The radial and tangential deformations in a single growth ring of Norway spruce, which was subjected to moderate tensile loading in its radial direction, were measured by use of digital speckle photography. From the measured displacement field, the transverse coefficients of elasticity E R , E T , G RT and n TR were determined with respect to radial position in the growth ring. As a result of the abrupt change in stiffness from latewood to earlywood in the growth ring, it was possible to establish all four coefficients solely from the radial tension test. The elastic modulus E T was found to be a factor 15 larger in latewood than in earlywood, whereas the corresponding variation for E R was merely a factor 3. The measured variations were in reasonable agreement with predictions from simple two-dimensional honeycomb models of the growth ring cellular structure.The average elastic moduli of the growth ring were found to be twice as large as E R and E T measured in conventional tests on macroscale specimens, whereas the reverse was true for the shear modulus. An explanation to these differences is sought by analysing the loading conditions and deformation behaviour of macroscale specimens used in transverse stiffness testing of wood.
In this study an experimental methodology to study surface wear of injection moulds on a full scale polymer injection moulding machine is developed. A comparative study of four different tool materials for mould cavities is carried out in situ. The polymer injection conditions (geometry cavities, machine settings, polymer) are chosen in order to accelerate the degradation of the mould cavity surface. The reinforced polycarbonate resin Lexan 341R-739, containing 40% of weight of short glass fibres, well known for their abrasive character, was injected with jetting and normal injection conditions. Jetting conditions implies high pressure and velocity of the injected resin. The die wear is discussed in relation to the polymer flow conditions and the die materials.
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