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The use of long glass fiber reinforced polypropylene (PP) in injection molded parts has found new applications due to ease of processing attractive economics and good balance of properties. The glass fiber provides mechanical strength and dimensional stability. Part performance is influenced by glass fiber length processing technique and resin formulation including coupling chemistry additives and colorants. The balance of material properties may allow substitution from engineered resins like PC/ABS blends ABS SAN SMA to lower cost resin options like polypropylene. The demonstrated property balance may allow reduction of wall thickness. Applications for long fiber reinforced thermoplastics continue to grow with new automotive applications in development such as front end carriers instrument panels door modules lower and overhead console reinforcements. Dow Automotive has been developing Long Glass Fiber Reinforced Polypropylene systems for various applications including instrument panels and front end systems. Dow has developed a fundamental understanding of the effect of additives and different processing methodologies and their effect on property performance. This paper reviews the mechanical properties for the various LGF processes from fully formulated granulates to direct processes as well as the impact of additives on performance.
Although not a common feature on vehicles originating in the North American market European automakers have been installing underbody closure systems on their passenger vehicles for some time. Starting with small plates intended to protect the engine and gear box these shields have evolved into complete under-floor closure systems offering a number of benefits. First they reduce the vehicles aerodynamic drag which helps improve fuel economy ± vital in a market segment where fuel prices average 0.98 ± 1.56 ¼ /liter ($5-8USD/gal). Second they function much like the protective vinyl coating sprayed on the underside of most North American vehicles to reduce stone impingement salt spray and other damage to the undercarriage. Unlike the spray coatings however the shields also protect the undercarriage on bad roads and for off-road usage. Third they reduce noise ± both inside the cockpit for occupants as well as curb noise as vehicles pass through congested cities with narrow streets. As underbody closure systems have proliferated different materials and process development programs have been commercialized. Each participating OEM has sought to tailor these closure systems to achieve specific combinations of cost performance and mass for the various vehicle segments in which they compete. Although no single material / process option currently meets all OEM needs in all segments 3 technologies±all thermoplastic± have emerged in Europe to dominate underbody closure systems. This paper discusses current material / process options and the kinds of application criteria where each are best suited.
Polylactide (PLA) is a biodegradable compostable thermoplastic polymer produced from corn an annually renewable resource. In moving towards developing a sustainable vehicle use of materials such as PLA could greatly contribute to the goal of a more environmentally friendly vehicle. To date several non-automotive applications of PLA have been commercialized. These include PLA fiber/textile applications for clothing carpeting and linens; as well as blow molded articles for food packaging. Thus far for automotive use a single niche application of compression molded PLA has been developed. Here we seek to optimize the injection molding process conditions and composition of PLA composites for automotive interior applications. The effects of adding various reinforcements to the PLA resin for property improvements were assessed. Crystallinity modulus and strength properties were evaluated by differential scanning calorimetry (DSC) tensile and flexuarl testing.
The preparation of nanoclay-reinforced poly(lactic acid) (PLA) nanocomposites by means of melt processing has been investigated. In order to optimize the dispersion of the nanoclays and the nanoclay-matrix interface strong interaction between the nanoclay and the polymer matrix is required preferably at the atomic level. Different chemistries of the organo-nanoclay have been carefully considered in order to optimize the chemical interaction between the organic and inorganic phases during processing. Various processing conditions have been examined with the aim of minimizing the degradation and oxidation of the materials both the matrix and the organo-nanoclay while at the same time maximizing clay dispersion and the interaction between the polymer matrix and the clay. X-ray diffraction scanning electron microscopy (SEM) transmission electron microscopy (TEM) differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were used to respectively characterize the dispersion of the nanoclay the crystalline structure and the mechanical behavior of the PLA nanocomposites. The relationship between formulation structure and performance is discussed.
The use of renewable materials in commercial products has gained attention over the past several years. Biomaterials can offer significant advantages over conventional materials such as: sustainability reduction of petroleum dependence lighter weight of components and potential lower cost. In our studies we demonstrate the use of soy-derived materials in two primary thermoset applications: sheet molding compounds (SMC) and polyurethane foam. SMC composites were produced using soy resin in place of a portion of the vinyl ester resin to evaluate mechanical performance process capabilities and component performance. In addition composite reinforcements of continuous hemp fiber non-woven hemp mats fiberglass and hybrids (fiberglass/continuous hemp twine mixtures) were examined. Results indicate that the soy resin composites demonstrate equivalent properties to those of the vinyl ester resin composites and are equally able to be molded in to complex geometries. While substitution of glass reinforcement with natural fibers was found to reduce the mechanical performance of the composites hybrid composites of glass and hemp fibers provided promising results. Hydroxylized soy oil has also been used as a polyol in flexible polyurethane foam formulations. Foam formulations have been optimized for mechanical and processing performance. One of the key technical challenges of soy foams are their inherent odor. Two odor reduction methods will be discussed including a novel low odor method to functionalize soybean oil.
