Composites manufacturing: materials, product, and process engineering , Composites manufacturing: materials, product, and process engineering , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Composites Manufacturing: Materials, Product, and Process Engineering

Emerging trends in manufacturing such as light weighting, increased performance and functionality increases the use of multi-material, hybrid structures and thus the need for joining of dissimilar materials. The properties of the different materials are jointly utilised to achieve product performance. The joining processes can, on the other hand be challenging due to the same different properties. This paper reviews and summarizes state of the art research in joining dissimilar materials. Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes. Methods for process selection are described and future challenges for research on joining dissimilar materials are summarized.

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Joining of dissimilar materials

A large variety of plate theories are described and assessed in the present work to evaluate the bending and vibration of sandwich structures. A brief survey of available works is first given. Such a survey includes significant review papers and latest developments on sandwich structure modelings. The kinematics of classical, higher order, zigzag, layerwise, and mixed theories is described. An exhaustive numerical assessment of the whole theories is provided in the case of closed form solutions of simply supported panels made of orthotropic layers. Reference is made to the unified formulation that has recently been introduced by the first author for a plate/shell analysis. Attention has been given to displacements, stresses (both in-plane and out-of-plane components), and the free vibration response. Only simply supported orthotropic panels loaded by a transverse distribution of bisinusoidal pressure have been analyzed. Five benchmark problems are treated. The accuracy of the plate theories is established with respect to the length-to-thickness-ratio (LTR) geometrical parameters and to the face-to-core-stiffness-ratio (FCSR) mechanical parameters. Two main sources of error are outlined, which are related to LTR and FCSR, respectively. It has been concluded that higher order theories (HOTs) can be conveniently used to reduce the error due to LTR in thick plate cases. But HOTs are not effective in increasing the accuracy of the classical theory analysis whenever the error is caused by increasing FCSR values; layerwise analysis becomes mandatory in this case.

A Survey With Numerical Assessment of Classical and Refined Theories for the Analysis of Sandwich Plates

The increased usage of fiber reinforced polymer composites in load bearing applications requires a detailed understanding of the process induced residual stresses and their effect on the shape distortions. This is utmost necessary in order to have more reliable composite manufacturing since the residual stresses alter the internal stress level of the composite part during the service life and the residual shape distortions may lead to not meeting the desired geometrical tolerances. The occurrence of residual stresses during the manufacturing process inherently contains diverse interactions between the involved physical phenomena mainly related to material flow, heat transfer and polymerization or crystallization. Development of numerical process models is required for virtual design and optimization of the composite manufacturing process which avoids the expensive trial-and-error based approaches. The process models as well as applications focusing on the prediction of residual stresses and shape distortions taking place in composite manufacturing are discussed in this study. The applications on both thermoset and thermoplastic based composites are reviewed in detail.

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A Review on the Mechanical Modeling of Composite Manufacturing Processes

A method is proposed for simulating the dynamic behavior of rigid and flexible fibers in a flow field. The fiber is regarded as made up of spheres that are lined up and bonded to each neighbor. Each pair of bonded spheres can stretch, bend, and twist, by changing bond distance, bond angle, and torsion angle between spheres, respectively. The strength of bonding, or flexibility of the fiber model, is defined by three parameters of stretching, bending, and twisting constants. By altering these parameters, the property of the fiber model can be changed to be rigid to flexible. The motion of the fiber model in a flow field is determined by solving the translational and rotational equations for individual spheres under the hydrodynamic force and torque exerting on. This method was applied to simulate rotational motions with and without bending deformation of the fiber in a simple shear flow under the conditions of infinitely dilute system, no hydrodynamic interaction and low Reynolds number of a particle. For the rigid fiber, the computed period of rotation and the computed distribution of orientation angle agree with those calculated by Jeffery’s equation with an equivalent ellipsoidal aspect ratio. For the flexible fiber, the period of rotation decreases rapidly with the growth of bending deformation of the fiber and rotation orbits deviate from a circular one of the rigid fiber. These tendencies are similar to experimental ones described by Forgacs and Mason. These results show that the proposed method using bonded spheres’ model can reproduce the dynamic behavior of rigid and flexible fibers in a flow field successfully.

