied from 25.0 to 74.1% and contributed significantly to the total oil content of the whole seed. A similar relationship existed in the case of the 100-seed weight.     

Reusable Dry Adhesive: Aluminium-Aluminium Bonding by Self-Vulcanisable Blend Based on Carboxylated Nitrile Rubber and Chlorobutyl Rubber

A self-vulcanisable blend of chlorobutyl rubber and carboxylated nitrile rubber can be used as an adhesive for aluminium-aluminium bonding. The peel strength depends on the state of cure of the adhesive, testing temperature and carboxyl content of the carboxylated nitrile rubber. At moulding times below 15 minutes, the adhesive was found to be reusable after repeated post-peel mouldings.     

Torsion of an elastic layer by two circular dies

Two circular discs of rigid material and of different radii are bonded to the opposite faces of an infinite elastic layer. The torques T₁ and T₂ have been calculated when the discs are rotated through different angles.     

Studies on the nutritional quality of some cucurbit kernel proteins

The nutritional quality of proteins of four cultivated cucurbit species was measured by nitrogen balance. The biological value of muskmelon, watermelon and pumpkin proteins were 59, 64, and 67 respectively. A value of 70 for bittergourd kernels was calculated from chemical score. Lysine was the first limiting essential amino acid in all the proteins. The leucine:isoleucine and leucine:lysine ratios did not show imbalance.     

Scanning electron microscopy studies on tensile rupture of rubber

Tensile rupture of natural rubber (NR) and styrene-butadiene rubber (SBR), vulcanized by sulphur and peroxide systems, both with and without fillers, has been studied by scanning electron microscopy (SEM). NR gum fracture surfaces show evidence of straininduced crystallization, which is absent in SBR. The fracture surfaces of filler-reinforced NR and SBR vulcanizates are characterized by their roughness and by the presence of short and curved tear lines. Increase of cross-link density changes the fracture mode. Peroxide-cured SBR undergoes brittle fracture, whereas sulphur-cured SBR shows a smooth surface with a few straight tear lines.