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A successful prototype knowledge-based system has been developed for polymer composites design. This reporting focuses on the expansion and extension of the prototype. The expansion effort widens the scope of the system to include additional matrix and fiber constituents. Initially, the system designs a single composite material meeting the desired performance characteristics. The first extension effort involves modifications to produce a family of designs, presenting a more effective aide to composite designers. Another extension effort involves the selection of manufacturing methods for the composites produced. These improvements give rise to a design system that is approaching industrial level effectiveness.

Although the RTM process is being widely used, there is a critical lack of understanding related to microstructure-proeess-property interactions. Due to this, futf advantage is not being taken of the opportunities offered by RTM, including local tailoring of reinforcement, parts integration, fabrication with tight tolerances, and designing materials for damage containment. The choice of fabric architecture and fiber volume fraction, for example, have a significant effect on the design of the tool with regard to the location and design of both the gating and venting arrangements, among other factors. Preforms have to be designed simultaneously from both the structural and resin infusion aspects. In this paper, we investigate the effect of preform architecture on flow in resin transfer molding. Previous investigations aimed at permeability determination (Adams et al., 1986) have focused on only one type of fabric architecture and used ideal fluids.

The compression characteristics of thermoformable glass mat reinforcements with polyester binders have been studied as functions of temperature and platen closure rate. The mats were found to be more compliant and more compressible with increasing platen closure rate. At low closure rates, increasing the platen temperature has less of an effect on compressibility than at higher rates. Increasing the temperature also causes the mat to become more compliant. The compaction curves for the mats are described well with a logarithmic relation. This information is of interest to composite consolidation processes.

The toughness or impact resistance of thermoset resin laminates can be enhanced by the addition of low cost thermoplastic polyester fibers. A continuous thermoplastic polyester fiber mat manufactured by Hoechst Celanese Corp., trade name Trevira, has been successfully utilized to enhance the toughness and reduce the density of marine laminates. This thermoplastic polyester fiber mat has been used in both E-glass and carbon fiber laminates, with and without cores. The laminates are primarily hand lay-up in open molds, some with vacuum bagging. The polyester mat has elastic modulus and strength values similar to the resin, however the strain to failure of the fibers is about 30 percent. These tough fibers inhibit crack formation and growth in the laminate, and allow higher inter-ply shear strains when interleaved between plies of high modulus reinforcing fibers.

Typical sand-casting techniques have been shown to be inappropriate in pouring particulate reinforced aluminum metal matrix composite (Al-MMC) castings. New gating/risering configurations were necessary to produce castings of acceptable soundness. Several automotive components, including brake rotors, cylinder liners and camshaft thrust plates, were prepared using special techniques. Initial durability test results of several Al-MMC prototype components are presented.

The effect of compaction and fiber volume fraction on the transverse permeability of a fluid flowing through stacked layers of fiber mats has been experimentally studied. A Unifilo-101 random mat of continuous glass strands, held together with a binder soluble in styrene was used. The stacked layers were compacted using a Wabash instrumented press. Changing the maximum load, resulted in different fiber volume fractions. Mixtures of glycerol and water with viscosities between 85 and 100 mPa-s were used. This fluid is passed in a rectangular cell, through the fibers arranged transverse to the direction of flow. The pressure drop across the mat and the flow rate were monitored. The study was carried out at different flow rates of the fluid and was repeated for other fiber volume fractions. A power-law relation was observed between the permeability and the fiber volume fraction.

The injection molding of thermoset composites gives certain advantages over compression molding techniques such as higher productivity rates, better part quality, and better adaptability to automation. The disadvantages of the injection molding process for thermoset composites include lower mechanical properties and fiber orientation effects. Recent developments in process and materials have significantly improved the mechanical properties and surface smoothness of injection molded thermoset composites. Even with these material improvements several molding problems occur in the injection molding production process. Two important production problems are cracks and porosity at the knitline areas and cracks during the handling of the hot part immediately after molding and other elevated temperature processes. This paper will illustrate the development of a unique mold configuration to simulate knitlines in a ribbed rectangular injection mold.

