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.
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Long-Fiber Reinforced Thermoplastic LFT-D & Thermosetting D-SMC Processes for Lightweight Parts Production - Trends & Recent Applications
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.
Development of an Adhesive-Primer for Polypropylene Composites
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.
Electrically-Heated Moulds of CRP Composite Materials for Automotive Application
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.
Fatigue & Vibration Response of Long Fiber Reinforced Thermoplastics
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.
Automotive Thermoplastic Composites...Industry Structure & New Technologies Respond to a Global Recession
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.
Structural Thermoplastic Composites: Filling the Gap between Stamped Steel & Molded Composites
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.
Latest in Additive Developments for Long Fibre Reinforced Polymers
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.
Digimat Material eXpert - From the Material Lab to the Efficient & Optimal Design of Reinforced Plastic Parts
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.
Damage Modeling of Injection-Molded Short- & Long-Fiber Thermoplastics
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.
Sensing When the Molding Cycle is Over.... The Key to Productivity & Product Consistency
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.
Engineering Aspects of Designing with Pultruded Carbon-Fiber Composites
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.
Progress in Simulations for Short & Long Glass Fiber Thermoplastic Composites
The development and implementation of lightweight materials using fiber composites made by injection molding represents an engineering challenge due to the inability to control the fiber orientation in the required direction of mechanical demand. This paper presents progress in developing the capability of predicting fiber orientation in simple and complex flow geometries for highly concentrated short-glass-fiber suspensions and the extension of this approach to long-glass-fiber suspensions. Three important aspects included in the approach are the implementation of new theories to model fiber orientation the evaluation of model parameters from rheological experiments and the use of stable numerical methods based on discontinuous Galerkin finite-element method.
Initial Finite Element Analysis of Bond-Line Read-Through in Composite Automotive Body Panels Subject to Elevated Temperature Cure
The Automotive Composites Consortium (ACC) is conducting a multiyear project to develop a better understanding of the root causes of the visual surface deformation effect known as bond-line read-through (BLRT). BLRT is associated with bonded automotive Class A exterior panels and produces out-of-plane deformations on the order of 0.010- 0.050 mm. The ACC is studying the relationship between material and process factors and BLRT severity. The majority of the investigations have focused on SMC composite panels bonded with urethane and epoxy adhesives under elevated-temperature cure conditions and subsequently primed and topcoat painted. An investigation was conducted to see if analytical tools could predict the BLRT effect observed in the physical experiments. The present work describes the initial effort to model the BLRT effect using a finite-element analysis (FEA)-based approach. As part of this effort detailed threedimensional FEA solid models were developed for two idealized panel configurations: (a) an outer panel with an adhesive bead and drops and (b) a bonded outer/inner panel assembly. Results were predicted for the case of an idealized elevated-temperature adhesive cure condition using a steady-state thermo-elastic analysis. The predicted surface curvature results indicated a good qualitative agreement to available measurement data with the analysis over-predicting the BLRT severity.
Progressive Ply Failure Analysis for Composite Structures
Design engineers working with composite materials typically use a linear finite-element-analysis (FEA) solution and a failure-index calculation based on the current state of stress in the model. However this type of analysis can only provide accurate results up to first-ply failure because of the linear assumption. This presentation will show how nonlinear progressive-ply failure analysis can go beyond first-ply failure and simulate subsequent damage propagation through a structure. This allows engineers to make a better assessment of conditions for ultimate failure so they can optimize their designs and also provide guidance on the most appropriate physical-test program.
Analysis of Woven Glass Fiber Reinforced Thermoplastic Composites under Varying Strain Rates
Increased use of polymer matrix composites depend on having a deeper understanding of their mechanical response under varying strain rates. In this study the mechanical behavior of thermoplastic woven composites was investigated under varying strain rates between 5.0 x 10-5 s-1 and 5.0 x 102 s-1 using a screw-driven universal testing machine and an impact testing and imaging apparatus. Results yielded stress vs. strain curves over the full range of loading rates highlighting the strain-rate sensitivity exhibited by the thermoplastic composites. In addition the non-contact strain-measurement system revealed the effect of woven architecture on the mechanical behavior of thermoplastic woven composites.
THERMAL AND ELECTRICAL CONDUCTIVITY OF CARBON/LIQUID CRYSTAL POLYMER COMPOSITES FOR FUEL CELL BIPOLAR PLATES
One emerging market for thermally and electrically conductive resins is for bipolar plates for use in fuel cells. Bipolar plates require high thermal and electrical conductivity. In this study, carbon black and synthetic graphite were added to a liquid crystal polymer and the resulting composites were tested for thermal and electrical conductivity. Single filler composites containing 2.5 to 15 wt% carbon black and 10 to 75 wt% synthetic graphite were tested.
APPLICATIONS AND USES OF BYK-GARDNER HAZE-GARD PLUS
The haze-gard plus is a versatile instrument used to measure transparent characteristics for the plastics industry. From liquid raw materials to transparent films and sheet goods, the haze-gard plus is equipped with hardware to measure all. This paper will discuss the capability of the haze-gard plus and many of its diverse applications. Additionally, this paper will explore trends in data measured by the instrument, and what those data reveal about process.
NANOCOMPOSITE HIERARCHICAL STRUCTURES IN BLAST MITIGATION
Development of new, cost-effective materials with multifunctional characteristics is of critical importance to the aerospace, naval and homeland security industries especially in the areas of blast-ballistic impact mitigation and containment. Research efforts address this need by the use of nanocomposites in the design of hierarchical structures. Experimental data indicate that the vinyl ester nanocomposites of this study have enhanced cost-effectiveness, energy absorption, structural integrity and reduced smoke density characteristics
MODELLING OF MICROMOULDING
Computer modelling of micromoulding faces potential challenges relating to extreme process conditions in accurate descriptions of constitutive behaviour, and various model parameters, including heat transfer and thermal conductivity coefficients. We have some initial studies using in-house code (previously developed for fluid-assisted injection moulding). Progress in the development and application of this code will be discussed, and compared with experimental data from our laboratory, for simple geometry micromoulded components.
NUMERICAL SIMULATION OF ENHANCED MELT MODULATION APPLIED TO INJECTION MOLDING
A new approach to the control of melt modulation during injection molding processes has been investigated using numerical simulation. Based on a new development in melt flow control for cold runner base injection molding, numerical simulations were used to replicate the behavior of a melt flow with multiple control valves incorporated into a single runner system. It is demonstrated that a new control technique in which all valves can be controlled as a function of ram position allows the user to locally determine the amount of flow in each runner section more precisely.
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