Textile Composite Damage Analysis Taking into Account the Forming Process

Abstract

The internal structure of composite materials is modified during manufacturing. The formation of woven prepregs or dry preforms changes the angle between the warp and weft yarns. The damage behaviour of the consolidated composite is modified by these changes of angle. It is important when designing a composite part to consider this modification when calculating the damage in order to achieve a correct dimensioning. In this paper, a damage calculation approach of the consolidated textile composite that takes into account the change in orientation of the yarns due to forming is proposed. The angles after forming are determined by a simulation of the draping based on a hypoelastic behaviour of the woven fabric reinforcement. Two orthogonal frames based on the warp and weft directions of the textile reinforcement are used for the objective integration of stresses. Damage analysis of the cured woven composite with non-perpendicular warp and weft directions is achieved by replacing it with two equivalent Unidirectional (UD) plies representing the yarn directions. For each ply, a model based on Continuum Damage Mechanics (CDM) describes the progressive damage. Two examples are presented, a bias extension specimen and the hemispherical forming coupon. In both cases, the angles between the warp and weft yarns are changed. It is shown that the damage calculated by taking into account these angle changes is greatly modified.

The Tensile Behavior of Hybrid Bonded Bolted Composite Joints: 3D-Digital Image Correlation versus Finite Element Analysis

“…The fabrics were modeled using a technique discussed by Gordon et al [20], which involves substituting one fabric ply with four unidirectional (UD) plies to form a symmetric sublaminate and stacking together to form the woven fabric laminate. This technique of replacing fabric layers with UD plies has been used by other researchers as well [21,22]. In addition, the sublaminate formed by the four UD plies has the same thickness as the fabric, but the thickness ratio of the ply complies with Equation ( 2), as suggested by [23].…”

Modified constitutive relation error for field identification: Theoretical and experimental assessments on fiber orientation identification in a composite material

“…Problem (11) reduces to the linear problem (12). This approach has the notational advantage that the solution of this problem is exactly u, and not a restriction of it, nor a vector containing u and Lagrange multipliers.…”

“…The methods will be presented formally in the case when the constraints are satisfied by substitution, but they are of course applicable with any constrained minimization method. One can show that Problem (10) is equivalent to problem (11):…”

“…This problem is for example studied in Reference 10. In Reference 11, the authors show how to carry on a numerical structure computation from the knowledge of this field of orientations.…”