Estimating mechanical properties of 2D triaxially braided textile composites based on microstructure properties

Abstract

Textile composites manufactured using Resin Transfer Modeling (RTM) can offer advantages in some automotive applications including reduction in weight, while being relatively simpler to fabricate than standard laminated composites used for aerospace applications. However, one of the challenges that arise with these textile composite materials is that the mechanical properties are inherently dependent on the local and final (in-situ) architecture of the textile itself as a result of the molding and curing processes. While this provides additional latitude in the composite design process it also necessitates the development of analytical models that can estimate the mechanical properties of a textile composite based on the textile architecture and the properties of the manufactured component. In this paper, an analytical model is developed and its estimations are compared against experimental in-plane engineering properties for composites with various textile architectures. Results from the model are also compared against finite element (FE) based computational results. The microstructures of the 2D triaxially braided composite (2DTBC) studied were extensively characterized. The microstructure properties thus measured were used in the analytical model to estimate the mechanical properties. Uniaxial tension and V-notched rail shear tests were conducted on 2DTBC with different textile architectures. Good agreement between the analytical, computational, and experimental results were observed and are reported here. Furthermore, computational estimations of matrix mechanical properties are limited to the linear elastic range of a representative material volume (unit cell) and coupon data. Full mechanical response of larger 2DTBC structures, albeit of prime interest, is beyond the scope of this work and could be the focus of follow up studies.

A multi-scale correlating model for predicting the mechanical properties of tri-axial braided composites

“…Geometrical properties of the composites are listed below each figure, where ''V '' denotes the volume fraction of each tow and ''V f '' is the fiber volume fraction of the composite. Figures 5 and 6 compare the results obtained from the present model with those obtained experimentally by Kier et al 30 and analytically by Hwang et al 29 Parametric studies are also performed to examine the effect of geometrical parameters such as braid angle and bias tow undulation on the resulting effective modulus of tri-axial braided composites. This work also shows the capability of the multi-scale correlating model for design applications.…”

Buckling and Post-Buckling Behavior of Unitized, Stiffened Tri-Axially Braided Composite Textile Plates

“…The material is assumed to be linear elastic and orthotropic, with the homogenized properties calculated using the procedure described in Ref. 5. S4R shell elements are used in the model.…”

“…Note that while the constituents (TBC fiber and matrix) are the same as in Ref. 5, the VARTM process changes details like the fiber volume fraction and tow packing arrangement. The VARTM process consolidates the fibers more than the specimens used in Ref.…”

“…The VARTM process consolidates the fibers more than the specimens used in Ref. 5, so the fiber volume fraction is expected to be higher. While a full characterization of the VARTM material as used is planned, the material properties from Ref.…”

“…Either of these two methods are far more energy intensive than the energy required to delaminate a traditionally bonded stiffener 4 . The increased energy needed to fully separate the stiffener could result in two predicted behaviors: either the unitized, stiffened panel will gradually fail rather than catastrophically fail, or another failure mode will initiate before complete stiffener delamination occurs 5 .…”