Issue 39

M. Romano et alii, Frattura ed Integrità Strutturale, 39 (2016) 226-247; DOI: 10.3221/IGF-ESIS.39.22 244 0,0 0,5 1,0 1,5 2,0 2,5 0,00 0,01 0,02 0,03 0,04 0,05 Leinwand CFK einseitig el. geb. vs. beidseitig el. geb. 0,0 0,5 1,0 1,5 2,0 2,5 0,00 0,01 0,02 0,03 0,04 0,05 Leinwand CFK einseitig el. geb. vs. beidseitig el. geb. versus versus ~~ ~~ . . . . . . Degree of ondulation Õ = A / L . . . . . . M y, o /M y, t mesomech. kinematic ε y ,kin ~ ~ M x, o /M x, t elastic part ε x ,kin ~ ~ . . . . . . Degree of ondulation Õ = A / L . . . . . . Plain weave fabric HT-carbon fib r reinf EP one-sided el. sup. versus two-sided el. sup. Plain weave fabric HT-carbon fiber reinf EP one-sided el. sup. versus two-sided el. sup. Figure 8 : Relations of the sensitivity of the mesomechanic kinematic of the model with one-sided elastic support to the one of two- sided elastic support for the kinematic part (left) and for the difference of the longitudinal deformation (right). The relations of the sensitivity of the values of the slopes y M  over the degree of ondulation O  for the applied deformations x  for a balanced plain weave fabric construction of HT-carbon fiber reinforced epoxy are illustrated in Fig. 8, left for the kinematic parts y ,kin  (20) and right for the difference of the applied and evaluated longitudinal deformation x ,kin  (23). In case of the kinematic parts y ,kin  (20) the model with a one-sided elastic support shows a 1.8 times higher sensitivity as the model with a two-sided one. In case of the difference of the applied and evaluated longitudinal deformation x ,kin  (23) the model with a one-sided elastic support only slightly differs from the model with a two-sided elastic one. Correspondingly the relation of the sensitivities x, x M M o ,t /   plotted over the degrees of ondulation O  is almost constant about approximately 1. C ONCLUSIONS he identified correlations in the analytical and numerical investigations definitely prove and verify the acting of a mesomechanic kinematic due to geometric constraints. Within the limits of the validity of the analytical and numerical model a direct linear coupling between the applied longitudinal deformations and the mesomechanic kinematic exists. In case of the FE-calculations the transversal deformation due to Poisson effects as an elastic reaction is separated and corrected, in order to obtain the purely mesomechanic kinematic. Yet, the simplifying presumptions of the analytical model are suitable only to describe the tendency of the kinematic behavior, because the idealized stiffnesses only qualitatively represent the huge differences of the stiffnesses in the direction of the fibers and transverse to it. In order to obtain more precise results, more parameters, especially in the FE-calculations, can be varied in further investigations. Considering plain representative sequences, amongst others, correlations regarding loading and displacements or deformations as well as detailed analyses of the resulting stress condition are relevant. A parameter identification of the mesomechanic kinematic regarding the resulting correlations of load and displacement provides the basis for the identification of the influence of the kind of reinforcement fiber (glass, aramid, basalt compared to carbon) and of the kind of fabric construction (twill weave, satin weave (balanced and unbalanced) compared to plain weave) on the structural mesomechanic material behavior of fabrics. Detailed analyses of the stress conditions allow the description of damage mechanisms and the formulation of failure criteria. The consideration of a linear visco-elastic material model instead of a linear-elastic material model, and the consideration of the sensitivity of the material behavior on the kind of deformation (tension or compression) provide another expansion of the limits of the model conceptions. The expansion T