Variable angle fibres

Variable angle fibres using continuous tow shearing... 

Figure 4.9 compares the average thickness of optimum designs obtained using VICONOPT with straight fibre laminates and variable angle tows obtained using either CTS or AFP techniques where the latter assumes shifted (similar) tow paths obtained... 

ATR-FTIR was used to determine the concentration of a chemical additive (cationic polyacrylamide resin) within a pulp fibre. The depth distribution of the additive was determined by sputter etching the fibre surface. The obtained profile was compared qualitatively with that obtained by the variable-angle ATR-FTIR depth profiling method. Most of the additive was located at the surface, with some distributed within the fibre (137). 

A 10 m roof, with a variable angle of inclination, was erected and covered with rigid PVC, and normal and flame-retarded glass fibre-reinforced polyester corrugated sheet at angles of —30°, 0° (horizontal), and -f 20°. 5 and then 10 dm of gasoline was ignited in an iron tray of 0.3 or 0.6 m. ... 

FRACTURE MECHANISMS IN SHORT FIBRE POLYMER COMPOSITES THE INFLUENCE OF EXTERNAL VARIABLES ON CRITICAL FIBRE ANGLE... 

The variation of Kc with fibre orientation and the transition between the two regimes at a critical angle depend on external variables as well as on the constitution of the material. 

Figure 4.9 Comparison of average thickness (solid lines) and buckling strains (dashed) for straight fibre optimum designs and variable fibre angle designs obtained using continuous tow shearing and automated fibre placement. In all cases, the panels are 250 mm wide and 750 mm long with simple supports.

The approach developed by Brandt (1985) was illustrated by examples of optimal solutions for an element subjected to tension and another to bending. As an objective function the fracture energy accumulated up to a specified limit state was selected. The results calculated were obtained after derivation of proposed simplified expressions with respect to the only variable - the angle 6 of fibre system orientation. Later, the tests of specimens with various fibre orientation were executed and analyzed. All details of calculation and testing may be found in papers by Brandt (1986, 1991) and final results are summarized in Figures 8.20a and 8.20b. From these curves certain confirmation of theoretical results may be concluded, at least in the general shape of the curves and characteristic numerical values. However, there were no tests of elements with small values of angle 0 <6 <30° and the existence of an extremum for 0 0° was neither confirmed nor excluded because of techni-... 

The angle 0 of the direction of the first system of fibres and the angle a between the two systems are independent variables. 

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