Solubility and viscosity predictions for solutions of a thermoplastic polymer with several supercritical gases indicate that significant viscosity reduction and solubility are achieved when the processing conditions are closely matched with the critical properties of the dissolved gas. For the solubility predictions, PVT behavior was modeled by the lattice theory based Sanchez - Lacombe equation-of-state (EOS). Viscosity was estimated by employing the Kelley - Bueche free volume theory coupled with the volumetric calculations of the EOS. Unlike conventional solvents, supercritical solvents add significant free volume to supercritical gas / polymer mixtures; this added free volume provides remarkable viscosity reduction. Viscosity reductions of up to two orders of magnitude are predicted for a supercritical gas / polymer system, compared to the undiluted polymer when the critical temperature for the supercritical gas is matched to the polymer processing temperature.

Proprietary process technology was first introduced commercially in 1975 for producing Al-Pb metal/metal composite bearing material by means of powder roiling. Evolutionary refinements and improvements in powder atomizing, powder rolling and subsequent laminating and heat treatment processes have since led to enhanced product performance levels and successful use of this material for increasingly demanding engine and powertrain bearing applications. Several competing technologies have since come into commercial use for producing Al-Pb bearing materials with similar compositions. A number of theoretical and practical engineering studies have also been published, which contribute to a better understanding of the characteristics and capabilities of these materials.

This paper presents a study of the effects of a resin soluble thermoplastic preform binder on the Resin Transfer Molding (RTM) process. The focus of the study is the rate of dissolution of the binder in the resin and the associated viscosity changes in the resin. Tests on the rate of binder dissolution from continuous strand glass mats show that after one minute of exposure to styrene, roughly half of the medium solubility binder from Unifilo 750 will dissolve and all of the high solubility binder from Unifilo 101 will dissolve. As the concentration of binder in the resin increases from 0 to 5 wt. percent, the viscosity of a vinyl ester resin increases from 125 cps to 280 cps. The viscosity of the resin has also been monitored in continuous flow experiments through the mats placed in a rectangular plague mold, at different flowrates. In these runs, the viscosity varied from 245 mPa-s to 145 mPa-s when the fill time was 2.2 minutes.

Duralcan reinforced aluminum composites (hereafter referred to as aluminum composites) include foundry composites which typically consist of 20 volume % silicon carbide in an aluminum-silicon casting alloy matrix. Addition of the silicon carbide leads to a combination of properties that are not available in unreinforced aluminum alloys, e.g. high specific stiffness, and improved friction and wear behavior. These properties combined with their low density make these materials attractive as substitutes for cast iron in brake rotors in order to reduce the unsprung weight of an automobile. The objective of this study was to determine the friction and wear performance of aluminum composites relevant to automotive braking systems. Testing consisted of sliding the aluminum composites against brake pads materials (friction materials). The aluminum composites studied encompassed changes in the base alloy, the volume fraction of reinforcement, and the reinforcement particle size.

Squeeze casting is, nowadays, the more widely accepted industrial process to produce Aluminum Alloy heavy duty pistons reinforced with short ceramic fibers (FRM). However, rapidly solidified aluminum alloys (RSA) have not yet received much attention as an alternative material for local piston reinforcement, although they have far more strength than the fiber preforms, the starting raw material to produce FRM. The aim of this paper is to show the production routes to manufacture bowl rim reinforced pistons with FRM and RSA, followed by the analysis of some criteria affecting the mechanical properties of FRM (related to the fiber geometry and their chemical reaction with the metal matrix) and of RSA (powder metallurgy versus spray deposition). The resulting macro-interface is also considered as a discontinuity of properties. Finally, some engine test results obtained with pistons reinforced with FRM and RSA are compared with the results obtained on baseline Aluminum Alloy pistons.

A newly developed process allows the near-net shape fabrication of alumina/aluminum composite bodies via the immersion of a sacrificial oxide preform into a molten aluminum alloy bath. The resulting composite possesses an attractive range of properties for application in several automotive components. These properties include: high strength and stiffness, appreciable thermal and electrical conductivity, high strength at elevated temperatures, coefficient of thermal expansion of 10 X 10-6 C-1 and relative ease of machinability. Low cost fabrication renders this material/process ideal for components such as brake rotors and calipers, cylinder bore liners, piston components.

The tensile and fatigue strengths of squeeze cast F332 aluminum alloy and its composites reinforced with 15 volume percent of discontinuous Fiberfrax® fiber after T5 heat treatment were determined at 400°C. Rotating beam fatigue testing was performed to determine the endurance strength of these composites for 50% probability of failure at 10 million cycles. Substantial improvements in tensile and fatigue strengths were observed for the reinforced material compared to the matrix alloy. Long term 400°C thermal aging study indicates that there is no significant difference in fatigue strength between 100 hour and 1,000 hour aged samples.

