A method for automated generation of finite element meshes for unidirectional composites with waviness defects is proposed. Images used as input for mesh generation are recorded with X-ray computed micro-tomography. Quality and contrast of the scanned images is such that fiber directions cannot be detected everywhere. To generate finite elements mesh that follow fiber directions it is suggested...

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA’s Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoin...

The key objective of this work is to highlight the effect of manufacturing-induced fiber waviness defects on the compressive failure of glass fiber-reinforced unidirectional specimens. For this purpose, in-plane, through-thickness waviness defects (with different waviness severities) are induced during the manufacturing of the laminate. Numerical and experimental results show that the compressi...

The onset of electrical percolation in nanotube-reinforced composites is often modeled by considering the geometric percolation of a system of penetrable, straight, rigid, capped cylinders, or spherocylinders, despite the fact that embedded nanotubes are not straight and do not penetrate one another. In Part I of this work we investigated the applicability of the soft-core model to the present ...

Using a micromechanics approach, we recently investigated the theoretical limits on achievable moduli in nanotube mats by stiffening of bonds. However, the waviness intrinsic to many manufacturing processes also clearly plays an important role in stiffness of these materials. To study the effect of waviness on mechanical properties, we modeled fiber segments as sinusoids, generated networks com...

applications of thermoplastic composites have developed extensively. the thermoplastic composites in comparison with the thermoset composites have many advantages. thermoplastic composites can be melted and remolded many times. the duration of manufacturing process of these composites is short, producing very tough material, and the welding ability and multiple recyclings are their further adva...

effective elastic properties for carbon nanotube reinforced composites are obtained through a variety of micromechanics techniques. an embedded carbon nanotube  in  a  polymer  matrix  and  its surrounding  interphase  is  replaced with an equivalent fiber for  predicting  the  mechanical  properties of  the  carbon  nanotube/polymer composite. the effects of an interphase layer between the nan...

Prior static studies of three-dimensionally woven carbon/epoxy textile composites show that large interlaminar normal and shear strains occur as a result of layer waviness under static compression loading. This study addresses the dynamic response of 3D through-thickness angle interlock textile composites, and how interaction between different layer waviness influences the modal frequencies. Th...

Abstract Automated Fiber Placement (AFP) process is widely used to produce lightweight composite components owing its excellent flexibility and efficiency. However, the out-of-plane fiber waviness induced by gaps overlaps inevitably formed in AFP lack experimental studies. Therefore, an research proposed study influence mechanism of waviness. Herein, based on description shape waviness, relatio...

Purpose Second harmonic generation signals (SHG) are emitted preferentially from collagenous tissue structures and have been used to evaluate photochemically-induced (CXL) crosslinking changes in the cornea. Since therapeutic tissue crosslinking (TXL) using sodium hydroxymethylglycinate (SMG) of the sclera is a potential treatment for high myopia, we explored the use of SHG microscopy to evalua...