Internal geometry of structurally stitched NCF preforms

Internal geometry of a textile reinforcement is an important factor of the reinforcement performance during the composite manufacturing and service life. In this article, generalized geometrical models of structural stitching loops are presented for the sewing, tufting, and dual-needle stitching methods. The term 'structural' presumes here that the stitching yarn does not only consolidate the plies (as the non-structural one does) but forms also a through-the-thickness (3D) reinforcement. The models account for the general features of the yarn loop geometry and are believed to allow for enough precise modelling on the meso-scale (textile unit cell) level. The modelling approach is validated with experimental data

Damage in textile laminates of various inter-ply shift

Deformation mechanisms and failure of textile laminates are strongly affected by inter-layer configurations – a mutual shift of the plies. To model it within a traditional framework, one must construct a representative volume element (RVE), which includes all the plies. This is a time consuming and computationally expensive work. As an alternative, the paper suggests boundary conditions (BC) imitating the interaction with the surrounding non-periodic media. This makes possible analysis on a single unit cell of one ply. The proposed BC respect inter-ply configurations, account for the number of plies, distinguish the ply position, and reproduce the meso stress state with a good accuracy. The BC are constructed through (1) averaging of the known periodic solutions with respect to the ply shifts, (2) separation of the solution to the outer and inner ply cases, (3) energy equilibrium of heterogeneous and effective media. The unit cell finite element (FE) modelling is validated by reference full scale solution on the entire laminate

Fibre distribution inside yarns of textile composite: gemetrical and FE modelling

This article addresses the experimental investigation and modelling of the uneven fibre distribution inside yarns of a textile composite. The test data is given for the tri-axial carbon-fibre braid; a considerable irregularity is revealed for the fibre distribution along and across the yarns. The importance of this effect for the damage resistance is illustrated with a simple finite-element (FE) model. The geometrical modelling of the internal geometry is also discussed

FE modelling of a structurally stitched multilayer composite

Finite-element models are presented for a typical structurally stitched carbonfibre composite. The term 'structural' means that the stitching yarn is thick enough to form a through-the-thickness reinforcement. The influences of different model features are revealed. The stitching, on the one hand, is shown to increase the stiffness, especially its out-plane component. On the other hand, it creates prominent stress-strain concentrators

A statistical treatment of the loss of stiffness during cyclic loading for short fiber reinforced injection molded composites

Injection molded short fiber reinforced composites (SFRC) have different local fiber orientation distribution (FOD) at every point. SN curves of short fiber reinforced composites are known to depend on the fiber orientation distribution. Such materials also suffer from continuous loss of stiffness during cyclic loading. It is not known whether the loss of stiffness is different for SFRC with different FOD. A statistical analysis of the loss of stiffness curves is presented in this paper. Tension-tension fatigue experiments are performed and loss of stiffness is collected for every data point in the SN curve. A systematic method for comparing the loss of stiffness is developed. It is concluded that the difference in loss of stiffness curves for coupons of SFRC with different FOD is not statistically significant. (C) 2016 Elsevier Ltd. All rights reserved

Crossing geographical, legal and moral boundaries: the Belgian cigarette black market

Objectives: To describe and analyse the cigarette smuggling trade in Belgium and its role in the international cigarette black market. Design: Analysis of Belgian customs and prosecution files concerning the cigarette smuggling trade in the period 2000 to 2006 and interviews with law enforcement authorities and private tobacco industry. Results: Analyses were made of the geographical aspects, the modus operandi and the participants of the cigarette smuggling trade in Belgium. Belgium is mainly a transit country. The cigarettes are transported via the fine-meshed Belgian highway network to the UK, which is often the destination country of the cigarettes. China is the most popular country of origin, especially for counterfeited cigarettes. In order to transport the cigarettes often use was made of legal transport companies and warehouses were frequently used to store the cigarettes. Many of the persons involved in the Belgian cigarette smuggling trade are strongly connected to legitimate business activities. Conclusions: Belgium is an important transit country for cigarette smuggling to the UK. This study pictures the illicit tobacco trade as a complex, ambiguous phenomenon involving several legal and illegal participants whereby the transit of cigarettes across the licit/illicit divide is paralleled by the moral careers of those who smuggle them, not to mention those who consume them. From the legal world to the illegal and back again, this trade and its practitioners and customers blur the line between criminality and non- criminality. Dealing with this phenomenon therefore requires more than a strategy focusing on these lawbreakers alone