Department of Agricultural Engineering

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Browsing Department of Agricultural Engineering by Subject "Sisal"

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    Fatigue evaluation and dynamic mechanical thermal analysis of sisal fibre–thermosetting resin composites
    (Elsevier, 2007-08-10) Towo, Arnold N; Ansell, Martin P.
    Sisal composites were manufactured in a hot press from as-received and 0.06 M NaOH treated sisal fibres with polyester and epoxy resin matrices. Tensile tests were conducted on the composites to establish loading levels for fatigue testing. A fatigue evaluation of the sisal fibre–thermosetting resin composites was undertaken at loading levels of 75%, 60%, 50% and 35% of static tensile strength and at an R ratio of 0.1. S–N curves for the composites are presented for untreated and 0.06 M NaOH treated sisal fibres. Epoxy matrix composites have a longer fatigue life than polyester matrix composites. The effect of chemical treatment on fatigue life is significantly positive for polyester matrix composites but has much less influence on the fatigue life of epoxy matrix composites. Dynamic mechanical thermal analysis (DMTA) was conducted on samples from failed epoxy resin fatigue specimens and the influence of fatigue history on the Tanδ peak temperatures and Tg of the composites is examined. Significant shifts in Tg are observed following fatigue testing. The fatigue performance of natural fibre composites suggests that they are suitable for use in dynamically loaded structures and may be used as a substitute for Glass Fibre Reinforced Plastic composites in fatigue.
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    THE POTENTIAL FOR MECHANICAL HARVEST OF SISAL
    (American Society of Agricultural Engineers, 1997) Majaja, B. A.; Chancellor, W. J.
    With current renewed interest in natural fibers, traditional suppliers of sisal such as those in Tanzania are looking to reestablish high production levels despite the shortage of field workers for laborious and hazardous harvest operations. Cutting force and energy determinations made with Agave sisalana leaves indicated that these parameters were well within the capabilities of workers even at a work rate twice that of current levels. Measurements of leaf bending resistance, friction coefficients, and mass distribution were made to assist designers of equipment to handle sisal leaves. Physical simulations of cutting operations with worker aids aimed at obviating the stooping currently required of harvest workers, indicated that only tools powered by some external energy source could match or exceed the current traditional work rate of one leaf per 2.9 s. Among the design concepts formulated for in-field leaf handling, collection and transport devices, there was an indication that an inverted umbrella type leaf catcher may have economic potential. Because the cutting operation is complex and selective, it was concluded that the most immediate potential for sisal harvest mechanization would involve manually operated cutting mechanisms using worker aids, combined with mechanized infield collection, handling and transport of leaves.