| A novel tailoring concept for increased energy dissipation and yield-type response in composite material 1D members subject to tensile loading is proposed, modeled and experimentally verified in this work. The concept was developed in connection with constrained arrest problems of practical interest.; The beneficial response is obtained through the use of flexible composites, obtained by reinforcing an elastomeric matrix material with high performance elastic fibers, to create a structure with redundant load paths and progressive failure. In the interest of generality, the constitutive equations used to model the response of the flexible composite allow for elastic or viscoelastic matrix response, as well as circular or elliptical fiber cross-section.; Three analytical models capturing the essential characteristics of the response under quasistatic loading were developed and their governing parameters were identified. Extensions of the three models for the case of impulsive loading were also developed. Model predictions are illustrated for a selected configuration, together with response changes corresponding to single-parameter perturbations around the selected configuration. An alternate configuration, considered more illustrative of the tailoring concept potential, was also considered and the predicted response is shown. In all cases, the response of the tailored configuration is compared with that of corresponding conventional counterparts of identical length, total cross-sectional area and material properties.; An experimental program aimed at verifying the predictive capabilities of the developed models was undertaken. Based upon availability and cost considerations, a commercially available prepreg consisting of a rubber resin reinforced with glass-fiber yarns was selected. Tailored and conventional specimens were manufactured and tested under quasistatic loading, using a universal hydraulic testing machine, and under impulsive loading, using a custom designed instrumented drop test stand. Measurement results were compared to analytical predictions and a very good agreement was found with regard to both failure sequence and load developed.; As an application it was shown that for a typical helicopter vertical crash condition adequate protection can be offered by a stroking support system incorporating a tailored composite member. The case of a falling person being arrested by a tailored composite member was also analyzed.; Several refinements and extensions of this work are suggested. |
