Issue 39

M. Romano et alii, Frattura ed Integrità Strutturale, 39 (2016) 226-247; DOI: 10.3221/IGF-ESIS.39.22 227 geometry of fabric reinforced single layers cannot be considered sufficiently by relatively simple homogenization approaches. Yet, mesomechanic correlations are distinctly different as they significantly influence the mechanical properties of a structure. R ESEARCH ENVIRONMENT he research environment is the description of the structural mechanic behavior of fabric reinforced plastics. A chronological literature review is presented. The conclusions lead to the pursued mechanical principle. Literature review Naik and Shembekar 1992 [1] present linear-elastic investigations of plain-weave fabric reinforced single layers. The ondulation influences the plane structural mechanical material properties. There is a significant discrepancy between the one-dimensional analytical and numerical investigations to them of the experiments. In contrast the two-dimensional analytical and numerical investigations correlate very well with the experiments. Mital, Murthy and Chamis 1996 [2] investigate the micromechanics of plain weave composites. As a result the effects of the fabric reinforcement have been described analytically and basically verified numerically. The fiber-orientation in the mesoscopic dimension has been described by sinusoid parts in the ondulation region connected by straight parts above and under the ondulated yarn. For means of simplicity and in order to reduce computation time symmetry characteristics has been used in the model. Guan 1997 [3] investigates the visco-elastic damping in fabric reinforced single layers by FE-calculations. A plain-weave fabric is modeled by representative volume elements. A sensitivity analysis regarding the length of the ondulation shows, that the model is relatively insensitive to a variation of this geometric parameter. A basic validation is carried out by the decay of vibrating flat beam-like specimens. Byun 2000 [4] presents an analytical model of a so called unit cell in a mesomechanic scale in order to calculate the geometric characteristic and the three-dimensional structural material properties. In detail the ondulation is presumed continuously differentiable and investigated by coordinate transformation. A validation in one-dimensional tensile tests is carried out for seven different fabric constructions. Huang 2000 [5] treats the structural mechanical properties of laminates of fabrics according to the introduced the so- called bridging model. It describes linear-elastic, plastic and strength aspects of balanced plain-weave fabrics under arbitrary loading. The presumed geometry causes three mechanically different regions, namely warp and fill yarn and surrounding matrix. Several geometric parameters are considered for a verification of the model. An experimental validation yields a good correlation with the results of the analytic model. Guan and Gibson 2001 [6] suppose the acting of a mesomechanic mechanism for damping in fabric reinforced composites. Therefore a pain-weave construction is investigated numerically and validated basically by the decay of vibrating flat beam-like specimens. Tabiei and Yi 2002 [7] confront different methods for the determination of structural mechanic material properties of fabric reinforced plastics, amongst representative volume elements, four-cell-method and three-dimensional FE- calculations. In detail results of different numerical investigations with FE-calculations are confronted. Besides precision the numerical efficiency and thereby the applicability is taken into account. Le Page et al. 2004 [8] carry out two-dimensional FE-calculations, presuming plane stress and considering mesomechanic geometric parameters. The aim is the prediction of damage propagation in fabric reinforced laminates as a function of the number of layers. Thereby layups with different numbers of single layers of plane-weave fabrics are investigated under the presumption of the “in-phase” arrangement and “out-of-phase” arrangement. Against this background parametrical FE- calculations are carried out. Wielage et al. 2005 [9] emphasize the relevance of a detailed mesomechanic description of laminates of fabric reinforced single layers. The carried out FE-calculations consider representative volume elements of three kinds of fabrics, namely plain-weave, twill 2/2 and satin 1/4. The independent structural mechanic material properties of the ondulated rovings are presumed as 0°-unidirectionally reinforced regions. The structural mechanic stiffnesses and the thermal expansion coefficients are calculated and validated experimentally. Barbero et al. 2006 [10] describe a FE-model for the calculation of laminates of plain-weave fabrics. The basically different arrangements, namely “in-phase” (here called “iso-phase”) and “out-of-phase”, are considered. The difference between the global and local fiber volume content is discussed. The determination of the local fiber volume content in the T