Industrial hemp fibre is one of the strongest and stiffest available natural fibres and therefore has great potential in composite materials . Incorporated into a thermoplastic matrix it gives a structural material that is cheap light-weight and recyclable. However natural fibres are commonly incompatible with common moulding thermoplastics such as polypropylene which limits the performance of the composites produced. The main objective of the current work was to investigate the use of fungi to treat hemp fibre to create better bonding characteristics in natural fibre reinforced polypropylene composites. X-ray diffraction (XRD) lignin testing thermal analysis and scanning electron microscopy (SEM) were used to characterise the effect of treatment on hemp fibres. A combined alkali and fungal fibre treatment produced a composite tensile strength of 48.3 MPa representing a 32% increase as well as increased thermal stability compared to composites with untreated fibre.
Industrial hemp fibre reinforced thermoplastic composites are increasingly being used in the automotive industry. These composites are strong stiff lightweight and recyclable but possess mechanical properties well below their potential values. The aim of this research was to improve the composite tensile strength and fibre/ matrix interfacial bond strength by means of fibre treatment and use of a coupling agent. Hemp fibre was digested in a small pressure vessel with either a solution of 10wt% NaOH or 5wt% NaOH/2wt% Na2SO3. Single fibre tensile tests were performed on treated and untreated fibres and it was found that the 5wt% NaOH / 2wt%Na2SO3 treatment produced the strongest fibres with a good level of fibre separation. The treated fibres polypropylene and a maleicanhydride modified polypropylene (MAPP) coupling agent were then compounded in a twin-screw extruder and injection moulded into composite tensile test specimens. Tensile tests revealed that the optimum composite consisted of polypropylene with 40wt% fibre (treated with 5wt% NaOH /2wt%Na2SO3) and 4wt% MAPP and had a tensile strength of 50.5 MPa and Young’s modulus of 5.31 GPa. The effect of MAPP on the interface of 5wt% NaOH / 2wt% Na2 SO3 treated hemp fibre/polypropylene composites was assessed by means of the single fibre fragmentation test. It was found that a MAPP content of 4wt% greatly improved the stress transfer efficiency at the fibre/matrix interface.
In this work natural fiber and wood composites based on neat and recycled polypropylene (PP) were fabricated by melt processing. Different formulations including various reinforcement content different types of coupling agents different types of reactive additives and an impact modifier were developed. The reinforcements were in the form of natural fibers like banana flax rice husk and palm fibers and of wood sawdust. For the long fiber composite systems processing was done by compression molding of piles of long fiber mat and extruded polypropylene film. For the short fiber composite the samples were prepared by extrusion followed by injection molding. The tensile flexural and impact performance were characterized and all composites show superior mechanical properties when compared with the pristine matrix. Mechanical performance of the wood composites was also evaluated before and after conditioning in water for 1 and 7 days. Results indicate that the composites resist to humidity very well. The results also demonstrate the effect of formulations on the performance of the recycled composites.
BMC composites have long been used in automotive applications because of the excellent mechanical properties creep and thermal resistance. Components such as headlamp reflectors engine/valve covers front timing chain covers and small electric motors have benefited from this technology for many years. Recent advances in the formulations have opened up new opportunities in automotive under the hood applications. BMC composite material technology is quickly finding its way into applications that require extremely tight molded dimensions and dimensional stability over a temperature range. Some of these applications include Electronic Throttle Controls (ETC) Air Control Valves (ACV) and transmission components. This paper investigates the critical characteristics of these performance parts and the properties of BMC composite which help make the system work.
Hennecke with its PUR-CSM Technology developed a flexible and efficient production system that has already proven successful in numerous applications. There are now six (6) PUR-CSM variants of the system w hich address various transportation parts¶ m anufacturing needs Multitech multi layered composite construction; Baydur thin walled high strength glass reinforced; Baypreg NF high strength reinforced with natural fibers; Baypreg–high strength/low weight sandwich structure with added fiberglass partial reinforcement capability; Baytec polyurethane spray skin technology; Bayflex filled flexible polyurethane with enhanced properties especially acoustical.
