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Pointe-Claire, Canada

Alemi-Ardakani M.,University of British Columbia | Milani A.S.,University of British Columbia | Yannacopoulos S.,University of British Columbia | Borazghi H.,AS Composite Inc.
International Journal of Impact Engineering | Year: 2015

Abstract Taguchi design of experiments is a much known statistical method for cost/time reduction during experimental investigation and quality engineering of complex systems and processes. In the present article, efficiency, accuracy, strengths and limitations of this method in predicting and discretely optimizing impact response of FRP composites have been studied through a case study on polypropylene/E-glass laminates with unidirectional, plain, and twill weave architectures. In parallel, drop weight impact tests, X-ray micro-tomography, and pre- and post-impact four-point flexural testing are employed for two purposes: (a) gaining further knowledge on induced impact damage mechanisms, and (b) further assessment and verification of the Taguchi results. In spite of the fact that impact events of the FRP laminates are highly nonlinear and accompany high level of uncertainty, it was found that this design of experiments method is capable of predicting and maximizing the absorbed impact energy with a reduced number of runs and reasonable error. Finally, by correlating macro-level predictions to micro-level damage observations via X-ray tomography, the underlying assumptions of the method were further scrutinized, and in particular it was found that the plies interaction effect is not a limiting factor in predicting the total absorbed energy of the laminates. Overall, the experimental time/cost saving in the performed impact optimization case study was over 50% using the Taguchi L9 orthogonal array. © 2015 Elsevier Ltd.

Azad M.,Concordia University at Montreal | Hojjati M.,Concordia University at Montreal | Borazghi H.,AS Composite Inc.
Proceedings of the American Society for Composites - 30th Technical Conference, ACS 2015 | Year: 2015

Using a chemical foaming agent (CFA) along with a thermoplastic polymer in a foam extrusion process has a significant effect on the density and thickness of the final product so that highly light-weight and low-cost structures could be achieved. In this experimental study we have investigated the thermal and chemical behavior of two different types of CFA and their effect on the foam quality and physical/mechanical properties of the final product in an extrusion foaming process. A polypropylene-based thermoplastic (PP) sheet was produced via a plastic extrusion machine with 12″ width and 4mm thickness. An exothermic foaming agent Azodicarbonamide (EV AZ-3.0) was added into the PP pellets in 5 wt%. They were completely mixed and melted inside the extruder to decompose and liberate gas. The melt temperature and pressure must be high enough to guarantee a total decomposition of the foaming agent and make the generated gas dissolved inside the polymer melt until it exits from the die opening. The same trial was conducted with an endothermic CFA named Styrene-Ethylene/Butylene-Styrene (PN-40E). Our thermal TGA analysis and physical tests demonstrate that each of the foaming agents has its own unique specifications which could be utilized based on the operating temperature and pressure. However, using the exothermic CFA is recommended for the PP-based thermoplastic foams as it can build up the product with low weight and high specific stiffness. Copyright © 2015 by DEStech Publications, Inc. and American Society for Composites. All rights reserved.

Alemi-Ardakani M.,University of British Columbia | Milani A.S.,University of British Columbia | Yannacopoulos S.,University of British Columbia | Shokouhi G.,AS Composite Inc.
Materials Today Communications | Year: 2015

The use of fiber reinforced polymers (FRPs) is rapidly increasing in air, land, and marine manufacturing sectors. This is despite the fact that a universal methodology has not been yet developed to assist designers in selecting optimum reinforcing fiber architectures under different loading scenarios. The focus of the present article is to recommend a systematic approach for selecting the architecture of long-fiber fabric reinforcements in FRP composite structures under impact events. Namely, nine design criteria were selected and quantified for four types of PP/glass laminates through drop tower impact testing under 200. J energy, four-point flexural bending before and after impact, as well as microtomographic damage analysis of impacted samples. Subsequently, ranking of the candidate laminates was found using a multiple criteria decision making (MCDM) technique to aid in selecting the overall best performing fiber reinforcement option under the presence of conflicting and inter-dependent design attributes. © 2015 Elsevier Ltd.

Lynam C.,University of British Columbia | Milani A.S.,University of British Columbia | Trudel-Boucher D.,Industrial Materials Institute of Canada | Borazghi H.,AS Composite Inc.
Journal of Composite Materials | Year: 2014

Thermal deformations that occur during formation of long-fiber-reinforced composites have been a continued challenge for manufacturers as the final shape of a given part can be different from the original mold shape. The ensuing dimensional distortions can be difficult to predict due to complex thermo-mechanical behaviour of composite laminates during different forming cycles. This study intends to model the fundamental mechanisms that lead to thermal deformations during forming of a thermoplastic matrix composite comprised of comingled polypropylene and E-glass fibers. While the discussion is framed around a custom-design multi-stage roll-forming process, it is also relevant to a wider range of thermoplastic composites manufacturing processes. A methodology is developed to characterize the thermal mechanical behavior of the material, optimize the manufacturing process, and predict the magnitude of resulting spring-in angle due to thermal deformations. It is found that the process control parameters can be optimized first such that the crystallization of the matrix occurs at an ideal position along the forming line. Once the process is optimized, the developed numerical model, with a thermoelastic material behaviour, can give an adequate prediction of spring-in at the end of the process. Finally, through a comparative study, it is discussed how for other manufacturing processes, such as compression molding, including a thermoviscoelastic liquid/solid material behaviour may be required to yield accurate spring-in predictions. © The Author(s) 2013.

Schuetze D.D.C.,University of British Columbia | Gordnian K.,University of British Columbia | Milani A.S.,University of British Columbia | Poursartip A.,University of British Columbia | And 2 more authors.
International SAMPE Technical Conference | Year: 2013

Thermal profile during the forming processes of polymer matrix composites is known to have a significant effect on the associated, often undesired, deformations such as spring-in or spring forward in the finished products. This article discusses comprehensive heat transfer finite element modeling of a multi-stage roll forming process on a typical thermoplastic composite, in order to assist in predicting and adjusting the thermal profile of the material along the forming line, and therefore controlling the dimensional distortion of the finished curved part. Copyright 2013 by Aurora Flight Sciences.

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