The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
This paper describes a mesoscopic approach of using beam and shell finite elements to model the forming of composite parts using an SMC woven fabric. Nonlinear constitutive models are implemented in ABAQUS/Explicit via user-defined material subroutines to describe the shear and tensile mechanical behavior of the woven fabric. Both single-ply and multiple-ply layups are modeled.
Saturated- and unsaturated-polyester resins containing glycols made from renewable or recycled sources are being developed as a way to become less dependent on petroleum-based glycols. In this study SMC performance of standard-density Class A automotive SMC containing polyester resins produced from petroleum-based glycols was compared to standard-density Class A automotive SMC containing polyester resins produced from renewable-source glycols. The evaluation included processing aesthetics and adhesion performance. Finally a new low-density Class A automotive SMC containing polyester resins produced from renewable-source glycols will be introduced.
Research on the use of soybeans to produce polyurethane polyols unsaturated polyester resins and thermoplastic fibers has been funded by the United Soybean Board (USB). The USB funds a wide range of activities including research and development of new industrial products made from soy. These developments have resulted in new patented technology. Commercialization of this technology has resulted in the production of unsaturated-polyester resins for fiberglass-reinforced composites and urethane polyols for polyurethane foams. The commercial applications of these bio-based polymers are found in a wide range of applications in the transportation markets.
In order to advance the commercialization of natural fiber reinforced plastics for automotive use a partnership was formed between academia natural fiber processor material supplier and OEM. This partnership improved the communication along the supply chain and resulted in optimized material properties to meet OEM specifications and application part performance. Several products have been developed that meet current material specifications offer significant weight savings over conventional mineral- and glass-reinforced composites and are competitively priced.
External trends have continued to drive end users in consumer and industrial applications to seek renewably sourced and sustainable solutions to use in more and more demanding applications. To meet this need a portfolio of renewably sourced engineering materials was developed. The products are designed to provide performance and functionality equivalent to or better than today’s petroleumbased materials while reducing the environmental footprint. The portfolio includes glass-reinforced thermoplastic grades for high strength and stiffness.
A unique approach to toughening thermosets has been identified by introducing small amounts of amphiphilic block copolymer. The result is a good viscosity-Tg-toughness balance. In this work the fracture behavior of these modified epoxies was carefully studied in an attempt to understand the toughening mechanisms that exist. The findings suggest that cavitation in even these nano-sized spherical micelles is the primary mechanism of toughening. These findings were also found to be a strong function of the cross-link density of the host network with higher levels of plastic deformation at the crack tip being observed in the low-cross-link density systems. Glass-fiber-reinforced composites made with epoxies modified with these toughening agents were found to have improved fatigue resistance.
In today’s environment there is an ever-increasing desire to ‘circle the square’ reaching high-performance durability light weight and manufacturing flexibility without increasing and even trying to lower overall system costs. This presentation will discuss a new enabling technology platform engineered towards these ends: cross-linked thermoset acrylics. These are non-flammable zero-emission systems that contain no volatile or hazardous components at any stage of their life cycle. They are easy to use in molding processes and ideally suited for today’s ‘greener’ lightweight automotive composites. Their application in natural fiber composites will also be outlined in the presentation.
The direct process of producing long-fiber-reinforced thermoplastics (LFT-D) is highly innovative and economical for producing semi-structural and structural components as well as cosmetic parts with grained surfaces. The advanced plastic-hybrid developments with tailored LFT and E-LFT technologies fulfill crashworthiness requirements. Similiarly the direct processing of fiber-reinforced thermosetting materials – direct strand molding compound (D-SMC) – is focused on the reproducible manufacturing of the compound resulting in a constant part production at a high level minimizing material costs and expensive post-mold operations and paint processes as well as reducing logistical costs. The high flexibility in composing the recipe in selecting the resins fillers and reinforcements result in the high degree of freedom of this process.
Joining is often one of the critical steps in the fabrication of composite products. However the low polarity and inert characteristics of polypropylene composite surfaces cause many problems in the assembly of these composites with dissimilar materials. In order to overcome the adhesion issues an epoxy-based primer was developed and the compatibility of several commercial adhesives with the primer was evaluated. Results showed very-good lap-shear strength of up to 15 MPa with substrate failure. The performance of the primer was also evaluated between -30 and 80°C and after conditioning in humidity. While lapshear strength decreased with increasing temperature it remained unchanged after conditioning. Finally different practical approaches to apply the primer film to a polypropylene continuous-fiber composite were investigated including techniques to apply the primer during and after composite consolidation.
The moulding system FIBRETEMP describes a procedure to heat moulding surfaces efficiently with a consistent distribution of temperature. The heart of this invention the use of carbon fibres to conduct electricity as well as integrating the heating element and the structure within the surface to be heated. These moulds are highly energyefficient and extraordinarily dimensionally stable while also being produced at low cost. This technology has already been proven in manufacturing composite parts and has nearly halved cycle time for some applications due to its efficient heating characteristics.