With the increasing amount of onboard electronics and microprocessor-controlled systems on automobiles it is important that the electronic sub-assemblies (ESAs) in a vehicle are designed to be electromagnetically compatible (EMC). Design for electromagnetically compatibility can be achieved in a number of ways including the use of enclosures or housings with shielding capabilities. There are a variety of enclosure design options to provide shielding to help meet EMC requirements including the use of conductive thermoplastic composites that offer intrinsic shielding. This paper will present information on GE Plastics LNP* Faradex* melt process able stainless steel filled thermoplastic composites and their potential for use as electromagnetic shields. Shielding models product performance features along with design and processing information critical to achieving effective shielding will be discussed.
High strength low density glass microspheres have been developed and commercialized for use in injection molded plastic parts and pressed composite structures. This new and innovative 3M TM Performance Additives iM30K product is low in density but has very high compressive strength survivability providing OEM designers and Tier 1 molders new application opportunities. This paper will detail potential application benefits for injection molded plastic parts containing iM30K including lower weight improved thermal expansion properties improved processing and improved dimensional stability (less warpage and sink marks). Addition of these materials will also result in the maintenance of important thermoplastic physical properties.
Today there are three global trends that call for a thermoplastic solution for horizontal body panels (hoods roofs and trunk lids): 1.Vehicle differentiation reducing the average annual production per name plate 2. Higher fuel cost demanding lightweight materials 3. Pedestrian safety regulations being enacted in Europe and Japan Market competition globalization new entrants and increasingly demanding consumers continue to drive automakers to differentiate and segment their portfolios. Over the last twenty years there has been a consistent decrease on average annual production per name plate. Parallel to that the same market forces are also reducing the life of models.
There is a growing trend in the automotive industry to offer more “non-traditional” roof configurations to the consumer. In many cases the non-traditional roof contains glass guides drives and other hardware that increase the cost and weight of the vehicle. Consequently suppliers are being challenged to offer designs that use lightweight materials integrate or eliminate components while maintaining or improving overall structural and dimensional performance of the vehicle. Based on a standard body in white" roof structure the innovative concepts described in this paper use molded polymers and composite materials that allow a vehicle to be fitted with a wide variety of roof “modules” each having customized performance content and value. The modules are designed to integrate components eliminate post painting increasing vehicle rigidity and reduce weight. Conceptual designs illustrated in this paper will include two different vehicle architectures and two different roof module constructions. Three different composite materials will be reviewed for their suitability in the roof module. Detailed section views are included to illustrate important part design features attachment methods performance considerations and general composite “know-how”. The concept’s value proposition is examined in four areas: cost weight safety and assembly. Technical and economic benefits to the value proposition include weight reduction design and styling freedom in-mold features attachment points color options fixed or moveable window design and improved roll-over safety due to the lowered center of gravity. Since the modular roof system starts with a component that is ready to assemble it offers a path forward for the supply chain which enables OEMs to decrease capital expenditures and reduce labor hours required to manufacture a vehicle. The backbone of the value proposition is a recently conducted case study comparing a traditional vehicle to the same vehicle fitted with a composite pol"
When modern saloon cars are re-engineered as roadsters it is typical for them to lose 50% or more of the body's torsional rigidity. Consequently the vehicles rarely handle quite as crisply nor do they ride as well as the coupes from which they derived. This presentation highlights the fundamental contributions of advanced composites in achieving the desired value of handling of the Murcièlago Roadster without penalizing the overall weight of the vehicle. To compensate for the absence of the roof structure the vehicle was strongly redesigned by introducing new structural members and reinforcing existing critical components. A new all-carbon/epoxy composite sub-frame which spans the entire engine bay compartment is comprised of elliptical tubular members and it is the first of its kind in a production vehicle. The paper highlights the fundamental contributions of advanced composites in the production of the body panels and integrated chassis components for the Murcièlago Roadster.
As part of a mass-savings initiative a composite intensive side door project was started at GM R&D. In order to allow more innovation in the design two normally limiting constraints were eliminated. Firstly the Class A requirement for the outer surface was relaxed and secondly labor intensive handcrafting was allowed for the purpose of prototyping. The composite door was constrained to fit the existing door opening and to use carry-over internal hardware. Using stiffness criteria finite element analysis was used to develop a minimum mass design using composite sandwich structures. Preforms were handcrafted from molded foam cores wrapped with a combination of woven and stitch-bonded unidirectional glass.