The recycling and reclamation of metal-matrix composites (MMC's) are critical aspects of the commercialization process. By recycling, we mean the economic processing of MMC scrap for reuse as composite. Reclamation refers to the separation and recovery of the individual components of the composite, i.e., the various aluminum alloys and ceramic particles. Three forms of MMC wrought alloy scrap have been considered; i.e., D. C. (direct chill) cast log ends, extrusion butts, and cut extrusion scrap. Recycling each of these forms of scrap back into D. C. cast extrusion billet has been demonstrated. This has been accomplished by recycling the scrap back through the basic mixing process. Various ratios of scrap to virgin composite have been explored and optimum blends are being studied. Similarly, for MMC foundry alloy (high silicon) gates and risers produced in shape-casting, fluxing and degassing techniques have been developed so these may be recycled back into useful castings.

A family of metal matrix composites comprised of 7000 series alloys reinforced with aluminum oxide particulate is under development. The matrices include the high strength 7050, 7075 and 7178 alloys as well as 7005. The reinforcement level in the composites varies between 10 and 20 volume percent (14 and 27 weight percent). The particulate is carefully graded aluminum oxide powder ranging in size from 10 to 21 microns. The powders were introduced into the aluminum matrix using ingot metallurgy processing and then DC cast into 178 mm diameter billet. The billet was extruded into bars, heat treated and the mechanical properties evaluated. Elastic modulii in all composites increased with the volume fraction of reinforcement. Uniaxial yield and tensile strengths in excess of 590 MPa and 660 MPa respectively were measured in the 7075 composites. Fatigue strengths of 7005 composites are shown as a function of volume fraction and loading conditions.

The effects of casting conditions and hot deformation processing on the mechanical properties of aluminum and magnesium cast composites were determined. A356 Al-20 vol.% SiCp composite ingot from Dural Composite Corporation was either squeeze cast under 140 MPa pressure or sand cast into a cylindrical shape. Both castings were subsequently hot worked via hot swaging to reductions of 33% to 95%. The AZ91 Mg-20 vol.% SiCp composites were prepared at Case Western Reserve University followed by either permanent mold and sand casting techniques to produce keel bars or squeeze casting at 140 MPa pressure. The squeeze cast Mg-SiCp cylinders were additionally hot extruded at 12:1 reduction ratio. Tensile strengths of A356 composite in the T6 condition improved from 235 to 280 MPa with squeeze casting: the tensile strength further increased to 339 MPa with hot deformation processing.

An eleven litre four stroke medium speed marine diesel engine has been studied with different wastegate turbocharging systems to improve low speed/part load engine performance. A previous Glasgow College model was adapted to simulate the engine operation under steady conditions. A variation to the Single Zone Fuel Model developed by Watson, Pilley and Marzouk was proposed and a Schwitzer-type wastegate turbocharger model was developed. A series of exhaust wastegate turbochargers have been simulated and tested to identify matching of the various turbomachinery configurations and the effects of these on engine performance. Both simulation and experimental results show that the wastegate bypass system can be modified to advantage by proper selection of the wastegate discharge flow mixing point along the engine exhaust system. The best low speed engine performance was obtained with the wastegate discharge flow exhausting directly to the atmosphere.

This paper refers to a numerical computation for vibration displacements and stresses of a crankshaft with a shear type rubber torsional damper by the three dimensional transfer matrix method. The accuracy of this computation method is confirmed by comparing computed results with measured ones. Especially, in this work, the numerical computation method is proposed to compute the vibration displacements and stresses by means of replacing the rubber part of rubber torsional damper with a spring-dashpot model. Then dynamic characteristics are estimated by the complex torsional stiffness derived from a three-element Maxwell model. As a result the torsional vibration stress and bending vibration stress and vibration displacements (angular and lateral displacements) can be computed with an adequate accuracy. This computation method is applicable to predicting the conditions of vibration displacements and stresses, and will contribute to optimum design of the crankshaft.

This paper presents some of our various test data, newly developed testing method and valuable field data about reliability of Variable Geometry Turbine (VGT) turbocharger. Influential parameters are reviewed item by item. Establishing durability of VGT nozzle and link system is essential for developing VGT turbocharger. However that is not enough to achieve reliability target of VGT turbocharger system only since operating range and conditions of VGT turbocharger is different from conventional system. It was also necessary to optimize other components such as thrust bearing, sealing mechanism and compressor wheel etc. to severer conditions than conventional system.