463 research outputs found
Supplementary_Figure_and_Table - Process- and material-induced heterogeneities in recycled thermoplastic composites
No full textSupplementary_Figure_and_Table for Process- and material-induced heterogeneities in recycled thermoplastic composites by Guillaume A Vincent, Thomas A de Bruijn, Sebastiaan Wijskamp, Martin van Drongelen and Remko Akkerman in Journal of Thermoplastic Composite Materials</p
JCM884101 Supplemetal Material - Supplemental material for Temperature variation during continuous laser-assisted adjacent hoop winding of type-IV pressure vessels: An experimental analysis
No full textSupplemental material, JCM884101 Supplemetal Material for Temperature variation during continuous laser-assisted adjacent hoop winding of type-IV pressure vessels: An experimental analysis by Amin Zaami, Martin Schäkel, Ismet Baran, Ton C Bor, Henning Janssen and Remko Akkerman in Journal of Composite Materials</p
Computational analysis of the interaction between impregnation, forming and curing in pultrusion
Full text linkNumerical and analytical models dealing with different physics involved in pultrusion are combined in the optic of an integrated analysis of the process. The impregnation stage is simulated by means of a CFD multiphase model, evaluating the pressure and velocity field in the liquid resin. Composite temperature and degree of cure are inferred using 3D thermo-chemical models. Finally, contact conditions, stresses and strains are derived applying computational simulation and analytical models, in order to predict the final pulling force. Different product sizes are considered, simulating suitable processing condition
The Effect of Product Size on the Pulling Force in Pultrusion
Full text linkIn the present work, pultrusion of a composite rod is simulated for various part thicknesses using the finite element method. The pultrusion process set-up is taken from literature in which the temperature and the degree of cure evolutions inside the rod were measured. The predicted temperature and degree of cure profiles in the three dimensional (3D) thermo-chemical analysis are found to agree well with the measured data. The contact pressure between the part and the heating die is calculated using a mechanical contact formulation in the 2D mechanical process model for 9 different part thickness values. Using the contact pressure distribution along the die, the process induced pulling force is predicted. For the simulated cases, a non-linear relation is found between the total force and the product size.<br/
Spring forward of woven fabric reinforced composites
Full text linkContinuous-fibre-reinforced plastic products are usually formed at elevated temperatures. They exhibit distortions when they are cooled to room temperature and released from the mould. For example, the enclosed angle of an L-shaped product decreases, see Fig. 1. This effect is known as spring-forward. It is mainly due to the anisotropic thermal shrinkage of the composite, which is small in the fibre direction and relatively large in the direction normal to the fibres. The costs of forming a product with the demanded dimensions by trial and error are high. To reduce these costs, the objective of the research described in this paper is to develop a model, which predicts the occurring distortions
Thermoforming of foam sheet
Full text linkThermoforming is a widely used process for the manufacture of foam sheet products. Polystyrene foam food trays for instance can be produced by first heating the thermoplastic foam sheet, causing the gas contained to build up pressure and expand, after which a vacuum pressure can be applied to draw the sheet in the required form on the mould. This production method appears to be a very sensitive process with respect to e.g. the sheet temperature, the pressures applied and the cooling time. More problems can be foreseen when for environmental reasons the blowing agent will be adapted (for instance replaced by a gas with a lower molecular weight). To gain more insight in the occuring phenomena the large deformations of a foam structure have been analysed using finite element modelling. To this end a constitutive model has to be defined. Starting from the basic theory given by Gibson & Ashby [1], the behaviour of a closed cubic cell has been elaborated for large strains. The total stiffness is then the sum of the contributions of the edges and faces of the cell and the gas contained in it. The large deformations cause anisotropy of the cells [2], which influences their tangential stiffness. The constitutive model developed here includes the effects of internal gas pressure and the evolving anisotropy
Braiding simulation for RTM preforms (CD-ROM)
Full text linkBraiding is a manufacturing process that is increasingly being used to manufacture pre-forms for Resin Transfer Moulding. A fast simulation method is presented for the prediction of the fibre distribution on complex braided parts and complex kinetic situations (e.g. changes in velocity, orientation). The implementation is suited for triangular surface representations as generated by many CAD software packages in use. Experimental results are presented to validate the model predictions, showing an acceptable correlation with the data predicted by the simulation method. The guide ring dimensions and spacing appear to have a significant effect on the accuracy of the predicted fibre orientations
Thermomechanical properties of woven fabric composites
Full text linkThe in-plane thermo-elastic behaviour of woven fabric reinforced composites is analysed using a combination of published micromechanics and finite element techniques. The repetitive unit of an arbitrary woven fabric composite is divided into elements of which the thermo-elastic properties are determined using micromechanics. The properties of the repetitive unit are obtained using the finite element model. The presented model predicts the laminate stiffness and thermally induced forces and moments, from which the thermal expansion and bending coefficients and the residual deformations of the fabric laminate are derived. The theoretical results are validated by experiments on thermoplastic PEI-carbon and PPS-carbon 5H satin weave fabric laminates
Impact damage in woven fabric reinforced composites
Full text linkVery often, woven fabrics are used as the reinforcement in advanced composite materials. Although the resulting inplane stiffness is lower than of their unidirectional counterparts, the excellent drapability of these materials eases the production of more general doubly curved components. In addition, the inherently low out-of-plane strength of these layered materials improves due to the undulating yarns. This paper considers both the initiation and growth of defects in these woven fabric reinforced plastics. Ten Cate Advanced Composites’ 5H Satin carbon reinforced PPS is taken as the model system. A 5H satin fabric exhibits very good drapability and PPS has a low viscosity above its melting point, enabling good yarn impregnation. Apart from this PPS has approved solvent resistance for aerospace applications and good temperature resistance. For a thermoplastic matrix, however, the material is fairly brittle
Investigation of tool-py friction of viscous textile composites (CD-rom)
Full text linkDynamic tool-ply friction for a thermoplastic viscous textile composite has been measured using a commercial rotational rheometer as a function of rate, temperature and normal pressure. Results of this novel experimental technique have enabled a general empirical equation to be determined relating the dynamic friction force to experimental conditions. The method has been corroborated using an alternative experimental technique. Advantages of using the rheometer include significantly faster production of data and more precise measurement of experimental conditions
- …