As part of the design for vehicle crashworthiness energy-absorbing structural elements have been successfully used in every field of transportation and composites have shown great advantages in energy absorbed per unit mass of material. One of the key factors preventing the widespread adoption of composites in primary crash-resistant structures is the absence of specialized test methods for the characterization of specific energy absorption (SEA). A relatively simple and inexpensive method is required to compare candidate material systems laminate designs fiber architectures processing methods to build an adequate property database. This paper reviews a portion of the existing body of literature concerned with the development of crush test methodologies and identifies the areas that require the most attention before being considered for adoption as test methods. The recently formed MIL-HDBK-17 Working Group (WG) on Crashworthiness which comprises representatives from the aerospace and automotive industry academia and government laboratories is presently dedicated to developing suitable test methods. In particular two test methodologies have been identified as the most mature for development and standardization one for plate coupons and the other for tubular specimens. The WG has started to collect and summarize current industry test practices which are many and not currently agreed upon and is already working in conjunction with ASTM Committee D-30 on Composite Materials to lay the foundations of tests standards for composite crashworthiness.
Decoma International Inc. contracted Multimatic to develop a modular Composite Intensive Vehicle (CIV) concept including closures and suspension suitable for production volumes of 50000 units per year. The proposed CIV was required to meet all typical OEM vehicle packaging standards and stiffness and applicable crash safety standards while offering the potential for overall mass reduction and meeting manufacturing cost and volume requirements. The primary structural materials considered in this study were fiberglass composite and metallic materials. The study to develop the CIV Body-In-White (BIW) closures and suspension systems concepts was conducted in 3 phases: (1) Development of the vehicle content requirements vehicle occupant and component package and structural performance targets based on program requirements provided styling surface and vehicle benchmarking. (2) Development of a package-feasible three-dimensional structural CAD concept model for the BIW closures and suspension system. (3) CAE-based structural stiffness optimization and crash performance assessment of the structures developed in (2). The resulting CIV vehicle concept was developed to a level suitable for prototype build detailed manufacturing feasibility verification and mass and cost assessment.
The integrity performance and service time of certain automotive subsystems is adversely affected by moisture ingress into contained environments. Corrosion of air conditioning (AC) system components caused by moisture initially present in the refrigerant and moisture permeated through the seals during the AC unit service life is one example. Another one is water vapor condensation in optical components used for night and rear vision systems as well as optical proximity sensors often causing their malfunction in changing environmental temperature and humidity conditions. Desiccating multiforms attached to a condenser coil have long been used in automotive AC units to absorb the residual moisture and the moisture permeating from outside. The new direction in AC moisture control is the use of sorbent-loaded polymer composites in AC structural parts that eliminate the need for individual desiccating multiforms their assembly operation as well as the associated noise from the assembly. Desiccating composite enclosures and seal materials are simultaneously targeted for improving performance of optical components. Volatile organic compound (VOC) emissions from fuel tanks and lines into atmosphere can also be reduced by using VOC absorbing composite materials as reactive barriers to permeation in fuel tank and supply line design. The performance of sorbent-loaded composites is evaluated from the standpoint of two distinct design targets: removal the target vapor from the contained environment and reducing the rate of ingress from the external environment. The concepts of the layer reactivity the adsorptive capacity and the sorption rate are applied to the homogeneously reactive media and the sorbent-loaded polymer composites. The corresponding differences in performance and design requirements are discussed.
This method of vehicle assembly consists of fabricating a vehicle body with floor and door openings roof pillars defining window openings and a roof supported on the pillars with a defined roof opening. The vehicle body is placed on a chassis. Then interior components are inserted through the opening in the roof and secured to the interior of the vehicle body. A roof module panel is placed on the roof to close the opening after the interior components have been inserted. One of the advantages of this method is that workers can assemble the vehicle without the problems of a cramped and hectic work area. Still another advantage is the reduction in cost of labor and workers compensation due to less labor required in the assembly process. Also all interior and exterior components including but not limited to roof racks skid racks sunroof radios DVD players antenna farms decorative lining etc. can be preassembled into the roof module panel with ease. A completely assembled roof panel can be attached to the vehicle body at the last sequential step when all interior components have been installed on the assembly line. Therefore this method of assembling a vehicle and integrated roof module is new efficient and provides an economical way to assemble vehicles that will help reduce assembly time and not be labor intensive.
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