SPE Library
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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Conference Proceedings
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.
A NEW NON-CONVENTIONAL CONCEPT FOR DESIGN OF SHEET EXTRUSION DIES
A new non-conventional die design for extrusion of plastic sheet is introduced. Instead of using a conventional sheet die design, such as the coat-hanger, or fishtail design, a completely non-conventional innovative die geometry was developed to achieve a highly uniform velocity distribution at the die exit (die balancing). While balancing the flow at the die exit, with the new die concept, the pressure drop in the die was reduced to about 29% of the original value, and the sharkskin instability was also eliminated from the extrusion process.
PROFILE EXTRUSION COOLING PROCESS OPTIMIZATION VIA SIMULATION
This paper deals with the optimization of the cooling process in profile extrusion through the use of simulation and its application on a real process. Firstly, it will be shown how the simulation is calibrated" with respect to the heat transfer conditions in the different parts of the cooling process to get realistic results. This leads to the development of a novel simulation approach for hollow profiles. It will also be shown how the improved understanding of the cooling was applied towards improving the process productivity."
POSS DISPERSANTS AND FLOW AIDS FOR HIGH TEMPERATURE THERMOPLASTICS
Polyhedral Oligomeric Silsesquioxanes (POSS) were tested as processing aids and dispersants in polyetheretherketone (PEEK). Up to a 500% increase in melt flow index was observed in neat PEEK with no noticeable change in mechanical properties. POSS silanols were used as filler dispersants and showed effects similar to stearic acid but with much greater thermal stability. Thermal analysis showed that POSS is stable up to 400 ?øC. These attributes compare favorably to commercial surfactants, which cannot survive similar processing temperatures.
MODELING THE FUTURE: MANAGING THE TOOLS THAT ENABLE INNOVATION
As the global economy evolves toward an increasingly complex future, businesses are searching for a strategy toensure long-term stability. The best strategy, in many cases, may simply be to learn how to change faster than the world changes around you ' to innovate faster than your competitors. To succeed at this, companies need to make effective choices on where to invest scarce resources. Good tools lead to good results, good decisions, and compelling products. So what defines a good tool?
THE DEVELOPMENT OF INTERNAL WATER COOLING TECHNIQUES FOR THE ROTATIONAL MOULDING PROCESS
This paper reports the findings from internal mould cooling trials using a water spray configuration applied at various internal mould air temperatures from 120?§C to 180?§C for an aluminium mould. To achieve maximum benefit in terms of cycle time reduction, internal mould water cooling was used in conjunction with a combination of external forced air and water cooling. Savings in cooling times of up to 30% were achieved compared to conventional external only forced air cooling.
NOVEL DESIGN METHODOLOGY FOR PLASTIC GEARS
This paper presents a unique methodology for designing plastic gears to enhance strength and life while allowing size and wear reduction. This new approach, trade named Direct Gear Design (DGD), optimizes the gear geometry to impart superior drive performance versus traditional gear design methods. This paper explains this alternative approach and demonstrates its effectiveness for plastic gear applications.
MICROSTRUCTURAL STUDY OF GRAPHITE FILLED POLYETHYLENE TEREPHTHALATE NANOCOMPOSITES
Nanographite (NG) produced from milling by high pressure homogenisation was compounded in a Twin Screw Extruder with Polyethylene Terephthalate (PET). The resultant PET-NG pellets, produced in a variety of compositions (0-2% w/w) were subjected to Rheology, DSC, Electrical Resistivity and Tensile Analysis. No nucleation of the PET was noted even at low concentrations - 0.1%w/w NG. Viscosity of the blends was increased with addition of NG thus allowing for greater continuity of the fibres spun at the faster haul off rate.
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