A method for dynamic simulation of rigid and flexible fibers in a flow field

A numerical technique is developed to determine the three-dimensional fiber orientation in complex flows. The fiber orientation state is specified in terms of orientation tensors, which are used in several constitutive models. This method is applied to quasi-steady state Hele-Shaw flows in order to predict the flow-induced fiber orientation during injection molding at zero volume fraction limit. At the inlet, a number of fibers are introduced at a specified rate into the flow and each fiber location is traced during the mold filling. Along these determined paths, the independent components of fourth order orientation tensors are solved, describing the orientation state. The numerical grid generation technique, which is suitable for complex mold shapes, is employed for the flow solution. Orientation ellipsoids are calculated from the second order tensors and are used to present the fiber orientation results. The numerical solutions are obtained for channel and converging flows. Planar, longitudinal, and transverse orientation results are generated from the orthogonal projections of the orientation ellipsoids.

Numerical prediction of three-dimensional fiber orientation in Hele-Shaw flows

This paper presents analytical and numerical thermal analysis for melting and consolidating impregnated composite tapes in the presence of a localized heat source. This analysis also leads to the prediction of the processing window for a given tape-laying configuration. Heat of melting/solidification is included in the form of a heat generation term. A separation of variables method is employed to solve the governing equations ana lytically. In the numerical analysis, the governing equations are discretized using a non uniform mesh and are solved using a finite difference approach. The processing parame ters, such as consolidation speed, heat intensity, heat source width, etc., as well as material properties are incorporated within the analysis. The results show large thermal gradients in the vicinity of the consolidation point. The error between the analytical solu tion and the numerical result is found to be 3 % for the maximum temperature, and the maximum error for the temperature over the entire domai...

Thermal Analysis of in-situ Thermoplastic Composite Tape Laying

A numerical investigation into the area of resin impregnation during the manufacturing of composite materials is undertaken using a macroscopic flow through porous media ap proach. This study is specifically directed at modeling the resin transfer molding and resin film stacking advanced composite manufacturing processes. Quasi-steady state isothermal flow is assumed and a two-dimensional Darcy Law based stream function formulation is utilized. The resultant single governing equation for each quasi-steady timestep is solved along with proper boundary conditions using the method of boundary-fitted coordinate systems encompassing numerical grid generation. The resultant code is validated by a comparison with previously published results for flow into a rectangular mold with a point source and a line sink. Streamlines, pressure distributions, velocity profiles, and temporal liquid free surface positions are then presented for the flow into a mold of general irregular geometry encasing both isotropic and anis...

Resin Impregnation During the Manufacturing of Composite Materials Subject to Prescribed Injection Rate

An experimental investigation of a novel approach for manufacturing of thermoplastic matrix composites, is described. The technique is based on using laser energy as the focused heat source to melt the matrix material for subsequent consolidation, and appears to be particularly suited for thermoplastic filament winding operations. An experimental set up is defined to produce multi ply rings, and the feasibility of this technique is demon strated by discussing several samples that were produced using Ryton AC40-60 prepreg tapes. The quality of consolidation is examined through cross-sectional micrographs.

Experimental Investigation of Laser-Assisted Thermoplastic Tape Consolidation

The laser-assisted consolidation process is a novel technology to produce thermoplastic composite parts of excellent quality and structural integrity. It combines the advantages of the traditional thermosetting filament winding technology with the faster processing times of thermoplastic composites in using automated tape laying processes based on on-line consolidation of the prepreg tape with the substrate The maximum sur face temperature and the time that the resin remains above the melt temperature are critical factors in determining the consolidation quality of the part. A thermal analysis of the fila ment winding process utilizing a CO2 laser beam is presented. Comparison of experimen tal process temperatures, measured using very fast response thermocouples, with tempera tures computed using a heat transfer model proposed by Beyeler and Guceri, suggests that only 20% of the laser energy is absorbed by the composite material in the process con figuration used in these experiments. It is hypothesized t...

Selçuk I. Güçeri

Papers

Numerical prediction of three-dimensional fiber orientation in Hele-Shaw flows

Thermal Analysis of in-situ Thermoplastic Composite Tape Laying

Resin Impregnation During the Manufacturing of Composite Materials Subject to Prescribed Injection Rate

Experimental Investigation of Laser-Assisted Thermoplastic Tape Consolidation

Thermal Characterization of the Laser-Assisted Consolidation Process