The relationship between the resin and fiber properties in polypropylene long fiber thermoplastics is further analyzed in the second part of this work. The properties of the maleic anhydride grafted polypropylene additives (coupling agents) are studied and correlations between the maleic anhydride content melt flow and base polymer used is presented. Polypropylene long fiber thermoplastics pellets were compounded with various coupling agents. The materials were then molded and tested. The results of the study are presented.
While numerous advances have been made in the manufacturing methods of long-fiber thermoplastics (LFTs) their dynamic response in terms of fatigue and vibration damping has been a subject of limited study. There is presently no standardized design information for a composites / automotive designer for use of LFTs in situations of longterm fatigue and vibration. The behavior of E-glass fiber / polypropylene LFT composites has been characterized for their fatigue behavior and vibration response in the present study. The work provides an understanding of the influence of extrusion / compression-molded long fibers and the fiber orientation that is generated during their processing. Results will be useful to designers in accounting for fatigue life and damping factors.
The deterioration of macroeconomic conditions has severely impacted automotive production and the autoplastics supply chain. Thermoplastic composites – especially long-glass-fiber versions – will benefit from these conditions via the development and implementation of new resin and compound technology as well as advances in fabrication technology adapted to the requirements of a new automotive paradigm and new applications. Our outlook is for gains in high-performance long-glass (and other fiber) reinforced-PP compounds in competition with shortglass and mineral-filled compounds.
For over 50 years the auto industry has been gradually replacing steel with plastics and molded composites. Substantial progress has been made particularly in applications where significant parts consolidation is possible using composites. The need is greater than ever for further substitution of composites for steel but large performance gaps between steel and composites limit the rate of progress. Current gap factors include: stiffness and strength molding thickness process cycle time ability to weld to steel and cost. This presentation will address approaches for eliminating each of these gap elements for non-appearance parts using a systems approach based on new thermoplastic composite technologies.
Composite parts made from long-fibre-reinforced thermoplastic (LFT) material systems are known for their high impact and tensile strength. And due to the benefits of the outstanding price to performance relationship of the in-line compounded (ILC) direct-LFT (LFT-D) technology used for production of composites based on the use of polypropylene and glass fibres it has achieved consistently more applications in the automotive industry. But LFT-based automotive applications are mainly used for parts with large surfaces which can contribute significantly to the total amount of VOCs and odor inside a car. The current work explains a feasible approach of using commercial additives – provided as a complete system – in combination with VOC- and odor-reducing additives to further enhance the mechanical and outgasing properties of the PP / GF composites produced by LFT-D / ILC technology.
Fast and cost-efficient design of higher quality lighter and more energy efficient vehicles is one of the key success factors for today’s automotive industry. Predictive CAE and the use of composites materials offering good weight to mechanical-performance ratio are two ingredients that will help the industry moving forward profitably. We will introduce the DIGIMAT nonlinear micromechanical-modeling technology which can be used to predict the nonlinear behavior and failure of multi-phase materials based on their underlying microstructure (e.g. fiber content fiber orientation fiber length etc.). The multi-scale material-modeling process used to model the reinforced plastic part will then be presented.
An integrated approach linking process to structural modeling has been developed to predict the nonlinear stress-strain responses and damage accumulations in injection-molded long-fiber thermoplastics (LFTs). The approach uses Autodesk® Moldflow® Plastics Insight’s fiber orientation results predicted by a new fiber-orientation model developed for LFTs and maps these results to an ABAQUS® finite-element mesh for damage analyses using a new damage model for LFTs. The damage model which has been implemented in ABAQUS via user-subroutines combines micromechanical modeling with a continuum damagemechanics description to predict the nonlinear behavior of LFTs due to plasticity coupled with damage. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses.
Dielectric cure monitoring has been used in thermoset laboratories for decades to characterize materials. Historically attempts to take the technology to the production floor where the benefits can be maximized in production tools have failed due to shortcomings in sensor durability and system reliability. Breakthroughs in dielectric sensor design have resulted in the development of durable in-mold sensors that can operate on the production floor. Thermoset molders can now “see” changes in flow and cure inside their production tools allowing automatic “real-time” adjustments for process variation and enabling significant gains in productivity and quality. Benefits to compression and injection molders include: 10-25% reductions in cycle time improvements in quality and reduction of scrap and a better understanding of flow and cure rates inside the mold.
Often times a composite component can be used to replace a metallic component providing a significant reduction in weight while providing little or no loss in strength or stiffness. For automotive engineers to further utilize composites in new applications it is important to understand the mechanical behavior of the material in all the critical loading directions. This paper focuses on the relevant tests necessary to characterize the mechanical properties of a pultruded carbon fiber composite material. The mechanical properties evaluated include tension compression interlaminar shear and fatigue testing in the fiber direction. Included is a discussion on key aspects of the testing in order to ensure reliable results. Also a set of design criteria is developed for the use of the material according to the measured properties.
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Brown, H. L. and Jones, D. H. 2016, May.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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